C8051F124-GQR [SILICON]
Microcontroller, 8-Bit, FLASH, 50MHz, CMOS, PQFP100, ROHS COMPLIANT, TQFP-100;
| 型号： | C8051F124-GQR |
| 厂家： | 
SILICON |
| 描述： | Microcontroller, 8-Bit, FLASH, 50MHz, CMOS, PQFP100, ROHS COMPLIANT, TQFP-100 微控制器和处理器 |
| 文件： | 总350页 (文件大小：1560K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Mixed Signal ISP Flash MCU Family
Analog Peripherals
High Speed 8051 µC Core
-
10 or 12-bit SAR ADC
-
Pipelined instruction architecture; executes 70% of
instruction set in 1 or 2 system clocks
•
•
•
± 1 LSB INL
Programmable throughput up to 100 ksps
Up to 8 external inputs; programmable as single-
ended or differential
-
-
100 MIPS or 50 MIPS throughput with on-chip PLL
2-cycle 16 x 16 MAC engine (C8051F120/1/2/3 and
C8051F130/1/2/3 only)
•
•
•
Programmable amplifier gain: 16, 8, 4, 2, 1, 0.5
Data-dependent windowed interrupt generator
Built-in temperature sensor
Memory
-
-
8-bit SAR ADC (‘F12x Only)
-
8448 bytes internal data RAM (8 k + 256)
•
•
•
Programmable throughput up to 500 ksps
8 external inputs (single-ended or differential)
Programmable amplifier gain: 4, 2, 1, 0.5
-
128 or 64 kB Banked Flash; in-system programma-
ble in 1024-byte sectors
Two 12-bit DACs (‘F12x Only)
-
External 64 kB data memory interface (programma-
ble multiplexed or non-multiplexed modes)
•
Can synchronize outputs to timers for jitter-free wave-
form generation
Digital Peripherals
-
-
-
Two Analog Comparators
Voltage Reference
-
-
-
8 byte-wide port I/O (100TQFP); 5 V tolerant
4 Byte-wide port I/O (64TQFP); 5 V tolerant
Hardware SMBus™ (I2C™ Compatible), SPI™, and
two UART serial ports available concurrently
Programmable 16-bit counter/timer array with
6 capture/compare modules
V
Monitor/Brown-Out Detector
DD
On-Chip JTAG Debug & Boundary Scan
-
-
-
On-chip debug circuitry facilitates full-speed, non-
intrusive in-circuit/in-system debugging
Provides breakpoints, single-stepping, watchpoints,
stack monitor; inspect/modify memory and registers
Superior performance to emulation systems using
ICE-chips, target pods, and sockets
-
-
-
5 general purpose 16-bit counter/timers
Dedicated watchdog timer; bi-directional reset pin
Clock Sources
-
-
IEEE1149.1 compliant boundary scan
Complete development kit
-
-
-
Internal precision oscillator: 24.5 MHz
Flexible PLL technology
External Oscillator: Crystal, RC, C, or clock
100-Pin TQFP or 64-Pin TQFP Packaging
-
Temperature Range: –40 to +85 °C
Voltage Supples
-
RoHS Available
-
Range: 2.7–3.6 V (50 MIPS) 3.0–3.6 V (100 MIPS)
-
Power saving sleep and shutdown modes
ANALOG PERIPHERALS
DIGITAL I/O
UART0
VREF
Port 0
10/12-bit
100ksps
ADC
UART1
Port 1
SMBus
PGA
Port 2
SPI Bus
PCA
+
-
+
Port 3
TEMP
SENSOR
-
Timer 0
Timer 1
Timer 2
Timer 3
Timer 4
VOLTAGE
COMPARATORS
Port 4
Port 5
Port 6
12-Bit
DAC
8-bit
PGA
500ksps
ADC
12-Bit
DAC
Port 7
C8051F12x Only
64 pin 100 pin
HIGH-SPEED CONTROLLER CORE
8051 CPU
128/64 kB 8448 B
16 x 16 MAC
(50 or 100MIPS) ISP FLASH SRAM ('F120/1/2/3, 'F13x)
20
DEBUG
CIRCUITRY
CLOCK / PLL
CIRCUIT
JTAG
INTERRUPTS
Preliminary Rev. 1.4 12/05
Copyright © 2005 by Silicon Laboratories
C8051F12x C8051F13x
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
NOTES:
2
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table of Contents
1. System Overview.................................................................................................... 19
1.1. CIP-51™ Microcontroller Core.......................................................................... 27
1.1.1. Fully 8051 Compatible.............................................................................. 27
1.1.2. Improved Throughput............................................................................... 27
1.1.3. Additional Features .................................................................................. 28
1.2. On-Chip Memory............................................................................................... 29
1.3. JTAG Debug and Boundary Scan..................................................................... 30
1.4. 16 x 16 MAC (Multiply and Accumulate) Engine............................................... 31
1.5. Programmable Digital I/O and Crossbar........................................................... 32
1.6. Programmable Counter Array........................................................................... 33
1.7. Serial Ports ....................................................................................................... 33
1.8. 12 or 10-Bit Analog to Digital Converter ........................................................... 34
1.9. 8-Bit Analog to Digital Converter....................................................................... 35
1.10.12-bit Digital to Analog Converters................................................................... 36
1.11.Analog Comparators......................................................................................... 37
2. Absolute Maximum Ratings .................................................................................. 38
3. Global DC Electrical Characteristics .................................................................... 39
4. Pinout and Package Definitions............................................................................ 41
5. ADC0 (12-Bit ADC, C8051F120/1/4/5 Only)........................................................... 55
5.1. Analog Multiplexer and PGA............................................................................. 55
5.2. ADC Modes of Operation.................................................................................. 57
5.2.1. Starting a Conversion............................................................................... 57
5.2.2. Tracking Modes........................................................................................ 58
5.2.3. Settling Time Requirements..................................................................... 59
5.3. ADC0 Programmable Window Detector ........................................................... 66
6. ADC0 (10-Bit ADC, C8051F122/3/6/7 and C8051F13x Only)................................ 73
6.1. Analog Multiplexer and PGA............................................................................. 73
6.2. ADC Modes of Operation.................................................................................. 75
6.2.1. Starting a Conversion............................................................................... 75
6.2.2. Tracking Modes........................................................................................ 76
6.2.3. Settling Time Requirements..................................................................... 77
6.3. ADC0 Programmable Window Detector ........................................................... 84
7. ADC2 (8-Bit ADC, C8051F12x Only)...................................................................... 91
7.1. Analog Multiplexer and PGA............................................................................. 91
7.2. ADC2 Modes of Operation................................................................................ 92
7.2.1. Starting a Conversion............................................................................... 92
7.2.2. Tracking Modes........................................................................................ 92
7.2.3. Settling Time Requirements..................................................................... 94
7.3. ADC2 Programmable Window Detector ......................................................... 100
7.3.1. Window Detector In Single-Ended Mode ............................................... 100
7.3.2. Window Detector In Differential Mode.................................................... 101
Rev. 1.4
3
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
8. DACs, 12-Bit Voltage Mode (C8051F12x Only) .................................................. 105
8.1. DAC Output Scheduling.................................................................................. 105
8.1.1. Update Output On-Demand ................................................................... 106
8.1.2. Update Output Based on Timer Overflow .............................................. 106
8.2. DAC Output Scaling/Justification.................................................................... 106
9. Voltage Reference ................................................................................................ 113
9.1. Reference Configuration on the C8051F120/2/4/6 ......................................... 113
9.2. Reference Configuration on the C8051F121/3/5/7 ......................................... 115
9.3. Reference Configuration on the C8051F130/1/2/3 ......................................... 117
10.Comparators ......................................................................................................... 119
11.CIP-51 Microcontroller ......................................................................................... 127
11.1.Instruction Set................................................................................................. 129
11.1.1.Instruction and CPU Timing ................................................................... 129
11.1.2.MOVX Instruction and Program Memory ............................................... 129
11.2.Memory Organization ..................................................................................... 133
11.2.1.Program Memory ................................................................................... 133
11.2.2.Data Memory.......................................................................................... 135
11.2.3.General Purpose Registers.................................................................... 135
11.2.4.Bit Addressable Locations...................................................................... 135
11.2.5.Stack ..................................................................................................... 135
11.2.6.Special Function Registers .................................................................... 136
11.2.7.Register Descriptions............................................................................. 151
11.3.Interrupt Handler............................................................................................. 154
11.3.1.MCU Interrupt Sources and Vectors ...................................................... 154
11.3.2.External Interrupts.................................................................................. 155
11.3.3.Interrupt Priorities................................................................................... 156
11.3.4.Interrupt Latency .................................................................................... 156
11.3.5.Interrupt Register Descriptions............................................................... 157
11.4.Power Management Modes............................................................................ 163
11.4.1.Idle Mode ............................................................................................... 163
11.4.2.Stop Mode.............................................................................................. 164
12.Multiply And Accumulate (MAC0)....................................................................... 165
12.1.Special Function Registers............................................................................. 165
12.2.Integer and Fractional Math............................................................................ 166
12.3.Operating in Multiply and Accumulate Mode.................................................. 167
12.4.Operating in Multiply Only Mode .................................................................... 167
12.5.Accumulator Shift Operations......................................................................... 167
12.6.Rounding and Saturation................................................................................ 168
12.7.Usage Examples ............................................................................................ 168
12.7.1.Multiply and Accumulate Example ......................................................... 168
12.7.2.Multiply Only Example............................................................................ 169
12.7.3.MAC0 Accumulator Shift Example......................................................... 169
4
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
13.Reset Sources....................................................................................................... 177
13.1.Power-on Reset.............................................................................................. 178
13.2.Power-fail Reset ............................................................................................. 178
13.3.External Reset................................................................................................ 179
13.4.Missing Clock Detector Reset ........................................................................ 179
13.5.Comparator0 Reset ........................................................................................ 179
13.6.External CNVSTR0 Pin Reset........................................................................ 179
13.7.Watchdog Timer Reset................................................................................... 179
13.7.1.Enable/Reset WDT ................................................................................ 180
13.7.2.Disable WDT.......................................................................................... 180
13.7.3.Disable WDT Lockout ............................................................................ 180
13.7.4.Setting WDT Interval.............................................................................. 180
14.Oscillators............................................................................................................. 185
14.1.Internal Calibrated Oscillator .......................................................................... 185
14.2.External Oscillator Drive Circuit...................................................................... 187
14.3.System Clock Selection.................................................................................. 187
14.4.External Crystal Example ............................................................................... 190
14.5.External RC Example ..................................................................................... 190
14.6.External Capacitor Example........................................................................... 190
14.7.Phase-Locked Loop (PLL).............................................................................. 191
14.7.1.PLL Input Clock and Pre-divider ............................................................ 191
14.7.2.PLL Multiplication and Output Clock ...................................................... 191
14.7.3.Powering on and Initializing the PLL...................................................... 192
15.Flash Memory ....................................................................................................... 199
15.1.Programming the Flash Memory .................................................................... 199
15.1.1.Non-volatile Data Storage...................................................................... 200
15.1.2.Erasing Flash Pages From Software ..................................................... 201
15.1.3.Writing Flash Memory From Software.................................................... 202
15.2.Security Options ............................................................................................. 203
15.2.1.Summary of Flash Security Options....................................................... 207
16.Branch Target Cache ........................................................................................... 211
16.1.Cache and Prefetch Operation....................................................................... 211
16.2.Cache and Prefetch Optimization................................................................... 212
17.External Data Memory Interface and On-Chip XRAM........................................ 219
17.1.Accessing XRAM............................................................................................ 219
17.1.1.16-Bit MOVX Example ........................................................................... 219
17.1.2.8-Bit MOVX Example ............................................................................. 219
17.2.Configuring the External Memory Interface.................................................... 219
17.3.Port Selection and Configuration.................................................................... 220
17.4.Multiplexed and Non-multiplexed Selection.................................................... 222
17.4.1.Multiplexed Configuration....................................................................... 222
17.4.2.Non-multiplexed Configuration............................................................... 223
17.5.Memory Mode Selection................................................................................. 224
17.5.1.Internal XRAM Only ............................................................................... 224
17.5.2.Split Mode without Bank Select.............................................................. 224
Rev. 1.4
5
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
17.5.3.Split Mode with Bank Select................................................................... 225
17.5.4.External Only.......................................................................................... 225
17.6.EMIF Timing ................................................................................................... 225
17.6.1.Non-multiplexed Mode ........................................................................... 227
17.6.2.Multiplexed Mode................................................................................... 230
18.Port Input/Output.................................................................................................. 235
18.1.Ports 0 through 3 and the Priority Crossbar Decoder..................................... 238
18.1.1.Crossbar Pin Assignment and Allocation............................................... 238
18.1.2.Configuring the Output Modes of the Port Pins...................................... 239
18.1.3.Configuring Port Pins as Digital Inputs................................................... 240
18.1.4.Weak Pullups ......................................................................................... 240
18.1.5.Configuring Port 1 Pins as Analog Inputs .............................................. 240
18.1.6.External Memory Interface Pin Assignments ......................................... 241
18.1.7.Crossbar Pin Assignment Example........................................................ 243
18.2.Ports 4 through 7 (100-pin TQFP devices only) ............................................. 252
18.2.1.Configuring Ports which are not Pinned Out.......................................... 252
18.2.2.Configuring the Output Modes of the Port Pins...................................... 252
18.2.3.Configuring Port Pins as Digital Inputs................................................... 253
18.2.4.Weak Pullups ......................................................................................... 253
18.2.5.External Memory Interface..................................................................... 253
19.System Management Bus / I2C Bus (SMBus0).................................................. 259
19.1.Supporting Documents................................................................................... 260
19.2.SMBus Protocol.............................................................................................. 260
19.2.1.Arbitration............................................................................................... 261
19.2.2.Clock Low Extension.............................................................................. 261
19.2.3.SCL Low Timeout................................................................................... 261
19.2.4.SCL High (SMBus Free) Timeout .......................................................... 261
19.3.SMBus Transfer Modes.................................................................................. 262
19.3.1.Master Transmitter Mode....................................................................... 262
19.3.2.Master Receiver Mode........................................................................... 262
19.3.3.Slave Transmitter Mode......................................................................... 263
19.3.4.Slave Receiver Mode............................................................................. 263
19.4.SMBus Special Function Registers ................................................................ 264
19.4.1.Control Register ..................................................................................... 264
19.4.2.Clock Rate Register ............................................................................... 267
19.4.3.Data Register ......................................................................................... 268
19.4.4.Address Register.................................................................................... 268
19.4.5.Status Register....................................................................................... 269
20.Enhanced Serial Peripheral Interface (SPI0)...................................................... 273
20.1.Signal Descriptions......................................................................................... 274
20.1.1.Master Out, Slave In (MOSI).................................................................. 274
20.1.2.Master In, Slave Out (MISO).................................................................. 274
20.1.3.Serial Clock (SCK) ................................................................................. 274
20.1.4.Slave Select (NSS) ................................................................................ 274
6
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
20.2.SPI0 Master Mode Operation......................................................................... 275
20.3.SPI0 Slave Mode Operation........................................................................... 277
20.4.SPI0 Interrupt Sources ................................................................................... 277
20.5.Serial Clock Timing......................................................................................... 278
20.6.SPI Special Function Registers...................................................................... 280
21.UART0.................................................................................................................... 287
21.1.UART0 Operational Modes ............................................................................ 288
21.1.1.Mode 0: Synchronous Mode .................................................................. 288
21.1.2.Mode 1: 8-Bit UART, Variable Baud Rate.............................................. 289
21.1.3.Mode 2: 9-Bit UART, Fixed Baud Rate .................................................. 291
21.1.4.Mode 3: 9-Bit UART, Variable Baud Rate.............................................. 292
21.2.Multiprocessor Communications .................................................................... 293
21.2.1.Configuration of a Masked Address....................................................... 293
21.2.2.Broadcast Addressing............................................................................ 293
21.3.Frame and Transmission Error Detection....................................................... 294
22.UART1.................................................................................................................... 299
22.1.Enhanced Baud Rate Generation................................................................... 300
22.2.Operational Modes ......................................................................................... 301
22.2.1.8-Bit UART............................................................................................. 301
22.2.2.9-Bit UART............................................................................................. 302
22.3.Multiprocessor Communications .................................................................... 303
23.Timers.................................................................................................................... 309
23.1.Timer 0 and Timer 1 ....................................................................................... 309
23.1.1.Mode 0: 13-bit Counter/Timer ................................................................ 309
23.1.2.Mode 1: 16-bit Counter/Timer ................................................................ 311
23.1.3.Mode 2: 8-bit Counter/Timer with Auto-Reload...................................... 311
23.1.4.Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)................................. 312
23.2.Timer 2, Timer 3, and Timer 4........................................................................ 317
23.2.1.Configuring Timer 2, 3, and 4 to Count Down........................................ 317
23.2.2.Capture Mode ........................................................................................ 318
23.2.3.Auto-Reload Mode ................................................................................. 319
23.2.4.Toggle Output Mode (Timer 2 and Timer 4 Only) .................................. 320
24.Programmable Counter Array ............................................................................. 325
24.1.PCA Counter/Timer ........................................................................................ 326
24.2.Capture/Compare Modules ............................................................................ 328
24.2.1.Edge-triggered Capture Mode................................................................ 329
24.2.2.Software Timer (Compare) Mode........................................................... 330
24.2.3.High Speed Output Mode....................................................................... 331
24.2.4.Frequency Output Mode ........................................................................ 332
24.2.5.8-Bit Pulse Width Modulator Mode......................................................... 333
24.2.6.16-Bit Pulse Width Modulator Mode....................................................... 334
24.3.Register Descriptions for PCA0...................................................................... 335
Rev. 1.4
7
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
25.JTAG (IEEE 1149.1) .............................................................................................. 341
25.1.Boundary Scan............................................................................................... 342
25.1.1.EXTEST Instruction................................................................................ 343
25.1.2.SAMPLE Instruction............................................................................... 343
25.1.3.BYPASS Instruction ............................................................................... 343
25.1.4.IDCODE Instruction................................................................................ 343
25.2.Flash Programming Commands..................................................................... 344
25.3.Debug Support ............................................................................................... 347
Document Change List............................................................................................. 349
Contact Information.................................................................................................. 350
8
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
List of Figures
1. System Overview
Figure 1.1. C8051F120/124 Block Diagram............................................................. 21
Figure 1.2. C8051F121/125 Block Diagram............................................................. 22
Figure 1.3. C8051F122/126 Block Diagram............................................................. 23
Figure 1.4. C8051F123/127 Block Diagram............................................................. 24
Figure 1.5. C8051F130/132 Block Diagram............................................................. 25
Figure 1.6. C8051F131/133 Block Diagram............................................................. 26
Figure 1.7. On-Board Clock and Reset .................................................................... 28
Figure 1.8. On-Chip Memory Map............................................................................ 29
Figure 1.9. Development/In-System Debug Diagram............................................... 30
Figure 1.10. MAC0 Block Diagram........................................................................... 31
Figure 1.11. Digital Crossbar Diagram ..................................................................... 32
Figure 1.12. PCA Block Diagram.............................................................................. 33
Figure 1.13. 12-Bit ADC Block Diagram................................................................... 34
Figure 1.14. 8-Bit ADC Diagram............................................................................... 35
Figure 1.15. DAC System Block Diagram ................................................................ 36
Figure 1.16. Comparator Block Diagram.................................................................. 37
2. Absolute Maximum Ratings
3. Global DC Electrical Characteristics
4. Pinout and Package Definitions
Figure 4.1. C8051F120/2/4/6 Pinout Diagram (TQFP-100) ..................................... 49
Figure 4.2. C8051F130/2 Pinout Diagram (TQFP-100) ........................................... 50
Figure 4.3. TQFP-100 Package Drawing ................................................................. 51
Figure 4.4. C8051F121/3/5/7 Pinout Diagram (TQFP-64) ....................................... 52
Figure 4.5. C8051F131/3 Pinout Diagram (TQFP-64) ............................................. 53
Figure 4.6. TQFP-64 Package Drawing ................................................................... 54
5. ADC0 (12-Bit ADC, C8051F120/1/4/5 Only)
Figure 5.1. 12-Bit ADC0 Functional Block Diagram ................................................. 55
Figure 5.2. Typical Temperature Sensor Transfer Function..................................... 56
Figure 5.3. ADC0 Track and Conversion Example Timing....................................... 58
Figure 5.4. ADC0 Equivalent Input Circuits.............................................................. 59
Figure 5.5. ADC0 Data Word Example .................................................................... 65
Figure 5.6. 12-Bit ADC0 Window Interrupt Example:
Right Justified Single-Ended Data......................................................... 68
Figure 5.7. 12-Bit ADC0 Window Interrupt Example:
Right Justified Differential Data ............................................................. 69
Figure 5.8. 12-Bit ADC0 Window Interrupt Example:
Left Justified Single-Ended Data ........................................................... 70
Figure 5.9. 12-Bit ADC0 Window Interrupt Example:
Left Justified Differential Data................................................................ 71
Rev. 1.4
9
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
6. ADC0 (10-Bit ADC, C8051F122/3/6/7 and C8051F13x Only)
Figure 6.1. 10-Bit ADC0 Functional Block Diagram ................................................. 73
Figure 6.2. Typical Temperature Sensor Transfer Function..................................... 74
Figure 6.3. ADC0 Track and Conversion Example Timing....................................... 76
Figure 6.4. ADC0 Equivalent Input Circuits.............................................................. 77
Figure 6.5. ADC0 Data Word Example .................................................................... 83
Figure 6.6. 10-Bit ADC0 Window Interrupt Example:
Right Justified Single-Ended Data......................................................... 86
Figure 6.7. 10-Bit ADC0 Window Interrupt Example:
Right Justified Differential Data ............................................................. 87
Figure 6.8. 10-Bit ADC0 Window Interrupt Example:
Left Justified Single-Ended Data ........................................................... 88
Figure 6.9. 10-Bit ADC0 Window Interrupt Example:
Left Justified Differential Data................................................................ 89
7. ADC2 (8-Bit ADC, C8051F12x Only)
Figure 7.1. ADC2 Functional Block Diagram............................................................ 91
Figure 7.2. ADC2 Track and Conversion Example Timing....................................... 93
Figure 7.3. ADC2 Equivalent Input Circuit................................................................ 94
Figure 7.4. ADC2 Data Word Example .................................................................... 99
Figure 7.5. ADC2 Window Compare Examples, Single-Ended Mode.................... 100
Figure 7.6. ADC2 Window Compare Examples, Differential Mode........................ 101
8. DACs, 12-Bit Voltage Mode (C8051F12x Only)
Figure 8.1. DAC Functional Block Diagram............................................................ 105
9. Voltage Reference
Figure 9.1. Voltage Reference Functional Block Diagram (C8051F120/2/4/6) ...... 114
Figure 9.2. Voltage Reference Functional Block Diagram (C8051F121/3/5/7) ...... 115
Figure 9.3. Voltage Reference Functional Block Diagram (C8051F130/1/2/3) ...... 117
10.Comparators
Figure 10.1. Comparator Functional Block Diagram .............................................. 119
Figure 10.2. Comparator Hysteresis Plot ............................................................... 121
11.CIP-51 Microcontroller
Figure 11.1. CIP-51 Block Diagram....................................................................... 128
Figure 11.2. Memory Map ...................................................................................... 133
Figure 11.3. Address Memory Map for Instruction Fetches (128 kB Flash Only)... 134
Figure 11.4. SFR Page Stack................................................................................. 137
Figure 11.5. SFR Page Stack While Using SFR Page 0x0F To Access Port 5...... 138
Figure 11.6. SFR Page Stack After ADC2 Window Comparator Interrupt Occurs. 139
Figure 11.7. SFR Page Stack Upon PCA Interrupt Occurring During an ADC2 ISR140
Figure 11.8. SFR Page Stack Upon Return From PCA Interrupt ........................... 140
Figure 11.9. SFR Page Stack Upon Return From ADC2 Window Interrupt ........... 141
12.Multiply And Accumulate (MAC0)
Figure 12.1. MAC0 Block Diagram......................................................................... 165
Figure 12.2. Integer Mode Data Representation .................................................... 166
Figure 12.3. Fractional Mode Data Representation................................................ 166
Figure 12.4. MAC0 Pipeline.................................................................................... 167
10
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
13.Reset Sources
Figure 13.1. Reset Sources.................................................................................... 177
Figure 13.2. Reset Timing ...................................................................................... 178
14.Oscillators
Figure 14.1. Oscillator Diagram.............................................................................. 185
Figure 14.2. PLL Block Diagram............................................................................. 191
15.Flash Memory
Figure 15.1. Flash Memory Map for MOVC Read and MOVX Write Operations ... 201
Figure 15.2. 128 kB Flash Memory Map and Security Bytes ................................. 204
Figure 15.3. 64 kB Flash Memory Map and Security Bytes ................................... 205
16.Branch Target Cache
Figure 16.1. Branch Target Cache Data Flow........................................................ 211
Figure 16.2. Branch Target Cache Organiztion...................................................... 212
Figure 16.3. Cache Lock Operation........................................................................ 214
17.External Data Memory Interface and On-Chip XRAM
Figure 17.1. Multiplexed Configuration Example.................................................... 222
Figure 17.2. Non-multiplexed Configuration Example............................................ 223
Figure 17.3. EMIF Operating Modes ...................................................................... 224
Figure 17.4. Non-multiplexed 16-bit MOVX Timing................................................ 227
Figure 17.5. Non-multiplexed 8-bit MOVX without Bank Select Timing ................. 228
Figure 17.6. Non-multiplexed 8-bit MOVX with Bank Select Timing ...................... 229
Figure 17.7. Multiplexed 16-bit MOVX Timing........................................................ 230
Figure 17.8. Multiplexed 8-bit MOVX without Bank Select Timing ......................... 231
Figure 17.9. Multiplexed 8-bit MOVX with Bank Select Timing .............................. 232
18.Port Input/Output
Figure 18.1. Port I/O Cell Block Diagram ............................................................... 235
Figure 18.2. Port I/O Functional Block Diagram..................................................... 237
Figure 18.3. Priority Crossbar Decode Table (EMIFLE = 0; P1MDIN = 0xFF)....... 238
Figure 18.4. Priority Crossbar Decode Table
(EMIFLE = 1; EMIF in Multiplexed Mode; P1MDIN = 0xFF)................ 241
Figure 18.5. Priority Crossbar Decode Table
(EMIFLE = 1; EMIF in Non-Multiplexed Mode; P1MDIN = 0xFF)........ 242
Figure 18.6. Crossbar Example.............................................................................. 244
19.System Management Bus / I2C Bus (SMBus0)
Figure 19.1. SMBus0 Block Diagram ..................................................................... 259
Figure 19.2. Typical SMBus Configuration............................................................. 260
Figure 19.3. SMBus Transaction............................................................................ 261
Figure 19.4. Typical Master Transmitter Sequence................................................ 262
Figure 19.5. Typical Master Receiver Sequence.................................................... 262
Figure 19.6. Typical Slave Transmitter Sequence.................................................. 263
Figure 19.7. Typical Slave Receiver Sequence...................................................... 263
20.Enhanced Serial Peripheral Interface (SPI0)
Figure 20.1. SPI Block Diagram ............................................................................. 273
Figure 20.2. Multiple-Master Mode Connection Diagram....................................... 276
Figure 20.3. 3-Wire Single Master and Slave Mode Connection Diagram............. 276
Rev. 1.4
11
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Figure 20.4. 4-Wire Single Master and Slave Mode Connection Diagram............. 276
Figure 20.5. Master Mode Data/Clock Timing........................................................ 278
Figure 20.6. Slave Mode Data/Clock Timing (CKPHA = 0).................................... 279
Figure 20.7. Slave Mode Data/Clock Timing (CKPHA = 1).................................... 279
Figure 20.8. SPI Master Timing (CKPHA = 0)........................................................ 283
Figure 20.9. SPI Master Timing (CKPHA = 1)........................................................ 283
Figure 20.10. SPI Slave Timing (CKPHA = 0)........................................................ 284
Figure 20.11. SPI Slave Timing (CKPHA = 1)........................................................ 284
21.UART0
Figure 21.1. UART0 Block Diagram ....................................................................... 287
Figure 21.2. UART0 Mode 0 Timing Diagram ........................................................ 288
Figure 21.3. UART0 Mode 0 Interconnect.............................................................. 288
Figure 21.4. UART0 Mode 1 Timing Diagram ....................................................... 289
Figure 21.5. UART0 Modes 2 and 3 Timing Diagram ............................................ 291
Figure 21.6. UART0 Modes 1, 2, and 3 Interconnect Diagram .............................. 292
Figure 21.7. UART Multi-Processor Mode Interconnect Diagram .......................... 294
22.UART1
Figure 22.1. UART1 Block Diagram ....................................................................... 299
Figure 22.2. UART1 Baud Rate Logic.................................................................... 300
Figure 22.3. UART Interconnect Diagram .............................................................. 301
Figure 22.4. 8-Bit UART Timing Diagram.............................................................. 301
Figure 22.5. 9-Bit UART Timing Diagram............................................................... 302
Figure 22.6. UART Multi-Processor Mode Interconnect Diagram .......................... 303
23.Timers
Figure 23.1. T0 Mode 0 Block Diagram.................................................................. 310
Figure 23.2. T0 Mode 2 Block Diagram.................................................................. 311
Figure 23.3. T0 Mode 3 Block Diagram.................................................................. 312
Figure 23.4. T2, 3, and 4 Capture Mode Block Diagram........................................ 318
Figure 23.5. Tn Auto-reload (T2,3,4) and Toggle Mode (T2,4) Block Diagram..... 319
24.Programmable Counter Array
Figure 24.1. PCA Block Diagram............................................................................ 325
Figure 24.2. PCA Counter/Timer Block Diagram.................................................... 326
Figure 24.3. PCA Interrupt Block Diagram ............................................................. 328
Figure 24.4. PCA Capture Mode Diagram.............................................................. 329
Figure 24.5. PCA Software Timer Mode Diagram.................................................. 330
Figure 24.6. PCA High Speed Output Mode Diagram............................................ 331
Figure 24.7. PCA Frequency Output Mode ............................................................ 332
Figure 24.8. PCA 8-Bit PWM Mode Diagram ......................................................... 333
Figure 24.9. PCA 16-Bit PWM Mode...................................................................... 334
25.JTAG (IEEE 1149.1)
12
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
List Of Tables
1. System Overview
Table 1.1. Product Selection Guide ......................................................................... 20
2. Absolute Maximum Ratings
Table 2.1. Absolute Maximum Ratings .................................................................... 38
3. Global DC Electrical Characteristics
Table 3.1. Global DC Electrical Characteristics
(C8051F120/1/2/3 and C8051F130/1/2/3) ............................................. 39
Table 3.2. Global DC Electrical Characteristics (C8051F124/5/6/7) ....................... 40
4. Pinout and Package Definitions
Table 4.1. Pin Definitions ......................................................................................... 41
5. ADC0 (12-Bit ADC, C8051F120/1/4/5 Only)
Table 5.1. 12-Bit ADC0 Electrical Characteristics (C8051F120/1/4/5) .................... 72
6. ADC0 (10-Bit ADC, C8051F122/3/6/7 and C8051F13x Only)
Table 6.1. 10-Bit ADC0 Electrical Characteristics
(C8051F122/3/6/7 and C8051F13x) ...................................................... 90
7. ADC2 (8-Bit ADC, C8051F12x Only)
Table 7.1. ADC2 Electrical Characteristics ............................................................ 103
8. DACs, 12-Bit Voltage Mode (C8051F12x Only)
Table 8.1. DAC Electrical Characteristics .............................................................. 111
9. Voltage Reference
Table 9.1. Voltage Reference Electrical Characteristics ....................................... 118
10.Comparators
Table 10.1. Comparator Electrical Characteristics ................................................ 126
11.CIP-51 Microcontroller
Table 11.1. CIP-51 Instruction Set Summary ........................................................ 129
Table 11.2. Special Function Register (SFR) Memory Map .................................. 144
Table 11.3. Special Function Registers ................................................................. 146
Table 11.4. Interrupt Summary .............................................................................. 155
12.Multiply And Accumulate (MAC0)
Table 12.1. MAC0 Rounding (MAC0SAT = 0) ....................................................... 168
13.Reset Sources
Table 13.1. Reset Electrical Characteristics .......................................................... 183
14.Oscillators
Table 14.1. Oscillator Electrical Characteristics .................................................... 185
Table 14.2. PLL Frequency Characteristics .......................................................... 195
Table 14.3. PLL Lock Timing Characteristics ........................................................ 196
15.Flash Memory
Table 15.1. Flash Electrical Characteristics .......................................................... 200
16.Branch Target Cache
17.External Data Memory Interface and On-Chip XRAM
Table 17.1. AC Parameters for External Memory Interface ................................... 233
Rev. 1.4
13
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
18.Port Input/Output
Table 18.1. Port I/O DC Electrical Characteristics ................................................. 236
19.System Management Bus / I2C Bus (SMBus0)
Table 19.1. SMB0STA Status Codes and States .................................................. 270
20.Enhanced Serial Peripheral Interface (SPI0)
Table 20.1. SPI Slave Timing Parameters ............................................................ 285
21.UART0
Table 21.1. UART0 Modes .................................................................................... 288
Table 21.2. Oscillator Frequencies for Standard Baud Rates ............................... 295
22.UART1
Table 22.1. Timer Settings for Standard Baud Rates
Using The Internal 24.5 MHz Oscillator ............................................... 305
Table 22.2. Timer Settings for Standard Baud Rates
Using an External 25.0 MHz Oscillator ................................................ 306
Table 22.3. Timer Settings for Standard Baud Rates
Using an External 22.1184 MHz Oscillator .......................................... 306
Table 22.4. Timer Settings for Standard Baud Rates Using the PLL .................... 307
Table 22.5. Timer Settings for Standard Baud Rates Using the PLL .................... 307
23.Timers
24.Programmable Counter Array
Table 24.1. PCA Timebase Input Options ............................................................. 326
Table 24.2. PCA0CPM Register Settings for PCA Capture/Compare Modules .... 329
25.JTAG (IEEE 1149.1)
Table 25.1. Boundary Data Register Bit Definitions .............................................. 342
14
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
List of Registers
SFR Definition 5.1. AMX0CF: AMUX0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 60
SFR Definition 5.2. AMX0SL: AMUX0 Channel Select . . . . . . . . . . . . . . . . . . . . . . . . 61
SFR Definition 5.3. ADC0CF: ADC0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
SFR Definition 5.4. ADC0CN: ADC0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
SFR Definition 5.5. ADC0H: ADC0 Data Word MSB . . . . . . . . . . . . . . . . . . . . . . . . . . 64
SFR Definition 5.6. ADC0L: ADC0 Data Word LSB . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
SFR Definition 5.7. ADC0GTH: ADC0 Greater-Than Data High Byte . . . . . . . . . . . . . 66
SFR Definition 5.8. ADC0GTL: ADC0 Greater-Than Data Low Byte . . . . . . . . . . . . . . 66
SFR Definition 5.9. ADC0LTH: ADC0 Less-Than Data High Byte . . . . . . . . . . . . . . . . 67
SFR Definition 5.10. ADC0LTL: ADC0 Less-Than Data Low Byte . . . . . . . . . . . . . . . 67
SFR Definition 6.1. AMX0CF: AMUX0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 78
SFR Definition 6.2. AMX0SL: AMUX0 Channel Select . . . . . . . . . . . . . . . . . . . . . . . . . 79
SFR Definition 6.3. ADC0CF: ADC0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
SFR Definition 6.4. ADC0CN: ADC0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
SFR Definition 6.5. ADC0H: ADC0 Data Word MSB . . . . . . . . . . . . . . . . . . . . . . . . . . 82
SFR Definition 6.6. ADC0L: ADC0 Data Word LSB . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
SFR Definition 6.7. ADC0GTH: ADC0 Greater-Than Data High Byte . . . . . . . . . . . . . 84
SFR Definition 6.8. ADC0GTL: ADC0 Greater-Than Data Low Byte . . . . . . . . . . . . . . 84
SFR Definition 6.9. ADC0LTH: ADC0 Less-Than Data High Byte . . . . . . . . . . . . . . . . 85
SFR Definition 6.10. ADC0LTL: ADC0 Less-Than Data Low Byte . . . . . . . . . . . . . . . 85
SFR Definition 7.1. AMX2CF: AMUX2 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 95
SFR Definition 7.2. AMX2SL: AMUX2 Channel Select . . . . . . . . . . . . . . . . . . . . . . . . 96
SFR Definition 7.3. ADC2CF: ADC2 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
SFR Definition 7.4. ADC2CN: ADC2 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
SFR Definition 7.5. ADC2: ADC2 Data Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
SFR Definition 7.6. ADC2GT: ADC2 Greater-Than Data Byte . . . . . . . . . . . . . . . . . . 102
SFR Definition 7.7. ADC2LT: ADC2 Less-Than Data Byte . . . . . . . . . . . . . . . . . . . . 102
SFR Definition 8.1. DAC0H: DAC0 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
SFR Definition 8.2. DAC0L: DAC0 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
SFR Definition 8.3. DAC0CN: DAC0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
SFR Definition 8.4. DAC1H: DAC1 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
SFR Definition 8.5. DAC1L: DAC1 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
SFR Definition 8.6. DAC1CN: DAC1 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
SFR Definition 9.1. REF0CN: Reference Control (C8051F120/2/4/6) . . . . . . . . . . . . 114
SFR Definition 9.2. REF0CN: Reference Control (C8051F121/3/5/7) . . . . . . . . . . . . 116
SFR Definition 9.3. REF0CN: Reference Control (C8051F130/1/2/3) . . . . . . . . . . . . 117
SFR Definition 10.1. CPT0CN: Comparator0 Control . . . . . . . . . . . . . . . . . . . . . . . . . 122
SFR Definition 10.2. CPT0MD: Comparator0 Mode Selection . . . . . . . . . . . . . . . . . 123
SFR Definition 10.3. CPT1CN: Comparator1 Control . . . . . . . . . . . . . . . . . . . . . . . . . 124
SFR Definition 10.4. CPT1MD: Comparator1 Mode Selection . . . . . . . . . . . . . . . . . 125
SFR Definition 11.1. PSBANK: Program Space Bank Select . . . . . . . . . . . . . . . . . . 134
SFR Definition 11.2. SFRPGCN: SFR Page Control . . . . . . . . . . . . . . . . . . . . . . . . . 142
SFR Definition 11.3. SFRPAGE: SFR Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Rev. 1.4
15
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 11.4. SFRNEXT: SFR Next Register . . . . . . . . . . . . . . . . . . . . . . . . . 143
SFR Definition 11.5. SFRLAST: SFR Last Register . . . . . . . . . . . . . . . . . . . . . . . . . 143
SFR Definition 11.6. SP: Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
SFR Definition 11.7. DPL: Data Pointer Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
SFR Definition 11.8. DPH: Data Pointer High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . 151
SFR Definition 11.9. PSW: Program Status Word . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
SFR Definition 11.10. ACC: Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
SFR Definition 11.11. B: B Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
SFR Definition 11.12. IE: Interrupt Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
SFR Definition 11.13. IP: Interrupt Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
SFR Definition 11.14. EIE1: Extended Interrupt Enable 1 . . . . . . . . . . . . . . . . . . . . . 159
SFR Definition 11.15. EIE2: Extended Interrupt Enable 2 . . . . . . . . . . . . . . . . . . . . . 160
SFR Definition 11.16. EIP1: Extended Interrupt Priority 1 . . . . . . . . . . . . . . . . . . . . . 161
SFR Definition 11.17. EIP2: Extended Interrupt Priority 2 . . . . . . . . . . . . . . . . . . . . . 162
SFR Definition 11.18. PCON: Power Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
SFR Definition 12.1. MAC0CF: MAC0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . 170
SFR Definition 12.2. MAC0STA: MAC0 Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
SFR Definition 12.3. MAC0AH: MAC0 A High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . 171
SFR Definition 12.4. MAC0AL: MAC0 A Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . 172
SFR Definition 12.5. MAC0BH: MAC0 B High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . 172
SFR Definition 12.6. MAC0BL: MAC0 B Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
SFR Definition 12.7. MAC0ACC3: MAC0 Accumulator Byte 3 . . . . . . . . . . . . . . . . . . 173
SFR Definition 12.8. MAC0ACC2: MAC0 Accumulator Byte 2 . . . . . . . . . . . . . . . . . 173
SFR Definition 12.9. MAC0ACC1: MAC0 Accumulator Byte 1 . . . . . . . . . . . . . . . . . 173
SFR Definition 12.10. MAC0ACC0: MAC0 Accumulator Byte 0 . . . . . . . . . . . . . . . . . 174
SFR Definition 12.11. MAC0OVR: MAC0 Accumulator Overflow . . . . . . . . . . . . . . . . 174
SFR Definition 12.12. MAC0RNDH: MAC0 Rounding Register High Byte . . . . . . . . . 174
SFR Definition 12.13. MAC0RNDL: MAC0 Rounding Register Low Byte . . . . . . . . . 175
SFR Definition 13.1. WDTCN: Watchdog Timer Control . . . . . . . . . . . . . . . . . . . . . . 181
SFR Definition 13.2. RSTSRC: Reset Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
SFR Definition 14.1. OSCICL: Internal Oscillator Calibration. . . . . . . . . . . . . . . . . . . 186
SFR Definition 14.2. OSCICN: Internal Oscillator Control . . . . . . . . . . . . . . . . . . . . . 186
SFR Definition 14.3. CLKSEL: System Clock Selection . . . . . . . . . . . . . . . . . . . . . . . 188
SFR Definition 14.4. OSCXCN: External Oscillator Control . . . . . . . . . . . . . . . . . . . . 189
SFR Definition 14.5. PLL0CN: PLL Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
SFR Definition 14.6. PLL0DIV: PLL Pre-divider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
SFR Definition 14.7. PLL0MUL: PLL Clock Scaler . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
SFR Definition 14.8. PLL0FLT: PLL Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
SFR Definition 15.1. FLACL: Flash Access Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
SFR Definition 15.2. FLSCL: Flash Memory Control . . . . . . . . . . . . . . . . . . . . . . . . . 208
SFR Definition 15.3. PSCTL: Program Store Read/Write Control . . . . . . . . . . . . . . . 209
SFR Definition 16.1. CCH0CN: Cache Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
SFR Definition 16.2. CCH0TN: Cache Tuning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
SFR Definition 16.3. CCH0LC: Cache Lock Control . . . . . . . . . . . . . . . . . . . . . . . . . 216
SFR Definition 16.4. CCH0MA: Cache Miss Accumulator . . . . . . . . . . . . . . . . . . . . . 217
16
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 16.5. FLSTAT: Flash Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
SFR Definition 17.1. EMI0CN: External Memory Interface Control . . . . . . . . . . . . . . 220
SFR Definition 17.2. EMI0CF: External Memory Configuration . . . . . . . . . . . . . . . . . 221
SFR Definition 17.3. EMI0TC: External Memory Timing Control . . . . . . . . . . . . . . . . 226
SFR Definition 18.1. XBR0: Port I/O Crossbar Register 0 . . . . . . . . . . . . . . . . . . . . . 245
SFR Definition 18.2. XBR1: Port I/O Crossbar Register 1 . . . . . . . . . . . . . . . . . . . . . 246
SFR Definition 18.3. XBR2: Port I/O Crossbar Register 2 . . . . . . . . . . . . . . . . . . . . . 247
SFR Definition 18.4. P0: Port0 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
SFR Definition 18.5. P0MDOUT: Port0 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . . 248
SFR Definition 18.6. P1: Port1 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
SFR Definition 18.7. P1MDIN: Port1 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
SFR Definition 18.8. P1MDOUT: Port1 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . . 250
SFR Definition 18.9. P2: Port2 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
SFR Definition 18.10. P2MDOUT: Port2 Output Mode . . . . . . . . . . . . . . . . . . . . . . . 251
SFR Definition 18.11. P3: Port3 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
SFR Definition 18.12. P3MDOUT: Port3 Output Mode . . . . . . . . . . . . . . . . . . . . . . . 252
SFR Definition 18.13. P4: Port4 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
SFR Definition 18.14. P4MDOUT: Port4 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 254
SFR Definition 18.15. P5: Port5 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
SFR Definition 18.16. P5MDOUT: Port5 Output Mode . . . . . . . . . . . . . . . . . . . . . . . 255
SFR Definition 18.17. P6: Port6 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256
SFR Definition 18.18. P6MDOUT: Port6 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 256
SFR Definition 18.19. P7: Port7 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
SFR Definition 18.20. P7MDOUT: Port7 Output Mode . . . . . . . . . . . . . . . . . . . . . . . 257
SFR Definition 19.1. SMB0CN: SMBus0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
SFR Definition 19.2. SMB0CR: SMBus0 Clock Rate . . . . . . . . . . . . . . . . . . . . . . . . . 267
SFR Definition 19.3. SMB0DAT: SMBus0 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268
SFR Definition 19.4. SMB0ADR: SMBus0 Address . . . . . . . . . . . . . . . . . . . . . . . . . . 269
SFR Definition 19.5. SMB0STA: SMBus0 Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
SFR Definition 20.1. SPI0CFG: SPI0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 280
SFR Definition 20.2. SPI0CN: SPI0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
SFR Definition 20.3. SPI0CKR: SPI0 Clock Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282
SFR Definition 20.4. SPI0DAT: SPI0 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282
SFR Definition 21.1. SCON0: UART0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296
SFR Definition 21.2. SSTA0: UART0 Status and Clock Selection . . . . . . . . . . . . . . . 297
SFR Definition 21.3. SBUF0: UART0 Data Buffer . . . . . . . . . . . . . . . . . . . . . . . . . . . 298
SFR Definition 21.4. SADDR0: UART0 Slave Address . . . . . . . . . . . . . . . . . . . . . . . 298
SFR Definition 21.5. SADEN0: UART0 Slave Address Enable . . . . . . . . . . . . . . . . . 298
SFR Definition 22.1. SCON1: Serial Port 1 Control . . . . . . . . . . . . . . . . . . . . . . . . . . 304
SFR Definition 22.2. SBUF1: Serial (UART1) Port Data Buffer . . . . . . . . . . . . . . . . . 305
SFR Definition 23.1. TCON: Timer Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
SFR Definition 23.2. TMOD: Timer Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
SFR Definition 23.3. CKCON: Clock Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
SFR Definition 23.4. TL0: Timer 0 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
SFR Definition 23.5. TL1: Timer 1 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316
Rev. 1.4
17
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 23.6. TH0: Timer 0 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316
SFR Definition 23.7. TH1: Timer 1 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316
SFR Definition 23.8. TMRnCN: Timer 2, 3, and 4 Control . . . . . . . . . . . . . . . . . . . . . 321
SFR Definition 23.9. TMRnCF: Timer 2, 3, and 4 Configuration . . . . . . . . . . . . . . . . 322
SFR Definition 23.10. RCAPnL: Timer 2, 3, and 4 Capture Register Low Byte . . . . . 323
SFR Definition 23.11. RCAPnH: Timer 2, 3, and 4 Capture Register High Byte . . . . 323
SFR Definition 23.12. TMRnL: Timer 2, 3, and 4 Low Byte . . . . . . . . . . . . . . . . . . . . 323
SFR Definition 23.13. TMRnH Timer 2, 3, and 4 High Byte . . . . . . . . . . . . . . . . . . . 324
SFR Definition 24.1. PCA0CN: PCA Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
SFR Definition 24.2. PCA0MD: PCA0 Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336
SFR Definition 24.3. PCA0CPMn: PCA0 Capture/Compare Mode . . . . . . . . . . . . . . 337
SFR Definition 24.4. PCA0L: PCA0 Counter/Timer Low Byte . . . . . . . . . . . . . . . . . . 338
SFR Definition 24.5. PCA0H: PCA0 Counter/Timer High Byte . . . . . . . . . . . . . . . . . . 338
SFR Definition 24.6. PCA0CPLn: PCA0 Capture Module Low Byte . . . . . . . . . . . . . . 338
SFR Definition 24.7. PCA0CPHn: PCA0 Capture Module High Byte . . . . . . . . . . . . 339
JTAG Register Definition 25.1. IR: JTAG Instruction Register . . . . . . . . . . . . . . . . . . 341
JTAG Register Definition 25.2. DEVICEID: JTAG Device ID . . . . . . . . . . . . . . . . . . . 343
JTAG Register Definition 25.3. FLASHCON: JTAG Flash Control . . . . . . . . . . . . . . . 345
JTAG Register Definition 25.4. FLASHDAT: JTAG Flash Data . . . . . . . . . . . . . . . . . 346
JTAG Register Definition 25.5. FLASHADR: JTAG Flash Address . . . . . . . . . . . . . . 346
18
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
1. System Overview
The C8051F12x and C8051F13x device families are fully integrated mixed-signal System-on-a-Chip
MCUs with 64 digital I/O pins (100-pin TQFP) or 32 digital I/O pins (64-pin TQFP).
Highlighted features are listed below. Refer to Table 1.1 for specific product feature selection.
•
•
•
•
•
•
•
•
•
•
•
•
•
High-Speed pipelined 8051-compatible CIP-51 microcontroller core (100 MIPS or 50 MIPS)
In-system, full-speed, non-intrusive debug interface (on-chip)
True 12 or 10-bit 100 ksps ADC with PGA and 8-channel analog multiplexer
True 8-bit 500 ksps ADC with PGA and 8-channel analog multiplexer (C8051F12x Family)
Two 12-bit DACs with programmable update scheduling (C8051F12x Family)
2-cycle 16 by 16 Multiply and Accumulate Engine (C8051F120/1/2/3 and C8051F130/1/2/3)
128 or 64 kB of in-system programmable Flash memory
8448 (8 k + 256) bytes of on-chip RAM
External Data Memory Interface with 64 kB address space
SPI, SMBus/I2C, and (2) UART serial interfaces implemented in hardware
Five general purpose 16-bit Timers
Programmable Counter/Timer Array with 6 capture/compare modules
On-chip Watchdog Timer, V Monitor, and Temperature Sensor
DD
With on-chip V monitor, Watchdog Timer, and clock oscillator, the C8051F12x and C8051F13x devices
DD
are truly stand-alone System-on-a-Chip solutions. All analog and digital peripherals are enabled/disabled
and configured by user firmware. The Flash memory can be reprogrammed even in-circuit, providing non-
volatile data storage, and also allowing field upgrades of the 8051 firmware.
On-board JTAG debug circuitry allows non-intrusive (uses no on-chip resources), full speed, in-circuit
debugging using the production MCU installed in the final application. This debug system supports inspec-
tion and modification of memory and registers, setting breakpoints, watchpoints, single stepping, run and
halt commands. All analog and digital peripherals are fully functional while debugging using JTAG.
Each MCU is specified for operation over the industrial temperature range (–45 to +85 °C). The Port I/O,
RST, and JTAG pins are tolerant for input signals up to 5 V. The devices are available in 100-pin TQFP or
64-pin TQFP packaging. Table 1.1 lists the specific device features and package offerings for each part
number. Figure 1.1 through Figure 1.6 show functional block diagrams for each device.
Rev. 1.4
19
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 1.1. Product Selection Guide
C8051F120
C8051F120-GQ 100 128 k 8448
C8051F121 100 128 k 8448
C8051F121-GQ 100 128 k 8448
C8051F122 100 128 k 8448
C8051F122-GQ 100 128 k 8448
C8051F123 100 128 k 8448
C8051F123-GQ 100 128 k 8448
C8051F124 50 128 k 8448
C8051F124-GQ 50 128 k 8448
C8051F125 50 128 k 8448
C8051F125-GQ 50 128 k 8448
C8051F126 50 128 k 8448
C8051F126-GQ 50 128 k 8448
C8051F127 50 128 k 8448
C8051F127-GQ 50 128 k 8448
C8051F130 100 128 k 8448
C8051F130-GQ 100 128 k 8448
C8051F131 100 128 k 8448
C8051F131-GQ 100 128 k 8448
C8051F132 100 64 k 8448
C8051F132-GQ 100 64 k 8448
C8051F133 100 64 k 8448
100 128 k 8448
-
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
64
64
32
32
64
64
32
32
64
64
32
32
64
64
32
32
64
64
32
32
64
64
32
32
8
8
8
8
-
-
-
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
-
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
-
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
-
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
-
-
100TQFP
100TQFP
64TQFP
64TQFP
100TQFP
100TQFP
64TQFP
64TQFP
100TQFP
100TQFP
64TQFP
64TQFP
100TQFP
100TQFP
64TQFP
64TQFP
100TQFP
100TQFP
64TQFP
64TQFP
100TQFP
100TQFP
64TQFP
64TQFP
-
-
-
8
8
8
8
-
-
-
-
-
-
8
8
8
8
-
-
-
-
-
-
-
-
-
-
8
8
8
8
8
8
8
8
8
8
8
8
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
C8051F133-GQ 100 64 k 8448
-
-
-
-
20
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
VDD
VDD
VDD
DGND
DGND
DGND
Port I/O
Config.
Digital Power
Analog Power
P0.0
UART0
P0
Drv
P0.7
SFR Bus
UART1
SMBus
SPI Bus
PCA
AV+
AV+
AGND
C
R
O
S
S
B
A
R
P1.0/AIN2.0
P1.7/AIN2.7
P1
Drv
AGND
8
0
5
1
256 byte
RAM
TCK
TMS
TDI
Boundary Scan
Debug HW
JTAG
Logic
Timers 0,
1, 2, 4
P2.0
P2.7
TDO
P2
Drv
8 kB
XRAM
Reset
RST
Timer 3/
RTC
VDD
Monitor
P3.0
P3.7
WDT
MONEN
P3
Drv
P0, P1,
P2, P3
Latches
External Data
Memory Bus
External Oscillator
Circuit
XTAL1
XTAL2
Crossbar
Config.
PLL
Circuitry
System
Clock
C
o
r
128 kB
FLASH
VREF2
Calibrated Internal
Oscillator
A
M
U
X
ADC
500 ksps
(8-Bit)
8:1
Prog
Gain
VREF
VREF
VREFD
P4.0
64x4 byte
cache
DAC1
(12-Bit)
e
DAC1
C
T
L
P4 Latch
Bus Control
P4
DRV
P4.4
P4.5/ALE
P4.6/RD
P4.7/WR
DAC0
(12-Bit)
DAC0
VREF0
P5.0/A8
P5 Latch
P6 Latch
P5
DRV
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
A
d
d
r
P5.7/A15
P6.0/A0
Address Bus
ADC
100 ksps
(12-Bit)
A
P6
DRV
Prog
Gain
M
U
X
P6.7/A7
P7.0/D0
P7.7/D7
D
a
t
P7 Latch
TEMP
SENSOR
P7
DRV
Data Bus
CP0+
CP0-
CP1+
CP1-
CP0
a
CP1
Figure 1.1. C8051F120/124 Block Diagram
Rev. 1.4
21
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
VDD
VDD
VDD
DGND
DGND
DGND
Port I/O
Config.
Digital Power
P0.0
P0.7
UART0
UART1
SMBus
SPI Bus
PCA
P0
Drv
SFR Bus
AV+
C
R
O
S
S
B
A
R
Analog Power
AGND
P1.0/AIN2.0
P1.7/AIN2.7
P1
Drv
8
0
5
1
256 byte
RAM
TCK
TMS
TDI
Boundary Scan
Debug HW
JTAG
Logic
Timers 0,
1, 2, 4
P2.0
P2.7
TDO
P2
Drv
8 kB
XRAM
Reset
RST
Timer 3/
RTC
VDD
Monitor
P3.0
P3.7
WDT
MONEN
P3
Drv
P0, P1,
P2, P3
Latches
External Data
Memory Bus
External Oscillator
Circuit
XTAL1
XTAL2
Crossbar
Config.
PLL
Circuitry
System
Clock
C
o
r
Calibrated Internal
Oscillator
128 kB
FLASH
A
M
U
X
ADC
500 ksps
(8-Bit)
8:1
Prog
Gain
VREF
DAC1
VREF
AV+
VREFA
64x4 byte
cache
DAC1
(12-Bit)
e
C
T
L
P4 Latch
Bus Control
P4
DRV
DAC0
(12-Bit)
DAC0
VREFA
P5 Latch
P6 Latch
P5
DRV
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
A
d
d
r
Address Bus
ADC
100 ksps
(12-Bit)
A
P6
DRV
Prog
Gain
M
U
X
D
a
t
P7 Latch
TEMP
SENSOR
P7
DRV
Data Bus
CP0+
CP0-
CP1+
CP1-
CP0
a
CP1
Figure 1.2. C8051F121/125 Block Diagram
22
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
VDD
VDD
VDD
DGND
DGND
DGND
Port I/O
Config.
Digital Power
Analog Power
P0.0
UART0
P0
Drv
P0.7
UART1
SMBus
SPI Bus
PCA
SFR Bus
AV+
AV+
AGND
C
R
O
S
S
B
A
R
P1.0/AIN2.0
P1.7/AIN2.7
P1
Drv
AGND
8
0
5
1
256 byte
RAM
TCK
TMS
TDI
Boundary Scan
Debug HW
JTAG
Logic
Timers 0,
1, 2, 4
P2.0
P2.7
TDO
P2
Drv
8 kB
XRAM
Reset
RST
Timer 3/
RTC
VDD
Monitor
P3.0
P3.7
WDT
MONEN
P3
Drv
P0, P1,
P2, P3
Latches
External Data
Memory Bus
External Oscillator
Circuit
XTAL1
XTAL2
Crossbar
Config.
PLL
Circuitry
System
Clock
C
o
r
VREF2
Calibrated Internal
Oscillator
128 kB
FLASH
A
M
U
X
ADC
500 ksps
(8-Bit)
8:1
Prog
Gain
VREF
VREF
VREFD
P4.0
64x4 byte
cache
DAC1
(12-Bit)
e
DAC1
C
T
L
P4 Latch
Bus Control
P4
DRV
P4.4
P4.5/ALE
P4.6/RD
P4.7/WR
DAC0
(12-Bit)
DAC0
VREF0
P5.0/A8
P5 Latch
P6 Latch
P5
DRV
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
A
d
d
r
P5.7/A15
P6.0/A0
Address Bus
ADC
100 ksps
(10-Bit)
A
P6
DRV
Prog
Gain
M
U
X
P6.7/A7
P7.0/D0
P7.7/D7
D
a
t
P7 Latch
TEMP
SENSOR
P7
DRV
Data Bus
CP0+
CP0-
CP1+
CP1-
CP0
a
CP1
Figure 1.3. C8051F122/126 Block Diagram
Rev. 1.4
23
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
VDD
VDD
VDD
DGND
DGND
DGND
Port I/O
Config.
Digital Power
P0.0
P0.7
UART0
UART1
SMBus
SPI Bus
PCA
P0
Drv
SFR Bus
AV+
C
R
O
S
S
B
A
R
Analog Power
AGND
P1.0/AIN2.0
P1.7/AIN2.7
P1
Drv
8
0
5
1
256 byte
RAM
TCK
TMS
TDI
Boundary Scan
Debug HW
JTAG
Logic
Timers 0,
1, 2, 4
P2.0
P2.7
TDO
P2
Drv
8 kb
XRAM
Reset
RST
Timer 3/
RTC
VDD
Monitor
P3.0
P3.7
WDT
MONEN
P3
Drv
P0, P1,
P2, P3
Latches
External Data
Memory Bus
External Oscillator
Circuit
XTAL1
XTAL2
Crossbar
Config.
PLL
Circuitry
System
Clock
C
o
r
Calibrated Internal
Oscillator
128 kb
FLASH
A
M
U
X
ADC
500 ksps
(8-Bit)
8:1
Prog
Gain
VREF
DAC1
VREF
AV+
VREFA
64x4 byte
cache
DAC1
(12-Bit)
e
C
T
L
P4 Latch
Bus Control
P4
DRV
DAC0
(12-Bit)
DAC0
VREFA
P5 Latch
P6 Latch
P5
DRV
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
A
d
d
r
Address Bus
ADC
100 ksps
(10-Bit)
A
P6
DRV
Prog
Gain
M
U
X
D
a
t
P7 Latch
TEMP
SENSOR
P7
DRV
Data Bus
CP0+
CP0-
CP1+
CP1-
CP0
a
CP1
Figure 1.4. C8051F123/127 Block Diagram
24
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
VDD
VDD
VDD
DGND
DGND
DGND
Port I/O
Config.
Digital Power
Analog Power
P0.0
UART0
P0
Drv
P0.7
UART1
SMBus
SPI Bus
PCA
SFR Bus
AV+
AV+
AGND
C
R
O
S
S
B
A
R
P1.0/AIN2.0
P1.7/AIN2.7
P1
Drv
AGND
8
0
5
1
256 byte
RAM
TCK
TMS
TDI
Boundary Scan
Debug HW
JTAG
Logic
Timers 0,
1, 2, 4
P2.0
P2.7
TDO
P2
Drv
8kbyte
XRAM
Reset
RST
Timer 3/
RTC
VDD
Monitor
P3.0
P3.7
WDT
MONEN
P3
Drv
P0, P1,
P2, P3
Latches
External Data
Memory Bus
External Oscillator
Circuit
XTAL1
XTAL2
Crossbar
Config.
PLL
Circuitry
System
Clock
C
o
r
Calibrated Internal
Oscillator
FLASH
128kbyte
(‘F130)
64kbyte
(‘F132)
VREF
VREF
P4.0
e
C
T
L
P4 Latch
Bus Control
P4
DRV
P4.4
P4.5/ALE
P4.6/RD
P4.7/WR
64x4 byte
cache
VREF0
P5.0/A8
P5 Latch
P6 Latch
P5
DRV
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
A
d
d
r
P5.7/A15
P6.0/A0
Address Bus
ADC
100ksps
(10-Bit)
A
P6
DRV
Prog
Gain
M
U
X
P6.7/A7
P7.0/D0
P7.7/D7
D
a
t
P7 Latch
TEMP
SENSOR
P7
DRV
Data Bus
CP0+
CP0-
CP1+
CP1-
CP0
a
CP1
Figure 1.5. C8051F130/132 Block Diagram
Rev. 1.4
25
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
VDD
VDD
VDD
DGND
DGND
DGND
Port I/O
Config.
Digital Power
P0.0
P0.7
UART0
UART1
SMBus
SPI Bus
PCA
P0
Drv
SFR Bus
AV+
C
R
O
S
S
B
A
R
Analog Power
AGND
P1.0/AIN2.0
P1.7/AIN2.7
P1
Drv
8
0
5
1
256 byte
RAM
TCK
TMS
TDI
Boundary Scan
Debug HW
JTAG
Logic
Timers 0,
1, 2, 4
P2.0
P2.7
TDO
P2
Drv
8kbyte
XRAM
Reset
RST
Timer 3/
RTC
VDD
Monitor
P3.0
P3.7
WDT
MONEN
P3
Drv
P0, P1,
P2, P3
Latches
External Data
Memory Bus
External Oscillator
Circuit
XTAL1
XTAL2
Crossbar
Config.
PLL
Circuitry
System
Clock
C
o
r
Calibrated Internal
Oscillator
FLASH
128kbyte
(‘F131)
64kbyte
(‘F133)
VREF
VREF
e
C
T
L
P4 Latch
Bus Control
P4
DRV
64x4 byte
cache
VREF0
P5 Latch
P6 Latch
P5
DRV
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
A
d
d
r
Address Bus
ADC
100ksps
(10-Bit)
A
P6
DRV
Prog
Gain
M
U
X
D
a
t
P7 Latch
TEMP
SENSOR
P7
DRV
Data Bus
CP0+
CP0-
CP1+
CP1-
CP0
a
CP1
Figure 1.6. C8051F131/133 Block Diagram
26
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
1.1. CIP-51™ Microcontroller Core
1.1.1. Fully 8051 Compatible
The C8051F12x and C8051F13x utilize Silicon Labs’ proprietary CIP-51 microcontroller core. The CIP-51
is fully compatible with the MCS-51™ instruction set; standard 803x/805x assemblers and compilers can
be used to develop software. The core has all the peripherals included with a standard 8052, including five
16-bit counter/timers, two full-duplex UARTs, 256 bytes of internal RAM, 128 byte Special Function Regis-
ter (SFR) address space, and 8/4 byte-wide I/O Ports.
1.1.2. Improved Throughput
The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the stan-
dard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system
clock cycles to execute with a maximum system clock of 12-to-24 MHz. By contrast, the CIP-51 core exe-
cutes 70% of its instructions in one or two system clock cycles, with only four instructions taking more than
four system clock cycles.
The CIP-51 has a total of 109 instructions. The table below shows the total number of instructions that
require each execution time.
Clocks to Execute
Number of Instructions
1
26
2
50
2/3
5
3
14
3/4
7
4
3
4/5
1
5
2
8
1
With the CIP-51's maximum system clock at 100 MHz, the C8051F120/1/2/3 and C8051F130/1/2/3 have a
peak throughput of 100 MIPS (the C8051F124/5/6/7 have a peak throughput of 50 MIPS).
Rev. 1.4
27
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
1.1.3. Additional Features
Several key enhancements are implemented in the CIP-51 core and peripherals to improve overall perfor-
mance and ease of use in end applications.
The extended interrupt handler provides 20 interrupt sources into the CIP-51 (as opposed to 7 for the stan-
dard 8051), allowing the numerous analog and digital peripherals to interrupt the controller. An interrupt
driven system requires less intervention by the MCU, giving it more effective throughput. The extra inter-
rupt sources are very useful when building multi-tasking, real-time systems.
There are up to seven reset sources for the MCU: an on-board V monitor, a Watchdog Timer, a missing
DD
clock detector, a voltage level detection from Comparator0, a forced software reset, the CNVSTR0 input
pin, and the RST pin. The RST pin is bi-directional, accommodating an external reset, or allowing the inter-
nally generated POR to be output on the RST pin. Each reset source except for the V monitor and Reset
DD
Input pin may be disabled by the user in software; the V
monitor is enabled/disabled via the MONEN
DD
pin. The Watchdog Timer may be permanently enabled in software after a power-on reset during MCU ini-
tialization.
The MCU has an internal, stand alone clock generator which is used by default as the system clock after
any reset. If desired, the clock source may be switched on the fly to the external oscillator, which can use a
crystal, ceramic resonator, capacitor, RC, or external clock source to generate the system clock. This can
be extremely useful in low power applications, allowing the MCU to run from a slow (power saving) exter-
nal crystal source, while periodically switching to the 24.5 MHz internal oscillator as needed. Additionally,
an on-chip PLL is provided to achieve higher system clock speeds for increased throughput.
VDD
CNVSTR
Crossbar
(Port I/O)
Supply
Monitor
(CNVSTR
reset
enable)
Supply
Reset
Timeout
+
-
RST
(wired-OR)
Comparator0
CP0+
CP0-
+
-
(CP0
reset
enable)
Reset
Funnel
Missing
Clock
Detector
(one-
shot)
WDT
EN
EN
PRE
Internal
Clock
Generator
System
Clock
PLL
Circuitry
Software Reset
System Reset
CIP-51
Microcontroller
Core
XTAL1
XTAL2
OSC
Clock Select
Extended Interrupt
Handler
Figure 1.7. On-Board Clock and Reset
28
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
1.2. On-Chip Memory
The CIP-51 has a standard 8051 program and data address configuration. It includes 256 bytes of data
RAM, with the upper 128 bytes dual-mapped. Indirect addressing accesses the upper 128 bytes of general
purpose RAM, and direct addressing accesses the 128 byte SFR address space. The lower 128 bytes of
RAM are accessible via direct and indirect addressing. The first 32 bytes are addressable as four banks of
general purpose registers, and the next 16 bytes can be byte addressable or bit addressable.
The devices include an on-chip 8k byte RAM block and an external memory interface (EMIF) for accessing
off-chip data memory. The on-chip 8k byte block can be addressed over the entire 64k external data mem-
ory address range (overlapping 8k boundaries). External data memory address space can be mapped to
on-chip memory only, off-chip memory only, or a combination of the two (addresses up to 8k directed to on-
chip, above 8k directed to EMIF). The EMIF is also configurable for multiplexed or non-multiplexed
address/data lines.
On the C8051F12x and C8051F130/1, the MCU’s program memory consists of 128 k bytes of banked
Flash memory. The 1024 bytes from addresses 0x1FC00 to 0x1FFFF are reserved. On the C8051F132/3,
the MCU’s program memory consists of 64 k bytes of Flash memory. This memory may be reprogrammed
in-system in 1024 byte sectors, and requires no special off-chip programming voltage.
On all devices, there are also two 128 byte sectors at addresses 0x20000 to 0x200FF, which may be used
by software for data storage. See Figure 1.8 for the MCU system memory map.
PROGRAM/DATA MEMORY
(FLASH)
DATA MEMORY (RAM)
INTERNAL DATA ADDRESS SPACE
C8051F120/1/2/3/4/5/6/7
C8051F130/1
Upper 128 RAM
(Indirect Addressing
Only)
Special Function
Registers
(Direct Addressing Only)
0x200FF
0x20000
0x1FFFF
0x1FC00
0x1FBFF
Scrachpad Memory
(DATA only)
0
1
2
3
RESERVED
(Direct and Indirect
Addressing)
Up To
256 SFR Pages
Lower 128 RAM
(Direct and Indirect
Addressing)
FLASH
Bit Addressable
(In-System
Programmable in 1024
Byte Sectors)
General Purpose
Registers
0x00000
EXTERNAL DATA ADDRESS SPACE
0xFFFF
C8051F132/3
0x200FF
0x20000
Scrachpad Memory
(DATA only)
Off-chip XRAM space
0x0FFFF
FLASH
(In-System
Programmable in 1024
Byte Sectors)
0x2000
0x1FFF
XRAM - 8192 Bytes
(accessable using MOVX
instruction)
0x0000
0x00000
Figure 1.8. On-Chip Memory Map
Rev. 1.4
29
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
1.3. JTAG Debug and Boundary Scan
JTAG boundary scan and debug circuitry is included which provides non-intrusive, full speed, in-circuit
debugging using the production part installed in the end application, via the four-pin JTAG interface. The
JTAG port is fully compliant to IEEE 1149.1, providing full boundary scan for test and manufacturing pur-
poses.
Silicon Labs' debugging system supports inspection and modification of memory and registers, break-
points, watchpoints, a stack monitor, and single stepping. No additional target RAM, program memory, tim-
ers, or communications channels are required. All the digital and analog peripherals are functional and
work correctly while debugging. All the peripherals (except for the ADC and SMBus) are stalled when the
MCU is halted, during single stepping, or at a breakpoint in order to keep them synchronized.
The C8051F120DK development kit provides all the hardware and software necessary to develop applica-
tion code and perform in-circuit debugging with the C8051F12x or C8051F13x MCUs.
The kit includes a Windows (95 or later) development environment, a serial adapter for connecting to the
JTAG port, and a target application board with a C8051F120 MCU installed. All of the necessary commu-
nication cables and a wall-mount power supply are also supplied with the development kit. Silicon Labs’
debug environment is a vastly superior configuration for developing and debugging embedded applications
compared to standard MCU emulators, which use on-board "ICE Chips" and target cables and require the
MCU in the application board to be socketed. Silicon Labs' debug environment both increases ease of use
and preserves the performance of the precision, on-chip analog peripherals.
Silicon Labs Integrated
Development Environment
WINDOWS 95 OR LATER
JTAG (x4), VDD, GND
Serial
Adapter
TARGET PCB
C8051
F12x/13x
Figure 1.9. Development/In-System Debug Diagram
30
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
1.4. 16 x 16 MAC (Multiply and Accumulate) Engine
The C8051F120/1/2/3 and C8051F130/1/2/3 devices include a multiply and accumulate engine which can
be used to speed up many mathematical operations. MAC0 contains a 16-by-16 bit multiplier and a 40-bit
adder, which can perform integer or fractional multiply-accumulate and multiply operations on signed input
values in two SYSCLK cycles. A rounding engine provides a rounded 16-bit fractional result after an addi-
tional (third) SYSCLK cycle. MAC0 also contains a 1-bit arithmetic shifter that will left or right-shift the con-
tents of the 40-bit accumulator in a single SYSCLK cycle.
MAC0 A Register
MAC0AH MAC0AL
MAC0 B Register
MAC0BH MAC0BL
MAC0MS
MAC0FM
16 x 16 Multiply
0
1
0
40 bit Add
MAC0 Accumulator
MAC0ACC3 MAC0ACC2 MAC0ACC1 MAC0ACC0
MAC0OVR
1 bit Shift
Rounding Engine
Flag Logic
MAC0 Rounding Register
MAC0RNDH MAC0RNDL
MAC0CF
MAC0STA
Figure 1.10. MAC0 Block Diagram
Rev. 1.4
31
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
1.5. Programmable Digital I/O and Crossbar
The standard 8051 8-bit Ports (0, 1, 2, and 3) are available on the MCUs. The devices in the larger (100-
pin TQFP) packaging have 4 additional ports (4, 5, 6, and 7) for a total of 64 general-purpose port I/O. The
Port I/O behave like the standard 8051 with a few enhancements.
Each Port I/O pin can be configured as either a push-pull or open-drain output. Also, the "weak pullups"
which are normally fixed on an 8051 can be globally disabled, providing additional power saving capabili-
ties for low-power applications.
Perhaps the most unique enhancement is the Digital Crossbar. This is a large digital switching network that
allows mapping of internal digital system resources to Port I/O pins on P0, P1, P2, and P3. (See
Figure 1.11) Unlike microcontrollers with standard multiplexed digital I/O, all combinations of functions are
supported.
The on-chip counter/timers, serial buses, HW interrupts, ADC Start of Conversion inputs, comparator out-
puts, and other digital signals in the controller can be configured to appear on the Port I/O pins specified in
the Crossbar Control registers. This allows the user to select the exact mix of general purpose Port I/O and
digital resources needed for the particular application.
XBR0, XBR1,
XBR2, P1MDIN
Registers
P0MDOUT, P1MDOUT,
P2MDOUT, P3MDOUT
Registers
2
4
Highest
Priority
UART0
SPI
External
Pins
2
2
7
SMBus
UART1
PCA
Priority
Decoder
P0.0
Highest
Priority
P0
I/O
Cells
8
8
8
8
P0.7
2
Comptr.
Outputs
Digital
Crossbar
P1.0
P1.7
P1
I/O
Cells
T0, T1,
T2, T2EX,
T4,T4EX
/INT0,
8
P2.0
P2.7
/INT1
P2
I/O
Cells
Lowest
Priority
/SYSCLK divided by 1,2,4, or 8
2
CNVSTR0/2
P3.0
P3.7
P3
I/O
Cells
8
Lowest
Priority
P0
(P0.0-P0.7)
8
P1
P2
P3
(P1.0-P1.7)
8
To External
Memory
Interface
(EMIF)
Port
Latches
To ADC2 Input
(‘F12x Only)
(P2.0-P2.7)
8
(P3.0-P3.7)
Figure 1.11. Digital Crossbar Diagram
32
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
1.6. Programmable Counter Array
An on-board Programmable Counter/Timer Array (PCA) is included in addition to the five 16-bit general
purpose counter/timers. The PCA consists of a dedicated 16-bit counter/timer time base with 6 program-
mable capture/compare modules. The timebase is clocked from one of six sources: the system clock
divided by 12, the system clock divided by 4, Timer 0 overflow, an External Clock Input (ECI pin), the sys-
tem clock, or the external oscillator source divided by 8.
Each capture/compare module can be configured to operate in one of six modes: Edge-Triggered Capture,
Software Timer, High Speed Output, Frequency Output, 8-Bit Pulse Width Modulator, or 16-Bit Pulse Width
Modulator. The PCA Capture/Compare Module I/O and External Clock Input are routed to the MCU Port I/
O via the Digital Crossbar.
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
PCA
16-Bit Counter/Timer
CLOCK
MUX
ECI
SYSCLK
External Clock/8
Capture/Compare
Module 0
Capture/Compare
Module 1
Capture/Compare
Module 2
Capture/Compare
Module 3
Capture/Compare
Module 4
Capture/Compare
Module 5
Crossbar
Port I/O
Figure 1.12. PCA Block Diagram
1.7. Serial Ports
Serial peripherals included on the devices are two Enhanced Full-Duplex UARTs, SPI Bus, and SMBus/
I2C. Each of the serial buses is fully implemented in hardware and makes extensive use of the CIP-51's
interrupts, thus requiring very little intervention by the CPU. The serial buses do not "share" resources
such as timers, interrupts, or Port I/O, so any or all of the serial buses may be used together with any other.
Rev. 1.4
33
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
1.8. 12 or 10-Bit Analog to Digital Converter
All devices include either a 12 or 10-bit SAR ADC (ADC0) with a 9-channel input multiplexer and program-
mable gain amplifier. With a maximum throughput of 100 ksps, the 12 and 10-bit ADCs offer true 12-bit lin-
earity with an INL of ±1LSB. The ADC0 voltage reference can be selected from an external VREF pin, or
(on the C8051F12x devices) the DAC0 output. On the 100-pin TQFP devices, ADC0 has its own dedicated
Voltage Reference input pin; on the 64-pin TQFP devices, the ADC0 shares a Voltage Reference input pin
with the 8-bit ADC2. The on-chip voltage reference may generate the voltage reference for other system
components or the on-chip ADCs via the VREF output pin.
The ADC is under full control of the CIP-51 microcontroller via its associated Special Function Registers.
One input channel is tied to an internal temperature sensor, while the other eight channels are available
externally. Each pair of the eight external input channels can be configured as either two single-ended
inputs or a single differential input. The system controller can also put the ADC into shutdown mode to
save power.
A programmable gain amplifier follows the analog multiplexer. The gain can be set in software from 0.5 to
16 in powers of 2. The gain stage can be especially useful when different ADC input channels have widely
varied input voltage signals, or when it is necessary to "zoom in" on a signal with a large DC offset (in dif-
ferential mode, a DAC could be used to provide the DC offset).
Conversions can be started in four ways; a software command, an overflow of Timer 2, an overflow of
Timer 3, or an external signal input. This flexibility allows the start of conversion to be triggered by software
events, external HW signals, or a periodic timer overflow signal. Conversion completions are indicated by a
status bit and an interrupt (if enabled). The resulting 10 or 12-bit data word is latched into two SFRs upon
completion of a conversion. The data can be right or left justified in these registers under software control.
Window Compare registers for the ADC data can be configured to interrupt the controller when ADC data
is within or outside of a specified range. The ADC can monitor a key voltage continuously in background
mode, but not interrupt the controller unless the converted data is within the specified window.
Analog Multiplexer
Window
Compare
Interrupt
Configuration, Control, and Data
Registers
Window Compare
Logic
+
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
-
Programmable Gain
Amplifier
+
-
9-to-1
AMUX
(SE or
DIFF)
AV+
12-Bit
SAR
+
12
ADC Data
Registers
+
-
X
-
+
ADC
Conversion
Complete
Interrupt
-
TEMP
SENSOR
Write to AD0BUSY
External VREF
Pin
Start
Conversion
VREF
Timer 3 Overflow
CNVSTR0
AGND
DAC0 Output
Timer 2 Overflow
Figure 1.13. 12-Bit ADC Block Diagram
34
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
1.9. 8-Bit Analog to Digital Converter
The C8051F12x devices have an on-board 8-bit SAR ADC (ADC2) with an 8-channel input multiplexer and
programmable gain amplifier. This ADC features a 500 ksps maximum throughput and true 8-bit linearity
with an INL of ±1LSB. Eight input pins are available for measurement. The ADC is under full control of the
CIP-51 microcontroller via the Special Function Registers. The ADC2 voltage reference is selected
between the analog power supply (AV+) and an external VREF pin. On the 100-pin TQFP devices, ADC2
has its own dedicated Voltage Reference input pin; on the 64-pin TQFP devices, ADC2 shares a Voltage
Reference input pin with ADC0. User software may put ADC2 into shutdown mode to save power.
A programmable gain amplifier follows the analog multiplexer. The gain stage can be especially useful
when different ADC input channels have widely varied input voltage signals, or when it is necessary to
"zoom in" on a signal with a large DC offset (in differential mode, a DAC could be used to provide the DC
offset). The PGA gain can be set in software to 0.5, 1, 2, or 4.
A flexible conversion scheduling system allows ADC2 conversions to be initiated by software commands,
timer overflows, or an external input signal. ADC2 conversions may also be synchronized with ADC0 soft-
ware-commanded conversions. Conversion completions are indicated by a status bit and an interrupt (if
enabled), and the resulting 8-bit data word is latched into an SFR upon completion.
Analog Multiplexer
Window
Compare
Logic
Window
Compare
Interrupt
Configuration, Control, and Data Registers
AIN2.0
AIN2.1
AIN2.2
AIN2.3
AIN2.4
AIN2.5
AIN2.6
AIN2.7
Programmable Gain
Amplifier
AV+
8-Bit
SAR
8-to-1
AMUX
8
ADC Data
Register
+
-
X
Conversion
Complete
Interrupt
ADC
Write to AD2BUSY
Timer 3 Overflow
CNVSTR2 Input
Timer 2 Overflow
External VREF
Pin
VREF
Start Conversion
AV+
Write to AD0BUSY
(synchronized with
ADC0)
Figure 1.14. 8-Bit ADC Diagram
Rev. 1.4
35
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
1.10. 12-bit Digital to Analog Converters
The C8051F12x devices have two integrated 12-bit Digital to Analog Converters (DACs). The MCU data
and control interface to each DAC is via the Special Function Registers. The MCU can place either or both
of the DACs in a low power shutdown mode.
The DACs are voltage output mode and include a flexible output scheduling mechanism. This scheduling
mechanism allows DAC output updates to be forced by a software write or scheduled on a Timer 2, 3, or 4
overflow. The DAC voltage reference is supplied from the dedicated VREFD input pin on the 100-pin TQFP
devices or via the internal Voltage reference on the 64-pin TQFP devices. The DACs are especially useful
as references for the comparators or offsets for the differential inputs of the ADCs.
DAC0EN
DAC0MD1
DAC0MD0
DAC0DF2
DAC0DF1
DAC0DF0
REF
AV+
8
8
8
8
12
DAC0
DAC0
AGND
DAC1EN
DAC1MD1
DAC1MD0
DAC1DF2
DAC1DF1
DAC1DF0
REF
AV+
8
8
8
8
12
DAC1
DAC1
AGND
Figure 1.15. DAC System Block Diagram
36
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
1.11. Analog Comparators
Two analog comparators with dedicated input pins are included on-chip. The comparators have software
programmable hysteresis and response time. Each comparator can generate an interrupt on a rising edge,
falling edge, or both. The interrupts are capable of waking up the MCU from sleep mode, and Comparator
0 can be used as a reset source. The output state of the comparators can be polled in software or routed to
Port I/O pins via the Crossbar. The comparators can be programmed to a low power shutdown mode when
not in use.
CPn Output
CROSSBAR
(Port I/O)
2 Comparators
SFR's
CIP-51
and
Interrupt
Handler
CPn+
CPn-
+
(Data
and
Control)
CPn
-
Figure 1.16. Comparator Block Diagram
Rev. 1.4
37
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
2. Absolute Maximum Ratings
*
Table 2.1. Absolute Maximum Ratings
Parameter
Conditions
Min
Typ
—
Max
125
150
Units
°C
Ambient temperature under bias
–55
–65
–0.3
Storage Temperature
—
°C
Voltage on any Pin (except VDD and Port I/O) with
Respect to DGND
—
VDD
0.3
+
V
Voltage on any Port I/O Pin or RST with Respect to
DGND
–0.3
—
5.8
V
Voltage on VDD with Respect to DGND
–0.3
—
—
—
4.2
V
Maximum Total Current through VDD, AV+, DGND,
and AGND
800
mA
Maximum Output Current Sunk by any Port pin
Maximum Output Current Sunk by any other I/O pin
Maximum Output Current Sourced by any Port pin
—
—
—
—
—
—
—
—
100
50
mA
mA
mA
mA
100
50
Maximum Output Current Sourced by any other I/O
Pin
*Note: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device.
This is a stress rating only and functional operation of the devices at those or any other conditions above those
indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for
extended periods may affect device reliability.
38
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
3. Global DC Electrical Characteristics
Table 3.1. Global DC Electrical Characteristics
(C8051F120/1/2/3 and C8051F130/1/2/3)
–40 to +85 °C, 100 MHz System Clock unless otherwise specified.
Parameter
Conditions
Min
Typ
Max
Units
Analog Supply Voltage1
SYSCLK = 0 to 50 MHz
SYSCLK > 50 MHz
2.7
3.0
3.0
3.3
3.6
3.6
V
V
Analog Supply Current
Internal REF, ADCs, DACs, Com-
parators all active
—
1.7
—
mA
Analog Supply Current with Internal REF, ADCs, DACs, Com-
analog sub-systems inactive parators all disabled, oscillator
disabled
—
0.2
—
µA
Analog-to-Digital Supply
Delta (|VDD – AV+|)
—
—
0.5
V
Digital Supply Voltage
SYSCLK = 0 to 50 MHz
SYSCLK > 50 MHz
2.7
3.0
3.0
3.3
3.6
3.6
V
V
Digital Supply Current with
CPU active
VDD = 3.0 V, Clock = 100 MHz
VDD = 3.0 V, Clock = 50 MHz
VDD = 3.0 V, Clock = 1 MHz
VDD = 3.0 V, Clock = 32 kHz
—
65
35
1
—
mA
mA
mA
µA
33
Digital Supply Current with
CPU inactive (not accessing
Flash)
VDD = 3.0 V, Clock = 100 MHz
—
40
20
0.4
15
—
mA
mA
mA
µA
VDD = 3.0 V, Clock = 50 MHz
VDD = 3.0 V, Clock = 1 MHz
VDD = 3.0 V, Clock = 32 kHz
Digital Supply Current (shut- Oscillator not running
down)
—
—
0.4
1.5
—
—
—
µA
V
Digital Supply RAM Data
Retention Voltage
SYSCLK (System Clock)2,3
VDD, AV+ = 2.7 to 3.6 V
0
0
50
100
MHz
MHz
V
DD, AV+ = 3.0 to 3.6 V
Specified Operating Temper-
ature Range
–40
—
+85
°C
Notes:
1. Analog Supply AV+ must be greater than 1 V for VDD monitor to operate.
2. SYSCLK is the internal device clock. For operational speeds in excess of 30 MHz, SYSCLK must be derived
from the Phase-Locked Loop (PLL).
3. SYSCLK must be at least 32 kHz to enable debugging.
Rev. 1.4
39
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 3.2. Global DC Electrical Characteristics (C8051F124/5/6/7)
–40 to +85 °C, 50 MHz System Clock unless otherwise specified.
Parameter
Conditions
Min
Typ
Max
Units
Analog Supply Voltage1
Analog Supply Current
2.7
3.0
3.6
V
Internal REF, ADC, DAC, Com-
parators all active
—
—
1.7
0.2
—
—
mA
µA
Analog Supply Current with Internal REF, ADC, DAC, Com-
analog sub-systems inactive parators all disabled, oscillator
disabled
Analog-to-Digital Supply
Delta (|VDD – AV+|)
—
—
0.5
V
V
Digital Supply Voltage
2.7
—
3.0
3.6
—
Digital Supply Current with
CPU active
VDD = 3.0 V, Clock = 50 MHz
VDD = 3.0 V, Clock = 1 MHz
VDD = 3.0 V, Clock = 32 kHz
35
1
33
mA
mA
µA
Digital Supply Current with
CPU inactive (not accessing
Flash)
VDD = 3.0 V, Clock = 50 MHz
—
27
0.4
15
—
mA
mA
µA
VDD = 3.0 V, Clock = 1 MHz
DD = 3.0 V, Clock = 32 kHz
V
Digital Supply Current (shut- Oscillator not running
down)
—
—
0.4
1.5
—
—
µA
V
Digital Supply RAM Data
Retention Voltage
SYSCLK (System Clock)2,3
0
—
—
50
MHz
°C
Specified Operating
Temperature Range
–40
+85
Notes:
1. Analog Supply AV+ must be greater than 1 V for VDD monitor to operate.
2. SYSCLK is the internal device clock. For operational speeds in excess of 30 MHz, SYSCLK must be derived
from the phase-locked loop (PLL).
3. SYSCLK must be at least 32 kHz to enable debugging.
40
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
4. Pinout and Package Definitions
Table 4.1. Pin Definitions
Pin Numbers
‘F120 ‘F121 ‘F130 ‘F131
‘F122 ‘F123 ‘F132 ‘F133
‘F124 ‘F125
Name
Type
Description
‘F126 ‘F127
VDD
DGND
AV+
37,
24,
37,
24,
Digital Supply Voltage. Must be tied to +2.7 to
+3.6 V.
64, 90 41, 57 64, 90 41, 57
38, 25, 38, 25,
63, 89 40, 56 63, 89 40, 56
Digital Ground. Must be tied to Ground.
11, 14
6
11, 14
6
Analog Supply Voltage. Must be tied to +2.7 to
+3.6 V.
AGND
TMS
TCK
TDI
10, 13
5
10, 13
5
Analog Ground. Must be tied to Ground.
1
2
3
58
59
60
1
2
3
58
59
60
D In JTAG Test Mode Select with internal pullup.
D In JTAG Test Clock with internal pullup.
D In JTAG Test Data Input with internal pullup. TDI is
latched on the rising edge of TCK.
TDO
RST
4
5
61
62
4
5
61 D Out JTAG Test Data Output with internal pullup. Data
is shifted out on TDO on the falling edge of TCK.
TDO output is a tri-state driver.
62
D I/O Device Reset. Open-drain output of internal VDD
monitor. Is driven low when VDD is < VRST and
MONEN is high. An external source can initiate
a system reset by driving this pin low.
XTAL1
26
17
26
17
A In Crystal Input. This pin is the return for the inter-
nal oscillator circuit for a crystal or ceramic reso-
nator. For a precision internal clock, connect a
crystal or ceramic resonator from XTAL1 to
XTAL2. If overdriven by an external CMOS
clock, this becomes the system clock.
XTAL2
27
28
18
19
27
28
18 A Out Crystal Output. This pin is the excitation driver
for a crystal or ceramic resonator.
MONEN
19
D In VDD Monitor Enable. When tied high, this pin
enables the internal VDD monitor, which forces a
system reset when VDD is < VRST. When tied
low, the internal VDD monitor is disabled.
This pin must be tied high or low.
Rev. 1.4
41
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 4.1. Pin Definitions (Continued)
Pin Numbers
‘F120 ‘F121 ‘F130 ‘F131
‘F122 ‘F123 ‘F132 ‘F133
‘F124 ‘F125
Name
Type
Description
‘F126 ‘F127
VREF
12
7
12
7
A I/O Bandgap Voltage Reference Output
(all devices).
DAC Voltage Reference Input
(C8051F121/3/5/7 only).
VREFA
VREF0
VREF2
VREFD
AIN0.0
8
A In ADC0 and ADC2 Voltage Reference Input.
A In ADC0 Voltage Reference Input.
A In ADC2 Voltage Reference Input.
A In DAC Voltage Reference Input.
16
17
15
18
16
17
15
18
8
9
9
A In ADC0 Input Channel 0 (See ADC0 Specification
for complete description).
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
19
20
21
22
23
24
25
10
11
12
13
14
15
16
19
20
21
22
23
24
25
10
11
12
13
14
15
16
A In ADC0 Input Channel 1 (See ADC0 Specification
for complete description).
A In ADC0 Input Channel 2 (See ADC0 Specification
for complete description).
A In ADC0 Input Channel 3 (See ADC0 Specification
for complete description).
A In ADC0 Input Channel 4 (See ADC0 Specification
for complete description).
A In ADC0 Input Channel 5 (See ADC0 Specification
for complete description).
A In ADC0 Input Channel 6 (See ADC0 Specification
for complete description).
A In ADC0 Input Channel 7 (See ADC0 Specification
for complete description).
CP0+
CP0-
9
8
4
3
9
8
7
6
4
3
2
1
A In Comparator 0 Non-Inverting Input.
A In Comparator 0 Inverting Input.
A In Comparator 1 Non-Inverting Input.
A In Comparator 1 Inverting Input.
CP1+
CP1–
DAC0
7
2
6
1
100
64
A Out Digital to Analog Converter 0 Voltage Output.
(See DAC Specification for complete descrip-
tion).
42
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 4.1. Pin Definitions (Continued)
Pin Numbers
‘F120 ‘F121 ‘F130 ‘F131
‘F122 ‘F123 ‘F132 ‘F133
‘F124 ‘F125
Name
Type
Description
‘F126 ‘F127
DAC1
99
63
A Out Digital to Analog Converter 1 Voltage Output.
(See DAC Specification for complete descrip-
tion).
P0.0
P0.1
62
61
60
59
58
57
55
54
53
52
51
50
62
61
60
59
58
57
55
54
53
52
51
50
D I/O Port 0.0. See Port Input/Output section for com-
plete description.
D I/O Port 0.1. See Port Input/Output section for com-
plete description.
P0.2
D I/O Port 0.2. See Port Input/Output section for com-
plete description.
P0.3
D I/O Port 0.3. See Port Input/Output section for com-
plete description.
P0.4
D I/O Port 0.4. See Port Input/Output section for com-
plete description.
ALE/P0.5
D I/O ALE Strobe for External Memory Address bus
(multiplexed mode)
Port 0.5
See Port Input/Output section for complete
description.
RD/P0.6
WR/P0.7
56
55
36
49
48
29
56
55
36
49
48
29
D I/O /RD Strobe for External Memory Address bus
Port 0.6
See Port Input/Output section for complete
description.
D I/O /WR Strobe for External Memory Address bus
Port 0.7
See Port Input/Output section for complete
description.
AIN2.0/A8/P1.0
A In ADC2 Input Channel 0 (See ADC2 Specification
D I/O for complete description).
Bit 8 External Memory Address bus (Non-multi-
plexed mode)
Port 1.0
See Port Input/Output section for complete
description.
AIN2.1/A9/P1.1
35
28
35
28
A In Port 1.1. See Port Input/Output section for com-
D I/O plete description.
Rev. 1.4
43
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 4.1. Pin Definitions (Continued)
Pin Numbers
‘F120 ‘F121 ‘F130 ‘F131
‘F122 ‘F123 ‘F132 ‘F133
‘F124 ‘F125
Name
Type
Description
‘F126 ‘F127
AIN2.2/A10/P1.2 34
27
26
23
22
21
20
37
34
33
32
31
30
29
46
27
26
23
22
21
20
37
A In Port 1.2. See Port Input/Output section for com-
D I/O plete description.
AIN2.3/A11/P1.3
33
A In Port 1.3. See Port Input/Output section for com-
D I/O plete description.
AIN2.4/A12/P1.4 32
AIN2.5/A13/P1.5 31
AIN2.6/A14/P1.6 30
AIN2.7/A15/P1.7 29
A In Port 1.4. See Port Input/Output section for com-
D I/O plete description.
A In Port 1.5. See Port Input/Output section for com-
D I/O plete description.
A In Port 1.6. See Port Input/Output section for com-
D I/O plete description.
A In Port 1.7. See Port Input/Output section for com-
D I/O plete description.
A8m/A0/P2.0
46
D I/O Bit 8 External Memory Address bus (Multiplexed
mode)
Bit 0 External Memory Address bus (Non-multi-
plexed mode)
Port 2.0
See Port Input/Output section for complete
description.
A9m/A1/P2.1
A10m/A2/P2.2
A11m/A3/P2.3
A12m/A4/P2.4
A13m/A5/P2.5
A14m/A6/P2.6
A15m/A7/P2.7
45
44
43
42
41
40
39
36
35
34
33
32
31
30
45
44
43
42
41
40
39
36
35
34
33
32
31
30
D I/O Port 2.1. See Port Input/Output section for com-
plete description.
D I/O Port 2.2. See Port Input/Output section for com-
plete description.
D I/O Port 2.3. See Port Input/Output section for com-
plete description.
D I/O Port 2.4. See Port Input/Output section for com-
plete description.
D I/O Port 2.5. See Port Input/Output section for com-
plete description.
D I/O Port 2.6. See Port Input/Output section for com-
plete description.
D I/O Port 2.7. See Port Input/Output section for com-
plete description.
44
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 4.1. Pin Definitions (Continued)
Pin Numbers
‘F120 ‘F121 ‘F130 ‘F131
‘F122 ‘F123 ‘F132 ‘F133
‘F124 ‘F125
Name
Type
Description
‘F126 ‘F127
AD0/D0/P3.0
54
47
54
47
D I/O Bit 0 External Memory Address/Data bus (Multi-
plexed mode)
Bit 0 External Memory Data bus (Non-multi-
plexed mode)
Port 3.0
See Port Input/Output section for complete
description.
AD1/D1/P3.1
AD2/D2/P3.2
AD3/D3/P3.3
AD4/D4/P3.4
AD5/D5/P3.5
AD6/D6/P3.6
AD7/D7/P3.7
P4.0
53
52
51
50
49
48
47
98
97
96
95
94
46
45
44
43
42
39
38
53
52
51
50
49
48
47
98
97
96
95
94
46
45
44
43
42
39
38
D I/O Port 3.1. See Port Input/Output section for com-
plete description.
D I/O Port 3.2. See Port Input/Output section for com-
plete description.
D I/O Port 3.3. See Port Input/Output section for com-
plete description.
D I/O Port 3.4. See Port Input/Output section for com-
plete description.
D I/O Port 3.5. See Port Input/Output section for com-
plete description.
D I/O Port 3.6. See Port Input/Output section for com-
plete description.
D I/O Port 3.7. See Port Input/Output section for com-
plete description.
D I/O Port 4.0. See Port Input/Output section for com-
plete description.
P4.1
D I/O Port 4.1. See Port Input/Output section for com-
plete description.
P4.2
D I/O Port 4.2. See Port Input/Output section for com-
plete description.
P4.3
D I/O Port 4.3. See Port Input/Output section for com-
plete description.
P4.4
D I/O Port 4.4. See Port Input/Output section for com-
plete description.
Rev. 1.4
45
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 4.1. Pin Definitions (Continued)
Pin Numbers
‘F120 ‘F121 ‘F130 ‘F131
‘F122 ‘F123 ‘F132 ‘F133
‘F124 ‘F125
Name
Type
Description
‘F126 ‘F127
ALE/P4.5
93
93
D I/O ALE Strobe for External Memory Address bus
(multiplexed mode)
Port 4.5
See Port Input/Output section for complete
description.
RD/P4.6
WR/P4.7
A8/P5.0
92
91
88
92
91
88
D I/O /RD Strobe for External Memory Address bus
Port 4.6
See Port Input/Output section for complete
description.
D I/O /WR Strobe for External Memory Address bus
Port 4.7
See Port Input/Output section for complete
description.
D I/O Bit 8 External Memory Address bus (Non-multi-
plexed mode)
Port 5.0
See Port Input/Output section for complete
description.
A9/P5.1
A10/P5.2
A11/P5.3
A12/P5.4
A13/P5.5
A14/P5.6
A15/P5.7
87
86
85
84
83
82
81
87
86
85
84
83
82
81
D I/O Port 5.1. See Port Input/Output section for com-
plete description.
D I/O Port 5.2. See Port Input/Output section for com-
plete description.
D I/O Port 5.3. See Port Input/Output section for com-
plete description.
D I/O Port 5.4. See Port Input/Output section for com-
plete description.
D I/O Port 5.5. See Port Input/Output section for com-
plete description.
D I/O Port 5.6. See Port Input/Output section for com-
plete description.
D I/O Port 5.7. See Port Input/Output section for com-
plete description.
46
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 4.1. Pin Definitions (Continued)
Pin Numbers
‘F120 ‘F121 ‘F130 ‘F131
‘F122 ‘F123 ‘F132 ‘F133
‘F124 ‘F125
Name
Type
Description
‘F126 ‘F127
A8m/A0/P6.0
80
80
D I/O Bit 8 External Memory Address bus (Multiplexed
mode)
Bit 0 External Memory Address bus (Non-multi-
plexed mode)
Port 6.0
See Port Input/Output section for complete
description.
A9m/A1/P6.1
A10m/A2/P6.2
A11m/A3/P6.3
A12m/A4/P6.4
A13m/A5/P6.5
A14m/A6/P6.6
A15m/A7/P6.7
AD0/D0/P7.0
79
78
77
76
75
74
73
72
79
78
77
76
75
74
73
72
D I/O Port 6.1. See Port Input/Output section for com-
plete description.
D I/O Port 6.2. See Port Input/Output section for com-
plete description.
D I/O Port 6.3. See Port Input/Output section for com-
plete description.
D I/O Port 6.4. See Port Input/Output section for com-
plete description.
D I/O Port 6.5. See Port Input/Output section for com-
plete description.
D I/O Port 6.6. See Port Input/Output section for com-
plete description.
D I/O Port 6.7. See Port Input/Output section for com-
plete description.
D I/O Bit 0 External Memory Address/Data bus (Multi-
plexed mode)
Bit 0 External Memory Data bus (Non-multi-
plexed mode)
Port 7.0
See Port Input/Output section for complete
description.
AD1/D1/P7.1
AD2/D2/P7.2
AD3/D3/P7.3
AD4/D4/P7.4
71
70
69
68
71
70
69
68
D I/O Port 7.1. See Port Input/Output section for com-
plete description.
D I/O Port 7.2. See Port Input/Output section for com-
plete description.
D I/O Port 7.3. See Port Input/Output section for com-
plete description.
D I/O Port 7.4. See Port Input/Output section for com-
plete description.
Rev. 1.4
47
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 4.1. Pin Definitions (Continued)
Pin Numbers
‘F120 ‘F121 ‘F130 ‘F131
‘F122 ‘F123 ‘F132 ‘F133
‘F124 ‘F125
Name
Type
Description
‘F126 ‘F127
AD5/D5/P7.5
AD6/D6/P7.6
AD7/D7/P7.7
NC
67
66
65
67
66
65
D I/O Port 7.5. See Port Input/Output section for com-
plete description.
D I/O Port 7.6. See Port Input/Output section for com-
plete description.
D I/O Port 7.7. See Port Input/Output section for com-
plete description.
15, 63, 64
No Connection.
17,
99,
100
48
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
TMS
TCK
1
2
3
4
5
6
7
8
9
75 A13m/A5/P6.5
74 A14m/A6/P6.6
73 A15m/A7/P6.7
72 AD0/D0/P7.0
71 AD1/D1/P7.1
70 AD2/D2/P7.2
69 AD3/D3/P7.3
68 AD4/D4/P7.4
67 AD5/D5/P7.5
66 AD6/D6/P7.6
TDI
TDO
/RST
CP1-
CP1+
CP0-
CP0+
AGND 10
AV+ 11
C8051F120
65 AD7/D7/P7.7
64 VDD
VREF 12
AGND 13
AV+ 14
C8051F122
C8051F124
C8051F126
63 DGND
62 P0.0
VREFD 15
VREF0 16
VREF2 17
AIN0.0 18
AIN0.1 19
AIN0.2 20
AIN0.3 21
AIN0.4 22
AIN0.5 23
AIN0.6 24
AIN0.7 25
61 P0.1
60 P0.2
59 P0.3
58 P0.4
57 ALE/P0.5
56 /RD/P0.6
55 /WR/P0.7
54 AD0/D0/P3.0
53 AD1/D1/P3.1
52 AD2/D2/P3.2
51 AD3/D3/P3.3
Figure 4.1. C8051F120/2/4/6 Pinout Diagram (TQFP-100)
Rev. 1.4
49
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
TMS
TCK
1
2
3
4
5
6
7
8
9
75 A13m/A5/P6.5
74 A14m/A6/P6.6
73 A15m/A7/P6.7
72 AD0/D0/P7.0
71 AD1/D1/P7.1
70 AD2/D2/P7.2
69 AD3/D3/P7.3
68 AD4/D4/P7.4
67 AD5/D5/P7.5
66 AD6/D6/P7.6
65 AD7/D7/P7.7
64 VDD
TDI
TDO
/RST
CP1-
CP1+
CP0-
CP0+
AGND 10
AV+ 11
VREF 12
AGND 13
AV+ 14
C8051F130
C8051F132
63 DGND
62 P0.0
NC 15
61 P0.1
VREF0 16
NC 17
60 P0.2
59 P0.3
AIN0.0 18
AIN0.1 19
AIN0.2 20
AIN0.3 21
AIN0.4 22
AIN0.5 23
AIN0.6 24
AIN0.7 25
58 P0.4
57 ALE/P0.5
56 /RD/P0.6
55 /WR/P0.7
54 AD0/D0/P3.0
53 AD1/D1/P3.1
52 AD2/D2/P3.2
51 AD3/D3/P3.3
Figure 4.2. C8051F130/2 Pinout Diagram (TQFP-100)
50
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
D
MIN NOM MAX
(mm) (mm) (mm)
D1
A
-
-
-
1.20
0.15
A1 0.05
A2 0.95 1.00 1.05
b
D
0.17 0.22 0.27
-
-
-
-
-
16.00
14.00
0.50
-
-
-
-
-
E1
E
D1
e
E
16.00
14.00
E1
L
100
0.45 0.60 0.75
PIN 1
DESIGNATOR
1
e
A2
L
A
b
A1
Figure 4.3. TQFP-100 Package Drawing
Rev. 1.4
51
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
CP1-
CP1+
CP0-
1
2
3
4
5
6
7
8
9
48 /WR/P0.7
47 AD0/D0/P3.0
46 AD1/D1/P3.1
45 AD2/D2/P3.2
44 AD3/D3/P3.3
43 AD4/D4/P3.4
42 AD5/D5/P3.5
41 VDD
CP0+
AGND
AV+
C8051F121
C8051F123
C8051F125
C8051F127
VREF
VREFA
AIN0.0
40 DGND
AIN0.1 10
AIN0.2 11
AIN0.3 12
AIN0.4 13
AIN0.5 14
AIN0.6 15
AIN0.7 16
39 AD6/D6/P3.6
38 AD7/D7/P3.7
37 A8m/A0/P2.0
36 A9m/A1/P2.1
35 A10m/A2/P2.2
34 A11m/A3/P2.3
33 A12m/A4/P2.4
Figure 4.4. C8051F121/3/5/7 Pinout Diagram (TQFP-64)
52
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
CP1-
CP1+
CP0-
1
2
3
4
5
6
7
8
9
48 /WR/P0.7
47 AD0/D0/P3.0
46 AD1/D1/P3.1
45 AD2/D2/P3.2
44 AD3/D3/P3.3
43 AD4/D4/P3.4
42 AD5/D5/P3.5
41 VDD
CP0+
AGND
AV+
VREF
VREF0
AIN0.0
C8051F131
C8051F133
40 DGND
AIN0.1 10
AIN0.2 11
AIN0.3 12
AIN0.4 13
AIN0.5 14
AIN0.6 15
AIN0.7 16
39 AD6/D6/P3.6
38 AD7/D7/P3.7
37 A8m/A0/P2.0
36 A9m/A1/P2.1
35 A10m/A2/P2.2
34 A11m/A3/P2.3
33 A12m/A4/P2.4
Figure 4.5. C8051F131/3 Pinout Diagram (TQFP-64)
Rev. 1.4
53
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
D
MIN NOM MAX
(mm) (mm) (mm)
D1
A
-
-
-
1.20
0.15
A1 0.05
A2 0.95 1.00 1.05
E1
E
b
D
0.17 0.22 0.27
-
-
-
-
-
12.00
10.00
0.50
-
-
-
-
-
D1
e
64
PIN 1
DESIGNATOR
E
12.00
10.00
1
e
A2
L
E1
L
A
0.45 0.60 0.75
b
A1
Figure 4.6. TQFP-64 Package Drawing
54
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
5. ADC0 (12-Bit ADC, C8051F120/1/4/5 Only)
The ADC0 subsystem for the C8051F120/1/4/5 consists of a 9-channel, configurable analog multiplexer
(AMUX0), a programmable gain amplifier (PGA0), and a 100 ksps, 12-bit successive-approximation-regis-
ter ADC with integrated track-and-hold and Programmable Window Detector (see block diagram in
Figure 5.1). The AMUX0, PGA0, Data Conversion Modes, and Window Detector are all configurable under
software control via the Special Function Registers shown in Figure 5.1. The voltage reference used by
ADC0 is selected as described in Section “9. Voltage Reference” on page 113. The ADC0 subsystem
(ADC0, track-and-hold and PGA0) is enabled only when the AD0EN bit in the ADC0 Control register
(ADC0CN) is set to logic 1. The ADC0 subsystem is in low power shutdown when this bit is logic 0.
ADC0GTH
+
ADC0GTL
ADC0LTH
ADC0LTL
24
Comb.
Logic
AD0WINT
12
AV+
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
AD0EN
AV+
-
+
-
9-to-1
AMUX
(SE or
DIFF)
12-Bit
SAR
+
+
12
X
-
-
+
ADC
AGND
-
TEMP
SENSOR
00
01
10
11
AD0BUSY (W)
Timer 3 Overflow
CNVSTR0
Start Conversion
AGND
Timer 2 Overflow
AMX0SL
AMX0CF
ADC0CF
ADC0CN
Figure 5.1. 12-Bit ADC0 Functional Block Diagram
5.1. Analog Multiplexer and PGA
Eight of the AMUX channels are available for external measurements while the ninth channel is internally
connected to an on-chip temperature sensor (temperature transfer function is shown in Figure 5.2). AMUX
input pairs can be programmed to operate in either differential or single-ended mode. This allows the user
to select the best measurement technique for each input channel, and even accommodates mode
changes "on-the-fly". The AMUX defaults to all single-ended inputs upon reset. There are two registers
associated with the AMUX: the Channel Selection register AMX0SL (SFR Definition 5.2), and the Configu-
ration register AMX0CF (SFR Definition 5.1). The table in SFR Definition 5.2 shows AMUX functionality by
channel, for each possible configuration. The PGA amplifies the AMUX output signal by an amount deter-
mined by the states of the AMP0GN2-0 bits in the ADC0 Configuration register, ADC0CF (SFR Definition
5.3). The PGA can be software-programmed for gains of 0.5, 2, 4, 8 or 16. Gain defaults to unity on reset.
Rev. 1.4
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The Temperature Sensor transfer function is shown in Figure 5.2. The output voltage (VTEMP) is the PGA
input when the Temperature Sensor is selected by bits AMX0AD3-0 in register AMX0SL; this voltage will
be amplified by the PGA according to the user-programmed PGA settings. Typical values for the Slope and
Offset parameters can be found in Table 5.1.
Slope (V / deg C)
Offset (V at 0 Celsius)
VTEMP = (Slope x TempC) + Offset
TempC = (VTEMP - Offset) / Slope
-50
0
50
100
Temperature (Celsius)
Figure 5.2. Typical Temperature Sensor Transfer Function
56
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5.2. ADC Modes of Operation
ADC0 has a maximum conversion speed of 100 ksps. The ADC0 conversion clock is derived from the sys-
tem clock divided by the value held in the ADCSC bits of register ADC0CF.
5.2.1. Starting a Conversion
A conversion can be initiated in one of four ways, depending on the programmed states of the ADC0 Start
of Conversion Mode bits (AD0CM1, AD0CM0) in ADC0CN. Conversions may be initiated by:
1. Writing a ‘1’ to the AD0BUSY bit of ADC0CN;
2. A Timer 3 overflow (i.e. timed continuous conversions);
3. A rising edge detected on the external ADC convert start signal, CNVSTR0;
4. A Timer 2 overflow (i.e. timed continuous conversions).
The AD0BUSY bit is set to logic 1 during conversion and restored to logic 0 when conversion is complete.
The falling edge of AD0BUSY triggers an interrupt (when enabled) and sets the AD0INT interrupt flag
(ADC0CN.5). Converted data is available in the ADC0 data word MSB and LSB registers, ADC0H, ADC0L.
Converted data can be either left or right justified in the ADC0H:ADC0L register pair (see example in
Figure 5.5) depending on the programmed state of the AD0LJST bit in the ADC0CN register.
When initiating conversions by writing a ‘1’ to AD0BUSY, the AD0INT bit should be polled to determine
when a conversion has completed (ADC0 interrupts may also be used). The recommended polling proce-
dure is shown below.
Step 1. Write a ‘0’ to AD0INT;
Step 2. Write a ‘1’ to AD0BUSY;
Step 3. Poll AD0INT for ‘1’;
Step 4. Process ADC0 data.
When CNVSTR0 is used as a conversion start source, it must be enabled in the crossbar, and the corre-
sponding pin must be set to open-drain, high-impedance mode (see Section “18. Port Input/Output” on
page 235 for more details on Port I/O configuration).
Rev. 1.4
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5.2.2. Tracking Modes
The AD0TM bit in register ADC0CN controls the ADC0 track-and-hold mode. In its default state, the ADC0
input is continuously tracked when a conversion is not in progress. When the AD0TM bit is logic 1, ADC0
operates in low-power track-and-hold mode. In this mode, each conversion is preceded by a tracking
period of 3 SAR clocks (after the start-of-conversion signal). When the CNVSTR0 signal is used to initiate
conversions in low-power tracking mode, ADC0 tracks only when CNVSTR0 is low; conversion begins on
the rising edge of CNVSTR0 (see Figure 5.3). Tracking can also be disabled (shutdown) when the entire
chip is in low power standby or sleep modes. Low-power track-and-hold mode is also useful when AMUX
or PGA settings are frequently changed, to ensure that settling time requirements are met (see Section
“5.2.3. Settling Time Requirements” on page 59).
A. ADC Timing for External Trigger Source
CNVSTR0
(AD0CM[1:0]=10)
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16
SAR Clocks
Low Power
or Convert
ADC0TM=1
ADC0TM=0
Track
Convert
Convert
Low Power Mode
Track
Track Or Convert
B. ADC Timing for Internal Trigger Sources
Timer 2, Timer 3 Overflow;
Write '1' to AD0BUSY
(AD0CM[1:0]=00, 01, 11)
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19
SAR Clocks
ADC0TM=1
Low Power
or Convert
Track
Convert
Low Power Mode
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16
SAR Clocks
ADC0TM=0
Track or
Convert
Convert
Track
Figure 5.3. ADC0 Track and Conversion Example Timing
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5.2.3. Settling Time Requirements
A minimum tracking time is required before an accurate conversion can be performed. This tracking time is
determined by the ADC0 MUX resistance, the ADC0 sampling capacitance, any external source resis-
tance, and the accuracy required for the conversion. Figure 5.4 shows the equivalent ADC0 input circuits
for both Differential and Single-ended modes. Notice that the equivalent time constant for both input cir-
cuits is the same. The required settling time for a given settling accuracy (SA) may be approximated by
Equation 5.1. When measuring the Temperature Sensor output, R
reduces to RMUX. An absolute
TOTAL
minimum settling time of 1.5 µs is required after any MUX or PGA selection. Note that in low-power track-
ing mode, three SAR clocks are used for tracking at the start of every conversion. For most applications,
these three SAR clocks will meet the tracking requirements.
2n
SA
------
t = ln
RTOTALCSAMPLE
Equation 5.1. ADC0 Settling Time Requirements
Where:
SA is the settling accuracy, given as a fraction of an LSB (for example, 0.25 to settle within 1/4 LSB)
t is the required settling time in seconds
RTOTAL is the sum of the ADC0 MUX resistance and any external source resistance.
n is the ADC resolution in bits (12).
Differential Mode
Single-Ended Mode
MUX Select
MUX Select
AIN0.x
AIN0.x
RMUX = 5k
RMUX = 5k
CSAMPLE = 10pF
CSAMPLE = 10pF
RCInput= RMUX * CSAMPLE
RCInput= RMUX * CSAMPLE
CSAMPLE = 10pF
AIN0.y
RMUX = 5k
MUX Select
Figure 5.4. ADC0 Equivalent Input Circuits
Rev. 1.4
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SFR Definition 5.1. AMX0CF: AMUX0 Configuration
SFR Page:
SFR Address:
0
0xBA
R/W
-
R/W
R/W
-
R/W
-
R/W
R/W
R/W
R/W
Reset Value
-
AIN67IC AIN45IC AIN23IC AIN01IC 00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bits7–4: UNUSED. Read = 0000b; Write = don’t care.
Bit3:
Bit2:
Bit1:
Bit0:
AIN67IC: AIN0.6, AIN0.7 Input Pair Configuration Bit.
0: AIN0.6 and AIN0.7 are independent single-ended inputs.
1: AIN0.6, AIN0.7 are (respectively) +, – differential input pair.
AIN45IC: AIN0.4, AIN0.5 Input Pair Configuration Bit.
0: AIN0.4 and AIN0.5 are independent single-ended inputs.
1: AIN0.4, AIN0.5 are (respectively) +, – differential input pair.
AIN23IC: AIN0.2, AIN0.3 Input Pair Configuration Bit.
0: AIN0.2 and AIN0.3 are independent single-ended inputs.
1: AIN0.2, AIN0.3 are (respectively) +, – differential input pair.
AIN01IC: AIN0.0, AIN0.1 Input Pair Configuration Bit.
0: AIN0.0 and AIN0.1 are independent single-ended inputs.
1: AIN0.0, AIN0.1 are (respectively) +, – differential input pair.
Note:
The ADC0 Data Word is in 2’s complement format for channels configured as differential.
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SFR Definition 5.2. AMX0SL: AMUX0 Channel Select
SFR Page:
SFR Address:
0
0xBB
R/W
-
R/W
R/W
-
R/W
-
R/W
R/W
R/W
R/W
Reset Value
-
AMX0AD3 AMX0AD2 AMX0AD1 AMX0AD0 00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bits7–4: UNUSED. Read = 0000b; Write = don’t care.
Bits3–0: AMX0AD3–0: AMX0 Address Bits.
0000-1111b: ADC Inputs selected per chart below.
AMX0AD3–0
0100
0000
0001
0010
0011
0101
0110
0111
1xxx
TEMP
SENSOR
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.4
AIN0.4
AIN0.4
AIN0.5
AIN0.6
AIN0.6
AIN0.6
AIN0.6
AIN0.6
AIN0.6
AIN0.6
AIN0.6
AIN0.7
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
+(AIN0.0)
–(AIN0.1)
TEMP
SENSOR
AIN0.2
AIN0.3
AIN0.5
AIN0.5
AIN0.5
AIN0.7
AIN0.7
AIN0.7
AIN0.7
AIN0.7
AIN0.7
AIN0.7
+(AIN0.2)
–(AIN0.3)
TEMP
SENSOR
AIN0.0
AIN0.1
AIN0.1
AIN0.1
AIN0.1
AIN0.1
AIN0.1
AIN0.1
+(AIN0.0)
–(AIN0.1)
+(AIN0.2)
–(AIN0.3)
TEMP
SENSOR
+(AIN0.4)
–(AIN0.5)
TEMP
SENSOR
AIN0.0
AIN0.2
AIN0.2
AIN0.3
AIN0.3
+(AIN0.0)
–(AIN0.1)
+(AIN0.4)
–(AIN0.5)
TEMP
SENSOR
+(AIN0.2)
–(AIN0.3)
+(AIN0.4)
–(AIN0.5)
TEMP
SENSOR
AIN0.0
+(AIN0.0)
–(AIN0.1)
+(AIN0.2)
–(AIN0.3)
+(AIN0.4)
–(AIN0.5)
TEMP
SENSOR
+(AIN0.6)
–(AIN0.7)
TEMP
SENSOR
AIN0.0
AIN0.2
AIN0.2
AIN0.3
AIN0.3
AIN0.4
AIN0.4
AIN0.4
AIN0.4
AIN0.5
AIN0.5
AIN0.5
AIN0.5
+(AIN0.0)
–(AIN0.1)
+(AIN0.6)
–(AIN0.7)
TEMP
SENSOR
+(AIN0.2)
–(AIN0.3)
+(AIN0.6)
–(AIN0.7)
TEMP
SENSOR
AIN0.0
+(AIN0.0)
–(AIN0.1)
+(AIN0.2)
–(AIN0.3)
+(AIN0.6)
–(AIN0.7)
TEMP
SENSOR
+(AIN0.4)
–(AIN0.5)
+(AIN0.6)
–(AIN0.7)
TEMP
SENSOR
AIN0.0
AIN0.2
AIN0.2
AIN0.3
AIN0.3
+(AIN0.0)
–(AIN0.1)
+(AIN0.4)
–(AIN0.5)
+(AIN0.6)
–(AIN0.7)
TEMP
SENSOR
+(AIN0.2)
–(AIN0.3)
+(AIN0.4)
–(AIN0.5)
+(AIN0.6)
–(AIN0.7)
TEMP
SENSOR
AIN0.0
+(AIN0.0)
–(AIN0.1)
+(AIN0.2)
–(AIN0.3)
+(AIN0.4)
–(AIN0.5)
+(AIN0.6)
–(AIN0.7)
TEMP
SENSOR
Rev. 1.4
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SFR Definition 5.3. ADC0CF: ADC0 Configuration
SFR Page:
SFR Address:
0
0xBC
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
AD0SC4 AD0SC3 AD0SC2 AD0SC1 AD0SC0 AMP0GN2 AMP0GN1 AMP0GN0 11111000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bits7–3: AD0SC4–0: ADC0 SAR Conversion Clock Period Bits.
The SAR Conversion clock is derived from system clock by the following equation, where
AD0SC refers to the 5-bit value held in AD0SC4-0, and CLKSAR0 refers to the desired ADC0
SAR clock (Note: the ADC0 SAR Conversion Clock should be less than or equal to
2.5 MHz).
SYSCLK
2 CLKSAR0
-------------------------------
AD0SC =
– 1
AD0SC 00000b
When the AD0SC bits are equal to 00000b, the SAR Conversion clock is equal to SYSCLK
to facilitate faster ADC conversions at slower SYSCLK speeds.
Bits2–0: AMP0GN2–0: ADC0 Internal Amplifier Gain (PGA).
000: Gain = 1
001: Gain = 2
010: Gain = 4
011: Gain = 8
10x: Gain = 16
11x: Gain = 0.5
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SFR Definition 5.4. ADC0CN: ADC0 Control
SFR Page:
SFR Address:
0
0xE8
(bit addressable)
R/W
AD0EN
Bit7
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
AD0TM AD0INT AD0BUSY AD0CM1 AD0CM0 AD0WINT AD0LJST 00000000
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit7:
Bit6:
Bit5:
AD0EN: ADC0 Enable Bit.
0: ADC0 Disabled. ADC0 is in low-power shutdown.
1: ADC0 Enabled. ADC0 is active and ready for data conversions.
AD0TM: ADC Track Mode Bit.
0: When the ADC is enabled, tracking is continuous unless a conversion is in process.
1: Tracking Defined by ADCM1-0 bits.
AD0INT: ADC0 Conversion Complete Interrupt Flag.
This flag must be cleared by software.
0: ADC0 has not completed a data conversion since the last time this flag was cleared.
1: ADC0 has completed a data conversion.
AD0BUSY: ADC0 Busy Bit.
Bit4:
Read:
0: ADC0 Conversion is complete or a conversion is not currently in progress. AD0INT is set
to logic 1 on the falling edge of AD0BUSY.
1: ADC0 Conversion is in progress.
Write:
0: No Effect.
1: Initiates ADC0 Conversion if AD0CM1-0 = 00b.
Bits3–2: AD0CM1–0: ADC0 Start of Conversion Mode Select.
If AD0TM = 0:
00: ADC0 conversion initiated on every write of ‘1’ to AD0BUSY.
01: ADC0 conversion initiated on overflow of Timer 3.
10: ADC0 conversion initiated on rising edge of external CNVSTR0.
11: ADC0 conversion initiated on overflow of Timer 2.
If AD0TM = 1:
00: Tracking starts with the write of ‘1’ to AD0BUSY and lasts for 3 SAR clocks, followed by
conversion.
01: Tracking started by the overflow of Timer 3 and lasts for 3 SAR clocks, followed by con-
version.
10: ADC0 tracks only when CNVSTR0 input is logic low; conversion starts on rising
CNVSTR0 edge.
11: Tracking started by the overflow of Timer 2 and lasts for 3 SAR clocks, followed by con-
version.
Bit1:
Bit0:
AD0WINT: ADC0 Window Compare Interrupt Flag.
This bit must be cleared by software.
0: ADC0 Window Comparison Data match has not occurred since this flag was last cleared.
1: ADC0 Window Comparison Data match has occurred.
AD0LJST: ADC0 Left Justify Select.
0: Data in ADC0H:ADC0L registers are right-justified.
1: Data in ADC0H:ADC0L registers are left-justified.
Rev. 1.4
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SFR Definition 5.5. ADC0H: ADC0 Data Word MSB
SFR Page:
SFR Address:
0
0xBF
R/W
Bit7
R/W
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
Bit6
Bits7–0: ADC0 Data Word High-Order Bits.
For AD0LJST = 0: Bits 7–4 are the sign extension of Bit3. Bits 3–0 are the upper 4 bits of the
12-bit ADC0 Data Word.
For AD0LJST = 1: Bits 7–0 are the most-significant bits of the 12-bit ADC0 Data Word.
SFR Definition 5.6. ADC0L: ADC0 Data Word LSB
SFR Page:
SFR Address:
0
0xBE
R/W
R/W
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
Bit7
Bit6
Bits7–0: ADC0 Data Word Low-Order Bits.
For AD0LJST = 0: Bits 7–0 are the lower 8 bits of the 12-bit ADC0 Data Word.
For AD0LJST = 1: Bits 7–4 are the lower 4 bits of the 12-bit ADC0 Data Word. Bits 3–0 will
always read ‘0’.
64
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12-bit ADC0 Data Word appears in the ADC0 Data Word Registers as follows:
ADC0H[3:0]:ADC0L[7:0], if AD0LJST = 0
(ADC0H[7:4] will be sign-extension of ADC0H.3 for a differential reading, otherwise
=
0000b).
ADC0H[7:0]:ADC0L[7:4], if AD0LJST = 1
(ADC0L[3:0] = 0000b).
Example: ADC0 Data Word Conversion Map, AIN0.0 Input in Single-Ended Mode
(AMX0CF = 0x00, AMX0SL = 0x00)
AIN0.0–AGND
(Volts)
ADC0H:ADC0L
(AD0LJST = 0)
ADC0H:ADC0L
(AD0LJST = 1)
VREF x (4095/4096)
VREF / 2
0x0FFF
0x0800
0x07FF
0x0000
0xFFF0
0x8000
0x7FF0
0x0000
VREF x (2047/4096)
0
Example: ADC0 Data Word Conversion Map, AIN0.0-AIN0.1 Differential Input Pair
(AMX0CF = 0x01, AMX0SL = 0x00)
AIN0.0–AIN0.1
(Volts)
ADC0H:ADC0L
(AD0LJST = 0)
ADC0H:ADC0L
(AD0LJST = 1)
VREF x (2047/2048)
VREF / 2
0x07FF
0x0400
0x7FF0
0x4000
0x0010
0x0000
0xFFF0
0xC000
0x8000
VREF x (1/2048)
0
0x0001
0x0000
–VREF x (1/2048)
–VREF / 2
0xFFFF (–1d)
0xFC00 (–1024d)
0xF800 (–2048d)
–VREF
For AD0LJST = 0:
Gain
---------------
n
Code = Vin
2 ; ‘n’ = 12 for Single-Ended; ‘n’=11 for Differential.
VREF
Figure 5.5. ADC0 Data Word Example
Rev. 1.4
65
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C8051F130/1/2/3
5.3. ADC0 Programmable Window Detector
The ADC0 Programmable Window Detector continuously compares the ADC0 output to user-programmed
limits, and notifies the system when an out-of-bound condition is detected. This is especially effective in an
interrupt-driven system, saving code space and CPU bandwidth while delivering faster system response
times. The window detector interrupt flag (AD0WINT in ADC0CN) can also be used in polled mode. The
high and low bytes of the reference words are loaded into the ADC0 Greater-Than and ADC0 Less-Than
registers (ADC0GTH, ADC0GTL, ADC0LTH, and ADC0LTL). Reference comparisons are shown starting
on page 68. Notice that the window detector flag can be asserted when the measured data is inside or out-
side the user-programmed limits, depending on the programming of the ADC0GTx and ADC0LTx regis-
ters.
SFR Definition 5.7. ADC0GTH: ADC0 Greater-Than Data High Byte
SFR Page:
SFR Address:
0
0xC5
R/W
Bit7
R/W
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
11111111
Bit6
Bits7–0: High byte of ADC0 Greater-Than Data Word.
SFR Definition 5.8. ADC0GTL: ADC0 Greater-Than Data Low Byte
SFR Page:
SFR Address:
0
0xC4
R/W
R/W
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
11111111
Bit7
Bit6
Bits7–0: Low byte of ADC0 Greater-Than Data Word.
66
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SFR Definition 5.9. ADC0LTH: ADC0 Less-Than Data High Byte
SFR Page:
SFR Address:
0
0xC7
R/W
Bit7
R/W
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
Bit6
Bits7–0: High byte of ADC0 Less-Than Data Word.
SFR Definition 5.10. ADC0LTL: ADC0 Less-Than Data Low Byte
SFR Page:
SFR Address:
0
0xC6
R/W
R/W
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
Bit7
Bit6
Bits7–0: Low byte of ADC0 Less-Than Data Word.
Rev. 1.4
67
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C8051F130/1/2/3
Input Voltage
ADC Data
Input Voltage
(AD0.0 - AGND)
ADC Data
Word
(AD0.0 - AGND)
Word
REF x (4095/4096)
0x0FFF
REF x (4095/4096)
0x0FFF
AD0WINT
not affected
AD0WINT=1
0x0201
0x0201
REF x (512/4096)
REF x (256/4096)
0x0200
0x01FF
ADC0LTH:ADC0LTL
AD0WINT=1
REF x (512/4096)
REF x (256/4096)
0x0200
0x01FF
ADC0GTH:ADC0GTL
AD0WINT
not affected
0x0101
0x0100
0x0101
0x0100
ADC0GTH:ADC0GTL
ADC0LTH:ADC0LTL
0x00FF
0x00FF
AD0WINT=1
AD0WINT
not affected
0x0000
0x0000
0
0
Given:
Given:
AMX0SL = 0x00, AMX0CF = 0x00
AD0LJST = ‘0’,
AMX0SL = 0x00, AMX0CF = 0x00,
AD0LJST = ‘0’,
ADC0LTH:ADC0LTL = 0x0200,
ADC0GTH:ADC0GTL = 0x0100.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x0200 and > 0x0100.
ADC0LTH:ADC0LTL = 0x0100,
ADC0GTH:ADC0GTL = 0x0200.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
> 0x0200 or < 0x0100.
Figure 5.6. 12-Bit ADC0 Window Interrupt Example: Right Justified Single-Ended
Data
68
Rev. 1.4
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C8051F130/1/2/3
Input Voltage
(AD0.0 - AD0.1)
Input Voltage
ADC Data
ADC Data
Word
(AD0.0 - AD0.1)
Word
REF x (2047/2048)
0x07FF
REF x (2047/2048)
0x07FF
AD0WINT
not affected
AD0WINT=1
0x0101
0x0101
REF x (256/2048)
REF x (-1/2048)
0x0100
0x00FF
ADC0LTH:ADC0LTL
AD0WINT=1
REF x (256/2048)
REF x (-1/2048)
0x0100
0x00FF
ADC0GTH:ADC0GTL
AD0WINT
not affected
0x0000
0xFFFF
0x0000
0xFFFF
ADC0GTH:ADC0GTL
ADC0LTH:ADC0LTL
AD0WINT=1
0xFFFE
0xFFFE
AD0WINT
not affected
0xF800
0xF800
-REF
-REF
Given:
Given:
AMX0SL = 0x00, AMX0CF = 0x01,
AD0LJST = ‘0’,
AMX0SL = 0x00, AMX0CF = 0x01,
AD0LJST = ‘0’,
ADC0LTH:ADC0LTL = 0x0100,
ADC0GTH:ADC0GTL = 0xFFFF.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x0100 and > 0xFFFF. (In 2s-complement
math, 0xFFFF = -1.)
ADC0LTH:ADC0LTL = 0xFFFF,
ADC0GTH:ADC0GTL = 0x0100.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0xFFFF or > 0x0100. (In 2s-complement
math, 0xFFFF = -1.)
Figure 5.7. 12-Bit ADC0 Window Interrupt Example: Right Justified Differential
Data
Rev. 1.4
69
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C8051F130/1/2/3
Input Voltage
ADC Data
Input Voltage
(AD0.0 - AGND)
ADC Data
Word
(AD0.0 - AGND)
Word
REF x (4095/4096)
0xFFF0
REF x (4095/4096)
0xFFF0
AD0WINT
not affected
AD0WINT=1
0x2010
0x2010
REF x (512/4096)
REF x (256/4096)
0x2000
0x1FF0
ADC0LTH:ADC0LTL
AD0WINT=1
REF x (512/4096)
REF x (256/4096)
0x2000
0x1FF0
ADC0GTH:ADC0GTL
AD0WINT
not affected
0x1010
0x1000
0x1010
0x1000
ADC0GTH:ADC0GTL
ADC0LTH:ADC0LTL
AD0WINT=1
0x0FF0
0x0FF0
AD0WINT
not affected
0x0000
0x0000
0
0
Given:
Given:
AMX0SL = 0x00, AMX0CF = 0x00,
AD0LJST = ‘1’,
AMX0SL = 0x00, AMX0CF = 0x00,
AD0LJST = ‘1’
ADC0LTH:ADC0LTL = 0x2000,
ADC0GTH:ADC0GTL = 0x1000.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x2000 and > 0x1000.
ADC0LTH:ADC0LTL = 0x1000,
ADC0GTH:ADC0GTL = 0x2000.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x1000 or > 0x2000.
Figure 5.8. 12-Bit ADC0 Window Interrupt Example: Left Justified Single-Ended
Data
70
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Input Voltage
(AD0.0 - AD0.1)
Input Voltage
ADC Data
ADC Data
Word
(AD0.0 - AD0.1)
Word
REF x (2047/2048)
0x7FF0
REF x (2047/2048)
0x7FF0
AD0WINT
not affected
AD0WINT=1
0x1010
0x1010
REF x (256/2048)
REF x (-1/2048)
0x1000
0x0FF0
ADC0LTH:ADC0LTL
AD0WINT=1
REF x (256/2048)
REF x (-1/2048)
0x1000
0x0FF0
ADC0GTH:ADC0GTL
AD0WINT
not affected
0x0000
0xFFF0
0x0000
0xFFF0
ADC0GTH:ADC0GTL
ADC0LTH:ADC0LTL
0xFFE0
0xFFE0
AD0WINT=1
AD0WINT
not affected
0x8000
0x8000
-REF
-REF
Given:
Given:
AMX0SL = 0x00, AMX0CF = 0x01,
AD0LJST = ‘1’,
AMX0SL = 0x00, AMX0CF = 0x01,
AD0LJST = ‘1’,
ADC0LTH:ADC0LTL = 0x1000,
ADC0GTH:ADC0GTL = 0xFFF0.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x1000 and > 0xFFF0. (2s-complement
math.)
ADC0LTH:ADC0LTL = 0xFFF0,
ADC0GTH:ADC0GTL = 0x1000.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0xFFF0 or > 0x1000. (2s-complement math.)
Figure 5.9. 12-Bit ADC0 Window Interrupt Example: Left Justified Differential Data
Rev. 1.4
71
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C8051F130/1/2/3
Table 5.1. 12-Bit ADC0 Electrical Characteristics (C8051F120/1/4/5)
VDD = 3.0 V, AV+ = 3.0 V, VREF = 2.40 V (REFBE = 0), PGA Gain = 1, –40 to +85 °C unless otherwise specified.
Parameter
Conditions
Min
Typ
Max
Units
DC Accuracy
Resolution
12
—
bits
LSB
Integral Nonlinearity
Differential Nonlinearity
Offset Error
—
—
—
—
—
±1
±1
—
—
—
Guaranteed Monotonic
Differential mode
—
LSB
–3±1
–7±3
±0.25
LSB
Full Scale Error
LSB
Offset Temperature Coefficient
ppm/°C
Dynamic Performance (10 kHz sine-wave input, 0 to 1 dB below Full Scale, 100 ksps
Signal-to-Noise Plus Distortion
Total Harmonic Distortion
66
—
—
—
–75
80
—
—
—
dB
dB
dB
Up to the 5th harmonic
Spurious-Free Dynamic Range
Conversion Rate
SAR Clock Frequency
—
16
1.5
—
—
—
—
—
2.5
—
MHz
clocks
µs
Conversion Time in SAR Clocks
Track/Hold Acquisition Time
Throughput Rate
—
100
ksps
Analog Inputs
Input Voltage Range
Single-ended operation
0
AGND
—
—
—
10
VREF
AV+
—
V
V
*Common-mode Voltage Range Differential operation
Input Capacitance
pF
Temperature Sensor
Linearity1
Offset
—
—
—
—
—
±0.2
776
—
—
—
—
—
°C
mV
(Temp = 0 °C)
(Temp = 0 °C)
Offset Error1, 2
Slope
±8.5
mV
2.86
mV / °C
mV / °C
Slope Error2
±0.034
Power Specifications
Operating Mode, 100 ksps
Power Supply Current
(AV+ supplied to ADC)
—
—
450
900
—
µA
Power Supply Rejection
±0.3
mV/V
Notes:
1. Includes ADC offset, gain, and linearity variations.
2. Represents one standard deviation from the mean.
72
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C8051F130/1/2/3
6. ADC0 (10-Bit ADC, C8051F122/3/6/7 and C8051F13x Only)
The ADC0 subsystem for the C8051F122/3/6/7 and C8051F13x consists of a 9-channel, configurable ana-
log multiplexer (AMUX0), a programmable gain amplifier (PGA0), and a 100 ksps, 10-bit successive-
approximation-register ADC with integrated track-and-hold and Programmable Window Detector (see
block diagram in Figure 6.1). The AMUX0, PGA0, Data Conversion Modes, and Window Detector are all
configurable under software control via the Special Function Registers shown in Figure 6.1. The voltage
reference used by ADC0 is selected as described in Section “9. Voltage Reference” on page 113. The
ADC0 subsystem (ADC0, track-and-hold and PGA0) is enabled only when the AD0EN bit in the ADC0
Control register (ADC0CN) is set to logic 1. The ADC0 subsystem is in low power shutdown when this bit is
logic 0.
ADC0GTH
+
ADC0GTL
ADC0LTH
ADC0LTL
20
Comb.
Logic
AD0WINT
10
AV+
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
AD0EN
AV+
-
+
-
9-to-1
AMUX
(SE or
DIFF)
10-Bit
SAR
+
+
10
X
-
-
+
ADC
AGND
-
TEMP
SENSOR
00
01
10
11
AD0BUSY (W)
Timer 3 Overflow
CNVSTR0
Start Conversion
AGND
Timer 2 Overflow
AMX0SL
AMX0CF
ADC0CF
ADC0CN
Figure 6.1. 10-Bit ADC0 Functional Block Diagram
6.1. Analog Multiplexer and PGA
Eight of the AMUX channels are available for external measurements while the ninth channel is internally
connected to an on-chip temperature sensor (temperature transfer function is shown in Figure 6.2). AMUX
input pairs can be programmed to operate in either differential or single-ended mode. This allows the user
to select the best measurement technique for each input channel, and even accommodates mode
changes "on-the-fly". The AMUX defaults to all single-ended inputs upon reset. There are two registers
associated with the AMUX: the Channel Selection register AMX0SL (SFR Definition 6.2), and the Configu-
ration register AMX0CF (SFR Definition 6.1). The table in SFR Definition 6.2 shows AMUX functionality by
channel, for each possible configuration. The PGA amplifies the AMUX output signal by an amount deter-
mined by the states of the AMP0GN2-0 bits in the ADC0 Configuration register, ADC0CF (SFR Definition
6.3). The PGA can be software-programmed for gains of 0.5, 2, 4, 8 or 16. Gain defaults to unity on reset.
Rev. 1.4
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C8051F130/1/2/3
The Temperature Sensor transfer function is shown in Figure 6.2. The output voltage (VTEMP) is the PGA
input when the Temperature Sensor is selected by bits AMX0AD3-0 in register AMX0SL; this voltage will
be amplified by the PGA according to the user-programmed PGA settings. Typical values for the Slope and
Offset parameters can be found in Table 6.1.
Slope (V / deg C)
Offset (V at 0 Celsius)
VTEMP = (Slope x TempC) + Offset
TempC = (VTEMP - Offset) / Slope
-50
0
50
100
Temperature (Celsius)
Figure 6.2. Typical Temperature Sensor Transfer Function
74
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C8051F130/1/2/3
6.2. ADC Modes of Operation
ADC0 has a maximum conversion speed of 100 ksps. The ADC0 conversion clock is derived from the sys-
tem clock divided by the value held in the ADCSC bits of register ADC0CF.
6.2.1. Starting a Conversion
A conversion can be initiated in one of four ways, depending on the programmed states of the ADC0 Start
of Conversion Mode bits (AD0CM1, AD0CM0) in ADC0CN. Conversions may be initiated by:
1. Writing a ‘1’ to the AD0BUSY bit of ADC0CN;
2. A Timer 3 overflow (i.e. timed continuous conversions);
3. A rising edge detected on the external ADC convert start signal, CNVSTR0;
4. A Timer 2 overflow (i.e. timed continuous conversions).
The AD0BUSY bit is set to logic 1 during conversion and restored to logic 0 when conversion is complete.
The falling edge of AD0BUSY triggers an interrupt (when enabled) and sets the AD0INT interrupt flag
(ADC0CN.5). Converted data is available in the ADC0 data word MSB and LSB registers, ADC0H, ADC0L.
Converted data can be either left or right justified in the ADC0H:ADC0L register pair (see example in
Figure 6.5) depending on the programmed state of the AD0LJST bit in the ADC0CN register.
When initiating conversions by writing a ‘1’ to AD0BUSY, the AD0INT bit should be polled to determine
when a conversion has completed (ADC0 interrupts may also be used). The recommended polling proce-
dure is shown below.
Step 1. Write a ‘0’ to AD0INT;
Step 2. Write a ‘1’ to AD0BUSY;
Step 3. Poll AD0INT for ‘1’;
Step 4. Process ADC0 data.
When CNVSTR0 is used as a conversion start source, it must be enabled in the crossbar, and the corre-
sponding pin must be set to open-drain, high-impedance mode (see Section “18. Port Input/Output” on
page 235 for more details on Port I/O configuration).
Rev. 1.4
75
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C8051F130/1/2/3
6.2.2. Tracking Modes
The AD0TM bit in register ADC0CN controls the ADC0 track-and-hold mode. In its default state, the ADC0
input is continuously tracked when a conversion is not in progress. When the AD0TM bit is logic 1, ADC0
operates in low-power track-and-hold mode. In this mode, each conversion is preceded by a tracking
period of 3 SAR clocks (after the start-of-conversion signal). When the CNVSTR0 signal is used to initiate
conversions in low-power tracking mode, ADC0 tracks only when CNVSTR0 is low; conversion begins on
the rising edge of CNVSTR0 (see Figure 6.3). Tracking can also be disabled (shutdown) when the entire
chip is in low power standby or sleep modes. Low-power track-and-hold mode is also useful when AMUX
or PGA settings are frequently changed, to ensure that settling time requirements are met (see Section
“6.2.3. Settling Time Requirements” on page 77).
A. ADC Timing for External Trigger Source
CNVSTR0
(AD0CM[1:0]=10)
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16
SAR Clocks
Low Power
or Convert
ADC0TM=1
ADC0TM=0
Track
Convert
Convert
Low Power Mode
Track
Track Or Convert
B. ADC Timing for Internal Trigger Sources
Timer 2, Timer 3 Overflow;
Write '1' to AD0BUSY
(AD0CM[1:0]=00, 01, 11)
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19
SAR Clocks
ADC0TM=1
Low Power
or Convert
Track
Convert
Low Power Mode
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16
SAR Clocks
ADC0TM=0
Track or
Convert
Convert
Track
Figure 6.3. ADC0 Track and Conversion Example Timing
76
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C8051F130/1/2/3
6.2.3. Settling Time Requirements
A minimum tracking time is required before an accurate conversion can be performed. This tracking time is
determined by the ADC0 MUX resistance, the ADC0 sampling capacitance, any external source resis-
tance, and the accuracy required for the conversion. Figure 6.4 shows the equivalent ADC0 input circuits
for both Differential and Single-ended modes. Notice that the equivalent time constant for both input cir-
cuits is the same. The required settling time for a given settling accuracy (SA) may be approximated by
Equation 6.1. When measuring the Temperature Sensor output, R
reduces to RMUX. An absolute
TOTAL
minimum settling time of 1.5 µs is required after any MUX or PGA selection. Note that in low-power track-
ing mode, three SAR clocks are used for tracking at the start of every conversion. For most applications,
these three SAR clocks will meet the tracking requirements.
2n
SA
------
t = ln
RTOTALCSAMPLE
Equation 6.1. ADC0 Settling Time Requirements
Where:
SA is the settling accuracy, given as a fraction of an LSB (for example, 0.25 to settle within 1/4 LSB)
t is the required settling time in seconds
RTOTAL is the sum of the ADC0 MUX resistance and any external source resistance.
n is the ADC resolution in bits (10).
Differential Mode
Single-Ended Mode
MUX Select
MUX Select
AIN0.x
AIN0.x
RMUX = 5k
RMUX = 5k
CSAMPLE = 10pF
CSAMPLE = 10pF
RCInput= RMUX * CSAMPLE
RCInput= RMUX * CSAMPLE
CSAMPLE = 10pF
AIN0.y
RMUX = 5k
MUX Select
Figure 6.4. ADC0 Equivalent Input Circuits
Rev. 1.4
77
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C8051F130/1/2/3
SFR Definition 6.1. AMX0CF: AMUX0 Configuration
SFR Page:
SFR Address:
0
0xBA
R/W
-
R/W
R/W
-
R/W
-
R/W
R/W
R/W
R/W
Reset Value
-
AIN67IC AIN45IC AIN23IC AIN01IC 00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bits7–4: UNUSED. Read = 0000b; Write = don’t care.
Bit3:
Bit2:
Bit1:
Bit0:
AIN67IC: AIN0.6, AIN0.7 Input Pair Configuration Bit.
0: AIN0.6 and AIN0.7 are independent single-ended inputs.
1: AIN0.6, AIN0.7 are (respectively) +, - differential input pair.
AIN45IC: AIN0.4, AIN0.5 Input Pair Configuration Bit.
0: AIN0.4 and AIN0.5 are independent single-ended inputs.
1: AIN0.4, AIN0.5 are (respectively) +, - differential input pair.
AIN23IC: AIN0.2, AIN0.3 Input Pair Configuration Bit.
0: AIN0.2 and AIN0.3 are independent single-ended inputs.
1: AIN0.2, AIN0.3 are (respectively) +, - differential input pair.
AIN01IC: AIN0.0, AIN0.1 Input Pair Configuration Bit.
0: AIN0.0 and AIN0.1 are independent single-ended inputs.
1: AIN0.0, AIN0.1 are (respectively) +, - differential input pair.
Note: The ADC0 Data Word is in 2’s complement format for channels configured as differential.
78
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C8051F130/1/2/3
SFR Definition 6.2. AMX0SL: AMUX0 Channel Select
SFR Page:
SFR Address:
0
0xBB
R/W
-
R/W
R/W
-
R/W
-
R/W
R/W
R/W
R/W
Reset Value
-
AMX0AD3 AMX0AD2 AMX0AD1 AMX0AD0 00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bits7–4: UNUSED. Read = 0000b; Write = don’t care.
Bits3–0: AMX0AD3–0: AMX0 Address Bits.
0000-1111b: ADC Inputs selected per chart below.
AMX0AD3-0
0100
0000
0001
0010
0011
0101
0110
0111
1xxx
TEMP
SENSOR
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.4
AIN0.4
AIN0.4
AIN0.5
AIN0.6
AIN0.6
AIN0.6
AIN0.6
AIN0.6
AIN0.6
AIN0.6
AIN0.6
AIN0.7
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
+(AIN0.0)
–(AIN0.1)
TEMP
SENSOR
AIN0.2
AIN0.3
AIN0.5
AIN0.5
AIN0.5
AIN0.7
AIN0.7
AIN0.7
AIN0.7
AIN0.7
AIN0.7
AIN0.7
+(AIN0.2)
–(AIN0.3)
TEMP
SENSOR
AIN0.0
AIN0.1
AIN0.1
AIN0.1
AIN0.1
AIN0.1
AIN0.1
AIN0.1
+(AIN0.0)
–(AIN0.1)
+(AIN0.2)
–(AIN0.3)
TEMP
SENSOR
+(AIN0.4)
–(AIN0.5)
TEMP
SENSOR
AIN0.0
AIN0.2
AIN0.2
AIN0.3
AIN0.3
+(AIN0.0)
–(AIN0.1)
+(AIN0.4)
–(AIN0.5)
TEMP
SENSOR
+(AIN0.2)
–(AIN0.3)
+(AIN0.4)
–(AIN0.5)
TEMP
SENSOR
AIN0.0
+(AIN0.0)
–(AIN0.1)
+(AIN0.2)
–(AIN0.3)
+(AIN0.4)
–(AIN0.5)
TEMP
SENSOR
+(AIN0.6)
–(AIN0.7)
TEMP
SENSOR
AIN0.0
AIN0.2
AIN0.2
AIN0.3
AIN0.3
AIN0.4
AIN0.4
AIN0.4
AIN0.4
AIN0.5
AIN0.5
AIN0.5
AIN0.5
+(AIN0.0)
–(AIN0.1)
+(AIN0.6)
–(AIN0.7)
TEMP
SENSOR
+(AIN0.2)
–(AIN0.3)
+(AIN0.6)
–(AIN0.7)
TEMP
SENSOR
AIN0.0
+(AIN0.0)
–(AIN0.1)
+(AIN0.2)
–(AIN0.3)
+(AIN0.6)
–(AIN0.7)
TEMP
SENSOR
+(AIN0.4)
–(AIN0.5)
+(AIN0.6)
–(AIN0.7)
TEMP
SENSOR
AIN0.0
AIN0.2
AIN0.2
AIN0.3
AIN0.3
+(AIN0.0)
–(AIN0.1)
+(AIN0.4)
–(AIN0.5)
+(AIN0.6)
–(AIN0.7)
TEMP
SENSOR
+(AIN0.2)
–(AIN0.3)
+(AIN0.4)
–(AIN0.5)
+(AIN0.6)
–(AIN0.7)
TEMP
SENSOR
AIN0.0
+(AIN0.0)
–(AIN0.1)
+(AIN0.2)
–(AIN0.3)
+(AIN0.4)
–(AIN0.5)
+(AIN0.6)
–(AIN0.7)
TEMP
SENSOR
Rev. 1.4
79
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C8051F130/1/2/3
SFR Definition 6.3. ADC0CF: ADC0 Configuration
SFR Page:
SFR Address:
0
0xBC
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
AD0SC4 AD0SC3 AD0SC2 AD0SC1 AD0SC0 AMP0GN2 AMP0GN1 AMP0GN0 11111000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bits7–3: AD0SC4–0: ADC0 SAR Conversion Clock Period Bits.
SAR Conversion clock is derived from system clock by the following equation, where
AD0SC refers to the 5-bit value held in AD0SC4-0, and CLKSAR0 refers to the desired ADC0
SAR clock (Note: the ADC0 SAR Conversion Clock should be less than or equal to
2.5 MHz).
SYSCLK
2 CLKSAR0
-------------------------------
AD0SC =
– 1
AD0SC 00000b
When the AD0SC bits are equal to 00000b, the SAR Conversion clock is equal to SYSCLK
to facilitate faster ADC conversions at slower SYSCLK speeds.
Bits2–0: AMP0GN2–0: ADC0 Internal Amplifier Gain (PGA).
000: Gain = 1
001: Gain = 2
010: Gain = 4
011: Gain = 8
10x: Gain = 16
11x: Gain = 0.5
80
Rev. 1.4
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C8051F130/1/2/3
SFR Definition 6.4. ADC0CN: ADC0 Control
SFR Page:
SFR Address:
0
0xE8
(bit addressable)
R/W
AD0EN
Bit7
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
AD0TM AD0INT AD0BUSY AD0CM1 AD0CM0 AD0WINT AD0LJST 00000000
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit7:
Bit6:
Bit5:
AD0EN: ADC0 Enable Bit.
0: ADC0 Disabled. ADC0 is in low-power shutdown.
1: ADC0 Enabled. ADC0 is active and ready for data conversions.
AD0TM: ADC Track Mode Bit.
0: When the ADC is enabled, tracking is continuous unless a conversion is in process.
1: Tracking Defined by ADCM1-0 bits.
AD0INT: ADC0 Conversion Complete Interrupt Flag.
This flag must be cleared by software.
0: ADC0 has not completed a data conversion since the last time this flag was cleared.
1: ADC0 has completed a data conversion.
AD0BUSY: ADC0 Busy Bit.
Bit4:
Read:
0: ADC0 Conversion is complete or a conversion is not currently in progress. AD0INT is set
to logic 1 on the falling edge of AD0BUSY.
1: ADC0 Conversion is in progress.
Write:
0: No Effect.
1: Initiates ADC0 Conversion if AD0CM1-0 = 00b.
Bits3–2: AD0CM1–0: ADC0 Start of Conversion Mode Select.
If AD0TM = 0:
00: ADC0 conversion initiated on every write of ‘1’ to AD0BUSY.
01: ADC0 conversion initiated on overflow of Timer 3.
10: ADC0 conversion initiated on rising edge of external CNVSTR0.
11: ADC0 conversion initiated on overflow of Timer 2.
If AD0TM = 1:
00: Tracking starts with the write of ‘1’ to AD0BUSY and lasts for 3 SAR clocks, followed by
conversion.
01: Tracking started by the overflow of Timer 3 and lasts for 3 SAR clocks, followed by con-
version.
10: ADC0 tracks only when CNVSTR0 input is logic low; conversion starts on rising
CNVSTR0 edge.
11: Tracking started by the overflow of Timer 2 and lasts for 3 SAR clocks, followed by con-
version.
Bit1:
Bit0:
AD0WINT: ADC0 Window Compare Interrupt Flag.
This bit must be cleared by software.
0: ADC0 Window Comparison Data match has not occurred since this flag was last cleared.
1: ADC0 Window Comparison Data match has occurred.
AD0LJST: ADC0 Left Justify Select.
0: Data in ADC0H:ADC0L registers are right-justified.
1: Data in ADC0H:ADC0L registers are left-justified.
Rev. 1.4
81
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 6.5. ADC0H: ADC0 Data Word MSB
SFR Page:
SFR Address:
0
0xBF
R/W
Bit7
R/W
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
Bit6
Bits7–0: ADC0 Data Word High-Order Bits.
For AD0LJST = 0: Bits 7–4 are the sign extension of Bit3. Bits 3–0 are the upper 4 bits of the
10-bit ADC0 Data Word.
For AD0LJST = 1: Bits 7–0 are the most-significant bits of the 10-bit ADC0 Data Word.
SFR Definition 6.6. ADC0L: ADC0 Data Word LSB
SFR Page:
SFR Address:
0
0xBE
R/W
R/W
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
Bit7
Bit6
Bits7–0: ADC0 Data Word Low-Order Bits.
For AD0LJST = 0: Bits 7–0 are the lower 8 bits of the 10-bit ADC0 Data Word.
For AD0LJST = 1: Bits 7–4 are the lower 4 bits of the 10-bit ADC0 Data Word. Bits 3–0 will
always read ‘0’.
82
Rev. 1.4
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C8051F130/1/2/3
10-bit ADC0 Data Word appears in the ADC0 Data Word Registers as follows:
ADC0H[1:0]:ADC0L[7:0], if AD0LJST = 0
(ADC0H[7:2] will be sign-extension of ADC0H.1 for a differential reading, otherwise
=
000000b).
ADC0H[7:0]:ADC0L[7:6], if AD0LJST = 1
(ADC0L[5:0] = 00b).
Example: ADC0 Data Word Conversion Map, AIN0.0 Input in Single-Ended Mode
(AMX0CF = 0x00, AMX0SL = 0x00)
AIN0.0–AGND
(Volts)
ADC0H:ADC0L
(AD0LJST = 0)
ADC0H:ADC0L
(AD0LJST = 1)
VREF x (1023/1024)
VREF / 2
0x03FF
0x0200
0x01FF
0x0000
0xFFC0
0x8000
0x7FC0
0x0000
VREF x (511/1024)
0
Example: ADC0 Data Word Conversion Map, AIN0.0-AIN0.1 Differential Input Pair
(AMX0CF = 0x01, AMX0SL = 0x00)
AIN0.0–AIN0.1
(Volts)
ADC0H:ADC0L
(AD0LJST = 0)
ADC0H:ADC0L
(AD0LJST = 1)
VREF x (511/512)
VREF / 2
0x01FF
0x0100
0x7FC0
0x4000
0x0040
0x0000
0xFFC0
0xC000
0x8000
VREF x (1/512)
0
0x0001
0x0000
–VREF x (1/512)
–VREF / 2
–VREF
0xFFFF (–1d)
0xFF00 (–256d)
0xFE00 (–512d)
For AD0LJST = 0:
Gain
---------------
n
Code = Vin
2 ; ‘n’ = 10 for Single-Ended; ‘n’= 9 for Differential.
VREF
Figure 6.5. ADC0 Data Word Example
Rev. 1.4
83
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
6.3. ADC0 Programmable Window Detector
The ADC0 Programmable Window Detector continuously compares the ADC0 output to user-programmed
limits, and notifies the system when an out-of-bound condition is detected. This is especially effective in an
interrupt-driven system, saving code space and CPU bandwidth while delivering faster system response
times. The window detector interrupt flag (AD0WINT in ADC0CN) can also be used in polled mode. The
high and low bytes of the reference words are loaded into the ADC0 Greater-Than and ADC0 Less-Than
registers (ADC0GTH, ADC0GTL, ADC0LTH, and ADC0LTL). Reference comparisons are shown starting
on page 87. Notice that the window detector flag can be asserted when the measured data is inside or out-
side the user-programmed limits, depending on the programming of the ADC0GTx and ADC0LTx regis-
ters.
SFR Definition 6.7. ADC0GTH: ADC0 Greater-Than Data High Byte
SFR Page:
SFR Address:
0
0xC5
R/W
Bit7
R/W
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
11111111
Bit6
Bits7–0: High byte of ADC0 Greater-Than Data Word.
SFR Definition 6.8. ADC0GTL: ADC0 Greater-Than Data Low Byte
SFR Page:
SFR Address:
0
0xC4
R/W
R/W
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
11111111
Bit7
Bit6
Bits7–0: Low byte of ADC0 Greater-Than Data Word.
84
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 6.9. ADC0LTH: ADC0 Less-Than Data High Byte
SFR Page:
SFR Address:
0
0xC7
R/W
Bit7
R/W
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
Bit6
Bits7–0: High byte of ADC0 Less-Than Data Word.
SFR Definition 6.10. ADC0LTL: ADC0 Less-Than Data Low Byte
SFR Page:
SFR Address:
0
0xC6
R/W
R/W
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
Bit7
Bit6
Bits7–0: Low byte of ADC0 Less-Than Data Word.
Rev. 1.4
85
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Input Voltage
ADC Data
Input Voltage
(AD0.0 - AGND)
ADC Data
Word
(AD0.0 - AGND)
Word
REF x (1023/1024)
0x03FF
REF x (1023/1024)
0x03FF
ADWINT
not affected
ADWINT=1
0x0201
0x0201
REF x (512/1024)
REF x (256/1024)
0x0200
0x01FF
ADC0LTH:ADC0LTL
ADWINT=1
REF x (512/1024)
REF x (256/1024)
0x0200
0x01FF
ADC0GTH:ADC0GTL
ADWINT
not affected
0x0101
0x0100
0x0101
0x0100
ADC0GTH:ADC0GTL
ADC0LTH:ADC0LTL
0x00FF
0x00FF
ADWINT=1
ADWINT
not affected
0x0000
0x0000
0
0
Given:
Given:
AMX0SL = 0x00, AMX0CF = 0x00
AD0LJST = ‘0’,
AMX0SL = 0x00, AMX0CF = 0x00,
AD0LJST = ‘0’,
ADC0LTH:ADC0LTL = 0x0200,
ADC0GTH:ADC0GTL = 0x0100.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x0200 and > 0x0100.
ADC0LTH:ADC0LTL = 0x0100,
ADC0GTH:ADC0GTL = 0x0200.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
> 0x0200 or < 0x0100.
Figure 6.6. 10-Bit ADC0 Window Interrupt Example: Right Justified Single-Ended
Data
86
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Input Voltage
(AD0.0 - AD0.1)
Input Voltage
ADC Data
ADC Data
Word
(AD0.0 - AD0.1)
Word
REF x (511/512)
0x01FF
REF x (511/512)
0x01FF
ADWINT
not affected
ADWINT=1
0x0101
0x0101
REF x (256/512)
REF x (-1/512)
0x0100
0x00FF
ADC0LTH:ADC0LTL
ADWINT=1
REF x (256/512)
REF x (-1/512)
0x0100
0x00FF
ADC0GTH:ADC0GTL
ADWINT
not affected
0x0000
0xFFFF
0x0000
0xFFFF
ADC0GTH:ADC0GTL
ADC0LTH:ADC0LTL
ADWINT=1
0xFFFE
0xFFFE
ADWINT
not affected
0xFE00
0xFE00
-REF
-REF
Given:
Given:
AMX0SL = 0x00, AMX0CF = 0x01,
AD0LJST = ‘0’,
AMX0SL = 0x00, AMX0CF = 0x01,
AD0LJST = ‘0’,
ADC0LTH:ADC0LTL = 0x0100,
ADC0GTH:ADC0GTL = 0xFFFF.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x0100 and > 0xFFFF. (In 2s-complement
math, 0xFFFF = -1.)
ADC0LTH:ADC0LTL = 0xFFFF,
ADC0GTH:ADC0GTL = 0x0100.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0xFFFF or > 0x0100. (In 2s-complement
math, 0xFFFF = -1.)
Figure 6.7. 10-Bit ADC0 Window Interrupt Example: Right Justified Differential
Data
Rev. 1.4
87
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Input Voltage
ADC Data
Input Voltage
(AD0.0 - AGND)
ADC Data
Word
(AD0.0 - AGND)
Word
REF x (1023/1024)
0xFFC0
REF x (1023/1024)
0xFFC0
ADWINT
not affected
ADWINT=1
0x8040
0x8040
REF x (512/1024)
REF x (256/1024)
0x8000
0x7FC0
ADC0LTH:ADC0LTL
ADWINT=1
REF x (512/1024)
REF x (256/1024)
0x8000
0x7FC0
ADC0GTH:ADC0GTL
ADWINT
not affected
0x4040
0x4000
0x4040
0x4000
ADC0GTH:ADC0GTL
ADC0LTH:ADC0LTL
ADWINT=1
0x3FC0
0x3FC0
ADWINT
not affected
0x0000
0x0000
0
0
Given:
Given:
AMX0SL = 0x00, AMX0CF = 0x00,
AD0LJST = ‘1’,
AMX0SL = 0x00, AMX0CF = 0x00,
AD0LJST = ‘1’
ADC0LTH:ADC0LTL = 0x2000,
ADC0GTH:ADC0GTL = 0x1000.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x2000 and > 0x1000.
ADC0LTH:ADC0LTL = 0x1000,
ADC0GTH:ADC0GTL = 0x2000.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x1000 or > 0x2000.
Figure 6.8. 10-Bit ADC0 Window Interrupt Example: Left Justified Single-Ended
Data
88
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Input Voltage
(AD0.0 - AD0.1)
Input Voltage
ADC Data
ADC Data
Word
(AD0.0 - AD0.1)
Word
REF x (511/512)
0x7FC0
REF x (511/512)
0x7FC0
ADWINT
not affected
ADWINT=1
0x2040
0x2040
REF x (128/512)
REF x (-1/512)
0x2000
0x1FC0
ADC0LTH:ADC0LTL
ADWINT=1
REF x (128/512)
REF x (-1/512)
0x2000
0x1FC0
ADC0GTH:ADC0GTL
ADWINT
not affected
0x0000
0xFFC0
0x0000
0xFFC0
ADC0GTH:ADC0GTL
ADC0LTH:ADC0LTL
0xFF80
0xFF80
ADWINT=1
ADWINT
not affected
0x8000
0x8000
-REF
-REF
Given:
Given:
AMX0SL = 0x00, AMX0CF = 0x01,
AD0LJST = ‘1’,
AMX0SL = 0x00, AMX0CF = 0x01,
AD0LJST = ‘1’,
ADC0LTH:ADC0LTL = 0x2000,
ADC0GTH:ADC0GTL = 0xFFC0.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x2000 and > 0xFFC0. (2s-complement
math.)
ADC0LTH:ADC0LTL = 0xFFC0,
ADC0GTH:ADC0GTL = 0x2000.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0xFFC0 or > 0x2000. (2s-complement
math.)
Figure 6.9. 10-Bit ADC0 Window Interrupt Example: Left Justified Differential Data
Rev. 1.4
89
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 6.1. 10-Bit ADC0 Electrical Characteristics (C8051F122/3/6/7 and C8051F13x)
VDD = 3.0 V, AV+ = 3.0 V, VREF = 2.40 V (REFBE = 0), PGA Gain = 1, –40 to +85 °C unless otherwise specified.
Parameter
Conditions
Min
Typ
Max
Units
DC Accuracy
Resolution
10
—
bits
LSB
Integral Nonlinearity
Differential Nonlinearity
Offset Error
—
—
—
—
—
±1
±1
—
—
—
Guaranteed Monotonic
Differential mode
—
LSB
±0.5
LSB
Full Scale Error
–1.5±0.5
±0.25
LSB
Offset Temperature Coefficient
ppm/°C
Dynamic Performance (10 kHz sine-wave input, 0 to 1 dB below Full Scale, 100 ksps
Signal-to-Noise Plus Distortion
Total Harmonic Distortion
59
—
—
—
–70
80
—
—
—
dB
dB
dB
Up to the 5th harmonic
Spurious-Free Dynamic Range
Conversion Rate
SAR Clock Frequency
—
16
1.5
—
—
—
—
—
2.5
—
MHz
clocks
µs
Conversion Time in SAR Clocks
Track/Hold Acquisition Time
Throughput Rate
—
100
ksps
Analog Inputs
Input Voltage Range
Single-ended operation
0
AGND
—
—
—
10
VREF
AV+
—
V
V
*Common-mode Voltage Range Differential operation
Input Capacitance
pF
Temperature Sensor
Linearity1
Offset
—
—
—
—
—
±0.2
776
—
—
—
—
—
°C
mV
(Temp = 0 °C)
(Temp = 0 °C)
Offset Error1,2
Slope
±8.5
mV
2.86
mV/°C
mV/°C
Slope Error2
±0.034
Power Specifications
Operating Mode, 100 ksps
Power Supply Current
(AV+ supplied to ADC)
—
—
450
900
—
µA
Power Supply Rejection
±0.3
mV/V
Notes:
1. Includes ADC offset, gain, and linearity variations.
2. Represents one standard deviation from the mean.
90
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
7. ADC2 (8-Bit ADC, C8051F12x Only)
The C8051F12x devices include a second ADC peripheral (ADC2), which consists of an 8-channel, config-
urable analog multiplexer, a programmable gain amplifier, and a 500 ksps, 8-bit successive-approximation-
register ADC with integrated track-and-hold (see block diagram in Figure 7.1). ADC2 is fully configurable
under software control via the Special Function Registers shown in Figure 7.1. The ADC2 subsystem (8-bit
ADC, track-and-hold and PGA) is enabled only when the AD2EN bit in the ADC2 Control register
(ADC2CN) is set to logic 1. The ADC2 subsystem is in low power shutdown when this bit is logic 0. The
voltage reference used by ADC2 is selected as described in Section “9. Voltage Reference” on
page 113.
ADC2GTH
ADC2LTH
16
Dig
Comp
AV+
AD2WINT
AD2EN
+
AIN2.0 (P1.0)
AIN2.1 (P1.1)
AIN2.2 (P1.2)
AIN2.3 (P1.3)
AIN2.4 (P1.4)
AIN2.5 (P1.5)
AIN2.6 (P1.6)
AIN2.7 (P1.7)
8
AV+
-
+
8-Bit
SAR
-
+
-
8
8
8-to-1
AMUX
X
+
ADC
-
AGND
+
000
001
010
011
1xx
Write to AD2BUSY
Timer 3 Overflow
CNVSTR2
-
Start Conversion
Timer 2 Overflow
Write to AD0BUSY
(synchronized with
ADC0)
AMX2CF
ADC2CF
AMX2SL
ADC2CN
Figure 7.1. ADC2 Functional Block Diagram
7.1. Analog Multiplexer and PGA
Eight ADC2 channels are available for measurement, as selected by the AMX2SL register (see SFR Defi-
nition 7.2). The PGA amplifies the ADC2 output signal by an amount determined by the states of the
AMP2GN2-0 bits in the ADC2 Configuration register, ADC2CF (SFR Definition 7.3). The PGA can be soft-
ware-programmed for gains of 0.5, 1, 2, or 4. Gain defaults to 0.5 on reset.
Important Note: AIN2 pins also function as Port 1 I/O pins, and must be configured as analog inputs when
used as ADC2 inputs. To configure an AIN2 pin for analog input, set to ‘0’ the corresponding bit in register
P1MDIN. Port 1 pins selected as analog inputs are skipped by the Digital I/O Crossbar. See Section
“18.1.5. Configuring Port 1 Pins as Analog Inputs” on page 240 for more information on configuring
the AIN2 pins.
Rev. 1.4
91
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
7.2. ADC2 Modes of Operation
ADC2 has a maximum conversion speed of 500 ksps. The ADC2 conversion clock (SAR2 clock) is a
divided version of the system clock, determined by the AD2SC bits in the ADC2CF register. The maximum
ADC2 conversion clock is 6 MHz.
7.2.1. Starting a Conversion
A conversion can be initiated in one of five ways, depending on the programmed states of the ADC2 Start
of Conversion Mode bits (AD2CM2-0) in ADC2CN. Conversions may be initiated by:
1. Writing a ‘1’ to the AD2BUSY bit of ADC2CN;
2. A Timer 3 overflow (i.e. timed continuous conversions);
3. A rising edge detected on the external ADC convert start signal, CNVSTR2;
4. A Timer 2 overflow (i.e. timed continuous conversions);
5. Writing a ‘1’ to the AD0BUSY of register ADC0CN (initiate conversion of ADC2 and ADC0 with
a single software command).
During conversion, the AD2BUSY bit is set to logic 1 and restored to 0 when conversion is complete. The
falling edge of AD2BUSY triggers an interrupt (when enabled) and sets the interrupt flag in ADC2CN. Con-
verted data is available in the ADC2 data word, ADC2.
When a conversion is initiated by writing a ‘1’ to AD2BUSY, it is recommended to poll AD2INT to determine
when the conversion is complete. The recommended procedure is:
Step 1. Write a ‘0’ to AD2INT;
Step 2. Write a ‘1’ to AD2BUSY;
Step 3. Poll AD2INT for ‘1’;
Step 4. Process ADC2 data.
When CNVSTR2 is used as a conversion start source, it must be enabled in the crossbar, and the corre-
sponding pin must be set to open-drain, high-impedance mode (see Section “18. Port Input/Output” on
page 235 for more details on Port I/O configuration).
7.2.2. Tracking Modes
The AD2TM bit in register ADC2CN controls the ADC2 track-and-hold mode. In its default state, the ADC2
input is continuously tracked, except when a conversion is in progress. When the AD2TM bit is logic 1,
ADC2 operates in low-power track-and-hold mode. In this mode, each conversion is preceded by a track-
ing period of 3 SAR clocks (after the start-of-conversion signal). When the CNVSTR2 signal is used to ini-
tiate conversions in low-power tracking mode, ADC2 tracks only when CNVSTR2 is low; conversion
begins on the rising edge of CNVSTR2 (see Figure 7.2). Tracking can also be disabled (shutdown) when
the entire chip is in low power standby or sleep modes. Low-power Track-and-Hold mode is also useful
when AMUX or PGA settings are frequently changed, due to the settling time requirements described in
Section “7.2.3. Settling Time Requirements” on page 94.
92
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
A. ADC Timing for External Trigger Source
CNVSTR2
(AD2CM[2:0]=010)
1
2
3
4
5
6
7
8
9
SAR Clocks
AD2TM=1
Low Power
or Convert
Track
Convert
Convert
Low Power Mode
Track
AD2TM=0
Track or Convert
B. ADC Timing for Internal Trigger Source
Write '1' to AD2BUSY,
Timer 3 Overflow,
Timer 2 Overflow,
Write '1' to AD0BUSY
(AD2CM[2:0]=000, 001, 011, 1xx)
1
1
2
3
4
4
5
5
6
6
7
8
9
10 11 12
SAR Clocks
AD2TM=1
Low Power
or Convert
Track
Convert
Low Power Mode
2
3
7
8
9
SAR Clocks
AD2TM=0
Track or
Convert
Convert
Track
Figure 7.2. ADC2 Track and Conversion Example Timing
Rev. 1.4
93
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
7.2.3. Settling Time Requirements
A minimum tracking time is required before an accurate conversion can be performed. This tracking time is
determined by the ADC2 MUX resistance, the ADC2 sampling capacitance, any external source resis-
tance, and the accuracy required for the conversion. Figure 7.3 shows the equivalent ADC2 input circuit.
The required ADC2 settling time for a given settling accuracy (SA) may be approximated by Equation 7.1.
Note: An absolute minimum settling time of 800 ns required after any MUX selection. In low-power tracking
mode, three SAR2 clocks are used for tracking at the start of every conversion. For most applications,
these three SAR2 clocks will meet the tracking requirements.
2n
SA
------
t = ln
RTOTALCSAMPLE
Equation 7.1. ADC2 Settling Time Requirements
Where:
SA is the settling accuracy, given as a fraction of an LSB (for example, 0.25 to settle within 1/4 LSB)
t is the required settling time in seconds
RTOTAL is the sum of the ADC2 MUX resistance and any external source resistance.
n is the ADC resolution in bits (8).
Differential Mode
Single-Ended Mode
MUX Select
MUX Select
AIN2.x
AIN2.x
RMUX = 5k
RMUX = 5k
CSAMPLE = 5pF
CSAMPLE = 5pF
RCInput= RMUX * CSAMPLE
RCInput= RMUX * CSAMPLE
CSAMPLE = 5pF
AIN2.y
RMUX = 5k
MUX Select
Note: When the PGA gain is set to 0.5, CSAMPLE = 3pF
Figure 7.3. ADC2 Equivalent Input Circuit
94
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 7.1. AMX2CF: AMUX2 Configuration
SFR Page:
SFR Address:
2
0xBA
R/W
-
R/W
R/W
-
R/W
-
R/W
R/W
R/W
R/W
Reset Value
-
PIN67IC PIN45IC PIN23IC PIN01IC 00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bits7–4: UNUSED. Read = 0000b; Write = don’t care.
Bit3:
Bit2:
Bit1:
Bit0:
PIN67IC: AIN2.6, AIN2.7 Input Pair Configuration Bit.
0: AIN2.6 and AIN2.7 are independent single-ended inputs.
1: AIN2.6 and AIN2.7 are (respectively) +, – differential input pair.
PIN45IC: AIN2.4, AIN2.5 Input Pair Configuration Bit.
0: AIN2.4 and AIN2.5 are independent single-ended inputs.
1: AIN2.4 and AIN2.5 are (respectively) +, – differential input pair.
PIN23IC: AIN2.2, AIN2.3 Input Pair Configuration Bit.
0: AIN2.2 and AIN2.3 are independent single-ended inputs.
1: AIN2.2 and AIN2.3 are (respectively) +, – differential input pair.
PIN01IC: AIN2.0, AIN2.1 Input Pair Configuration Bit.
0: AIN2.0 and AIN2.1 are independent single-ended inputs.
1: AIN2.0 and AIN2.1 are (respectively) +, – differential input pair.
Note: The ADC2 Data Word is in 2’s complement format for channels configured as differential.
Rev. 1.4
95
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 7.2. AMX2SL: AMUX2 Channel Select
SFR Page:
SFR Address:
2
0xBB
R/W
-
R/W
R/W
-
R/W
-
R/W
Bit3
R/W
R/W
R/W
Reset Value
-
AMX2AD2 AMX2AD1 AMX2AD0 00000000
Bit7
Bit6
Bit5
Bit4
Bit2
Bit1
Bit0
Bits7–3: UNUSED. Read = 00000b; Write = don’t care.
Bits2–0: AMX2AD2–0: AMX2 Address Bits.
000-111b: ADC Inputs selected per chart below.
AMX2AD2–0
000
001
010
011
100
101
110
111
AIN2.0
AIN2.1
AIN2.2
AIN2.3
AIN2.4
AIN2.5
AIN2.6
AIN2.7
0000
0001
+(AIN2.0)
–(AIN2.1)
AIN2.2
AIN2.3
AIN2.4
AIN2.4
AIN2.4
AIN2.5
AIN2.5
AIN2.5
AIN2.6
AIN2.7
AIN2.7
AIN2.7
AIN2.7
AIN2.7
AIN2.7
AIN2.7
+(AIN2.2)
–(AIN2.3)
AIN2.0
AIN2.1
AIN2.1
AIN2.1
AIN2.1
AIN2.1
AIN2.1
AIN2.1
AIN2.6
AIN2.6
AIN2.6
AIN2.6
AIN2.6
AIN2.6
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
+(AIN2.0)
–(AIN2.1)
+(AIN2.2)
–(AIN2.3)
+(AIN2.4)
–(AIN2.5)
AIN2.0
AIN2.2
AIN2.2
AIN2.3
AIN2.3
+(AIN2.0)
–(AIN2.1)
+(AIN2.4)
–(AIN2.5)
+(AIN2.2)
–(AIN2.3)
+(AIN2.4)
–(AIN2.5)
AIN2.0
+(AIN2.0)
–(AIN2.1)
+(AIN2.2)
–(AIN2.3)
+(AIN2.4)
–(AIN2.5)
+(AIN2.6)
–(AIN2.7)
AIN2.0
AIN2.2
AIN2.2
AIN2.3
AIN2.3
AIN2.4
AIN2.4
AIN2.4
AIN2.4
AIN2.5
AIN2.5
AIN2.5
AIN2.5
+(AIN2.0)
–(AIN2.1)
+(AIN2.6)
–(AIN2.7)
+(AIN2.2)
–(AIN2.3)
+(AIN2.6)
–(AIN2.7)
AIN2.0
+(AIN2.0)
–(AIN2.1)
+(AIN2.2)
–(AIN2.3)
+(AIN2.6)
–(AIN2.7)
+(AIN2.4)
–(AIN2.5)
+(AIN2.6)
–(AIN2.7)
AIN2.0
AIN2.2
AIN2.2
AIN2.3
AIN2.3
+(AIN2.0)
–(AIN2.1)
+(AIN2.4)
–(AIN2.5)
+(AIN2.6)
–(AIN2.7)
+(AIN2.2)
–(AIN2.3)
+(AIN2.4)
–(AIN2.5)
+(AIN2.6)
–(AIN2.7)
AIN2.0
+(AIN2.0)
–(AIN2.1)
+(AIN2.2)
–(AIN2.3)
+(AIN2.4)
–(AIN2.5)
+(AIN2.6)
–(AIN2.7)
96
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 7.3. ADC2CF: ADC2 Configuration
SFR Page:
SFR Address:
2
0xBC
R/W
R/W
R/W
R/W
R/W
R/W
-
R/W
R/W
Reset Value
AD2SC4 AD2SC3 AD2SC2 AD2SC1 AD2SC0
AMP2GN1 AMP2GN0 11111000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bits7–3: AD2SC4–0: ADC2 SAR Conversion Clock Period Bits.
SAR Conversion clock is derived from system clock by the following equation, where
AD2SC refers to the 5-bit value held in AD2SC4–0, and CLKSAR2 refers to the desired
ADC2 SAR clock (Note: the ADC2 SAR Conversion Clock should be less than or equal to
6 MHz).
SYSCLK
CLKSAR2
----------------------
AD2SC =
– 1
Bit2:
UNUSED. Read = 0b; Write = don’t care.
Bits1–0: AMP2GN1–0: ADC2 Internal Amplifier Gain (PGA).
00: Gain = 0.5
01: Gain = 1
10: Gain = 2
11: Gain = 4
Rev. 1.4
97
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 7.4. ADC2CN: ADC2 Control
SFR Page:
SFR Address:
2
0xE8
(bit addressable)
R/W
AD2EN
Bit7
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
AD2TM AD2INT AD2BUSY AD2CM2 AD2CM1 AD2CM0 AD2WINT 00000000
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit7:
Bit6:
AD2EN: ADC2 Enable Bit.
0: ADC2 Disabled. ADC2 is in low-power shutdown.
1: ADC2 Enabled. ADC2 is active and ready for data conversions.
AD2TM: ADC2 Track Mode Bit.
0: Normal Track Mode: When ADC2 is enabled, tracking is continuous unless a conversion
is in process.
1: Low-power Track Mode: Tracking Defined by AD2CM2-0 bits (see below).
AD2INT: ADC2 Conversion Complete Interrupt Flag.
This flag must be cleared by software.
0: ADC2 has not completed a data conversion since the last time this flag was cleared.
1: ADC2 has completed a data conversion.
AD2BUSY: ADC2 Busy Bit.
Bit5:
Bit4:
Read:
0: ADC2 Conversion is complete or a conversion is not currently in progress. AD2INT is set
to logic 1 on the falling edge of AD2BUSY.
1: ADC2 Conversion is in progress.
Write:
0: No Effect.
1: Initiates ADC2 Conversion if AD2CM2-0 = 000b
Bits3–1: AD2CM2–0: ADC2 Start of Conversion Mode Select.
AD2TM = 0:
000: ADC2 conversion initiated on every write of ‘1’ to AD2BUSY.
001: ADC2 conversion initiated on overflow of Timer 3.
010: ADC2 conversion initiated on rising edge of external CNVSTR2.
011: ADC2 conversion initiated on overflow of Timer 2.
1xx: ADC2 conversion initiated on write of ‘1’ to AD0BUSY (synchronized with ADC0 soft-
ware-commanded conversions).
AD2TM = 1:
000: Tracking initiated on write of ‘1’ to AD2BUSY for 3 SAR2 clocks, followed by conver-
sion.
001: Tracking initiated on overflow of Timer 3 for 3 SAR2 clocks, followed by conversion.
010: ADC2 tracks only when CNVSTR2 input is logic low; conversion starts on rising
CNVSTR2 edge.
011: Tracking initiated on overflow of Timer 2 for 3 SAR2 clocks, followed by conversion.
1xx: Tracking initiated on write of ‘1’ to AD0BUSY and lasts 3 SAR2 clocks, followed by con-
version.
Bit0:
AD2WINT: ADC2 Window Compare Interrupt Flag.
This bit must be cleared by software.
0: ADC2 Window Comparison Data match has not occurred since this flag was last cleared.
1: ADC2 Window Comparison Data match has occurred.
98
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 7.5. ADC2: ADC2 Data Word
SFR Page:
SFR Address:
2
0xBE
R/W
Bit7
R/W
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
Bit6
Bits7–0: ADC2 Data Word.
Single-Ended Example:
8-bit ADC Data Word appears in the ADC2 Data Word Register as follows:
Example: ADC2 Data Word Conversion Map, Single-Ended AIN2.0 Input
(AMX2CF = 0x00; AMX2SL = 0x00)
AIN2.0–AGND
ADC2
(Volts)
VREF * (255/256)
VREF * (128/256)
VREF * (64/256)
0
0xFF
0x80
0x40
0x00
Gain
VREF
---------------
Code = Vin
256
Differential Example:
8-bit ADC Data Word appears in the ADC2 Data Word Register as follows:
Example: ADC2 Data Word Conversion Map, Differential AIN2.0-AIN2.1 Input
(AMX2CF = 0x01; AMX2SL = 0x00)
AIN2.0–AIN2.1
ADC2
(Volts)
VREF * (127/128)
VREF * (64/128)
0
0x7F
0x40
0x00
–VREF * (64/128)
–VREF * (128/128)
0xC0 (-64d)
0x80 (-128d)
Gain
------------------------
Code = Vin
256
2 VREF
Figure 7.4. ADC2 Data Word Example
Rev. 1.4
99
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
7.3. ADC2 Programmable Window Detector
The ADC2 Programmable Window Detector continuously compares the ADC2 output to user-programmed
limits, and notifies the system when a desired condition is detected. This is especially effective in an inter-
rupt-driven system, saving code space and CPU bandwidth while delivering faster system response times.
The window detector interrupt flag (AD2WINT in register ADC2CN) can also be used in polled mode. The
ADC2 Greater-Than (ADC2GT) and Less-Than (ADC2LT) registers hold the comparison values. Example
comparisons for Differential and Single-ended modes are shown in Figure 7.6 and Figure 7.5, respectively.
Notice that the window detector flag can be programmed to indicate when measured data is inside or out-
side of the user-programmed limits, depending on the contents of the ADC2LT and ADC2GT registers.
7.3.1. Window Detector In Single-Ended Mode
Figure 7.5 shows two example window comparisons for Single-ended mode, with ADC2LT = 0x20 and
ADC2GT = 0x10. Notice that in Single-ended mode, the codes vary from 0 to VREF*(255/256) and are
represented as 8-bit unsigned integers. In the left example, an AD2WINT interrupt will be generated if the
ADC2 conversion word (ADC2) is within the range defined by ADC2GT and ADC2LT
(if 0x10 ADC2 0x20). In the right example, and AD2WINT interrupt will be generated if ADC2 is outside
of the range defined by ADC2GT and ADC2LT (if ADC2 0x10 or ADC2 0x20).
ADC2
0xFF
ADC2
0xFF
Input Voltage
(AIN2.x - AGND)
Input Voltage
(AIN2.x - AGND)
REF x (255/256)
REF x (255/256)
AD2WINT
not affected
AD2WINT=1
0x21
0x21
REF x (32/256)
REF x (16/256)
0x20
0x1F
ADC2LT
ADC2GT
REF x (32/256)
REF x (16/256)
0x20
0x1F
ADC2GT
AD2WINT
not affected
AD2WINT=1
0x11
0x10
0x11
0x10
ADC2LT
0x0F
0x0F
AD2WINT=1
AD2WINT
not affected
0x00
0x00
0
0
Figure 7.5. ADC2 Window Compare Examples, Single-Ended Mode
100
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
7.3.2. Window Detector In Differential Mode
Figure 7.6 shows two example window comparisons for differential mode, with ADC2LT = 0x10 (+16d) and
ADC2GT = 0xFF (-1d). Notice that in Differential mode, the codes vary from -VREF to VREF*(127/128)
and are represented as 8-bit 2’s complement signed integers. In the left example, an AD2WINT interrupt
will be generated if the ADC2 conversion word (ADC2L) is within the range defined by ADC2GT and
ADC2LT (if 0xFF (-1d) < ADC2 < 0x0F (16d)). In the right example, an AD2WINT interrupt will be gener-
ated if ADC2 is outside of the range defined by ADC2GT and ADC2LT (if ADC2 < 0xFF (-1d) or ADC2 >
0x10 (+16d)).
ADC2
ADC2
Input Voltage
Input Voltage
(AIN2.x - AIN2.y)
(AIN2.x - AIN2.y)
REF x (127/128)
0x7F (127d)
REF x (127/128)
0x7F (127d)
AD2WINT
not affected
AD2WINT=1
0x11 (17d)
0x11 (17d)
REF x (16/128)
REF x (-1/256)
0x10 (16d)
0x0F (15d)
ADC2LT
ADC2GT
REF x (16/128)
REF x (-1/256)
0x10 (16d)
0x0F (15d)
ADC2GT
AD2WINT
not affected
AD2WINT=1
0x00 (0d)
0x00 (0d)
0xFF (-1d)
0xFF (-1d)
ADC2LT
0xFE (-2d)
0xFE (-2d)
AD2WINT=1
AD2WINT
not affected
0x80 (-128d)
0x80 (-128d)
-REF
-REF
Figure 7.6. ADC2 Window Compare Examples, Differential Mode
Rev. 1.4
101
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 7.6. ADC2GT: ADC2 Greater-Than Data Byte
SFR Page:
SFR Address:
2
0xC4
R/W
Bit7
R/W
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
11111111
Bit6
Bits7–0: ADC2 Greater-Than Data Word.
SFR Definition 7.7. ADC2LT: ADC2 Less-Than Data Byte
SFR Page:
SFR Address:
2
0xC6
R/W
Bit7
R/W
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
Bit6
Bits7–0: ADC2 Less-Than Data Word.
102
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 7.1. ADC2 Electrical Characteristics
VDD = 3.0 V, AV+ = 3.0 V, VREF2 = 2.40 V (REFBE = 0), PGA gain = 1, –40 to +85 °C unless otherwise specified.
Parameter
Conditions
Min
Typ
Max
Units
DC Accuracy
Resolution
8
—
bits
LSB
Integral Nonlinearity
Differential Nonlinearity
Offset Error
—
—
—
—
—
±1
±1
—
—
—
Guaranteed Monotonic
Differential mode
—
LSB
0.5±0.3
–1±0.2
10
LSB
Full Scale Error
LSB
Offset Temperature Coefficient
ppm/°C
Dynamic Performance (10 kHz sine-wave input, 1 dB below Full Scale, 500 ksps
Signal-to-Noise Plus Distortion
Total Harmonic Distortion
45
—
—
47
-51
52
—
—
—
dB
dB
dB
Up to the 5th harmonic
Spurious-Free Dynamic Range
Conversion Rate
SAR Clock Frequency
—
8
—
—
—
—
6
—
MHz
clocks
ns
Conversion Time in SAR Clocks
Track/Hold Acquisition Time
Throughput Rate
300
—
—
500
ksps
Analog Inputs
Input Voltage Range
Input Capacitance
0
—
5
VREF
—
V
—
pF
Power Specifications
Power Supply Current
(AV+ supplied to ADC2)
—
—
420
900
—
µA
Operating Mode, 500 ksps
Power Supply Rejection
±0.3
mV/V
Rev. 1.4
103
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
NOTES:
104
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
8. DACs, 12-Bit Voltage Mode (C8051F12x Only)
The C8051F12x devices include two on-chip 12-bit voltage-mode Digital-to-Analog Converters (DACs).
Each DAC has an output swing of 0 V to (VREF-1LSB) for a corresponding input code range of 0x000 to
0xFFF. The DACs may be enabled/disabled via their corresponding control registers, DAC0CN and
DAC1CN. While disabled, the DAC output is maintained in a high-impedance state, and the DAC supply
current falls to 1 µA or less. The voltage reference for each DAC is supplied at the VREFD pin
(C8051F120/2/4/6 devices) or the VREF pin (C8051F121/3/5/7 devices). Note that the VREF pin on
C8051F121/3/5/7 devices may be driven by the internal voltage reference or an external source. If the
internal voltage reference is used it must be enabled in order for the DAC outputs to be valid. See Section
“9. Voltage Reference” on page 113 for more information on configuring the voltage reference for the
DACs.
8.1. DAC Output Scheduling
Each DAC features a flexible output update mechanism which allows for seamless full-scale changes and
supports jitter-free updates for waveform generation. The following examples are written in terms of DAC0,
but DAC1 operation is identical.
DAC0EN
DAC0MD1
DAC0MD0
DAC0DF2
DAC0DF1
DAC0DF0
REF
AV+
8
8
8
8
12
DAC0
DAC0
AGND
DAC1EN
DAC1MD1
DAC1MD0
DAC1DF2
DAC1DF1
DAC1DF0
REF
AV+
8
8
8
8
12
DAC1
DAC1
AGND
Figure 8.1. DAC Functional Block Diagram
Rev. 1.4
105
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
8.1.1. Update Output On-Demand
In its default mode (DAC0CN.[4:3] = ‘00’) the DAC0 output is updated “on-demand” on a write to the high-
byte of the DAC0 data register (DAC0H). It is important to note that writes to DAC0L are held, and have no
effect on the DAC0 output until a write to DAC0H takes place. If writing a full 12-bit word to the DAC data
registers, the 12-bit data word is written to the low byte (DAC0L) and high byte (DAC0H) data registers.
Data is latched into DAC0 after a write to the corresponding DAC0H register, so the write sequence
should be DAC0L followed by DAC0H if the full 12-bit resolution is required. The DAC can be used in 8-
bit mode by initializing DAC0L to the desired value (typically 0x00), and writing data to only DAC0H (also
see Section 8.2 for information on formatting the 12-bit DAC data word within the 16-bit SFR space).
8.1.2. Update Output Based on Timer Overflow
Similar to the ADC operation, in which an ADC conversion can be initiated by a timer overflow indepen-
dently of the processor, the DAC outputs can use a Timer overflow to schedule an output update event.
This feature is useful in systems where the DAC is used to generate a waveform of a defined sampling rate
by eliminating the effects of variable interrupt latency and instruction execution on the timing of the DAC
output. When the DAC0MD bits (DAC0CN.[4:3]) are set to ‘01’, ‘10’, or ‘11’, writes to both DAC data regis-
ters (DAC0L and DAC0H) are held until an associated Timer overflow event (Timer 3, Timer 4, or Timer 2,
respectively) occurs, at which time the DAC0H:DAC0L contents are copied to the DAC input latches allow-
ing the DAC output to change to the new value.
8.2. DAC Output Scaling/Justification
In some instances, input data should be shifted prior to a DAC0 write operation to properly justify data
within the DAC input registers. This action would typically require one or more load and shift operations,
adding software overhead and slowing DAC throughput. To alleviate this problem, the data-formatting fea-
ture provides a means for the user to program the orientation of the DAC0 data word within data registers
DAC0H and DAC0L. The three DAC0DF bits (DAC0CN.[2:0]) allow the user to specify one of five data
word orientations as shown in the DAC0CN register definition.
DAC1 is functionally the same as DAC0 described above. The electrical specifications for both DAC0 and
DAC1 are given in Table 8.1.
106
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 8.1. DAC0H: DAC0 High Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address: 0xD3
SFR Page: 0
Bits7–0: DAC0 Data Word Most Significant Byte.
SFR Definition 8.2. DAC0L: DAC0 Low Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address: 0xD2
SFR Page: 0
Bits7–0: DAC0 Data Word Least Significant Byte.
Rev. 1.4
107
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 8.3. DAC0CN: DAC0 Control
R/W
DAC0EN
Bit7
R/W
-
R/W
-
R/W
R/W
R/W
R/W
R/W
Reset Value
DAC0MD1 DAC0MD0 DAC0DF2 DAC0DF1 DAC0DF0 00000000
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xD4
SFR Page: 0
Bit7:
DAC0EN: DAC0 Enable Bit.
0: DAC0 Disabled. DAC0 Output pin is disabled; DAC0 is in low-power shutdown mode.
1: DAC0 Enabled. DAC0 Output pin is active; DAC0 is operational.
Bits6–5: UNUSED. Read = 00b; Write = don’t care.
Bits4–3: DAC0MD1–0: DAC0 Mode Bits.
00: DAC output updates occur on a write to DAC0H.
01: DAC output updates occur on Timer 3 overflow.
10: DAC output updates occur on Timer 4 overflow.
11: DAC output updates occur on Timer 2 overflow.
Bits2–0: DAC0DF2–0: DAC0 Data Format Bits:
000:
001:
010:
The most significant nibble of the DAC0 Data Word is in DAC0H[3:0], while the least
significant byte is in DAC0L.
DAC0H
DAC0L
MSB
LSB
The most significant 5-bits of the DAC0 Data Word is in DAC0H[4:0], while the least
significant 7-bits are in DAC0L[7:1].
DAC0H
DAC0L
MSB
LSB
The most significant 6-bits of the DAC0 Data Word is in DAC0H[5:0], while the least
significant 6-bits are in DAC0L[7:2].
DAC0H
DAC0L
MSB
LSB
011:
The most significant 7-bits of the DAC0 Data Word is in DAC0H[6:0], while the least
significant 5-bits are in DAC0L[7:3].
DAC0H
DAC0L
MSB
LSB
1xx:
The most significant 8-bits of the DAC0 Data Word is in DAC0H[7:0], while the least
significant 4-bits are in DAC0L[7:4].
DAC0H
DAC0L
MSB
LSB
108
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 8.4. DAC1H: DAC1 High Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address: 0xD3
SFR Page: 1
Bits7–0: DAC1 Data Word Most Significant Byte.
SFR Definition 8.5. DAC1L: DAC1 Low Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address: 0xD2
SFR Page: 1
Bits7–0: DAC1 Data Word Least Significant Byte.
Rev. 1.4
109
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 8.6. DAC1CN: DAC1 Control
R/W
DAC1EN
Bit7
R/W
-
R/W
-
R/W
R/W
R/W
R/W
R/W
Reset Value
DAC1MD1 DAC1MD0 DAC1DF2 DAC1DF1 DAC1DF0 00000000
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xD4
SFR Page: 1
Bit7:
DAC1EN: DAC1 Enable Bit.
0: DAC1 Disabled. DAC1 Output pin is disabled; DAC1 is in low-power shutdown mode.
1: DAC1 Enabled. DAC1 Output pin is active; DAC1 is operational.
Bits6–5: UNUSED. Read = 00b; Write = don’t care.
Bits4–3: DAC1MD1–0: DAC1 Mode Bits:
00: DAC output updates occur on a write to DAC1H.
01: DAC output updates occur on Timer 3 overflow.
10: DAC output updates occur on Timer 4 overflow.
11: DAC output updates occur on Timer 2 overflow.
Bits2–0: DAC1DF2: DAC1 Data Format Bits:
000:
001:
010:
The most significant nibble of the DAC1 Data Word is in DAC1H[3:0], while the least
significant byte is in DAC1L.
DAC1H
DAC1L
MSB
LSB
The most significant 5-bits of the DAC1 Data Word is in DAC1H[4:0], while the least
significant 7-bits are in DAC1L[7:1].
DAC1H
DAC1L
MSB
LSB
The most significant 6-bits of the DAC1 Data Word is in DAC1H[5:0], while the least
significant 6-bits are in DAC1L[7:2].
DAC1H
DAC1L
MSB
LSB
011:
The most significant 7-bits of the DAC1 Data Word is in DAC1H[6:0], while the least
significant 5-bits are in DAC1L[7:3].
DAC1H
DAC1L
MSB
LSB
1xx:
The most significant 8-bits of the DAC1 Data Word is in DAC1H[7:0], while the least
significant 4-bits are in DAC1L[7:4].
DAC1H
DAC1L
MSB
LSB
110
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
.
Table 8.1. DAC Electrical Characteristics
VDD = 3.0 V, AV+ = 3.0 V, VREF = 2.40 V (REFBE = 0), No Output Load unless otherwise specified
Parameter
Conditions
Min
Typ
Max
Units
Static Performance
Resolution
12
±1.5
—
bits
LSB
Integral Nonlinearity
—
—
—
—
±1
—
Differential Nonlinearity
LSB
250
128
41
µVrms
No Output Filter
100 kHz Output Filter
10 kHz Output Filter
Output Noise
Offset Error
Data Word = 0x014
—
—
—
—
—
±3
6
±30
—
mV
ppm/°C
mV
Offset Tempco
Full-Scale Error
Full-Scale Error Tempco
±20
10
±60
—
ppm/°C
dB
VDD Power Supply Rejection
Ratio
–60
—
Output Impedance in Shutdown
Mode
—
100
—
k
DACnEN = 0
Output Sink Current
—
—
300
15
—
—
µA
Output Short-Circuit Current
Data Word = 0xFFF
mA
Dynamic Performance
Voltage Output Slew Rate
Load = 40 pF
—
—
0.44
10
—
—
V/µs
µs
Load = 40 pF, Output swing from
code 0xFFF to 0x014
Output Settling Time to 1/2 LSB
0
—
VREF-
1LSB
V
Output Voltage Swing
Startup Time
—
10
—
µs
Analog Outputs
IL = 0.01 mA to 0.3 mA at code
0xFFF
—
—
60
—
ppm
µA
Load Regulation
Power Consumption (each DAC)
Power Supply Current (AV+
supplied to DAC)
110
400
Data Word = 0x7FF
Rev. 1.4
111
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
NOTES:
112
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
9. Voltage Reference
The voltage reference options available on the C8051F12x and C8051F13x device families vary according
to the device capabilities.
All devices include an internal voltage reference circuit, consisting of a 1.2 V, 15 ppm/°C (typical) bandgap
voltage reference generator and a gain-of-two output buffer amplifier. The internal reference may be routed
via the VREF pin to external system components or to the voltage reference input pins. The maximum load
seen by the VREF pin must be less than 200 µA to AGND. Bypass capacitors of 0.1 µF and 4.7 µF are rec-
ommended from the VREF pin to AGND.
The Reference Control Register, REF0CN enables/disables the internal reference generator and the inter-
nal temperature sensor on all devices. The BIASE bit in REF0CN enables the on-board reference genera-
tor while the REFBE bit enables the gain-of-two buffer amplifier which drives the VREF pin. When
disabled, the supply current drawn by the bandgap and buffer amplifier falls to less than 1 µA (typical) and
the output of the buffer amplifier enters a high impedance state. If the internal bandgap is used as the ref-
erence voltage generator, BIASE and REFBE must both be set to logic 1. If the internal reference is not
used, REFBE may be set to logic 0. Note that the BIASE bit must be set to logic 1 if any DACs or ADCs are
used, regardless of whether the voltage reference is derived from the on-chip reference or supplied by an
off-chip source. If no ADCs or DACs are being used, both of these bits can be set to logic 0 to conserve
power.
When enabled, the temperature sensor connects to the highest order input of the ADC0 input multiplexer.
The TEMPE bit within REF0CN enables and disables the temperature sensor. While disabled, the temper-
ature sensor defaults to a high impedance state. Any ADC measurements performed on the sensor while
disabled will result in undefined data.
The electrical specifications for the internal voltage reference are given in Table 9.1.
9.1. Reference Configuration on the C8051F120/2/4/6
On the C8051F120/2/4/6 devices, the REF0CN register also allows selection of the voltage reference
source for ADC0 and ADC2, as shown in SFR Definition 9.1. Bits AD0VRS and AD2VRS in the REF0CN
register select the ADC0 and ADC2 voltage reference sources, respectively. Three voltage reference input
pins allow each ADC and the two DACs to reference an external voltage reference or the on-chip voltage
reference output (with an external connection). ADC0 may also reference the DAC0 output internally, and
ADC2 may reference the analog power supply voltage, via the VREF multiplexers shown in Figure 9.1.
Rev. 1.4
113
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
REF0CN
ADC2
AV+
Ref
1
0
VREF2
VDD
External
Voltage
R1
Reference
Circuit
ADC0
DGND
VREF0
VREFD
VREF
Ref
0
1
DAC0
Ref
DAC1
BIASE
Bias to
ADCs,
DACs
EN
x2
1.2V
Band-Gap
+
4.7F
0.1F
REFBE
Recommended Bypass
Capacitors
Figure 9.1. Voltage Reference Functional Block Diagram (C8051F120/2/4/6)
SFR Definition 9.1. REF0CN: Reference Control (C8051F120/2/4/6)
SFR Page:
SFR Address:
0
0xD1
R/W
-
R/W
R/W
-
R/W
R/W
R/W
R/W
BIASE
Bit1
R/W
Reset Value
-
AD0VRS AD2VRS TEMPE
REFBE 00000000
Bit0
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bits7–5: UNUSED. Read = 000b; Write = don’t care.
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
AD0VRS: ADC0 Voltage Reference Select.
0: ADC0 voltage reference from VREF0 pin.
1: ADC0 voltage reference from DAC0 output.
AD2VRS: ADC2 Voltage Reference Select.
0: ADC2 voltage reference from VREF2 pin.
1: ADC2 voltage reference from AV+.
TEMPE: Temperature Sensor Enable Bit.
0: Internal Temperature Sensor Off.
1: Internal Temperature Sensor On.
BIASE: ADC/DAC Bias Generator Enable Bit. (Must be ‘1’ if using ADC, DAC, or VREF).
0: Internal Bias Generator Off.
1: Internal Bias Generator On.
REFBE: Internal Reference Buffer Enable Bit.
0: Internal Reference Buffer Off.
1: Internal Reference Buffer On. Internal voltage reference is driven on the VREF pin.
114
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
9.2. Reference Configuration on the C8051F121/3/5/7
On the C8051F121/3/5/7 devices, the REF0CN register also allows selection of the voltage reference
source for ADC0 and ADC2, as shown in SFR Definition 9.2. Bits AD0VRS and AD2VRS in the REF0CN
register select the ADC0 and ADC2 voltage reference sources, respectively. The VREFA pin provides a
voltage reference input for ADC0 and ADC2, which can be connected to an external precision reference or
the internal voltage reference. ADC0 may also reference the DAC0 output internally, and ADC2 may refer-
ence the analog power supply voltage, via the VREF multiplexers shown in Figure 9.2.
REF0CN
ADC2
AV+
VDD
R1
Ref
1
0
External
Voltage
Reference
Circuit
VREFA
DGND
ADC0
Ref
0
1
DAC0
Ref
DAC1
BIASE
Bias to
ADCs,
DACs
EN
VREF
x2
1.2V
Band-Gap
+
4.7F
0.1F
REFBE
Recommended Bypass
Capacitors
Figure 9.2. Voltage Reference Functional Block Diagram (C8051F121/3/5/7)
Rev. 1.4
115
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 9.2. REF0CN: Reference Control (C8051F121/3/5/7)
SFR Page:
SFR Address:
0
0xD1
R/W
-
R/W
R/W
-
R/W
R/W
R/W
R/W
BIASE
Bit1
R/W
Reset Value
-
AD0VRS AD2VRS TEMPE
REFBE 00000000
Bit0
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bits7–5: UNUSED. Read = 000b; Write = don’t care.
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
AD0VRS: ADC0 Voltage Reference Select.
0: ADC0 voltage reference from VREFA pin.
1: ADC0 voltage reference from DAC0 output.
AD2VRS: ADC2 Voltage Reference Select.
0: ADC2 voltage reference from VREFA pin.
1: ADC2 voltage reference from AV+.
TEMPE: Temperature Sensor Enable Bit.
0: Internal Temperature Sensor Off.
1: Internal Temperature Sensor On.
BIASE: ADC/DAC Bias Generator Enable Bit. (Must be ‘1’ if using ADC, DAC, or VREF).
0: Internal Bias Generator Off.
1: Internal Bias Generator On.
REFBE: Internal Reference Buffer Enable Bit.
0: Internal Reference Buffer Off.
1: Internal Reference Buffer On. Internal voltage reference is driven on the VREF pin.
116
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
9.3. Reference Configuration on the C8051F130/1/2/3
On the C8051F130/1/2/3 devices, the VREF0 pin provides a voltage reference input for ADC0, which can
be connected to an external precision reference or the internal voltage reference, as shown in Figure 9.3.
The REF0CN register for the C8051F130/1/2/3 is described in SFR Definition 9.3.
VDD
VREF0
External
Voltage
Ref
R1
Reference
Circuit
ADC0
DGND
REF0CN
EN
VREF
1.2V
x2
+
Band-Gap
4.7F
0.1F
Recommended Bypass
Capacitors
Figure 9.3. Voltage Reference Functional Block Diagram (C8051F130/1/2/3)
SFR Definition 9.3. REF0CN: Reference Control (C8051F130/1/2/3)
SFR Page:
SFR Address:
0
0xD1
R/W
-
R/W
R/W
-
R/W
R/W
R/W
R/W
BIASE
Bit1
R/W
Reset Value
-
Reserved Reserved TEMPE
REFBE 00000000
Bit0
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bits7–5: UNUSED. Read = 000b; Write = don’t care.
Bits4–3: Reserved: Must be written to 0.
Bit2:
Bit1:
Bit0:
TEMPE: Temperature Sensor Enable Bit.
0: Internal Temperature Sensor Off.
1: Internal Temperature Sensor On.
BIASE: ADC/DAC Bias Generator Enable Bit. (Must be ‘1’ if using ADC or VREF).
0: Internal Bias Generator Off.
1: Internal Bias Generator On.
REFBE: Internal Reference Buffer Enable Bit.
0: Internal Reference Buffer Off.
1: Internal Reference Buffer On. Internal voltage reference is driven on the VREF pin.
Rev. 1.4
117
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 9.1. Voltage Reference Electrical Characteristics
VDD = 3.0 V, AV+ = 3.0 V, –40 to +85 °C unless otherwise specified.
Parameter
Conditions
BIASE = 1
Min
Typ
Max
Units
Analog Bias Generator Power
Supply Current
—
100
—
µA
Internal Reference (REFBE = 1)
Output Voltage
25 °C ambient
2.36
2.43
—
2.48
30
—
V
VREF Short-Circuit Current
VREF Temperature Coefficient
Load Regulation
—
—
—
—
mA
15
0.5
2
ppm/°C
ppm/µA
ms
Load = 0 to 200 µA to AGND
—
4.7 µF tantalum, 0.1 µF ceramic
bypass
—
VREF Turn-on Time 1
VREF Turn-on Time 2
VREF Turn-on Time 3
0.1 µF ceramic bypass
no bypass cap
—
—
—
20
10
40
—
—
—
µs
µs
µA
Reference Buffer Power Sup-
ply Current
Power Supply Rejection
—
140
—
ppm/V
External Reference (REFBE = 0)
1.00
Input Voltage Range
Input Current
—
0
(AV+) – 0.3
1
V
—
µA
118
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
10. Comparators
Two on-chip programmable voltage comparators are included, as shown in Figure 10.1. The inputs of each
comparator are available at dedicated pins. The output of each comparator is optionally available at the
package pins via the I/O crossbar. When assigned to package pins, each comparator output can be pro-
grammed to operate in open drain or push-pull modes. See Section “18.1. Ports 0 through 3 and the
Priority Crossbar Decoder” on page 238 for Crossbar and port initialization details.
CP0RIE
CP0FIE
CP0MD
CP0MD1
CP0MD0
CP0EN
CP0OUT
CP0RIF
AV+
CP0FIF
CP0HYP1
CP0HYP0
CP0HYN1
CP0HYN0
Reset
Decision
Tree
CP0+
CP0-
+
-
SET
SET
CLR
D
Q
Q
D
Q
Q
Crossbar
CLR
Interrupt
Handler
(SYNCHRONIZER)
AGND
CP1RIE
CP1FIE
CP1MD
CP1MD1
CP1MD0
CP1EN
CP1OUT
CP1RIF
AV+
CP1FIF
CP1HYP1
CP1HYP0
CP1HYN1
CP1HYN0
CP1+
CP1-
+
-
SET
CLR
SET
CLR
D
Q
Q
D
Q
Q
Crossbar
Interrupt
Handler
(SYNCHRONIZER)
AGND
Figure 10.1. Comparator Functional Block Diagram
Rev. 1.4
119
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Comparator interrupts can be generated on rising-edge and/or falling-edge output transitions. (For inter-
rupt enable and priority control, see Section “11.3. Interrupt Handler” on page 154). The CP0FIF flag is
set upon a Comparator0 falling-edge interrupt, and the CP0RIF flag is set upon the Comparator0 rising-
edge interrupt. Once set, these bits remain set until cleared by software. The Output State of Comparator0
can be obtained at any time by reading the CP0OUT bit. Comparator0 is enabled by setting the CP0EN
bit to logic 1, and is disabled by clearing this bit to logic 0. Comparator0 can also be programmed as a
reset source; for details, see Section “13.5. Comparator0 Reset” on page 179.
Note that after being enabled, there is a Power-Up time (listed in Table 10.1) during which the comparator
outputs stabilize. The states of the Rising-Edge and Falling-Edge flags are indeterminant after comparator
Power-Up and should be explicitly cleared before the comparator interrupts are enabled or the compara-
tors are configured as a reset source.
Comparator0 response time may be configured in software via the CP0MD1-0 bits in register CPT0MD
(see SFR Definition 10.2). Selecting a longer response time reduces the amount of current consumed by
Comparator0. See Table 10.1 for complete timing and current consumption specifications.
The hysteresis of each comparator is software-programmable via its respective Comparator control regis-
ter (CPT0CN and CPT1CN for Comparator0 and Comparator1, respectively). The user can program both
the amount of hysteresis voltage (referred to the input voltage) and the positive and negative-going sym-
metry of this hysteresis around the threshold voltage. The output of the comparator can be polled in soft-
ware, or can be used as an interrupt source. Each comparator can be individually enabled or disabled
(shutdown). When disabled, the comparator output (if assigned to a Port I/O pin via the Crossbar) defaults
to the logic low state, its interrupt capability is suspended and its supply current falls to less than 100 nA.
Comparator inputs can be externally driven from –0.25 V to (AV+) + 0.25 V without damage or upset.
Comparator0 hysteresis is programmed using bits 3-0 in the Comparator0 Control Register CPT0CN
(shown in SFR Definition 10.1). The amount of negative hysteresis voltage is determined by the settings of
the CP0HYN bits. As shown in SFR Definition 10.1, the negative hysteresis can be programmed to three
different settings, or negative hysteresis can be disabled. In a similar way, the amount of positive hystere-
sis is determined by the setting the CP0HYP bits.
The operation of Comparator1 is identical to that of Comparator0, though Comparator1 may not be config-
ured as a reset source. Comparator1 is controlled by the CPT1CN Register (SFR Definition 10.3) and the
CPT1MD Register (SFR Definition 10.4). The complete electrical specifications for the Comparators are
given in Table 10.1.
120
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
CP0+
CP0-
VIN+
VIN-
+
CP0
_
OUT
CIRCUIT CONFIGURATION
Positive Hysteresis Voltage
(Programmed with CP0HYP Bits)
VIN-
Negative Hysteresis Voltage
(Programmed by CP0HYN Bits)
INPUTS
VIN+
VOH
OUTPUT
VOL
Negative Hysteresis
Disabled
Maximum
Negative Hysteresis
Positive Hysteresis
Disabled
Maximum
Positive Hysteresis
Figure 10.2. Comparator Hysteresis Plot
Rev. 1.4
121
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 10.1. CPT0CN: Comparator0 Control
SFR Page:
SFR Address:
1
0x88
R/W
CP0EN
Bit7
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
CP0OUT CP0RIF
CP0FIF CP0HYP1 CP0HYP0 CP0HYN1 CP0HYN0 00000000
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit7:
Bit6:
Bit5:
Bit4:
CP0EN: Comparator0 Enable Bit.
0: Comparator0 Disabled.
1: Comparator0 Enabled.
CP0OUT: Comparator0 Output State Flag.
0: Voltage on CP0+ < CP0–.
1: Voltage on CP0+ > CP0–.
CP0RIF: Comparator0 Rising-Edge Flag.
0: No Comparator0 Rising Edge has occurred since this flag was last cleared.
1: Comparator0 Rising Edge has occurred.
CP0FIF: Comparator0 Falling-Edge Flag.
0: No Comparator0 Falling-Edge has occurred since this flag was last cleared.
1: Comparator0 Falling-Edge has occurred.
Bits3–2: CP0HYP1–0: Comparator0 Positive Hysteresis Control Bits.
00: Positive Hysteresis Disabled.
01: Positive Hysteresis = 5 mV.
10: Positive Hysteresis = 10 mV.
11: Positive Hysteresis = 15 mV.
Bits1–0: CP0HYN1–0: Comparator0 Negative Hysteresis Control Bits.
00: Negative Hysteresis Disabled.
01: Negative Hysteresis = 5 mV.
10: Negative Hysteresis = 10 mV.
11: Negative Hysteresis = 15 mV.
122
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 10.2. CPT0MD: Comparator0 Mode Selection
SFR Page:
SFR Address:
1
0x89
R/W
-
R/W
R/W
R/W
R/W
-
R/W
-
R/W
R/W
Reset Value
-
CP0RIE CP0FIE
CP0MD1 CP0MD0 00000010
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bits7–6: UNUSED. Read = 00b, Write = don’t care.
Bit 5:
CP0RIE: Comparator 0 Rising-Edge Interrupt Enable Bit.
0: Comparator 0 rising-edge interrupt disabled.
1: Comparator 0 rising-edge interrupt enabled.
CP0FIE: Comparator 0 Falling-Edge Interrupt Enable Bit.
0: Comparator 0 falling-edge interrupt disabled.
1: Comparator 0 falling-edge interrupt enabled.
Bit 4:
Bits3–2: UNUSED. Read = 00b, Write = don’t care.
Bits1–0: CP0MD1–CP0MD0: Comparator0 Mode Select
These bits select the response time for Comparator0.
Mode
CP0MD1 CP0MD0
Notes
0
1
2
3
0
0
1
1
0
1
0
1
Fastest Response Time
—
—
Lowest Power Consumption
Rev. 1.4
123
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 10.3. CPT1CN: Comparator1 Control
SFR Page:
SFR Address:
2
0x88
R/W
CP1EN
Bit7
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
CP1OUT CP1RIF
CP1FIF CP1HYP1 CP1HYP0 CP1HYN1 CP1HYN0 00000000
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit7:
Bit6:
Bit5:
Bit4:
CP1EN: Comparator1 Enable Bit.
0: Comparator1 Disabled.
1: Comparator1 Enabled.
CP1OUT: Comparator1 Output State Flag.
0: Voltage on CP1+ < CP1–.
1: Voltage on CP1+ > CP1–.
CP1RIF: Comparator1 Rising-Edge Flag.
0: No Comparator1 Rising Edge has occurred since this flag was last cleared.
1: Comparator1 Rising Edge has occurred.
CP1FIF: Comparator1 Falling-Edge Flag.
0: No Comparator1 Falling-Edge has occurred since this flag was last cleared.
1: Comparator1 Falling-Edge Interrupt has occurred.
Bits3–2: CP1HYP1–0: Comparator1 Positive Hysteresis Control Bits.
00: Positive Hysteresis Disabled.
01: Positive Hysteresis = 5 mV.
10: Positive Hysteresis = 10 mV.
11: Positive Hysteresis = 15 mV.
Bits1–0: CP1HYN1–0: Comparator1 Negative Hysteresis Control Bits.
00: Negative Hysteresis Disabled.
01: Negative Hysteresis = 5 mV.
10: Negative Hysteresis = 10 mV.
11: Negative Hysteresis = 15 mV.
124
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 10.4. CPT1MD: Comparator1 Mode Selection
SFR Page:
SFR Address:
2
0x89
R/W
-
R/W
R/W
R/W
R/W
-
R/W
-
R/W
R/W
Reset Value
-
CP1RIE CP1FIE
CP1MD1 CP1MD0 00000010
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bits7–6: UNUSED. Read = 00b, Write = don’t care.
Bit 5:
CP1RIE: Comparator 1 Rising-Edge Interrupt Enable Bit.
0: Comparator 1 rising-edge interrupt disabled.
1: Comparator 1 rising-edge interrupt enabled.
CP1FIE: Comparator 0 Falling-Edge Interrupt Enable Bit.
0: Comparator 1 falling-edge interrupt disabled.
1: Comparator 1 falling-edge interrupt enabled.
Bit 4:
Bits3–2: UNUSED. Read = 00b, Write = don’t care.
Bits1–0: CP1MD1–CP1MD0: Comparator1 Mode Select
These bits select the response time for Comparator1.
Mode
CP0MD1 CP0MD0
Notes
0
1
2
3
0
0
1
1
0
1
0
1
Fastest Response Time
—
—
Lowest Power Consumption
Rev. 1.4
125
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 10.1. Comparator Electrical Characteristics
VDD = 3.0 V, AV+ = 3.0 V, –40 to +85 °C unless otherwise specified.
Parameter
Response Time:
Mode 0, VCM* = 1.5 V
Conditions
Min
—
—
—
—
—
—
—
—
Typ
100
Max
—
Units
ns
CPn+ – CPn- = 100 mV
CPn+ – CPn– = –100 mV
CPn+ – CPn– = 100 mV
CPn+ – CPn– = –100 mV
CPn+ – CPn– = 100 mV
CPn+ – CPn– = –100 mV
CPn+ – CPn– = 100 mV
CPn+ – CPn– = –100 mV
250
—
ns
175
—
ns
Response Time:
Mode 1, VCM* = 1.5 V
500
—
ns
320
—
ns
Response Time:
Mode 2, VCM* = 1.5 V
1100
1050
5200
—
ns
—
ns
Response Time:
Mode 3, VCM* = 1.5 V
—
ns
Common-Mode Rejection
Ratio
—
1.5
4
mV/V
Positive Hysteresis 1
Positive Hysteresis 2
Positive Hysteresis 3
Positive Hysteresis 4
Negative Hysteresis 1
Negative Hysteresis 2
Negative Hysteresis 3
Negative Hysteresis 4
CPnHYP1-0 = 00
CPnHYP1-0 = 01
CPnHYP1-0 = 10
CPnHYP1-0 = 11
CPnHYN1-0 = 00
CPnHYN1-0 = 01
CPnHYN1-0 = 10
CPnHYN1-0 = 11
—
2
0
4.5
9
1
7
mV
mV
mV
mV
mV
mV
mV
mV
4
13
25
1
10
—
2
17
0
4.5
9
7
4
13
25
10
17
Inverting or Non-Inverting
Input Voltage Range
(AV+)
+ 0.25
–0.25
—
V
Input Capacitance
Input Bias Current
Input Offset Voltage
—
–5
7
0.001
—
—
+5
pF
nA
–10
+10
mV
Power Supply
Power-Up Time
CPnEN from 0 to 1
—
—
—
—
—
—
20
0.1
7.6
3.2
1.3
0.4
—
1
µs
mV/V
µA
Power Supply Rejection
Mode 0
Mode 1
Mode 2
Mode 3
—
—
—
—
µA
Supply Current at DC
(each comparator)
µA
µA
*Note: VCM is the common-mode voltage on CPn+ and CPn-.
126
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
11. CIP-51 Microcontroller
The MCU system controller core is the CIP-51 microcontroller. The CIP-51 is fully compatible with the
MCS-51™ instruction set; standard 803x/805x assemblers and compilers can be used to develop soft-
ware. The MCU family has a superset of all the peripherals included with a standard 8051. Included are
five 16-bit counter/timers (see description in Section 23), two full-duplex UARTs (see description in Sec-
tion 21 and Section 22), 256 bytes of internal RAM, 128 byte Special Function Register (SFR) address
space (see Section 11.2.6), and 8/4 byte-wide I/O Ports (see description in Section 18). The CIP-51 also
includes on-chip debug hardware (see description in Section 25), and interfaces directly with the MCU’s
analog and digital subsystems providing a complete data acquisition or control-system solution in a single
integrated circuit.
The CIP-51 Microcontroller core implements the standard 8051 organization and peripherals as well as
additional custom peripherals and functions to extend its capability (see Figure 11.1 for a block diagram).
-
-
-
-
Fully Compatible with MCS-51 Instruction Set
100 or 50 MIPS Peak Using the On-Chip PLL
256 Bytes of Internal RAM
-
-
-
-
-
Extended Interrupt Handler
Reset Input
Power Management Modes
On-chip Debug Logic
8/4 Byte-Wide I/O Ports
Program and Data Memory Security
The CIP-51 includes the following features:
Performance
The CIP-51 employs a pipelined architecture that greatly increases its instruction throughput over the stan-
dard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system
clock cycles to execute, and usually have a maximum system clock of 12 MHz. By contrast, the CIP-51
core executes 70% of its instructions in one or two system clock cycles, with no instructions taking more
than eight system clock cycles.
With the CIP-51's system clock running at 100 MHz, it has a peak throughput of 100 MIPS. The CIP-51
has a total of 109 instructions. The table below shows the total number of instructions that require each
execution time.
Clocks to Execute
1
2
2/3
5
3
3/4
7
4
3
4/5
1
5
2
8
1
Number of Instructions
26
50
14
Rev. 1.4
127
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
DATA BUS
ACCUMULATOR
B REGISTER
STACK POINTER
TMP1
TMP2
SRAM
ADDRESS
REGISTER
SRAM
(256 X 8)
PSW
ALU
DATA BUS
SFR_ADDRESS
SFR_CONTROL
D8
BUFFER
SFR
BUS
INTERFACE
D8
SFR_WRITE_DATA
SFR_READ_DATA
D8
DATA POINTER
PC INCREMENTER
D8
MEM_ADDRESS
MEM_CONTROL
PROGRAM COUNTER (PC)
PRGM. ADDRESS REG.
PIPELINE
MEMORY
INTERFACE
A16
D8
MEM_WRITE_DATA
MEM_READ_DATA
CONTROL
LOGIC
RESET
CLOCK
SYSTEM_IRQs
INTERRUPT
INTERFACE
EMULATION_IRQ
D8
STOP
IDLE
POWER CONTROL
REGISTER
D8
Figure 11.1. CIP-51 Block Diagram
Programming and Debugging Support
A JTAG-based serial interface is provided for in-system programming of the Flash program memory and
communication with on-chip debug support logic. The re-programmable Flash can also be read and
changed by the application software using the MOVC and MOVX instructions. This feature allows program
memory to be used for non-volatile data storage as well as updating program code under software control.
The on-chip debug support logic facilitates full speed in-circuit debugging, allowing the setting of hardware
breakpoints and watch points, starting, stopping and single stepping through program execution (including
interrupt service routines), examination of the program's call stack, and reading/writing the contents of reg-
isters and memory. This method of on-chip debug is completely non-intrusive and non-invasive, requiring
no RAM, Stack, timers, or other on-chip resources.
The CIP-51 is supported by development tools from Silicon Labs and third party vendors. Silicon Labs pro-
vides an integrated development environment (IDE) including editor, macro assembler, debugger and pro-
grammer. The IDE's debugger and programmer interface to the CIP-51 via its JTAG interface to provide
fast and efficient in-system device programming and debugging. Third party macro assemblers and C
compilers are also available.
128
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
11.1. Instruction Set
The instruction set of the CIP-51 System Controller is fully compatible with the standard MCS-51™ instruc-
tion set; standard 8051 development tools can be used to develop software for the CIP-51. All CIP-51
instructions are the binary and functional equivalent of their MCS-51™ counterparts, including opcodes,
addressing modes and effect on PSW flags. However, instruction timing is different than that of the stan-
dard 8051.
11.1.1. Instruction and CPU Timing
In many 8051 implementations, a distinction is made between machine cycles and clock cycles, with
machine cycles varying from 2 to 12 clock cycles in length. However, the CIP-51 implementation is based
solely on clock cycle timing. All instruction timings are specified in terms of clock cycles.
Due to the pipelined architecture of the CIP-51, most instructions execute in the same number of clock
cycles as there are program bytes in the instruction. Conditional branch instructions take one less clock
cycle to complete when the branch is not taken as opposed to when the branch is taken. Table 11.1 is the
CIP-51 Instruction Set Summary, which includes the mnemonic, number of bytes, and number of clock
cycles for each instruction.
11.1.2. MOVX Instruction and Program Memory
In the CIP-51, the MOVX instruction serves three purposes: accessing on-chip XRAM, accessing off-chip
XRAM, and accessing on-chip program Flash memory. The Flash access feature provides a mechanism
for user software to update program code and use the program memory space for non-volatile data stor-
age (see Section “15. Flash Memory” on page 199). The External Memory Interface provides a fast
access to off-chip XRAM (or memory-mapped peripherals) via the MOVX instruction. Refer to Section
“17. External Data Memory Interface and On-Chip XRAM” on page 219 for details.
Table 11.1. CIP-51 Instruction Set Summary
Clock
Cycles
Mnemonic
Description
Arithmetic Operations
Bytes
ADD A, Rn
Add register to A
Add direct byte to A
Add indirect RAM to A
Add immediate to A
Add register to A with carry
Add direct byte to A with carry
Add indirect RAM to A with carry
Add immediate to A with carry
Subtract register from A with borrow
Subtract direct byte from A with borrow
Subtract indirect RAM from A with borrow
Subtract immediate from A with borrow
Increment A
1
2
1
2
1
2
1
2
1
2
1
2
1
1
2
1
1
2
2
2
1
2
2
2
1
2
2
2
1
1
2
2
ADD A, direct
ADD A, @Ri
ADD A, #data
ADDC A, Rn
ADDC A, direct
ADDC A, @Ri
ADDC A, #data
SUBB A, Rn
SUBB A, direct
SUBB A, @Ri
SUBB A, #data
INC A
INC Rn
INC direct
INC @Ri
Increment register
Increment direct byte
Increment indirect RAM
Rev. 1.4
129
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 11.1. CIP-51 Instruction Set Summary (Continued)
Clock
Cycles
Mnemonic
Description
Bytes
DEC A
Decrement A
1
1
2
1
1
1
1
1
1
1
2
2
1
4
8
1
DEC Rn
DEC direct
DEC @Ri
INC DPTR
MUL AB
DIV AB
Decrement register
Decrement direct byte
Decrement indirect RAM
Increment Data Pointer
Multiply A and B
Divide A by B
Decimal adjust A
DA A
Logical Operations
ANL A, Rn
ANL A, direct
ANL A, @Ri
ANL A, #data
ANL direct, A
ANL direct, #data
ORL A, Rn
ORL A, direct
ORL A, @Ri
ORL A, #data
ORL direct, A
ORL direct, #data
XRL A, Rn
XRL A, direct
XRL A, @Ri
XRL A, #data
XRL direct, A
XRL direct, #data
CLR A
AND Register to A
AND direct byte to A
AND indirect RAM to A
AND immediate to A
AND A to direct byte
AND immediate to direct byte
OR Register to A
OR direct byte to A
OR indirect RAM to A
OR immediate to A
OR A to direct byte
OR immediate to direct byte
Exclusive-OR Register to A
Exclusive-OR direct byte to A
Exclusive-OR indirect RAM to A
Exclusive-OR immediate to A
Exclusive-OR A to direct byte
Exclusive-OR immediate to direct byte
Clear A
Complement A
Rotate A left
Rotate A left through Carry
Rotate A right
Rotate A right through Carry
Swap nibbles of A
1
2
1
2
2
3
1
2
1
2
2
3
1
2
1
2
2
3
1
1
1
1
1
1
1
1
2
2
2
2
3
1
2
2
2
2
3
1
2
2
2
2
3
1
1
1
1
1
1
1
CPL A
RL A
RLC A
RR A
RRC A
SWAP A
Data Transfer
MOV A, Rn
Move Register to A
1
2
1
2
1
2
2
2
2
3
1
2
2
2
1
2
2
2
2
3
MOV A, direct
MOV A, @Ri
MOV A, #data
MOV Rn, A
MOV Rn, direct
MOV Rn, #data
MOV direct, A
MOV direct, Rn
MOV direct, direct
Move direct byte to A
Move indirect RAM to A
Move immediate to A
Move A to Register
Move direct byte to Register
Move immediate to Register
Move A to direct byte
Move Register to direct byte
Move direct byte to direct byte
130
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 11.1. CIP-51 Instruction Set Summary (Continued)
Clock
Cycles
Mnemonic
Description
Bytes
MOV direct, @Ri
MOV direct, #data
MOV @Ri, A
Move indirect RAM to direct byte
Move immediate to direct byte
Move A to indirect RAM
2
3
1
2
2
3
1
1
1
1
1
1
2
2
1
2
1
1
2
3
2
2
2
3
3
3
3
3
3
3
2
2
1
2
2
2
MOV @Ri, direct
MOV @Ri, #data
MOV DPTR, #data16
MOVC A, @A+DPTR
MOVC A, @A+PC
MOVX A, @Ri
MOVX @Ri, A
MOVX A, @DPTR
MOVX @DPTR, A
PUSH direct
Move direct byte to indirect RAM
Move immediate to indirect RAM
Load DPTR with 16-bit constant
Move code byte relative DPTR to A
Move code byte relative PC to A
Move external data (8-bit address) to A
Move A to external data (8-bit address)
Move external data (16-bit address) to A
Move A to external data (16-bit address)
Push direct byte onto stack
Pop direct byte from stack
Exchange Register with A
Exchange direct byte with A
Exchange indirect RAM with A
Exchange low nibble of indirect RAM with A
Boolean Manipulation
POP direct
XCH A, Rn
XCH A, direct
XCH A, @Ri
XCHD A, @Ri
CLR C
CLR bit
SETB C
SETB bit
CPL C
Clear Carry
Clear direct bit
Set Carry
Set direct bit
Complement Carry
Complement direct bit
AND direct bit to Carry
AND complement of direct bit to Carry
OR direct bit to carry
OR complement of direct bit to Carry
Move direct bit to Carry
Move Carry to direct bit
Jump if Carry is set
Jump if Carry is not set
1
2
1
2
1
2
2
2
2
2
2
2
2
2
3
3
3
1
2
1
2
1
2
2
2
2
2
2
2
2/3*
2/3*
3/4*
3/4*
3/4*
CPL bit
ANL C, bit
ANL C, /bit
ORL C, bit
ORL C, /bit
MOV C, bit
MOV bit, C
JC rel
JNC rel
JB bit, rel
JNB bit, rel
JBC bit, rel
Jump if direct bit is set
Jump if direct bit is not set
Jump if direct bit is set and clear bit
Program Branching
ACALL addr11
LCALL addr16
RET
Absolute subroutine call
Long subroutine call
Return from subroutine
Return from interrupt
Absolute jump
Long jump
Short jump (relative address)
Jump indirect relative to DPTR
2
3
1
1
2
3
2
1
3*
4*
5*
5*
3*
4*
3*
3*
RETI
AJMP addr11
LJMP addr16
SJMP rel
JMP @A+DPTR
Rev. 1.4
131
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 11.1. CIP-51 Instruction Set Summary (Continued)
Clock
Cycles
2/3*
2/3*
3/4*
Mnemonic
Description
Bytes
JZ rel
JNZ rel
CJNE A, direct, rel
CJNE A, #data, rel
Jump if A equals zero
2
2
3
3
Jump if A does not equal zero
Compare direct byte to A and jump if not equal
Compare immediate to A and jump if not equal
Compare immediate to Register and jump if not
equal
3/4*
CJNE Rn, #data, rel
CJNE @Ri, #data, rel
3
3
3/4*
4/5*
Compare immediate to indirect and jump if not
equal
DJNZ Rn, rel
DJNZ direct, rel
NOP
Decrement Register and jump if not zero
Decrement direct byte and jump if not zero
No operation
2
3
1
2/3*
3/4*
1
* Branch instructions will incur a cache-miss penalty if the branch target location is not already stored in
the Branch Target Cache. See Section “16. Branch Target Cache” on page 211 for more details.
Notes on Registers, Operands and Addressing Modes:
Rn - Register R0-R7 of the currently selected register bank.
@Ri - Data RAM location addressed indirectly through R0 or R1.
rel - 8-bit, signed (2s complement) offset relative to the first byte of the following instruction. Used by
SJMP and all conditional jumps.
direct - 8-bit internal data location’s address. This could be a direct-access Data RAM location (0x00-
0x7F) or an SFR (0x80-0xFF).
#data - 8-bit constant
#data16 - 16-bit constant
bit - Direct-accessed bit in Data RAM or SFR
addr11 - 11-bit destination address used by ACALL and AJMP. The destination must be within the same
2K-byte page of program memory as the first byte of the following instruction.
addr16 - 16-bit destination address used by LCALL and LJMP. The destination may be anywhere within
the 64K-byte program memory space.
There is one unused opcode (0xA5) that performs the same function as NOP.
All mnemonics copyrighted © Intel Corporation 1980.
132
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
11.2. Memory Organization
The memory organization of the CIP-51 System Controller is similar to that of a standard 8051. There are
two separate memory spaces: program memory and data memory. Program and data memory share the
same address space but are accessed via different instruction types. There are 256 bytes of internal data
memory and 128k bytes (C8051F12x and C8051F130/1) or 64k bytes (C8051F132/3) of internal program
memory address space implemented within the CIP-51. The CIP-51 memory organization is shown in
Figure 11.2.
PROGRAM/DATA MEMORY
(FLASH)
DATA MEMORY (RAM)
INTERNAL DATA ADDRESS SPACE
C8051F120/1/2/3/4/5/6/7
C8051F130/1
Upper 128 RAM
(Indirect Addressing
Only)
Special Function
Registers
(Direct Addressing Only)
0x200FF
0x20000
0x1FFFF
0x1FC00
0x1FBFF
Scrachpad Memory
(DATA only)
0
1
2
3
RESERVED
(Direct and Indirect
Addressing)
Up To
256 SFR Pages
Lower 128 RAM
(Direct and Indirect
Addressing)
FLASH
Bit Addressable
(In-System
Programmable in 1024
Byte Sectors)
General Purpose
Registers
0x00000
EXTERNAL DATA ADDRESS SPACE
0xFFFF
C8051F132/3
0x200FF
0x20000
Scrachpad Memory
(DATA only)
Off-chip XRAM space
0x0FFFF
FLASH
(In-System
Programmable in 1024
Byte Sectors)
0x2000
0x1FFF
XRAM - 8192 Bytes
(accessable using MOVX
instruction)
0x0000
0x00000
Figure 11.2. Memory Map
11.2.1. Program Memory
The C8051F12x and C8051F130/1 have a 128 kB program memory space. The MCU implements this pro-
gram memory space as in-system re-programmable Flash memory in four 32 kB code banks. A common
code bank (Bank 0) of 32 kB is always accessible from addresses 0x0000 to 0x7FFF. The three upper
code banks (Bank 1, Bank 2, and Bank 3) are each mapped to addresses 0x8000 to 0xFFFF, depending
on the selection of bits in the PSBANK register, as described in SFR Definition 11.1. The IFBANK bits
select which of the upper banks are used for code execution, while the COBANK bits select the bank to be
used for direct writes and reads of the Flash memory. Note: 1024 bytes of the memory in Bank 3
(0x1FC00 to 0x1FFFF) are reserved and are not available for user program or data storage. The
C8051F132/3 have a 64k byte program memory space implemented as in-system re-programmable Flash
memory, and organized in a contiguous block from address 0x00000 to 0x0FFFF.
Program memory is normally assumed to be read-only. However, the CIP-51 can write to program memory
by setting the Program Store Write Enable bit (PSCTL.0) and using the MOVX instruction. This feature pro-
vides a mechanism for the CIP-51 to update program code and use the program memory space for non-
volatile data storage. Refer to Section “15. Flash Memory” on page 199 for further details.
Rev. 1.4
133
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 11.1. PSBANK: Program Space Bank Select
R/W
-
R/W
-
R/W
R/W
Bit4
R/W
-
R/W
-
R/W
Bit1
R/W
Reset Value
COBANK
Bit5
IFBANK
00010001
Bit7
Bit6
Bit3
Bit2
Bit0
SFR Address: 0xB1
SFR Page: All Pages
Bits 7–6: Reserved.
Bits 5–4: COBANK: Constant Operations Bank Select.
These bits select which Flash bank is targeted during constant operations (MOVC and Flash
MOVX) involving addresses 0x8000 to 0xFFFF. These bits are ignored when accessing the
Scratchpad memory areas (see Section “15. Flash Memory” on page 199).
00: Constant Operations Target Bank 0 (note that Bank 0 is also mapped between 0x0000 to
0x7FFF).
01: Constant Operations Target Bank 1.
10: Constant Operations Target Bank 2.
11: Constant Operations Target Bank 3.
Bits 3–2: Reserved.
Bits 1–0: IFBANK: Instruction Fetch Operations Bank Select.
These bits select which Flash bank is used for instruction fetches involving addresses 0x8000 to
0xFFFF. These bits can only be changed from code in Bank 0 (see Figure 11.3).
00: Instructions Fetch From Bank 0 (note that Bank 0 is also mapped between 0x0000 to
0x7FFF).
01: Instructions Fetch From Bank 1.
10: Instructions Fetch From Bank 2.
11: Instructions Fetch From Bank 3.
*Note: On the C8051F132/3, the COBANK and IFBANK bits should both remain set to the default setting of ‘01’ to
ensure proper device functionality.
Internal
IFBANK = 0 IFBANK = 1 IFBANK = 2 IFBANK = 3
Address
0xFFFF
Bank 0
Bank 1
Bank 2
Bank 3
0x8000
0x7FFF
Bank 0
Bank 0
Bank 0
Bank 0
0x0000
Figure 11.3. Address Memory Map for Instruction Fetches (128 kB Flash Only)
134
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
11.2.2. Data Memory
The CIP-51 implements 256 bytes of internal RAM mapped into the data memory space from 0x00 through
0xFF. The lower 128 bytes of data memory are used for general purpose registers and memory. Either
direct or indirect addressing may be used to access the lower 128 bytes of data memory. Locations 0x00
through 0x1F are addressable as four banks of general purpose registers, each bank consisting of eight
byte-wide registers. The next 16 bytes, locations 0x20 through 0x2F, may either be addressed as bytes or
as 128 bit locations accessible with the direct addressing mode.
The upper 128 bytes of data memory are accessible only by indirect addressing. This region occupies the
same address space as the Special Function Registers (SFR) but is physically separate from the SFR
space. The addressing mode used by an instruction when accessing locations above 0x7F determines
whether the CPU accesses the upper 128 bytes of data memory space or the SFR’s. Instructions that use
direct addressing will access the SFR space. Instructions using indirect addressing above 0x7F access the
upper 128 bytes of data memory. Figure 11.2 illustrates the data memory organization of the CIP-51.
11.2.3. General Purpose Registers
The lower 32 bytes of data memory, locations 0x00 through 0x1F, may be addressed as four banks of gen-
eral-purpose registers. Each bank consists of eight byte-wide registers designated R0 through R7. Only
one of these banks may be enabled at a time. Two bits in the program status word, RS0 (PSW.3) and RS1
(PSW.4), select the active register bank (see description of the PSW in SFR Definition 11.9). This allows
fast context switching when entering subroutines and interrupt service routines. Indirect addressing modes
use registers R0 and R1 as index registers.
11.2.4. Bit Addressable Locations
In addition to direct access to data memory organized as bytes, the sixteen data memory locations at 0x20
through 0x2F are also accessible as 128 individually addressable bits. Each bit has a bit address from
0x00 to 0x7F. Bit 0 of the byte at 0x20 has bit address 0x00 while bit 7 of the byte at 0x20 has bit address
0x07. Bit 7 of the byte at 0x2F has bit address 0x7F. A bit access is distinguished from a full byte access by
the type of instruction used (bit source or destination operands as opposed to a byte source or destina-
tion). The MCS-51™ assembly language allows an alternate notation for bit addressing of the form XX.B
where XX is the byte address and B is the bit position within the byte.
For example, the instruction:
MOV
C, 22.3h
moves the Boolean value at 0x13 (bit 3 of the byte at location 0x22) into the Carry flag.
11.2.5. Stack
A programmer's stack can be located anywhere in the 256 byte data memory. The stack area is designated
using the Stack Pointer (SP, address 0x81) SFR. The SP will point to the last location used. The next value
pushed on the stack is placed at SP+1 and then SP is incremented. A reset initializes the stack pointer to
location 0x07; therefore, the first value pushed on the stack is placed at location 0x08, which is also the
first register (R0) of register bank 1. Thus, if more than one register bank is to be used, the SP should be
initialized to a location in the data memory not being used for data storage. The stack depth can extend up
to 256 bytes.
The MCUs also have built-in hardware for a stack record which is accessed by the debug logic. The stack
record is a 32-bit shift register, where each PUSH or increment SP pushes one record bit onto the register,
and each CALL pushes two record bits onto the register. (A POP or decrement SP pops one record bit,
Rev. 1.4
135
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
and a RET pops two record bits, also.) The stack record circuitry can also detect an overflow or underflow
on the 32-bit shift register, and can notify the debug software even with the MCU running at speed.
11.2.6. Special Function Registers
The direct-access data memory locations from 0x80 to 0xFF constitute the special function registers
(SFR’s). The SFR’s provide control and data exchange with the CIP-51's resources and peripherals. The
CIP-51 duplicates the SFR’s found in a typical 8051 implementation as well as implementing additional
SFR’s used to configure and access the sub-systems unique to the MCU. This allows the addition of new
functionality while retaining compatibility with the MCS-51™ instruction set. Table 11.2 lists the SFR’s
implemented in the CIP-51 System Controller.
The SFR registers are accessed whenever the direct addressing mode is used to access memory loca-
tions from 0x80 to 0xFF. SFR’s with addresses ending in 0x0 or 0x8 (e.g. P0, TCON, P1, SCON, IE, etc.)
are bit-addressable as well as byte-addressable. All other SFR’s are byte-addressable only. Unoccupied
addresses in the SFR space are reserved for future use. Accessing these areas will have an indeterminate
effect and should be avoided. Refer to the corresponding pages of the datasheet, as indicated in
Table 11.3, for a detailed description of each register.
11.2.6.1.SFR Paging
The CIP-51 features SFR paging, allowing the device to map many SFR’s into the 0x80 to 0xFF memory
address space. The SFR memory space has 256 pages. In this way, each memory location from 0x80 to
0xFF can access up to 256 SFR’s. The C8051F12x family of devices utilizes five SFR pages: 0, 1, 2, 3,
and F. SFR pages are selected using the Special Function Register Page Selection register, SFRPAGE
(see SFR Definition 11.3). The procedure for reading and writing an SFR is as follows:
1. Select the appropriate SFR page number using the SFRPAGE register.
2. Use direct accessing mode to read or write the special function register (MOV instruction).
11.2.6.2.Interrupts and SFR Paging
When an interrupt occurs, the SFR Page Register will automatically switch to the SFR page containing the
flag bit that caused the interrupt. The automatic SFR Page switch function conveniently removes the bur-
den of switching SFR pages from the interrupt service routine. Upon execution of the RETI instruction, the
SFR page is automatically restored to the SFR Page in use prior to the interrupt. This is accomplished via
a three-byte SFR Page Stack. The top byte of the stack is SFRPAGE, the current SFR Page. The second
byte of the SFR Page Stack is SFRNEXT. The third, or bottom byte of the SFR Page Stack is SFRLAST.
On interrupt, the current SFRPAGE value is pushed to the SFRNEXT byte, and the value of SFRNEXT is
pushed to SFRLAST. Hardware then loads SFRPAGE with the SFR Page containing the flag bit associated
with the interrupt. On a return from interrupt, the SFR Page Stack is popped resulting in the value of SFRN-
EXT returning to the SFRPAGE register, thereby restoring the SFR page context without software interven-
tion. The value in SFRLAST (0x00 if there is no SFR Page value in the bottom of the stack) of the stack is
placed in SFRNEXT register. If desired, the values stored in SFRNEXT and SFRLAST may be modified
during an interrupt, enabling the CPU to return to a different SFR Page upon execution of the RETI instruc-
tion (on interrupt exit). Modifying registers in the SFR Page Stack does not cause a push or pop of the
stack. Only interrupt calls and returns will cause push/pop operations on the SFR Page Stack.
136
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SFRPGCN Bit
Interrupt
Logic
SFRPAGE
CIP-51
SFRNEXT
SFRLAST
Figure 11.4. SFR Page Stack
Automatic hardware switching of the SFR Page on interrupts may be enabled or disabled as desired using
the SFR Automatic Page Control Enable Bit located in the SFR Page Control Register (SFRPGCN). This
function defaults to ‘enabled’ upon reset. In this way, the autoswitching function will be enabled unless dis-
abled in software.
A summary of the SFR locations (address and SFR page) is provided in Table 11.2. in the form of an SFR
memory map. Each memory location in the map has an SFR page row, denoting the page in which that
SFR resides. Note that certain SFR’s are accessible from ALL SFR pages, and are denoted by the “(ALL
PAGES)” designation. For example, the Port I/O registers P0, P1, P2, and P3 all have the “(ALL PAGES)”
designation, indicating these SFR’s are accessible from all SFR pages regardless of the SFRPAGE regis-
ter value.
Rev. 1.4
137
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C8051F130/1/2/3
11.2.6.3.SFR Page Stack Example
The following is an example that shows the operation of the SFR Page Stack during interrupts.
In this example, the SFR Page Control is left in the default enabled state (i.e., SFRPGEN = 1), and the
CIP-51 is executing in-line code that is writing values to Port 5 (SFR “P5”, located at address 0xD8 on SFR
Page 0x0F). The device is also using the Programmable Counter Array (PCA) and the 10-bit ADC (ADC2)
window comparator to monitor a voltage. The PCA is timing a critical control function in its interrupt service
routine (ISR), so its interrupt is enabled and is set to high priority. The ADC2 is monitoring a voltage that is
less important, but to minimize the software overhead its window comparator is being used with an associ-
ated ISR that is set to low priority. At this point, the SFR page is set to access the Port 5 SFR (SFRPAGE =
0x0F). See Figure 11.5 below.
SFR Page
Stack SFR's
0x0F
SFRPAGE
(Port 5)
SFRNEXT
SFRLAST
Figure 11.5. SFR Page Stack While Using SFR Page 0x0F To Access Port 5
While CIP-51 executes in-line code (writing values to Port 5 in this example), ADC2 Window Comparator
Interrupt occurs. The CIP-51 vectors to the ADC2 Window Comparator ISR and pushes the current SFR
Page value (SFR Page 0x0F) into SFRNEXT in the SFR Page Stack. The SFR page needed to access
ADC2’s SFR’s is then automatically placed in the SFRPAGE register (SFR Page 0x02). SFRPAGE is con-
sidered the “top” of the SFR Page Stack. Software can now access the ADC2 SFR’s. Software may switch
to any SFR Page by writing a new value to the SFRPAGE register at any time during the ADC2 ISR to
access SFR’s that are not on SFR Page 0x02. See Figure 11.6 below.
138
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C8051F130/1/2/3
SFR Page 0x02
Automatically
pushed on stack in
SFRPAGE on ADC2
interrupt
0x02
SFRPAGE
SFRNEXT
SFRLAST
(ADC2)
0x0F
SFRPAGE
pushed to
SFRNEXT
(Port 5)
Figure 11.6. SFR Page Stack After ADC2 Window Comparator Interrupt Occurs
While in the ADC2 ISR, a PCA interrupt occurs. Recall the PCA interrupt is configured as a high priority
interrupt, while the ADC2 interrupt is configured as a low priority interrupt. Thus, the CIP-51 will now vector
to the high priority PCA ISR. Upon doing so, the CIP-51 will automatically place the SFR page needed to
access the PCA’s special function registers into the SFRPAGE register, SFR Page 0x00. The value that
was in the SFRPAGE register before the PCA interrupt (SFR Page 2 for ADC2) is pushed down the stack
into SFRNEXT. Likewise, the value that was in the SFRNEXT register before the PCA interrupt (in this
case SFR Page 0x0F for Port 5) is pushed down to the SFRLAST register, the “bottom” of the stack. Note
that a value stored in SFRLAST (via a previous software write to the SFRLAST register) will be overwritten.
See Figure 11.7 below.
Rev. 1.4
139
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Page 0x00
Automatically
pushed on stack in
SFRPAGE on PCA
interrupt
0x00
SFRPAGE
SFRNEXT
SFRLAST
(PCA)
0x02
SFRPAGE
pushed to
SFRNEXT
(ADC2)
0x0F
SFRNEXT
pushed to
SFRLAST
(Port 5)
Figure 11.7. SFR Page Stack Upon PCA Interrupt Occurring During an ADC2 ISR
On exit from the PCA interrupt service routine, the CIP-51 will return to the ADC2 Window Comparator
ISR. On execution of the RETI instruction, SFR Page 0x00 used to access the PCA registers will be auto-
matically popped off of the SFR Page Stack, and the contents of the SFRNEXT register will be moved to
the SFRPAGE register. Software in the ADC2 ISR can continue to access SFR’s as it did prior to the PCA
interrupt. Likewise, the contents of SFRLAST are moved to the SFRNEXT register. Recall this was the
SFR Page value 0x0F being used to access Port 5 before the ADC2 interrupt occurred. See Figure 11.8
below.
SFR Page 0x00
Automatically
popped off of the
stack on return from
interrupt
0x02
SFRPAGE
(ADC2)
SFRNEXT
popped to
SFRPAGE
0x0F
SFRNEXT
(Port 5)
SFRLAST
popped to
SFRNEXT
SFRLAST
Figure 11.8. SFR Page Stack Upon Return From PCA Interrupt
140
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C8051F130/1/2/3
On the execution of the RETI instruction in the ADC2 Window Comparator ISR, the value in SFRPAGE
register is overwritten with the contents of SFRNEXT. The CIP-51 may now access the Port 5 SFR bits as
it did prior to the interrupts occurring. See Figure 11.9 below.
SFR Page 0x02
Automatically
popped off of the
stack on return from
interrupt
0x0F
SFRPAGE
(Port 5)
SFRNEXT
popped to
SFRPAGE
SFRNEXT
SFRLAST
Figure 11.9. SFR Page Stack Upon Return From ADC2 Window Interrupt
Note that in the above example, all three bytes in the SFR Page Stack are accessible via the SFRPAGE,
SFRNEXT, and SFRLAST special function registers. If the stack is altered while servicing an interrupt, it is
possible to return to a different SFR Page upon interrupt exit than selected prior to the interrupt call. Direct
access to the SFR Page stack can be useful to enable real-time operating systems to control and manage
context switching between multiple tasks.
Push operations on the SFR Page Stack only occur on interrupt service, and pop operations only occur on
interrupt exit (execution on the RETI instruction). The automatic switching of the SFRPAGE and operation
of the SFR Page Stack as described above can be disabled in software by clearing the SFR Automatic
Page Enable Bit (SFRPGEN) in the SFR Page Control Register (SFRPGCN). See SFR Definition 11.2.
Rev. 1.4
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SFR Definition 11.2. SFRPGCN: SFR Page Control
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
Reset Value
SFRPGEN 00000001
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x96
SFR Page: F
Bits7–1: Reserved.
Bit0: SFRPGEN: SFR Automatic Page Control Enable.
Upon interrupt, the C8051 Core will vector to the specified interrupt service routine and auto-
matically switch the SFR page to the corresponding peripheral or function’s SFR page. This
bit is used to control this autopaging function.
0: SFR Automatic Paging disabled. C8051 core will not automatically change to the appro-
priate SFR page (i.e., the SFR page that contains the SFR’s for the peripheral/function that
was the source of the interrupt).
1: SFR Automatic Paging enabled. Upon interrupt, the C8051 will switch the SFR page to
the page that contains the SFR’s for the peripheral or function that is the source of the inter-
rupt.
SFR Definition 11.3. SFRPAGE: SFR Page
R/W
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
Bit7
SFR Address: 0x84
SFR Page: All Pages
Bits7–0: SFR Page Bits: Byte Represents the SFR Page the C8051 MCU uses when reading or mod-
ifying SFR’s.
Write: Sets the SFR Page.
Read: Byte is the SFR page the C8051 MCU is using.
When enabled in the SFR Page Control Register (SFRPGCN), the C8051 will automatically
switch to the SFR Page that contains the SFR’s of the corresponding peripheral/function that
caused the interrupt, and return to the previous SFR page upon return from interrupt (unless
SFR Stack was altered before a returning from the interrupt).
SFRPAGE is the top byte of the SFR Page Stack, and push/pop events of this stack are
caused by interrupts (and not by reading/writing to the SFRPAGE register)
142
Rev. 1.4
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C8051F130/1/2/3
SFR Definition 11.4. SFRNEXT: SFR Next Register
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address: 0x85
SFR Page: All Pages
Bits7–0: SFR Page Stack Bits: SFR page context is retained upon interrupts/return from interrupts in
a 3 byte SFR Page Stack: SFRPAGE is the first entry, SFRNEXT is the second, and SFR-
LAST is the third entry. The SFR stack bytes may be used alter the context in the SFR Page
Stack, and will not cause the stack to ‘push’ or ‘pop’. Only interrupts and return from inter-
rupts cause pushes and pops of the SFR Page Stack.
Write: Sets the SFR Page contained in the second byte of the SFR Stack. This will cause
the SFRPAGE SFR to have this SFR page value upon a return from interrupt.
Read: Returns the value of the SFR page contained in the second byte of the SFR stack.
This is the value that will go to the SFR Page register upon a return from interrupt.
SFR Definition 11.5. SFRLAST: SFR Last Register
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address: 0x86
SFR Page: All Pages
Bits7–0: SFR Page Stack Bits: SFR page context is retained upon interrupts/return from interrupts in
a 3 byte SFR Page Stack: SFRPAGE is the first entry, SFRNEXT is the second, and SFR-
LAST is the third entry. The SFR stack bytes may be used alter the context in the SFR Page
Stack, and will not cause the stack to ‘push’ or ‘pop’. Only interrupts and return from inter-
rupts cause pushes and pops of the SFR Page Stack.
Write: Sets the SFR Page in the last entry of the SFR Stack. This will cause the SFRNEXT
SFR to have this SFR page value upon a return from interrupt.
Read: Returns the value of the SFR page contained in the last entry of the SFR stack.
Rev. 1.4
143
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C8051F130/1/2/3
Table 11.2. Special Function Register (SFR) Memory Map
0(8)
1(9)
2(A)
3(B)
4(C)
5(D)
6(E)
7(F)
0
1
2
3
F
0
1
2
3
F
0
1
2
3
F
0
1
2
3
F
0
1
2
3
F
0
1
2
3
F
0
1
2
3
F
0
1
2
3
F
SPI0CN
PCA0L
PCA0H
PCA0CPL0 PCA0CPH0 PCA0CPL1 PCA0CPH1
WDTCN
(ALL
PAGES)
F8
F0
E8
E0
D8
D0
C8
C0
P7
B
(ALL
PAGES)
EIP1
(ALL
PAGES)
EIP2
(ALL
PAGES)
ADC0CN PCA0CPL2 PCA0CPH2 PCA0CPL3 PCA0CPH3 PCA0CPL4 PCA0CPH4 RSTSRC
ADC2CN
P6
PCA0CPL5 PCA0CPH5
ACC
(ALL
PAGES)
EIE1
(ALL
PAGES)
EIE2
(ALL
PAGES)
XBR0
XBR1
XBR2
PCA0CN
PCA0MD PCA0CPM0 PCA0CPM1 PCA0CPM2 PCA0CPM3 PCA0CPM4 PCA0CPM5
P5
REF0CN
DAC0L
DAC1L
DAC0H
DAC1H
DAC0CN
DAC1CN
PSW
(ALL
PAGES)
TMR2CN
TMR3CN
TMR4CN
TMR2CF
TMR3CF
TMR4CF
RCAP2L
RCAP3L
RCAP4L
RCAP2H
RCAP3H
RCAP4H
TMR2L
TMR3L
TMR4L
TMR2H
TMR3H
TMR4H
SMB0CR
MAC0RNDL MAC0RNDH
P4
SMB0CN
SMB0STA SMB0DAT SMB0ADR ADC0GTL ADC0GTH ADC0LTL
ADC0LTH
ADC2GT
4(C)
ADC2LT
6(E)
MAC0STA
0(8)
MAC0AL
1(9)
MAC0AH
2(A)
MAC0CF
3(B)
5(D)
7(F)
144
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 11.2. Special Function Register (SFR) Memory Map (Continued)
0
1
2
3
F
0
1
2
3
F
0
1
2
3
F
0
1
2
3
F
0
1
2
3
F
0
1
2
3
F
0
1
2
3
F
0
1
2
3
F
SADEN0
AMX0CF
AMX0SL
ADC0CF
ADC0L
ADC0H
IP
(ALL
PAGES)
AMX2CF
AMX2SL
ADC2CF
ADC2
B8
B0
A8
A0
98
90
88
80
FLSCL
FLACL
P3
(ALL
PAGES)
PSBANK
(ALL
PAGES)
SADDR0
IE
(ALL
PAGES)
P1MDIN
EMI0TC
EMI0CN
EMI0CF
P2
(ALL
PAGES)
CCH0CN
SBUF0
SBUF1
CCH0TN
SPI0CFG
CCH0LC
SPI0DAT
P0MDOUT P1MDOUT P2MDOUT P3MDOUT
SPI0CKR
SCON0
SCON1
CCH0MA
P4MDOUT P5MDOUT P6MDOUT P7MDOUT
SSTA0
P1
(ALL
PAGES)
MAC0BL
MAC0BH MAC0ACC0 MAC0ACC1 MAC0ACC2 MAC0ACC3 MAC0OVR
SFRPGCN
CKCON
CLKSEL
PSCTL
TCON
CPT0CN
CPT1CN
TMOD
CPT0MD
CPT1MD
TL0
TL1
TH0
TH1
FLSTAT
PLL0CN
OSCICN
OSCICL
OSCXCN
PLL0DIV
PLL0MUL
PLL0FLT
P0
(ALL
PAGES)
SP
(ALL
PAGES)
DPL
(ALL
PAGES)
DPH
(ALL
PAGES)
SFRPAGE SFRNEXT SFRLAST
(ALL
PAGES)
PCON
(ALL
PAGES)
(ALL
PAGES)
(ALL
PAGES)
0(8)
1(9)
2(A)
3(B)
4(C)
5(D)
6(E)
7(F)
Rev. 1.4
145
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C8051F130/1/2/3
Table 11.3. Special Function Registers
SFRs are listed in alphabetical order. All undefined SFR locations are reserved.
SFR
Register
Address
Description
Page No.
Page
All Pages Accumulator
ADC0 Configuration
ACC
0xE0
0xBC
0xE8
0xC5
0xC4
0xBF
0xBE
0xC7
0xC6
0xBE
0xBC
0xE8
0xC4
0xC6
0xBA
0xBB
0xBA
page 153
1
2
2
2
2
2
2
2
2
ADC0CF
ADC0CN
ADC0GTH
ADC0GTL
ADC0H
0
0
0
0
0
0
0
0
2
2
2
2
2
0
0
2
2
page 62 , page 80
1
ADC0 Control
page 63 , page 81
1
ADC0 Greater-Than High Byte
ADC0 Greater-Than Low Byte
ADC0 Data Word High Byte
ADC0 Data Word Low Byte
ADC0 Less-Than High Byte
ADC0 Less-Than Low Byte
ADC2 Data Word
page 66 , page 84
1
page 66 , page 84
1
page 64 , page 82
1
ADC0L
page 64 , page 82
1
ADC0LTH
ADC0LTL
ADC2
page 67 , page 85
1
page 67 , page 85
3
page 99
3
ADC2CF
ADC2CN
ADC2GT
ADC2LT
AMX0CF
AMX0SL
AMX2CF
ADC2 Configuration
page 97
3
ADC2 Control
page 98
3
ADC2 Greater-Than
page 102
3
ADC2 Less-Than
page 102
1
2
2
ADC0 Multiplexer Configuration
ADC0 Multiplexer Channel Select
ADC2 Multiplexer Configuration
ADC2 Multiplexer Channel Select
page 60 , page 78
1
page 61 , page 79
3
page 95
3
AMX2SL
B
0xBB
0xF0
0xA1
0xA3
0x9A
0xA2
0x8E
0x97
0x88
0x89
0x88
0x89
0xD4
page 96
All Pages B Register
page 153
page 215
page 216
page 217
page 216
page 315
page 188
page 123
page 123
page 124
page 125
CCH0CN
CCH0LC
CCH0MA
CCH0TN
CKCON
CLKSEL
CPT0CN
CPT0MD
CPT1CN
CPT1MD
DAC0CN
F
F
F
F
0
F
1
1
2
2
0
Cache Control
Cache Lock
Cache Miss Accumulator
Cache Tuning
Clock Control
System Clock Select
Comparator 0 Control
Comparator 0 Configuration
Comparator 1 Control
Comparator 1 Configuration
DAC0 Control
3
page 108
3
DAC0H
DAC0L
DAC1CN
DAC1H
0xD3
0xD2
0xD4
0xD3
0
0
1
1
1
DAC0 High Byte
DAC0 Low Byte
DAC1 Control
page 107
3
page 107
3
page 110
3
DAC1 High Byte
DAC1 Low Byte
page 109
3
DAC1L
DPH
DPL
0xD2
0x83
0x82
page 109
All Pages Data Pointer High Byte
All Pages Data Pointer Low Byte
page 151
page 151
146
Rev. 1.4
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C8051F130/1/2/3
Table 11.3. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved.
SFR
Page
Register
Address
Description
Page No.
EIE1
EIE2
EIP1
EIP2
EMI0CF
EMI0CN
EMI0TC
FLACL
FLSCL
FLSTAT
IE
0xE6
0xE7
0xF6
0xF7
0xA3
0xA2
0xA1
0xB7
0xB7
0x88
0xA8
0xB8
0x93
All Pages Extended Interrupt Enable 1
All Pages Extended Interrupt Enable 2
All Pages Extended Interrupt Priority 1
All Pages Extended Interrupt Priority 2
page 159
page 160
page 161
page 162
page 221
page 220
page 226
page 206
page 208
page 217
page 157
page 158
0
0
0
F
0
F
EMIF Configuration
EMIF Control
EMIF Timing Control
Flash Access Limit
Flash Scale
Flash Status
All Pages Interrupt Enable
All Pages Interrupt Priority
IP
4
MAC0ACC0
3
3
3
3
3
3
3
3
3
3
3
3
MAC0 Accumulator Byte 0 (LSB)
page 174
page 173
page 173
page 173
page 171
page 172
page 172
page 172
page 170
page 174
page 174
page 175
page 171
4
4
4
4
4
4
4
4
4
4
4
4
MAC0ACC1
MAC0ACC2
MAC0ACC3
MAC0AH
0x94
0x95
0x96
0xC2
0xC1
0x92
0x91
0xC3
0x97
0xCF
0xCE
MAC0 Accumulator Byte 1
MAC0 Accumulator Byte 2
MAC0 Accumulator Byte 3 (MSB)
MAC0 A Register High Byte
MAC0 A Register Low Byte
MAC0 B Register High Byte
MAC0 B Register Low Byte
MAC0 Configuration
MAC0AL
MAC0BH
MAC0BL
MAC0CF
MAC0OVR
MAC0RNDH
MAC0RNDL
MAC0 Accumulator Overflow
MAC0 Rounding Register High Byte
MAC0 Rounding Register Low Byte
MAC0STA
OSCICL
OSCICN
OSCXCN
P0
P0MDOUT
P1
P1MDIN
P1MDOUT
P2
P2MDOUT
P3
P3MDOUT
P4
P4MDOUT
P5
P5MDOUT
0xC0
0x8B
0x8A
0x8C
0x80
0xA4
0x90
0xAD
0xA5
0xA0
0xA6
0xB0
0xA7
0xC8
0x9C
0xD8
0x9D
3
F
F
F
MAC0 Status Register
Internal Oscillator Calibration
Internal Oscillator Control
External Oscillator Control
page 186
page 186
page 189
page 248
page 248
page 249
page 249
page 250
page 250
page 251
page 251
page 252
page 254
page 254
page 255
page 255
All Pages Port 0 Latch
F
Port 0 Output Mode Configuration
All Pages Port 1 Latch
F
F
Port 1 Input Mode
Port 1 Output Mode Configuration
All Pages Port 2 Latch
F
Port 2 Output Mode Configuration
All Pages Port 3 Latch
F
F
F
F
F
Port 3 Output Mode Configuration
Port 4 Latch
Port 4 Output Mode Configuration
Port 5 Latch
Port 5 Output Mode Configuration
Rev. 1.4
147
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C8051F130/1/2/3
Table 11.3. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved.
SFR
Register
Address
Description
Page No.
Page
F
F
F
F
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
P6
P6MDOUT
P7
0xE8
0x9E
0xF8
0x9F
0xD8
0xFC
0xFE
0xEA
0xEC
0xEE
0xE2
0xFB
0xFD
0xE9
0xEB
0xED
0xE1
0xDA
0xDB
0xDC
0xDD
0xDE
0xDF
0xFA
0xF9
0xD9
0x87
0x89
0x8D
0x8F
0x8E
0xB1
0x8F
0xD0
0xCB
0xCA
0xCB
0xCA
0xCB
0xCA
Port 6 Latch
Port 6 Output Mode Configuration
Port 7 Latch
Port 7 Output Mode Configuration
PCA Control
page 256
page 256
page 257
page 257
page 335
page 339
page 339
page 339
page 339
page 339
page 339
page 338
page 338
page 338
page 338
page 338
page 338
page 337
page 337
page 337
page 337
page 337
page 337
page 338
page 338
page 336
page 164
page 193
page 194
page 195
page 194
page 134
page 209
page 152
page 323
page 323
page 323
page 323
page 323
page 323
P7MDOUT
PCA0CN
PCA0CPH0
PCA0CPH1
PCA0CPH2
PCA0CPH3
PCA0CPH4
PCA0CPH5
PCA0CPL0
PCA0CPL1
PCA0CPL2
PCA0CPL3
PCA0CPL4
PCA0CPL5
PCA0CPM0
PCA0CPM1
PCA0CPM2
PCA0CPM3
PCA0CPM4
PCA0CPM5
PCA0H
PCA Module 0 Capture/Compare High Byte
PCA Module 1 Capture/Compare High Byte
PCA Module 2 Capture/Compare High Byte
PCA Module 3 Capture/Compare High Byte
PCA Module 4 Capture/Compare High Byte
PCA Module 5 Capture/Compare High Byte
PCA Module 0 Capture/Compare Low Byte
PCA Module 1 Capture/Compare Low Byte
PCA Module 2 Capture/Compare Low Byte
PCA Module 3 Capture/Compare Low Byte
PCA Module 4 Capture/Compare Low Byte
PCA Module 5 Capture/Compare Low Byte
PCA Module 0 Mode
PCA Module 1 Mode
PCA Module 2 Mode
PCA Module 3 Mode
PCA Module 4 Mode
PCA Module 5 Mode
PCA Counter High Byte
PCA Counter Low Byte
PCA Mode
PCA0L
PCA0MD
PCON
0
All Pages Power Control
PLL0CN
F
F
F
F
PLL Control
PLL Divider
PLL Filter
PLL0DIV
PLL0FLT
PLL0MUL
PSBANK
PSCTL
PSW
RCAP2H
RCAP2L
RCAP3H
RCAP3L
RCAP4H
RCAP4L
PLL Multiplier
All Pages Flash Bank Select
0
Flash Write/Erase Control
All Pages Program Status Word
0
0
1
1
2
2
Timer/Counter 2 Capture/Reload High Byte
Timer/Counter 2 Capture/Reload Low Byte
Timer 3 Capture/Reload High Byte
Timer 3 Capture/Reload Low Byte
Timer/Counter 4 Capture/Reload High Byte
Timer/Counter 4 Capture/Reload Low Byte
148
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 11.3. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved.
SFR
Page
Register
Address
Description
Page No.
5
page 114 ,
6
REF0CN
0xD1
0
Voltage Reference Control
page 116 ,
7
page 117
RSTSRC
SADDR0
SADEN0
SBUF0
0xEF
0xA9
0xB9
0x99
0x99
0x98
0x98
0x86
0x85
0x84
0x96
0xC3
0xC0
0xCF
0xC2
0xC1
0x81
0x9A
0x9D
0xF8
0x9B
0x91
0x88
0x8C
0x8D
0x8A
0x8B
0x89
0xC9
0xC8
0xCD
0xCC
0xC9
0xC8
0xCD
0xCC
0xC9
0xC8
0xCD
0
0
0
0
1
0
1
Reset Source
page 182
page 298
page 298
page 298
page 305
page 296
page 304
page 143
page 143
page 142
page 142
page 269
page 266
page 267
page 268
page 269
page 151
page 280
page 282
page 281
page 282
page 297
page 313
page 316
page 316
page 315
page 316
page 314
page 324
page 324
page 324
page 323
page 324
page 324
page 324
page 323
page 324
page 324
page 324
UART 0 Slave Address
UART 0 Slave Address Mask
UART 0 Data Buffer
UART 1 Data Buffer
UART 0 Control
SBUF1
SCON0
SCON1
SFRLAST
SFRNEXT
SFRPAGE
SFRPGCN
SMB0ADR
SMB0CN
SMB0CR
SMB0DAT
SMB0STA
SP
SPI0CFG
SPI0CKR
SPI0CN
SPI0DAT
SSTA0
TCON
TH0
TH1
TL0
TL1
TMOD
TMR2CF
TMR2CN
TMR2H
TMR2L
TMR3CF
TMR3CN
TMR3H
TMR3L
UART 1 Control
All Pages SFR Stack Last Page
All Pages SFR Stack Next Page
All Pages SFR Page Select
F
0
0
0
0
0
SFR Page Control
SMBus Slave Address
SMBus Control
SMBus Clock Rate
SMBus Data
SMBus Status
All Pages Stack Pointer
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
2
2
2
SPI Configuration
SPI Clock Rate Control
SPI Control
SPI Data
UART 0 Status
Timer/Counter Control
Timer/Counter 0 High Byte
Timer/Counter 1 High Byte
Timer/Counter 0 Low Byte
Timer/Counter 1 Low Byte
Timer/Counter Mode
Timer/Counter 2 Configuration
Timer/Counter 2 Control
Timer/Counter 2 High Byte
Timer/Counter 2 Low Byte
Timer 3 Configuration
Timer 3 Control
Timer 3 High Byte
Timer 3 Low Byte
Timer/Counter 4 Configuration
Timer/Counter 4 Control
Timer/Counter 4 High Byte
TMR4CF
TMR4CN
TMR4H
Rev. 1.4
149
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 11.3. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved.
SFR
Page
Register
Address
Description
Page No.
TMR4L
WDTCN
XBR0
XBR1
XBR2
0xCC
0xFF
0xE1
0xE2
0xE3
2
Timer/Counter 4 Low Byte
page 323
page 181
page 245
page 246
page 247
All Pages Watchdog Timer Control
F
F
F
Port I/O Crossbar Control 0
Port I/O Crossbar Control 1
Port I/O Crossbar Control 2
Notes:
1. Refers to a register in the C8051F120/1/4/5 only.
2. Refers to a register in the C8051F122/3/6/7 and C8051F130/1/2/3 only.
3. Refers to a register in the C8051F120/1/2/3/4/5/6/7 only.
4. Refers to a register in the C8051F120/1/2/3 and C8051F130/1/2/3 only.
5. Refers to a register in the C8051F120/2/4/6 only.
6. Refers to a register in the C8051F121/3/5/7 only.
7. Refers to a register in the C8051F130/1/2/3 only.
150
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C8051F130/1/2/3
11.2.7. Register Descriptions
Following are descriptions of SFRs related to the operation of the CIP-51 System Controller. Reserved bits
should not be set to logic l. Future product versions may use these bits to implement new features in which
case the reset value of the bit will be logic 0, selecting the feature's default state. Detailed descriptions of
the remaining SFRs are included in the sections of the datasheet associated with their corresponding sys-
tem function.
SFR Definition 11.6. SP: Stack Pointer
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000111
SFR Address: 0x81
SFR Page: All Pages
Bits7–0: SP: Stack Pointer.
The Stack Pointer holds the location of the top of the stack. The stack pointer is incremented
before every PUSH operation. The SP register defaults to 0x07 after reset.
SFR Definition 11.7. DPL: Data Pointer Low Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address: 0x82
SFR Page: All Pages
Bits7–0: DPL: Data Pointer Low.
The DPL register is the low byte of the 16-bit DPTR. DPTR is used to access indirectly
addressed XRAM and Flash memory.
SFR Definition 11.8. DPH: Data Pointer High Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address: 0x83
SFR Page: All Pages
Bits7–0: DPH: Data Pointer High.
The DPH register is the high byte of the 16-bit DPTR. DPTR is used to access indirectly
addressed XRAM and Flash memory.
Rev. 1.4
151
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 11.9. PSW: Program Status Word
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R
Reset Value
CY
AC
F0
RS1
RS0
OV
F1
PARITY 00000000
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0xD0
SFR Page: All Pages
Bit7:
CY: Carry Flag.
This bit is set when the last arithmetic operation resulted in a carry (addition) or a borrow
(subtraction). It is cleared to 0 by all other arithmetic operations.
AC: Auxiliary Carry Flag
This bit is set when the last arithmetic operation resulted in a carry into (addition) or a borrow
from (subtraction) the high order nibble. It is cleared to 0 by all other arithmetic operations.
F0: User Flag 0.
Bit6:
Bit5:
This is a bit-addressable, general purpose flag for use under software control.
Bits4–3: RS1–RS0: Register Bank Select.
These bits select which register bank is used during register accesses.
RS1
RS0
Register Bank
Address
0
0
0
0x00–0x07
0
1
1
1
0
1
1
2
3
0x08–0x0F
0x10–0x17
0x18–0x1F
Bit2:
OV: Overflow Flag.
This bit is set to 1 under the following circumstances:
• An ADD, ADDC, or SUBB instruction causes a sign-change overflow.
• A MUL instruction results in an overflow (result is greater than 255).
• A DIV instruction causes a divide-by-zero condition.
The OV bit is cleared to 0 by the ADD, ADDC, SUBB, MUL, and DIV instructions in all other
cases.
Bit1:
Bit0:
F1: User Flag 1.
This is a bit-addressable, general purpose flag for use under software control.
PARITY: Parity Flag.
This bit is set to 1 if the sum of the eight bits in the accumulator is odd and cleared if the sum
is even.
152
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C8051F130/1/2/3
SFR Definition 11.10. ACC: Accumulator
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
ACC.7
ACC.6
ACC.5
ACC.4
ACC.3
ACC.2
ACC.1
ACC.0 00000000
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0xE0
SFR Page: All Pages
Bits7–0: ACC: Accumulator.
This register is the accumulator for arithmetic operations.
SFR Definition 11.11. B: B Register
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
B.7
B.6
B.5
B.4
B.3
B.2
B.1
B.0
00000000
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0xF0
SFR Page: All Pages
Bits7–0: B: B Register.
This register serves as a second accumulator for certain arithmetic operations.
Rev. 1.4
153
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C8051F130/1/2/3
11.3. Interrupt Handler
The CIP-51 includes an extended interrupt system supporting a total of 20 interrupt sources with two prior-
ity levels. The allocation of interrupt sources between on-chip peripherals and external input pins varies
according to the specific version of the device. Each interrupt source has one or more associated interrupt-
pending flag(s) located in an SFR. When a peripheral or external source meets a valid interrupt condition,
the associated interrupt-pending flag is set to logic 1.
If interrupts are enabled for the source, an interrupt request is generated when the interrupt-pending flag is
set. As soon as execution of the current instruction is complete, the CPU generates an LCALL to a prede-
termined address to begin execution of an interrupt service routine (ISR). Each ISR must end with an RETI
instruction, which returns program execution to the next instruction that would have been executed if the
interrupt request had not occurred. If interrupts are not enabled, the interrupt-pending flag is ignored by the
hardware and program execution continues as normal. (The interrupt-pending flag is set to logic 1 regard-
less of the interrupt's enable/disable state.)
Each interrupt source can be individually enabled or disabled through the use of an associated interrupt
enable bit in an SFR (IE, EIE1, or EIE2). However, interrupts must first be globally enabled by setting the
EA bit (IE.7) to logic 1 before the individual interrupt enables are recognized. Setting the EA bit to logic 0
disables all interrupt sources regardless of the individual interrupt-enable settings.
Note: Any instruction that clears the EA bit should be immediately followed by an instruction that has two
or more opcode bytes. For example:
// in 'C':
EA = 0; // clear EA bit.
EA = 0; // this is a dummy instruction with two-byte opcode.
; in assembly:
CLR EA ; clear EA bit.
CLR EA ; this is a dummy instruction with two-byte opcode.
If an interrupt is posted during the execution phase of a "CLR EA" opcode (or any instruction which clears
the EA bit), and the instruction is followed by a single-cycle instruction, the interrupt may be taken. How-
ever, a read of the EA bit will return a '0' inside the interrupt service routine. When the "CLR EA" opcode is
followed by a multi-cycle instruction, the interrupt will not be taken.
Some interrupt-pending flags are automatically cleared by the hardware when the CPU vectors to the ISR.
However, most are not cleared by the hardware and must be cleared by software before returning from the
ISR. If an interrupt-pending flag remains set after the CPU completes the return-from-interrupt (RETI)
instruction, a new interrupt request will be generated immediately and the CPU will re-enter the ISR after
the completion of the next instruction.
11.3.1. MCU Interrupt Sources and Vectors
The MCUs support 20 interrupt sources. Software can simulate an interrupt event by setting any interrupt-
pending flag to logic 1. If interrupts are enabled for the flag, an interrupt request will be generated and the
CPU will vector to the ISR address associated with the interrupt-pending flag. MCU interrupt sources,
associated vector addresses, priority order and control bits are summarized in Table 11.4. Refer to the
datasheet section associated with a particular on-chip peripheral for information regarding valid interrupt
conditions for the peripheral and the behavior of its interrupt-pending flag(s).
154
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C8051F130/1/2/3
11.3.2. External Interrupts
Two of the external interrupt sources (/INT0 and /INT1) are configurable as active-low level-sensitive or
active-low edge-sensitive inputs depending on the setting of bits IT0 (TCON.0) and IT1 (TCON.2). IE0
(TCON.1) and IE1 (TCON.3) serve as the interrupt-pending flag for the /INT0 and /INT1 external interrupts,
respectively. If an /INT0 or /INT1 external interrupt is configured as edge-sensitive, the corresponding
interrupt-pending flag is automatically cleared by the hardware when the CPU vectors to the ISR. When
configured as level sensitive, the interrupt-pending flag follows the state of the external interrupt's input pin.
The external interrupt source must hold the input active until the interrupt request is recognized. It must
then deactivate the interrupt request before execution of the ISR completes or another interrupt request
will be generated.
Table 11.4. Interrupt Summary
Interru
pt
Vector
Priority
Order
Enable
Flag
Priority
Control
Interrupt Source
Pending Flags
Always
Enabled Highest
Always
Reset
0x0000
Top None
N/A N/A
0
External Interrupt 0 (/INT0) 0x0003
Timer 0 Overflow 0x000B
External Interrupt 1 (/INT1) 0x0013
0
1
2
3
IE0 (TCON.1)
TF0 (TCON.5)
IE1 (TCON.3)
TF1 (TCON.7)
Y
Y
Y
Y
Y
Y
Y
Y
0
0
0
0
EX0 (IE.0) PX0 (IP.0)
ET0 (IE.1) PT0 (IP.1)
EX1 (IE.2) PX1 (IP.2)
ET1 (IE.3) PT1 (IP.3)
Timer 1 Overflow
0x001B
RI0 (SCON0.0)
TI0 (SCON0.1)
TF2 (TMR2CN.7)
EXF2 (TMR2CN.6)
SPIF (SPI0CN.7)
WCOL (SPI0CN.6)
MODF (SPI0CN.5)
RXOVRN (SPI0CN.4)
UART0
0x0023
4
5
Y
Y
0
0
ES0 (IE.4) PS0 (IP.4)
ET2 (IE.5) PT2 (IP.5)
Timer 2
0x002B
ESPI0
PSPI0
Serial Peripheral Interface 0x0033
6
Y
0
(EIE1.0) (EIP1.0)
ESMB0
PSMB0
SMBus Interface
0x003B
7
8
SI (SMB0CN.3)
Y
Y
Y
Y
Y
Y
0
0
0
1
1
2
(EIE1.1) (EIP1.1)
EWADC0 PWADC0
(EIE1.2) (EIP1.2)
AD0WINT
(ADC0CN.1)
CF (PCA0CN.7)
CCFn (PCA0CN.n)
ADC0 Window Comparator 0x0043
Programmable Counter
EPCA0
(EIE1.3) (EIP1.3)
ECP0F PCP0F
(EIE1.4) (EIP1.4)
ECP0R PCP0R
(EIE1.5) (EIP1.5)
ECP1F PCP1F
(EIE1.6) (EIP1.6)
PPCA0
0x004B
Array
9
Comparator 0 Falling Edge 0x0053
Comparator 0 Rising Edge 0x005B
Comparator 1 Falling Edge 0x0063
10
11
12
CP0FIF (CPT0CN.4)
CP0RIF (CPT0CN.5)
CP1FIF (CPT1CN.4)
Rev. 1.4
155
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 11.4. Interrupt Summary (Continued)
Interru
pt
Vector
Priority
Order
Enable
Flag
Priority
Control
Interrupt Source
Pending Flags
ECP1R
PCP1F
Comparator 1 Rising Edge 0x006B
Timer 3 0x0073
ADC0 End of Conversion 0x007B
Timer 4 0x0083
13
14
15
16
17
CP1RIF (CPT1CN.5)
Y
Y
Y
Y
Y
Y
2
1
0
2
2
2
(EIE1.7) (EIP1.7)
ET3 PT3
(EIE2.0) (EIP2.0)
EADC0 PADC0
(EIE2.1) (EIP2.1)
ET4 PT4
(EIE2.2) (EIP2.2)
EWADC2 PWADC2
(EIE2.3) (EIP2.3)
TF3 (TMR3CN.7)
EXF3 (TMR3CN.6)
AD0INT (ADC0CN.5)
TF4 (TMR4CN.7)
EXF4 (TMR4CN.7)
AD2WINT
ADC2 Window Comparator 0x008B
ADC2 End of Conversion 0x0093
(ADC2CN.0)
EADC2
(EIE2.4) (EIP2.4)
PADC2
18
19
20
AD2INT (ADC2CN.5)
RESERVED
UART1
0x009B
0x00A3
N/A
N/A N/A N/A N/A
ES1
N/A
PS1
RI1 (SCON1.0)
TI1 (SCON1.1)
Y
1
(EIE2.6) (EIP2.6)
11.3.3. Interrupt Priorities
Each interrupt source can be individually programmed to one of two priority levels: low or high. A low prior-
ity interrupt service routine can be preempted by a high priority interrupt. A high priority interrupt cannot be
preempted. Each interrupt has an associated interrupt priority bit in an SFR (IP-EIP2) used to configure its
priority level. Low priority is the default. If two interrupts are recognized simultaneously, the interrupt with
the higher priority is serviced first. If both interrupts have the same priority level, a fixed priority order is
used to arbitrate, given in Table 11.4.
11.3.4. Interrupt Latency
Interrupt response time depends on the state of the CPU when the interrupt occurs. Pending interrupts are
sampled and priority decoded each system clock cycle. Therefore, the fastest possible response time is
5 system clock cycles: 1 clock cycle to detect the interrupt and 4 clock cycles to complete the LCALL to the
ISR. Additional clock cycles will be required if a cache miss occurs (see Section “16. Branch Target
Cache” on page 211 for more details). If an interrupt is pending when a RETI is executed, a single instruc-
tion is executed before an LCALL is made to service the pending interrupt. Therefore, the maximum
response time for an interrupt (when no other interrupt is currently being serviced or the new interrupt is of
greater priority) is when the CPU is performing an RETI instruction followed by a DIV as the next instruc-
tion, and a cache miss event also occurs. If the CPU is executing an ISR for an interrupt with equal or
higher priority, the new interrupt will not be serviced until the current ISR completes, including the RETI
and following instruction.
156
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
11.3.5. Interrupt Register Descriptions
The SFRs used to enable the interrupt sources and set their priority level are described below. Refer to the
datasheet section associated with a particular on-chip peripheral for information regarding valid interrupt
conditions for the peripheral and the behavior of its interrupt-pending flag(s).
SFR Definition 11.12. IE: Interrupt Enable
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
EA
IEGF0
ET2
ES0
ET1
EX1
ET0
EX0
00000000
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0xA8
SFR Page: All Pages
Bit7:
EA: Enable All Interrupts.
This bit globally enables/disables all interrupts. It overrides the individual interrupt mask set-
tings.
0: Disable all interrupt sources.
1: Enable each interrupt according to its individual mask setting.
IEGF0: General Purpose Flag 0.
This is a general purpose flag for use under software control.
ET2: Enabler Timer 2 Interrupt.
Bit6:
Bit5:
This bit sets the masking of the Timer 2 interrupt.
0: Disable Timer 2 interrupt.
1: Enable Timer 2 interrupt.
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
ES0: Enable UART0 Interrupt.
This bit sets the masking of the UART0 interrupt.
0: Disable UART0 interrupt.
1: Enable UART0 interrupt.
ET1: Enable Timer 1 Interrupt.
This bit sets the masking of the Timer 1 interrupt.
0: Disable Timer 1 interrupt.
1: Enable Timer 1 interrupt.
EX1: Enable External Interrupt 1.
This bit sets the masking of External Interrupt 1.
0: Disable External Interrupt 1.
1: Enable External Interrupt 1.
ET0: Enable Timer 0 Interrupt.
This bit sets the masking of the Timer 0 interrupt.
0: Disable Timer 0 interrupts.
1: Enable Timer 0 interrupts.
EX0: Enable External Interrupt 0.
This bit sets the masking of External Interrupt 0.
0: Disable External Interrupt 0.
1: Enable External Interrupt 0.
Rev. 1.4
157
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 11.13. IP: Interrupt Priority
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
-
-
PT2
PS0
PT1
PX1
PT0
PX0
11000000
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0xB8
SFR Page: All Pages
Bits7–6: UNUSED. Read = 11b, Write = don't care.
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
PT2: Timer 2 Interrupt Priority Control.
This bit sets the priority of the Timer 2 interrupt.
0: Timer 2 interrupt set to low priority.
1: Timer 2 interrupt set to high priority.
PS0: UART0 Interrupt Priority Control.
This bit sets the priority of the UART0 interrupt.
0: UART0 interrupt set to low priority.
1: UART0 interrupts set to high priority.
PT1: Timer 1 Interrupt Priority Control.
This bit sets the priority of the Timer 1 interrupt.
0: Timer 1 interrupt set to low priority.
1: Timer 1 interrupts set to high priority.
PX1: External Interrupt 1 Priority Control.
This bit sets the priority of the External Interrupt 1 interrupt.
0: External Interrupt 1 set to low priority.
1: External Interrupt 1 set to high priority.
PT0: Timer 0 Interrupt Priority Control.
This bit sets the priority of the Timer 0 interrupt.
0: Timer 0 interrupt set to low priority.
1: Timer 0 interrupt set to high priority.
PX0: External Interrupt 0 Priority Control.
This bit sets the priority of the External Interrupt 0 interrupt.
0: External Interrupt 0 set to low priority.
1: External Interrupt 0 set to high priority.
158
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C8051F130/1/2/3
SFR Definition 11.14. EIE1: Extended Interrupt Enable 1
R/W
ECP1R
Bit7
R/W
ECP1F
Bit6
R/W
ECP0R
Bit5
R/W
ECP0F
Bit4
R/W
R/W
R/W
R/W
Reset Value
EPCA0 EWADC0 ESMB0
Bit3
ESPI0 00000000
Bit0
Bit2
Bit1
SFR Address: 0xE6
SFR Page: All Pages
Bit7:
ECP1R: Enable Comparator1 (CP1) Rising Edge Interrupt.
This bit sets the masking of the CP1 rising edge interrupt.
0: Disable CP1 rising edge interrupts.
1: Enable CP1 rising edge interrupts.
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
ECP1F: Enable Comparator1 (CP1) Falling Edge Interrupt.
This bit sets the masking of the CP1 falling edge interrupt.
0: Disable CP1 falling edge interrupts.
1: Enable CP1 falling edge interrupts.
ECP0R: Enable Comparator0 (CP0) Rising Edge Interrupt.
This bit sets the masking of the CP0 rising edge interrupt.
0: Disable CP0 rising edge interrupts.
1: Enable CP0 rising edge interrupts.
ECP0F: Enable Comparator0 (CP0) Falling Edge Interrupt.
This bit sets the masking of the CP0 falling edge interrupt.
0: Disable CP0 falling edge interrupts.
1: Enable CP0 falling edge interrupts.
EPCA0: Enable Programmable Counter Array (PCA0) Interrupt.
This bit sets the masking of the PCA0 interrupts.
0: Disable PCA0 interrupts.
1: Enable PCA0 interrupts.
EWADC0: Enable Window Comparison ADC0 Interrupt.
This bit sets the masking of ADC0 Window Comparison interrupt.
0: Disable ADC0 Window Comparison Interrupt.
1: Enable ADC0 Window Comparison Interrupt.
ESMB0: Enable System Management Bus (SMBus0) Interrupt.
This bit sets the masking of the SMBus interrupt.
0: Disable SMBus interrupts.
1: Enable SMBus interrupts.
ESPI0: Enable Serial Peripheral Interface (SPI0) Interrupt.
This bit sets the masking of SPI0 interrupt.
0: Disable SPI0 interrupts.
1: Enable SPI0 interrupts.
Rev. 1.4
159
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 11.15. EIE2: Extended Interrupt Enable 2
R/W
-
R/W
ES1
Bit6
R/W
-
R/W
R/W
R/W
ET4
Bit2
R/W
EADC0
Bit1
R/W
ET3
Bit0
Reset Value
EADC2 EWADC2
Bit4
00000000
Bit7
Bit5
Bit3
SFR Address: 0xE7
SFR Page: All Pages
Bit7:
Bit6:
UNUSED. Read = 0b, Write = don't care.
ES1: Enable UART1 Interrupt.
This bit sets the masking of the UART1 interrupt.
0: Disable UART1 interrupts.
1: Enable UART1 interrupts.
Bit5:
Bit4:
UNUSED. Read = 0b, Write = don't care.
EADC2: Enable ADC2 End Of Conversion Interrupt.
This bit sets the masking of the ADC2 End of Conversion interrupt.
0: Disable ADC2 End of Conversion interrupts.
1: Enable ADC2 End of Conversion Interrupts.
EWADC2: Enable Window Comparison ADC2 Interrupt.
This bit sets the masking of ADC2 Window Comparison interrupt.
0: Disable ADC2 Window Comparison Interrupts.
1: Enable ADC2 Window Comparison Interrupts.
ET4: Enable Timer 4 Interrupt
This bit sets the masking of the Timer 4 interrupt.
0: Disable Timer 4 interrupts.
1: Enable Timer 4 interrupts.
EADC0: Enable ADC0 End of Conversion Interrupt.
This bit sets the masking of the ADC0 End of Conversion Interrupt.
0: Disable ADC0 End of Conversion Interrupts.
1: Enable ADC0 End of Conversion Interrupts.
ET3: Enable Timer 3 Interrupt.
Bit3:
Bit2:
Bit1:
Bit0:
This bit sets the masking of the Timer 3 interrupt.
0: Disable Timer 3 interrupts.
1: Enable Timer 3 interrupts.
160
Rev. 1.4
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C8051F130/1/2/3
SFR Definition 11.16. EIP1: Extended Interrupt Priority 1
R/W
PCP1R
Bit7
R/W
PCP1F
Bit6
R/W
PCP0R
Bit5
R/W
PCP0F
Bit4
R/W
R/W
R/W
R/W
Reset Value
PPCA0 PWADC0 PSMB0
Bit3
PSPI0 00000000
Bit0
Bit2
Bit1
SFR Address: 0xF6
SFR Page: All Pages
Bit7:
PCP1R: Comparator1 (CP1) Rising Interrupt Priority Control.
This bit sets the priority of the CP1 interrupt.
0: CP1 rising interrupt set to low priority.
1: CP1 rising interrupt set to high priority.
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
PCP1F: Comparator1 (CP1) Falling Interrupt Priority Control.
This bit sets the priority of the CP1 interrupt.
0: CP1 falling interrupt set to low priority.
1: CP1 falling interrupt set to high priority.
PCP0R: Comparator0 (CP0) Rising Interrupt Priority Control.
This bit sets the priority of the CP0 interrupt.
0: CP0 rising interrupt set to low priority.
1: CP0 rising interrupt set to high priority.
PCP0F: Comparator0 (CP0) Falling Interrupt Priority Control.
This bit sets the priority of the CP0 interrupt.
0: CP0 falling interrupt set to low priority.
1: CP0 falling interrupt set to high priority.
PPCA0: Programmable Counter Array (PCA0) Interrupt Priority Control.
This bit sets the priority of the PCA0 interrupt.
0: PCA0 interrupt set to low priority.
1: PCA0 interrupt set to high priority.
PWADC0: ADC0 Window Comparator Interrupt Priority Control.
This bit sets the priority of the ADC0 Window interrupt.
0: ADC0 Window interrupt set to low priority.
1: ADC0 Window interrupt set to high priority.
PSMB0: System Management Bus (SMBus0) Interrupt Priority Control.
This bit sets the priority of the SMBus0 interrupt.
0: SMBus interrupt set to low priority.
1: SMBus interrupt set to high priority.
PSPI0: Serial Peripheral Interface (SPI0) Interrupt Priority Control.
This bit sets the priority of the SPI0 interrupt.
0: SPI0 interrupt set to low priority.
1: SPI0 interrupt set to high priority.
Rev. 1.4
161
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C8051F130/1/2/3
SFR Definition 11.17. EIP2: Extended Interrupt Priority 2
R/W
-
R/W
PS1
Bit6
R/W
-
R/W
R/W
R/W
PT4
Bit2
R/W
PADC0
Bit1
R/W
PT3
Bit0
Reset Value
PADC2 PWADC2
Bit4
00000000
Bit7
Bit5
Bit3
SFR Address: 0xF7
SFR Page: All Pages
Bit7:
Bit6:
UNUSED. Read = 0b, Write = don't care.
ES1: UART1 Interrupt Priority Control.
This bit sets the priority of the UART1 interrupt.
0: UART1 interrupt set to low priority.
1: UART1 interrupt set to high priority.
UNUSED. Read = 0b, Write = don't care.
Bit5:
Bit4:
PADC2: ADC2 End Of Conversion Interrupt Priority Control.
This bit sets the priority of the ADC2 End of Conversion interrupt.
0: ADC2 End of Conversion interrupt set to low priority.
1: ADC2 End of Conversion interrupt set to high priority.
PWADC2: ADC2 Window Compare Interrupt Priority Control.
This bit sets the priority of the ADC2 Window Compare interrupt.
0: ADC2 Window Compare interrupt set to low priority.
1: ADC2 Window Compare interrupt set to high priority.
PT4: Timer 4 Interrupt Priority Control.
This bit sets the priority of the Timer 4 interrupt.
0: Timer 4 interrupt set to low priority.
1: Timer 4 interrupt set to high priority.
PADC0: ADC0 End of Conversion Interrupt Priority Control.
This bit sets the priority of the ADC0 End of Conversion Interrupt.
0: ADC0 End of Conversion interrupt set to low priority.
1: ADC0 End of Conversion interrupt set to high priority.
PT3: Timer 3 Interrupt Priority Control.
Bit3:
Bit2:
Bit1:
Bit0:
This bit sets the priority of the Timer 3 interrupts.
0: Timer 3 interrupt set to low priority.
1: Timer 3 interrupt set to high priority.
162
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C8051F130/1/2/3
11.4. Power Management Modes
The CIP-51 core has two software programmable power management modes: Idle and Stop. Idle mode
halts the CPU while leaving the external peripherals and internal clocks active. In Stop mode, the CPU is
halted, all interrupts and timers (except the Missing Clock Detector) are inactive, and the system clock is
stopped. Since clocks are running in Idle mode, power consumption is dependent upon the system clock
frequency and the number of peripherals left in active mode before entering Idle. Stop mode consumes the
least power. SFR Definition 11.18 describes the Power Control Register (PCON) used to control the CIP-
51's power management modes.
Although the CIP-51 has Idle and Stop modes built in (as with any standard 8051 architecture), power
management of the entire MCU is better accomplished by enabling/disabling individual peripherals as
needed. Each analog peripheral can be disabled when not in use and put into low power mode. Digital
peripherals, such as timers or serial buses, draw little power whenever they are not in use. Turning off the
Flash memory saves power, similar to entering Idle mode. Turning off the oscillator saves even more
power, but requires a reset to restart the MCU.
11.4.1. Idle Mode
Setting the Idle Mode Select bit (PCON.0) causes the CIP-51 to halt the CPU and enter Idle mode as soon
as the instruction that sets the bit completes. All internal registers and memory maintain their original
data. All analog and digital peripherals can remain active during Idle mode.
Idle mode is terminated when an enabled interrupt or RST is asserted. The assertion of an enabled inter-
rupt will cause the Idle Mode Selection bit (PCON.0) to be cleared and the CPU to resume operation. The
pending interrupt will be serviced and the next instruction to be executed after the return from interrupt
(RETI) will be the instruction immediately following the one that set the Idle Mode Select bit. If Idle mode is
terminated by an internal or external reset, the CIP-51 performs a normal reset sequence and begins pro-
gram execution at address 0x00000.
If enabled, the WDT will eventually cause an internal watchdog reset and thereby terminate the Idle mode.
This feature protects the system from an unintended permanent shutdown in the event of an inadvertent
write to the PCON register. If this behavior is not desired, the WDT may be disabled by software prior to
entering the Idle mode if the WDT was initially configured to allow this operation. This provides the oppor-
tunity for additional power savings, allowing the system to remain in the Idle mode indefinitely, waiting for
an external stimulus to wake up the system. Refer to Section 13 for more information on the use and con-
figuration of the WDT.
Note: Any instruction which sets the IDLE bit should be immediately followed by an instruction which has
two or more opcode bytes. For example:
// in ‘C’:
PCON |= 0x01;
PCON = PCON;
// Set IDLE bit
// ... Followed by a 3-cycle Dummy Instruction
; in assembly:
ORL PCON, #01h
MOV PCON, PCON
; Set IDLE bit
; ... Followed by a 3-cycle Dummy Instruction
If the instruction following the write to the IDLE bit is a single-byte instruction and an interrupt occurs during
the execution of the instruction of the instruction which sets the IDLE bit, the CPU may not wake from IDLE
mode when a future interrupt occurs.
Rev. 1.4
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C8051F130/1/2/3
11.4.2. Stop Mode
Setting the Stop Mode Select bit (PCON.1) causes the CIP-51 to enter Stop mode as soon as the instruc-
tion that sets the bit completes. In Stop mode, the CPU and oscillators are stopped, effectively shutting
down all digital peripherals. Each analog peripheral must be shut down individually prior to entering Stop
Mode. Stop mode can only be terminated by an internal or external reset. On reset, the CIP-51 performs
the normal reset sequence and begins program execution at address 0x00000.
If enabled, the Missing Clock Detector will cause an internal reset and thereby terminate the Stop mode.
The Missing Clock Detector should be disabled if the CPU is to be put to sleep for longer than the MCD
timeout of 100 µs.
SFR Definition 11.18. PCON: Power Control
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
-
R/W
STOP
Bit1
R/W
IDLE
Bit0
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
SFR Address: 0x87
SFR Page: All Pages
Bits7–3: Reserved.
Bit1:
STOP: STOP Mode Select.
Writing a ‘1’ to this bit will place the CIP-51 into STOP mode. This bit will always read ‘0’.
1: CIP-51 forced into power-down mode. (Turns off oscillator).
IDLE: IDLE Mode Select.
Bit0:
Writing a ‘1’ to this bit will place the CIP-51 into IDLE mode. This bit will always read ‘0’.
1: CIP-51 forced into IDLE mode. (Shuts off clock to CPU, but clock to Timers, Interrupts,
and all peripherals remain active.)
164
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C8051F130/1/2/3
12. Multiply And Accumulate (MAC0)
The C8051F120/1/2/3 and C8051F130/1/2/3 devices include a multiply and accumulate engine which can
be used to speed up many mathematical operations. MAC0 contains a 16-by-16 bit multiplier and a 40-bit
adder, which can perform integer or fractional multiply-accumulate and multiply operations on signed input
values in two SYSCLK cycles. A rounding engine provides a rounded 16-bit fractional result after an addi-
tional (third) SYSCLK cycle. MAC0 also contains a 1-bit arithmetic shifter that will left or right-shift the con-
tents of the 40-bit accumulator in a single SYSCLK cycle. Figure 12.1 shows a block diagram of the MAC0
unit and its associated Special Function Registers.
MAC0 A Register
MAC0 B Register
MAC0AH MAC0AL
MAC0BH MAC0BL
MAC0MS
MAC0FM
16 x 16 Multiply
0
1
0
40 bit Add
MAC0 Accumulator
MAC0OVR
1 bit Shift
MAC0ACC3 MAC0ACC2 MAC0ACC1 MAC0ACC0
Rounding Engine
Flag Logic
MAC0 Rounding Register
MAC0RNDH MAC0RNDL
MAC0CF
MAC0STA
Figure 12.1. MAC0 Block Diagram
12.1. Special Function Registers
There are thirteen Special Function Register (SFR) locations associated with MAC0. Two of these regis-
ters are related to configuration and operation, while the other eleven are used to store multi-byte input
and output data for MAC0. The Configuration register MAC0CF (SFR Definition 12.1) is used to configure
and control MAC0. The Status register MAC0STA (SFR Definition 12.2) contains flags to indicate overflow
conditions, as well as zero and negative results. The 16-bit MAC0A (MAC0AH:MAC0AL) and MAC0B
(MAC0BH:MAC0BL) registers are used as inputs to the multiplier. The MAC0 Accumulator register is 40
bits long, and consists of five SFRs: MAC0OVR, MAC0ACC3, MAC0ACC2, MAC0ACC1, and
MAC0ACC0. The primary results of a MAC0 operation are stored in the Accumulator registers. If they are
needed, the rounded results are stored in the 16-bit Rounding Register MAC0RND
(MAC0RNDH:MAC0RNDL).
Rev. 1.4
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C8051F130/1/2/3
12.2. Integer and Fractional Math
MAC0 is capable of interpreting the 16-bit inputs stored in MAC0A and MAC0B as signed integers or as
signed fractional numbers. When the MAC0FM bit (MAC0CF.1) is cleared to ‘0’, the inputs are treated as
16-bit, 2’s complement, integer values. After the operation, the accumulator will contain a 40-bit, 2’s com-
plement, integer value. Figure 12.2 shows how integers are stored in the SFRs.
MAC0A and MAC0B Bit Weighting
High Byte
Low Byte
-(215) 214
213
212
211
210
29
28
27
26
25
24
23
22
21
20
MAC0 Accumulator Bit Weighting
MAC0ACC3 : MAC0ACC2 : MAC0ACC1 : MAC0ACC0
MAC0OVR
-(239) 238
233
232
231
230
229
228
24
23
22
21
20
Figure 12.2. Integer Mode Data Representation
When the MAC0FM bit is set to ‘1’, the inputs are treated at 16-bit, 2’s complement, fractional values. The
decimal point is located between bits 15 and 14 of the data word. After the operation, the accumulator will
contain a 40-bit, 2’s complement, fractional value, with the decimal point located between bits 31 and 30.
Figure 12.3 shows how fractional numbers are stored in the SFRs.
MAC0A, and MAC0B Bit Weighting
High Byte
Low Byte
-1
2-1
27
1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9
2-10 2-11 2-12 2-13 2-14 2-15
MAC0 Accumulator Bit Weighting
MAC0OVR
MAC0ACC3 : MAC0ACC2 : MAC0ACC1 : MAC0ACC0
-(28)
22
21
20
2-1
2-2
2-3
2-27 2-28 2-29 2-30 2-31
MAC0RND Bit Weighting
High Byte
2-3
Low Byte
2-9 2-10 2-11 2-12 2-13 2-14 2-15
* -2
2-1
2-2
2-4
2-5
2-6
2-7
2-8
* The MAC0RND register contains the 16 LSBs of a two's complement number. The MAC0N Flag can be
used to determine the sign of the MAC0RND register.
Figure 12.3. Fractional Mode Data Representation
166
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C8051F130/1/2/3
12.3. Operating in Multiply and Accumulate Mode
MAC0 operates in Multiply and Accumulate (MAC) mode when the MAC0MS bit (MAC0CF.0) is cleared to
‘0’. When operating in MAC mode, MAC0 performs a 16-by-16 bit multiply on the contents of the MAC0A
and MAC0B registers, and adds the result to the contents of the 40-bit MAC0 accumulator. Figure 12.4
shows the MAC0 pipeline. There are three stages in the pipeline, each of which takes exactly one SYS-
CLK cycle to complete. The MAC operation is initiated with a write to the MAC0BL register. After the
MAC0BL register is written, MAC0A and MAC0B are multiplied on the first SYSCLK cycle. During the sec-
ond stage of the MAC0 pipeline, the results of the multiplication are added to the current accumulator con-
tents, and the result of the addition is stored in the MAC0 accumulator. The status flags in the MAC0STA
register are set after the end of the second pipeline stage. During the second stage of the pipeline, the next
multiplication can be initiated by writing to the MAC0BL register, if it is desired. The rounded (and option-
ally, saturated) result is available in the MAC0RNDH and MAC0RNDL registers at the end of the third pipe-
line stage. If the MAC0CA bit (MAC0CF.3) is set to ‘1’ when the MAC operation is initiated, the accumulator
and all MAC0STA flags will be cleared during the next cycle of the controller’s clock (SYSCLK). The
MAC0CA bit will clear itself to ‘0’ when the clear operation is complete.
MAC0 Operation
Begins
Accumulator
Results Available
Rounded Results
Available
Write
Multiply
MAC0BL
Add
Round
Write
MAC0BL
Multiply
Add
Round
Next MAC0
Operation May
Be Initiated
Here
Figure 12.4. MAC0 Pipeline
12.4. Operating in Multiply Only Mode
MAC0 operates in Multiply Only mode when the MAC0MS bit (MAC0CF.0) is set to ‘1’. Multiply Only mode
is identical to Multiply and Accumulate mode, except that the multiplication result is added with a value of
zero before being stored in the MAC0 accumulator (i.e. it overwrites the current accumulator contents).
The result of the multiplication is available in the MAC0 accumulator registers at the end of the second
MAC0 pipeline stage (two SYSCLKs after writing to MAC0BL). As in MAC mode, the rounded result is
available in the MAC0 Rounding Registers after the third pipeline stage. Note that in Multiply Only mode,
the MAC0HO flag is not affected.
12.5. Accumulator Shift Operations
MAC0 contains a 1-bit arithmetic shift function which can be used to shift the contents of the 40-bit accu-
mulator left or right by one bit. The accumulator shift is initiated by writing a ‘1’ to the MAC0SC bit
(MAC0CF.5), and takes one SYSCLK cycle (the rounded result is available in the MAC0 Rounding Regis-
ters after a second SYSCLK cycle, and MAC0SC is cleared to ‘0’). The direction of the arithmetic shift is
controlled by the MAC0SD bit (MAC0CF.4). When this bit is cleared to ‘0’, the MAC0 accumulator will shift
left. When the MAC0SD bit is set to ‘1’, the MAC0 accumulator will shift right. Right-shift operations are
sign-extended with the current value of bit 39. Note that the status flags in the MAC0STA register are not
affected by shift operations.
Rev. 1.4
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C8051F130/1/2/3
12.6. Rounding and Saturation
A Rounding Engine is included, which can be used to provide a rounded result when operating on frac-
tional numbers. MAC0 uses an unbiased rounding algorithm to round the data stored in bits 31–16 of the
accumulator, as shown in Table 12.1. Rounding occurs during the third stage of the MAC0 pipeline, after
any shift operation, or on a write to the LSB of the accumulator. The rounded results are stored in the
rounding registers: MAC0RNDH (SFR Definition 12.12) and MAC0RNDL (SFR Definition 12.13). The
accumulator registers are not affected by the rounding engine. Although rounding is primarily used for frac-
tional data, the data in the rounding registers is updated in the same way when operating in integer mode.
Table 12.1. MAC0 Rounding (MAC0SAT = 0)
Accumulator Bits 15–0
Accumulator Bits 31–16
Rounding Rounded Results
(MAC0ACC1:MAC0ACC0) (MAC0ACC3:MAC0ACC2) Direction (MAC0RNDH:MAC0RNDL)
Greater Than 0x8000
Less Than 0x8000
Equal To 0x8000
Equal To 0x8000
Anything
Up
(MAC0ACC3:MAC0ACC2) + 1
(MAC0ACC3:MAC0ACC2)
(MAC0ACC3:MAC0ACC2) + 1
(MAC0ACC3:MAC0ACC2)
Anything
Down
Up
Odd (LSB = 1)
Even (LSB = 0)
Down
The rounding engine can also be used to saturate the results stored in the rounding registers. If the
MAC0SAT bit is set to ‘1’ and the rounding register overflows, the rounding registers will saturate. When a
positive overflow occurs, the rounding registers will show a value of 0x7FFF when saturated. For a nega-
tive overflow, the rounding registers will show a value of 0x8000 when saturated. If the MAC0SAT bit is
cleared to ‘0’, the rounding registers will not saturate.
12.7. Usage Examples
This section details some software examples for using MAC0. Section 12.7.1 shows a series of two MAC
operations using fractional numbers. Section 12.7.2 shows a single operation in Multiply Only mode with
integer numbers. The last example, shown in Section 12.7.3, demonstrates how the left-shift and right-
shift operations can be used to modify the accumulator. All of the examples assume that all of the flags in
the MAC0STA register are initially set to ‘0’.
12.7.1. Multiply and Accumulate Example
The example below implements the equation:
0.5 0.25 + 0.5 –0.25 = 0.125 – 0.125 = 0.0
MOV
MOV
MOV
MOV
MOV
MOV
MOV
NOP
NOP
MAC0CF, #0Ah
MAC0AH, #40h
MAC0AL, #00h
MAC0BH, #20h
MAC0BL, #00h
MAC0BH, #E0h
MAC0BL, #00h
; Set to Clear Accumulator, Use fractional numbers
; Load MAC0A register with 4000 hex = 0.5 decimal
; Load MAC0B register with 2000 hex = 0.25 decimal
; This line initiates the first MAC operation
; Load MAC0B register with E000 hex = -0.25 decimal
; This line initiates the second MAC operation
; After this instruction, the Accumulator should be equal to 0,
; and the MAC0STA register should be 0x04, indicating a zero
; After this instruction, the Rounding register is updated
NOP
168
Rev. 1.4
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C8051F130/1/2/3
12.7.2. Multiply Only Example
The example below implements the equation:
4660 –292 = –1360720
MOV
MOV
MOV
MOV
MOV
NOP
NOP
MAC0CF, #01h
MAC0AH, #12h
MAC0AL, #34h
MAC0BH, #FEh
MAC0BL, #DCh
; Use integer numbers, and multiply only mode (add to zero)
; Load MAC0A register with 1234 hex = 4660 decimal
; Load MAC0B register with FEDC hex = -292 decimal
; This line initiates the Multiply operation
; After this instruction, the Accumulator should be equal to
; FFFFEB3CB0 hex = -1360720 decimal. The MAC0STA register should
; be 0x01, indicating a negative result.
NOP
; After this instruction, the Rounding register is updated
12.7.3. MAC0 Accumulator Shift Example
The example below shifts the MAC0 accumulator left one bit, and then right two bits:
MOV
MOV
MOV
MOV
MOV
MOV
NOP
NOP
MOV
MOV
NOP
NOP
MAC0OVR, #40h
MAC0ACC3, #88h ; 4088442211 Hex.
MAC0ACC2, #44h
MAC0ACC1, #22h
MAC0ACC0, #11h
; The next few instructions load the accumulator with the value
MAC0CF, #20h
; Initiate a Left-shift
; After this instruction, the accumulator should be 0x8110884422
; The rounding register is updated after this instruction
; Initiate a Right-shift
; Initiate a second Right-shift
; After this instruction, the accumulator should be 0xE044221108
; The rounding register is updated after this instruction
MAC0CF, #30h
MAC0CF, #30h
Rev. 1.4
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C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 12.1. MAC0CF: MAC0 Configuration
R
-
R
-
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
MAC0SC MAC0SD MAC0CA MAC0SAT MAC0FM MAC0MS 00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xC3
SFR Page: 3
Bits 7–6: UNUSED: Read = 00b, Write = don’t care.
Bit 5:
Bit 4:
Bit 3:
MAC0SC: Accumulator Shift Control.
When set to 1, the 40-bit MAC0 Accumulator register will be shifted during the next SYSCLK
cycle. The direction of the shift (left or right) is controlled by the MAC0RS bit.
This bit is cleared to ‘0’ by hardware when the shift is complete.
MAC0SD: Accumulator Shift Direction.
This bit controls the direction of the accumulator shift activated by the MAC0SC bit.
0: MAC0 Accumulator will be shifted left.
1: MAC0 Accumulator will be shifted right.
MAC0CA: Clear Accumulator.
This bit is used to reset MAC0 before the next operation.
When set to ‘1’, the MAC0 Accumulator will be cleared to zero and the MAC0 Status regis-
ter will be reset during the next SYSCLK cycle.
This bit will be cleared to ‘0’ by hardware when the reset is complete.
MAC0SAT: Saturate Rounding Register.
Bit 2:
This bit controls whether the Rounding Register will saturate. If this bit is set and a Soft
Overflow occurs, the Rounding Register will saturate. This bit does not affect the operation
of the MAC0 Accumulator. See Section 12.6 for more details about rounding and saturation.
0: Rounding Register will not saturate.
1: Rounding Register will saturate.
Bit 1:
Bit 0:
MAC0FM: Fractional Mode.
This bit selects between Integer Mode and Fractional Mode for MAC0 operations.
0: MAC0 operates in Integer Mode.
1: MAC0 operates in Fractional Mode.
MAC0MS: Mode Select
This bit selects between MAC Mode and Multiply Only Mode.
0: MAC (Multiply and Accumulate) Mode.
1: Multiply Only Mode.
Note:
The contents of this register should not be changed by software during the first two MAC0
pipeline stages.
170
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 12.2. MAC0STA: MAC0 Status
R
R
R
R
R/W
R/W
R/W
R/W
Reset Value
-
-
-
-
MAC0HO MAC0Z MAC0SO MAC0N 00000100
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0xC0
SFR Page: 3
Bits 7–4: UNUSED: Read = 0000b, Write = don’t care.
Bit 3:
MAC0HO: Hard Overflow Flag.
This bit is set to ‘1’ whenever an overflow out of the MAC0OVR register occurs during a
MAC operation (i.e. when MAC0OVR changes from 0x7F to 0x80 or from 0x80 to 0x7F).
The hard overflow flag must be cleared in software by directly writing it to ‘0’, or by resetting
the MAC logic using the MAC0CA bit in register MAC0CF.
MAC0Z: Zero Flag.
This bit is set to ‘1’ if a MAC0 operation results in an Accumulator value of zero. If the result
is non-zero, this bit will be cleared to ‘0’.
MAC0SO: Soft Overflow Flag.
Bit 2:
Bit 1:
This bit is set to ‘1’ when a MAC operation causes an overflow into the sign bit (bit 31) of the
MAC0 Accumulator. If the overflow condition is corrected after a subsequent MAC opera-
tion, this bit is cleared to ‘0’.
Bit 0:
MAC0N: Negative Flag.
If the MAC Accumulator result is negative, this bit will be set to ‘1’. If the result is positive or
zero, this flag will be cleared to ‘0’.
*Note: The contents of this register should not be changed by software during the first two MAC0 pipeline stages.
SFR Definition 12.3. MAC0AH: MAC0 A High Byte
R
R
R
R
R
R
R
R
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xC2
SFR Page: 3
Bits 7–0: High Byte (bits 15–8) of MAC0 A Register.
Rev. 1.4
171
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 12.4. MAC0AL: MAC0 A Low Byte
R
R
R
R
R
R
R
R
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xC1
SFR Page: 3
Bits 7–0: Low Byte (bits 7–0) of MAC0 A Register.
SFR Definition 12.5. MAC0BH: MAC0 B High Byte
R
R
R
R
R
R
R
R
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x92
SFR Page: 3
Bits 7–0: High Byte (bits 15–8) of MAC0 B Register.
SFR Definition 12.6. MAC0BL: MAC0 B Low Byte
R
R
R
R
R
R
R
R
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x91
SFR Page: 3
Bits 7–0: Low Byte (bits 7–0) of MAC0 B Register.
A write to this register initiates a Multiply or Multiply and Accumulate operation.
*Note: The contents of this register should not be changed by software during the first MAC0 pipeline stage.
172
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 12.7. MAC0ACC3: MAC0 Accumulator Byte 3
R
R
R
R
R
R
R
R
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x96
SFR Page: 3
Bits 7–0: Byte 3 (bits 31–24) of MAC0 Accumulator.
*Note: The contents of this register should not be changed by software during the first two MAC0 pipeline stages.
SFR Definition 12.8. MAC0ACC2: MAC0 Accumulator Byte 2
R
R
R
R
R
R
R
R
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x95
SFR Page: 3
Bits 7–0: Byte 2 (bits 23–16) of MAC0 Accumulator.
*Note: The contents of this register should not be changed by software during the first two MAC0 pipeline stages.
SFR Definition 12.9. MAC0ACC1: MAC0 Accumulator Byte 1
R
R
R
R
R
R
R
R
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x94
SFR Page: 3
Bits 7–0: Byte 1 (bits 15–8) of MAC0 Accumulator.
*Note: The contents of this register should not be changed by software during the first two MAC0 pipeline stages.
Rev. 1.4
173
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 12.10. MAC0ACC0: MAC0 Accumulator Byte 0
R
R
R
R
R
R
R
R
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x93
SFR Page: 3
Bits 7–0: Byte 0 (bits 7–0) of MAC0 Accumulator.
*Note: The contents of this register should not be changed by software during the first two MAC0 pipeline stages.
SFR Definition 12.11. MAC0OVR: MAC0 Accumulator Overflow
R
R
R
R
R
R
R
R
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x97
SFR Page: 3
Bits 7–0: MAC0 Accumulator Overflow Bits (bits 39–32).
*Note: The contents of this register should not be changed by software during the first two MAC0 pipeline stages.
SFR Definition 12.12. MAC0RNDH: MAC0 Rounding Register High Byte
R
R
R
R
R
R
R
R
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xCF
SFR Page: 3
Bits 7–0: High Byte (bits 15–8) of MAC0 Rounding Register.
174
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 12.13. MAC0RNDL: MAC0 Rounding Register Low Byte
R
R
R
R
R
R
R
R
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xCE
SFR Page: 3
Bits 7–0: Low Byte (bits 7–0) of MAC0 Rounding Register.
Rev. 1.4
175
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
176
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
13. Reset Sources
Reset circuitry allows the controller to be easily placed in a predefined default condition. On entry to this
reset state, the following occur:
•
•
•
•
CIP-51 halts program execution.
Special Function Registers (SFRs) are initialized to their defined reset values.
External port pins are forced to a known configuration.
Interrupts and timers are disabled.
All SFRs are reset to the predefined values noted in the SFR detailed descriptions. The contents of internal
data memory are unaffected during a reset; any previously stored data is preserved. However, since the
stack pointer SFR is reset, the stack is effectively lost even though the data on the stack are not altered.
The I/O port latches are reset to 0xFF (all logic 1’s), activating internal weak pullups during and after the
reset. For V Monitor resets, the RST pin is driven low until the end of the V reset timeout.
DD
DD
On exit from the reset state, the program counter (PC) is reset, and the system clock defaults to the inter-
nal oscillator running at its lowest frequency. Refer to Section “14. Oscillators” on page 185 for informa-
tion on selecting and configuring the system clock source. The Watchdog Timer is enabled using its
longest timeout interval (see Section “13.7. Watchdog Timer Reset” on page 179). Once the system clock
source is stable, program execution begins at location 0x0000.
There are seven sources for putting the MCU into the reset state: power-on, power-fail, external RST pin,
external CNVSTR0 signal, software command, Comparator0, Missing Clock Detector, and Watchdog
Timer. Each reset source is described in the following sections.
VDD
CNVSTR
(Port
I/O)
Crossbar
Supply
Monitor
(CNVSTR
reset
enable)
Supply
Reset
Timeout
+
-
/RST
(wired-OR)
Comparator0
CP0+
CP0-
+
-
(CP0
reset
enable)
Reset
Funnel
Missing
Clock
Detector
(one-
shot)
WDT
EN
EN
PRE
Internal
Clock
Generator
System
Clock
PLL
Circuitry
Software Reset
System Reset
CIP-51
Microcontroller
Core
XTAL1
XTAL2
OSC
Clock Select
Extended Interrupt
Handler
Figure 13.1. Reset Sources
Rev. 1.4
177
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
13.1. Power-on Reset
The C8051F120/1/2/3/4/5/6/7 family incorporates a power supply monitor that holds the MCU in the reset
state until V rises above the V
level during power-up. See Figure 13.2 for timing diagram, and refer
DD
RST
to Table 13.1 for the Electrical Characteristics of the power supply monitor circuit. The RST pin is asserted
low until the end of the 100 ms V Monitor timeout in order to allow the V supply to stabilize. The V
DD
DD
DD
Monitor reset is enabled and disabled using the external V monitor enable pin (MONEN). When the V
DD
DD
Monitor is enabled, it is selected as a reset source using the PORSF bit. If the RSTSRC register is written
by firmware, PORSF (RSTSRC.1) must be written to ‘1’ for the V Monitor to be effective.
DD
On exit from a power-on reset, the PORSF flag (RSTSRC.1) is set by hardware to logic 1. All of the other
reset flags in the RSTSRC Register are indeterminate. PORSF is cleared by all other resets. Since all
resets cause program execution to begin at the same location (0x0000) software can read the PORSF flag
to determine if a power-up was the cause of reset. The contents of internal data memory should be
assumed to be undefined after a power-on reset.
2.70
VRST
2.55
2.0
1.0
t
/RST
Logic HIGH
100ms
100ms
Logic LOW
Power-On Reset
VDD Monitor Reset
Figure 13.2. Reset Timing
13.2. Power-fail Reset
When a power-down transition or power irregularity causes V
to drop below V , the power supply
RST
DD
monitor will drive the RST pin low and return the CIP-51 to the reset state. When V
returns to a level
DD
above VRST, the CIP-51 will leave the reset state in the same manner as that for the power-on reset (see
Figure 13.2). Note that even though internal data memory contents are not altered by the power-fail reset,
it is impossible to determine if V dropped below the level required for data retention. If the PORSF flag is
DD
set to logic 1, the data may no longer be valid.
178
Rev. 1.4
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C8051F130/1/2/3
13.3. External Reset
The external RST pin provides a means for external circuitry to force the MCU into a reset state. Asserting
the RST pin low will cause the MCU to enter the reset state. It may be desirable to provide an external pul-
lup and/or decoupling of the RST pin to avoid erroneous noise-induced resets. The MCU will remain in
reset until at least 12 clock cycles after the active-low RST signal is removed. The PINRSF flag (RST-
SRC.0) is set on exit from an external reset.
13.4. Missing Clock Detector Reset
The Missing Clock Detector is essentially a one-shot circuit that is triggered by the MCU system clock. If
the system clock goes away for more than 100 µs, the one-shot will time out and generate a reset. After a
Missing Clock Detector reset, the MCDRSF flag (RSTSRC.2) will be set, signifying the MSD as the reset
source; otherwise, this bit reads ‘0’. The state of the RST pin is unaffected by this reset. Setting the
MCDRSF bit, RSTSRC.2 (see Section “14. Oscillators” on page 185) enables the Missing Clock Detector.
13.5. Comparator0 Reset
Comparator0 can be configured as a reset input by writing a ‘1’ to the C0RSEF flag (RSTSRC.5).
Comparator0 should be enabled using CPT0CN.7 (see Section “10. Comparators” on page 119) prior to
writing to C0RSEF to prevent any turn-on chatter on the output from generating an unwanted reset. The
Comparator0 reset is active-low: if the non-inverting input voltage (CP0+ pin) is less than the inverting
input voltage (CP0- pin), the MCU is put into the reset state. After a Comparator0 Reset, the C0RSEF flag
(RSTSRC.5) will read ‘1’ signifying Comparator0 as the reset source; otherwise, this bit reads ‘0’. The state
of the RST pin is unaffected by this reset.
13.6. External CNVSTR0 Pin Reset
The external CNVSTR0 signal can be configured as a reset input by writing a ‘1’ to the CNVRSEF flag
(RSTSRC.6). The CNVSTR0 signal can appear on any of the P0, P1, P2 or P3 I/O pins as described in
Section “18.1. Ports 0 through 3 and the Priority Crossbar Decoder” on page 238. Note that the Cross-
bar must be configured for the CNVSTR0 signal to be routed to the appropriate Port I/O. The Crossbar
should be configured and enabled before the CNVRSEF is set. When configured as a reset, CNVSTR0 is
active-low and level sensitive. CNVSTR0 cannot be used to start ADC0 conversions when it is configured
as a reset source. After a CNVSTR0 reset, the CNVRSEF flag (RSTSRC.6) will read ‘1’ signifying
CNVSTR0 as the reset source; otherwise, this bit reads ‘0’. The state of the ⁄RST pin is unaffected by this
reset.
13.7. Watchdog Timer Reset
The MCU includes a programmable Watchdog Timer (WDT) running off the system clock. A WDT overflow
will force the MCU into the reset state. To prevent the reset, the WDT must be restarted by application soft-
ware before overflow. If the system experiences a software or hardware malfunction preventing the soft-
ware from restarting the WDT, the WDT will overflow and cause a reset. This should prevent the system
from running out of control.
Following a reset the WDT is automatically enabled and running with the default maximum time interval. If
desired the WDT can be disabled by system software or locked on to prevent accidental disabling. Once
locked, the WDT cannot be disabled until the next system reset. The state of the RST pin is unaffected by
this reset.
The WDT consists of a 21-bit timer running from the programmed system clock. The timer measures the
period between specific writes to its control register. If this period exceeds the programmed limit, a WDT
Rev. 1.4
179
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C8051F130/1/2/3
reset is generated. The WDT can be enabled and disabled as needed in software, or can be permanently
enabled if desired. Watchdog features are controlled via the Watchdog Timer Control Register (WDTCN)
shown in SFR Definition 13.1.
13.7.1. Enable/Reset WDT
The watchdog timer is both enabled and reset by writing 0xA5 to the WDTCN register. The user's applica-
tion software should include periodic writes of 0xA5 to WDTCN as needed to prevent a watchdog timer
overflow. The WDT is enabled and reset as a result of any system reset.
13.7.2. Disable WDT
Writing 0xDE followed by 0xAD to the WDTCN register disables the WDT. The following code segment
illustrates disabling the WDT:
CLR
MOV
MOV
SETB
EA
; disable all interrupts
WDTCN,#0DEh ; disable software watchdog timer
WDTCN,#0ADh
EA
; re-enable interrupts
The writes of 0xDE and 0xAD must occur within 4 clock cycles of each other, or the disable operation is
ignored. This means that the prefetch engine should be enabled and interrupts should be disabled during
this procedure to avoid any delay between the two writes.
13.7.3. Disable WDT Lockout
Writing 0xFF to WDTCN locks out the disable feature. Once locked out, the disable operation is ignored
until the next system reset. Writing 0xFF does not enable or reset the watchdog timer. Applications always
intending to use the watchdog should write 0xFF to WDTCN in the initialization code.
13.7.4. Setting WDT Interval
WDTCN.[2:0] control the watchdog timeout interval. The interval is given by the following equation:
4
3 + WDTCN2 – 0 Tsysclk ; where Tsysclk is the system clock period.
For a 3 MHz system clock, this provides an interval range of 0.021 ms to 349.5 ms. WDTCN.7 must be
logic 0 when setting this interval. Reading WDTCN returns the programmed interval. WDTCN.[2:0] reads
111b after a system reset.
180
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 13.1. WDTCN: Watchdog Timer Control
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Reset Value
xxxxx111
Bit0
SFR Address: 0xFF
SFR Page: All Pages
Bits7–0: WDT Control
Writing 0xA5 both enables and reloads the WDT.
Writing 0xDE followed within 4 system clocks by 0xAD disables the WDT.
Writing 0xFF locks out the disable feature.
Watchdog Status Bit (when Read)
Bit4:
Reading the WDTCN.[4] bit indicates the Watchdog Timer Status.
0: WDT is inactive
1: WDT is active
Bits2–0: Watchdog Timeout Interval Bits
The WDTCN.[2:0] bits set the Watchdog Timeout Interval. When writing these bits,
WDTCN.7 must be set to 0.
Rev. 1.4
181
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 13.2. RSTSRC: Reset Source
R
-
R/W
R/W
R/W
R
R/W
R/W
R/W
Reset Value
CNVRSEF C0RSEF SWRSEF WDTRSF MCDRSF PORSF
PINRSF 00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xEF
SFR Page: 0
Bit7:
Bit6:
Reserved.
CNVRSEF: Convert Start 0 Reset Source Enable and Flag
Write: 0: CNVSTR0 is not a reset source.
1: CNVSTR0 is a reset source (active low).
Read: 0: Source of prior reset was not CNVSTR0.
1: Source of prior reset was CNVSTR0.
Bit5:
Bit4:
C0RSEF: Comparator0 Reset Enable and Flag.
Write: 0: Comparator0 is not a reset source.
1: Comparator0 is a reset source (active low).
Read: 0: Source of last reset was not Comparator0.
1: Source of last reset was Comparator0.
SWRSF: Software Reset Force and Flag.
Write: 0: No effect.
1: Forces an internal reset. RST pin is not effected.
Read: 0: Source of last reset was not a write to the SWRSF bit.
1: Source of last reset was a write to the SWRSF bit.
WDTRSF: Watchdog Timer Reset Flag.
0: Source of last reset was not WDT timeout.
1: Source of last reset was WDT timeout.
MCDRSF: Missing Clock Detector Flag.
Bit3:
Bit2:
Write: 0: Missing Clock Detector disabled.
1: Missing Clock Detector enabled; triggers a reset if a missing clock condition is detected.
Read: 0: Source of last reset was not a Missing Clock Detector timeout.
1: Source of last reset was a Missing Clock Detector timeout.
Bit1:
PORSF: Power-On Reset Flag.
Write: If the VDD monitor circuitry is enabled (by tying the MONEN pin to a logic high state), this bit can
be written to select or de-select the VDD monitor as a reset source.
0: De-select the VDD monitor as a reset source.
1: Select the VDD monitor as a reset source.
Important: At power-on, the VDD monitor is enabled/disabled using the external VDD monitor
enable pin (MONEN). The PORSF bit does not disable or enable the VDD monitor circuit. It sim-
ply selects the VDD monitor as a reset source.
Read: This bit is set whenever a power-on reset occurs. This may be due to a true power-on reset or a
VDD monitor reset. In either case, data memory should be considered indeterminate following the
reset.
0: Source of last reset was not a power-on or VDD monitor reset.
1: Source of last reset was a power-on or VDD monitor reset.
Note: When this flag is read as '1', all other reset flags are indeterminate.
PINRSF: HW Pin Reset Flag.
Bit0:
Write: 0: No effect.
1: Forces a Power-On Reset. RST is driven low.
Read: 0: Source of prior reset was not RST pin.
1: Source of prior reset was RST pin.
182
Rev. 1.4
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C8051F130/1/2/3
Table 13.1. Reset Electrical Characteristics
–40 to +85 °C unless otherwise specified.
Parameter
Conditions
= 8.5 mA, V = 2.7 to 3.6 V
Min
—
Typ
Max
Units
I
RST Output Low Voltage
—
0.6
V
OL
DD
0.7 x V
RST Input High Voltage
RST Input Low Voltage
RST Input Leakage Current
—
—
—
0.3 x V
—
V
DD
—
—
DD
RST = 0.0 V
50
µA
V
V
for RST Output Valid
1.0
1.0
2.40
—
—
DD
AV+ for RST Output Valid
POR Threshold (V
—
—
V
V
)*
RST
2.55
2.70
V
DD
Minimum RST Low Time to Gen-
erate a System Reset
10
80
—
—
ns
ms
µs
RST rising edge after V
DD
Reset Time Delay
100
220
120
500
crosses V
threshold
RST
Time from last system clock to
reset initiation
Missing Clock Detector Timeout
100
*Note: When operating at frequencies above 50 MHz, minimum V
supply Voltage is 3.0 V.
DD
Rev. 1.4
183
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
NOTES:
184
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
14. Oscillators
The devices include a programmable internal oscillator and an external oscillator drive circuit. The internal
oscillator can be enabled, disabled, and calibrated using the OSCICN and OSCICL registers, as shown in
Figure 14.1. The system clock can be sourced by the external oscillator circuit, the internal oscillator, or the
on-chip phase-locked loop (PLL). The internal oscillator's electrical specifications are given in Table 14.1
on page 185.
OSCICL
OSCICN
CLKSEL
Option 3
XTAL1
AV+
XTAL2
Option 4
XTAL1
EN
Calibrated
Internal
Oscillator
n
00
01
10
Option 2
VDD
Option 1
XTAL1
XTAL2
SYSCLK
Input
Circuit
OSC
XTAL1
PLL
AGND
OSCXCN
Figure 14.1. Oscillator Diagram
Table 14.1. Oscillator Electrical Characteristics
–40°C to +85°C unless otherwise specified.
Parameter
Calibrated Internal Oscillator
Frequency
Conditions
Min
Typ
Max
Units
24
24.5
25
—
MHz
Internal Oscillator Supply
OSCICN.7 = 1
—
400
µA
Current (from V
)
DD
External Clock Frequency
0
—
—
—
30
—
—
MHz
ns
T
T
(External Clock High Time)
(External Clock Low Time)
15
15
XCH
XCL
ns
14.1. Internal Calibrated Oscillator
All devices include a calibrated internal oscillator that defaults as the system clock after a system reset.
The internal oscillator period can be adjusted via the OSCICL register as defined by SFR Definition 14.1.
OSCICL is factory calibrated to obtain a 24.5 MHz frequency.
Rev. 1.4
185
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Electrical specifications for the precision internal oscillator are given in Table 14.1. Note that the system
clock may be derived from the programmed internal oscillator divided by 1, 2, 4, or 8, as defined by the
IFCN bits in register OSCICN.
SFR Definition 14.1. OSCICL: Internal Oscillator Calibration.
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Reset Value
Variable
Bit0
SFR Address: 0x8B
SFR Page: F
Bits 7–0: OSCICL: Internal Oscillator Calibration Register.
This register calibrates the internal oscillator period. The reset value for OSCICL defines the
internal oscillator base frequency. The reset value is factory calibrated to generate an inter-
nal oscillator frequency of 24.5 MHz.
SFR Definition 14.2. OSCICN: Internal Oscillator Control
R/W
IOSCEN
Bit7
R
R/W
-
R
-
R/W
-
R/W
-
R/W
IFCN1
Bit1
R/W
Reset Value
IFRDY
Bit6
IFCN0 11000000
Bit0
Bit5
Bit4
Bit3
Bit2
SFR Address: 0x8A
SFR Page: F
Bit 7:
IOSCEN: Internal Oscillator Enable Bit.
0: Internal Oscillator Disabled.
1: Internal Oscillator Enabled.
Bit 6:
IFRDY: Internal Oscillator Frequency Ready Flag.
0: Internal Oscillator not running at programmed frequency.
1: Internal Oscillator running at programmed frequency.
Bits 5–2: Reserved.
Bits 1–0: IFCN1-0: Internal Oscillator Frequency Control Bits.
00: Internal Oscillator is divided by 8.
01: Internal Oscillator is divided by 4.
10: Internal Oscillator is divided by 2.
11: Internal Oscillator is divided by 1.
186
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
14.2. External Oscillator Drive Circuit
The external oscillator circuit may drive an external crystal, ceramic resonator, capacitor, or RC network. A
CMOS clock may also provide a clock input. For a crystal or ceramic resonator configuration, the crystal/
resonator must be wired across the XTAL1 and XTAL2 pins as shown in Option 1 of Figure 14.1. In RC,
capacitor, or CMOS clock configuration, the clock source should be wired to the XTAL2 and/or XTAL1
pin(s) as shown in Option 2, 3, or 4 of Figure 14.1. The type of external oscillator must be selected in the
OSCXCN register, and the frequency control bits (XFCN) must be selected appropriately (see SFR Defini-
tion 14.4).
14.3. System Clock Selection
The CLKSL1-0 bits in register CLKSEL select which oscillator source generates the system clock.
CLKSL1-0 must be set to ‘01’ for the system clock to run from the external oscillator; however the external
oscillator may still clock certain peripherals, such as the timers and PCA, when the internal oscillator or the
PLL is selected as the system clock. The system clock may be switched on-the-fly between the internal
and external oscillators or the PLL, so long as the selected oscillator source is enabled and settled. The
internal oscillator requires little start-up time, and may be enabled and selected as the system clock in the
same write to OSCICN. External crystals and ceramic resonators typically require a start-up time before
they are settled and ready for use as the system clock. The Crystal Valid Flag (XTLVLD in register
OSCXCN) is set to ‘1’ by hardware when the external oscillator is settled. To avoid reading a false
XTLVLD, in crystal mode software should delay at least 1 ms between enabling the external oscillator and
checking XTLVLD. RC and C modes typically require no startup time. The PLL also requires time to lock
onto the desired frequency, and the PLL Lock Flag (PLLLCK in register PLL0CN) is set to ‘1’ by hardware
once the PLL is locked on the correct frequency.
Rev. 1.4
187
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 14.3. CLKSEL: System Clock Selection
R/W
-
R/W
-
R/W
R/W
R/W
-
R/W
-
R/W
R/W
Reset Value
CLKDIV1 CLKDIV0
CLKSL1 CLKSL0 00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x97
SFR Page: F
Bits 7–6: Reserved.
Bits 5–4: CLKDIV1–0: Output SYSCLK Divide Factor.
These bits can be used to pre-divide SYSCLK before it is output to a port pin through the
crossbar.
00: Output will be SYSCLK.
01: Output will be SYSCLK/2.
10: Output will be SYSCLK/4.
11: Output will be SYSCLK/8.
See Section “18. Port Input/Output” on page 235 for more details about routing this out-
put to a port pin.
Bits 3–2: Reserved.
Bits 1–0: CLKSL1–0: System Clock Source Select Bits.
00: SYSCLK derived from the Internal Oscillator, and scaled as per the IFCN bits in
OSCICN.
01: SYSCLK derived from the External Oscillator circuit.
10: SYSCLK derived from the PLL.
11: Reserved.
188
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 14.4. OSCXCN: External Oscillator Control
R
R/W
R/W
R/W
R
-
R/W
XFCN2
Bit2
R/W
XFCN1
Bit1
R/W
Reset Value
XTLVLD XOSCMD2 XOSCMD1 XOSCMD0
XFCN0 00000000
Bit0
Bit7
Bit6
Bit5
Bit4
Bit3
SFR Address: 0x8C
SFR Page: F
Bit7:
XTLVLD: Crystal Oscillator Valid Flag.
(Valid only when XOSCMD = 11x.)
0: Crystal Oscillator is unused or not yet stable.
1: Crystal Oscillator is running and stable.
Bits6–4: XOSCMD2–0: External Oscillator Mode Bits.
00x: External Oscillator circuit off.
010: External CMOS Clock Mode (External CMOS Clock input on XTAL1 pin).
011: External CMOS Clock Mode with divide by 2 stage (External CMOS Clock input on
XTAL1 pin).
10x: RC/C Oscillator Mode with divide by 2 stage.
110: Crystal Oscillator Mode.
111: Crystal Oscillator Mode with divide by 2 stage.
RESERVED. Read = 0, Write = don't care.
Bit3:
Bits2–0: XFCN2–0: External Oscillator Frequency Control Bits.
000-111: see table below:
XFCN
000
001
010
011
100
101
110
Crystal (XOSCMD = 11x) RC (XOSCMD = 10x) C (XOSCMD = 10x)
f 32 kHz
f 25 kHz
K Factor = 0.87
K Factor = 2.6
K Factor = 7.7
K Factor = 22
K Factor = 65
K Factor = 180
K Factor = 664
K Factor = 1590
32 kHz f 84 kHz
84 kHz f 225 kHz
225 kHz f 590 kHz
590 kHz f 1.5 MHz
1.5 MHz f 4 MHz
4 MHz f 10 MHz
10 MHz f 30 MHz
25 kHz f 50 kHz
50 kHz f 100 kHz
100 kHz f 200 kHz
200 kHz f 400 kHz
400 kHz f 800 kHz
800 kHz f 1.6 MHz
1.6 MHz f 3.2 MHz
111
CRYSTAL MODE (Circuit from Figure 14.1, Option 1; XOSCMD = 11x)
Choose XFCN value to match crystal frequency.
RC MODE (Circuit from Figure 14.1, Option 2; XOSCMD = 10x)
Choose XFCN value to match frequency range:
3
f = 1.23(10 ) / (R * C), where
f = frequency of oscillation in MHz
C = capacitor value in pF
R = Pullup resistor value in k
C MODE (Circuit from Figure 14.1, Option 3; XOSCMD = 10x)
Choose K Factor (KF) for the oscillation frequency desired:
f = KF / (C * V ), where
DD
f = frequency of oscillation in MHz
C = capacitor value on XTAL1, XTAL2 pins in pF
V
= Power Supply on MCU in Volts
DD
Rev. 1.4
189
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
14.4. External Crystal Example
If a crystal or ceramic resonator is used as an external oscillator source for the MCU, the circuit should be
configured as shown in Figure 14.1, Option 1. The External Oscillator Frequency Control value (XFCN)
should be chosen from the Crystal column of the table in SFR Definition 14.4 (OSCXCN register). For
example, an 11.0592 MHz crystal requires an XFCN setting of 111b.
When the crystal oscillator is enabled, the oscillator amplitude detection circuit requires a settle time to
achieve proper bias. Waiting at least 1 ms between enabling the oscillator and checking the XTLVLD bit
will prevent a premature switch to the external oscillator as the system clock. Switching to the external
oscillator before the crystal oscillator has stabilized can result in unpredictable behavior. The recom-
mended procedure is:
Step 1. Enable the external oscillator.
Step 2. Wait at least 1 ms.
Step 3. Poll for XTLVLD => ‘1’.
Step 4. Switch the system clock to the external oscillator.
Important Note on External Crystals: Crystal oscillator circuits are quite sensitive to PCB layout. The
crystal should be placed as close as possible to the XTAL pins on the device. The traces should be as
short as possible and shielded with ground plane from any other traces which could introduce noise or
interference.
14.5. External RC Example
If an RC network is used as an external oscillator source for the MCU, the circuit should be configured as
shown in Figure 14.1, Option 2. The capacitor should be no greater than 100 pF; however for very small
capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. To deter-
mine the required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, first
select the RC network value to produce the desired frequency of oscillation. If the frequency desired is
100 kHz, let R = 246 k and C = 50 pF:
3
3
f = 1.23(10 )/RC = 1.23 (10 )/[246 x 50] = 0.1 MHz = 100 kHz
Referring to the table in SFR Definition 14.4, the required XFCN setting is 010.
14.6. External Capacitor Example
If a capacitor is used as an external oscillator for the MCU, the circuit should be configured as shown in
Figure 14.1, Option 3. The capacitor should be no greater than 100 pF; however for very small capacitors,
the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the
required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, select the capaci-
tor to be used and find the frequency of oscillation from the equations below. Assume V = 3.0 V and
DD
C = 50 pF:
f = KF/( C x V ) = KF/( 50 x 3 )
DD
f = KF/150
If a frequency of roughly 50 kHz is desired, select the K Factor from the table in SFR Definition 14.4
as KF = 7.7:
f = 7.7/150 = 0.051 MHz, or 51 kHz
Therefore, the XFCN value to use in this example is 010.
190
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
14.7. Phase-Locked Loop (PLL)
A Phase-Locked-Loop (PLL) is included, which is used to multiply the internal oscillator or an external
clock source to achieve higher CPU operating frequencies. The PLL circuitry is designed to produce an
output frequency between 25 MHz and 100 MHz, from a divided reference frequency between 5 MHz and
30 MHz. A block diagram of the PLL is shown in Figure 14.2.
PLL0CN
PLL0FLT
Divided
Reference
Clock
Internal
Oscillator
0
1
PLL Clock
Output
Phase /
Frequency
Detection
Current
Controlled
Oscillator
Loop Filter
External
Oscillator
PLL0DIV
PLL0MUL
Figure 14.2. PLL Block Diagram
14.7.1. PLL Input Clock and Pre-divider
The PLL circuitry can derive its reference clock from either the internal oscillator or an external clock
source. The PLLSRC bit (PLL0CN.2) controls which clock source is used for the reference clock (see SFR
Definition 14.5). If PLLSRC is set to ‘0’, the internal oscillator source is used. Note that the internal oscilla-
tor divide factor (as specified by bits IFCN1-0 in register OSCICN) will also apply to this clock. When
PLLSRC is set to ‘1’, an external oscillator source will be used. The external oscillator should be active and
settled before it is selected as a reference clock for the PLL circuit. The reference clock is divided down
prior to the PLL circuit, according to the contents of the PLLM4-0 bits in the PLL Pre-divider Register
(PLL0DIV), shown in SFR Definition 14.6.
14.7.2. PLL Multiplication and Output Clock
The PLL circuitry will multiply the divided reference clock by the multiplication factor stored in the
PLL0MUL register shown in SFR Definition 14.7. To accomplish this, it uses a feedback loop consisting of
a phase/frequency detector, a loop filter, and a current-controlled oscillator (ICO). It is important to config-
ure the loop filter and the ICO for the correct frequency ranges. The PLLLP3–0 bits (PLL0FLT.3–0) should
be set according to the divided reference clock frequency. Likewise, the PLLICO1–0 bits (PLL0FLT.5–4)
should be set according to the desired output frequency range. SFR Definition 14.8 describes the proper
settings to use for the PLLLP3–0 and PLLICO1–0 bits. When the PLL is locked and stable at the desired
frequency, the PLLLCK bit (PLL0CN.5) will be set to a ‘1’. The resulting PLL frequency will be set accord-
ing to the equation:
Where “Reference Frequency” is the selected source clock frequency, PLLN is the PLL Multiplier, and
PLLM is the PLL Pre-divider.
Rev. 1.4
191
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
PLLN
---------------
PLL Frequency = Reference Frequency
PLLM
14.7.3. Powering on and Initializing the PLL
To set up and use the PLL as the system clock after power-up of the device, the following procedure
should be implemented:
Step 1. Ensure that the reference clock to be used (internal or external) is running and stable.
Step 2. Set the PLLSRC bit (PLL0CN.2) to select the desired clock source for the PLL.
Step 3. Program the Flash read timing bits, FLRT (FLSCL.5–4) to the appropriate value for the
new clock rate (see Section “15. Flash Memory” on page 199).
Step 4. Enable power to the PLL by setting PLLPWR (PLL0CN.0) to ‘1’.
Step 5. Program the PLL0DIV register to produce the divided reference frequency to the PLL.
Step 6. Program the PLLLP3–0 bits (PLL0FLT.3–0) to the appropriate range for the divided
reference frequency.
Step 7. Program the PLLICO1–0 bits (PLL0FLT.5–4) to the appropriate range for the PLL output
frequency.
Step 8. Program the PLL0MUL register to the desired clock multiplication factor.
Step 9. Wait at least 5 µs, to provide a fast frequency lock.
Step 10. Enable the PLL by setting PLLEN (PLL0CN.1) to ‘1’.
Step 11. Poll PLLLCK (PLL0CN.4) until it changes from ‘0’ to ‘1’.
Step 12. Switch the System Clock source to the PLL using the CLKSEL register.
If the PLL characteristics need to be changed when the PLL is already running, the following procedure
should be implemented:
Step 1. The system clock should first be switched to either the internal oscillator or an external
clock source that is running and stable, using the CLKSEL register.
Step 2. Ensure that the reference clock to be used for the new PLL setting (internal or external) is
running and stable.
Step 3. Set the PLLSRC bit (PLL0CN.2) to select the new clock source for the PLL.
Step 4. If moving to a faster frequency, program the Flash read timing bits, FLRT (FLSCL.5–4) to
the appropriate value for the new clock rate (see Section “15. Flash Memory” on
page 199).
Step 5. Disable the PLL by setting PLLEN (PLL0CN.1) to ‘0’.
Step 6. Program the PLL0DIV register to produce the divided reference frequency to the PLL.
Step 7. Program the PLLLP3–0 bits (PLL0FLT.3–0) to the appropriate range for the divided
reference frequency.
Step 8. Program the PLLICO1-0 bits (PLL0FLT.5–4) to the appropriate range for the PLL output
frequency.
Step 9. Program the PLL0MUL register to the desired clock multiplication factor.
Step 10. Enable the PLL by setting PLLEN (PLL0CN.1) to ‘1’.
Step 11. Poll PLLLCK (PLL0CN.4) until it changes from ‘0’ to ‘1’.
Step 12. Switch the System Clock source to the PLL using the CLKSEL register.
Step 13. If moving to a slower frequency, program the Flash read timing bits, FLRT (FLSCL.5–4)
to the appropriate value for the new clock rate (see Section “15. Flash Memory” on
192
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
page 199). Important Note: Cache reads, cache writes, and the prefetch engine
should be disabled whenever the FLRT bits are changed to a lower setting.
To shut down the PLL, the system clock should be switched to the internal oscillator or a stable external
clock source, using the CLKSEL register. Next, disable the PLL by setting PLLEN (PLL0CN.1) to ‘0’.
Finally, the PLL can be powered off, by setting PLLPWR (PLL0CN.0) to ‘0’. Note that the PLLEN and
PLLPWR bits can be cleared at the same time.
SFR Definition 14.5. PLL0CN: PLL Control
R/W
-
R/W
-
R/W
-
R
R/W
0
R/W
R/W
R/W
Reset Value
PLLLCK
Bit4
PLLSRC PLLEN PLLPWR 00000000
Bit7
Bit6
Bit5
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x89
SFR Page: F
Bits 7–5: UNUSED: Read = 000b; Write = don’t care.
Bit 4:
PLLCK: PLL Lock Flag.
0: PLL Frequency is not locked.
1: PLL Frequency is locked.
Bit 3:
Bit 2:
RESERVED. Must write to ‘0’.
PLLSRC: PLL Reference Clock Source Select Bit.
0: PLL Reference Clock Source is Internal Oscillator.
1: PLL Reference Clock Source is External Oscillator.
PLLEN: PLL Enable Bit.
0: PLL is held in reset.
1: PLL is enabled. PLLPWR must be ‘1’.
PLLPWR: PLL Power Enable.
Bit 1:
Bit 0:
0: PLL bias generator is de-activated. No static power is consumed.
1: PLL bias generator is active. Must be set for PLL to operate.
Rev. 1.4
193
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 14.6. PLL0DIV: PLL Pre-divider
R/W
-
R/W
-
R/W
-
R/W
PLLM4
Bit4
R/W
PLLM3
Bit3
R/W
PLLM2
Bit2
R/W
PLLM1
Bit1
R/W
Reset Value
PLLM0 00000001
Bit0
Bit7
Bit6
Bit5
SFR Address: 0x8D
SFR Page: F
Bits 7–5: UNUSED: Read = 000b; Write = don’t care.
Bits 4–0: PLLM4–0: PLL Reference Clock Pre-divider.
These bits select the pre-divide value of the PLL reference clock. When set to any non-zero
value, the reference clock will be divided by the value in PLLM4–0. When set to ‘00000b’,
the reference clock will be divided by 32.
SFR Definition 14.7. PLL0MUL: PLL Clock Scaler
R/W
PLLN7
Bit7
R/W
PLLN6
Bit6
R/W
PLLN5
Bit5
R/W
PLLN4
Bit4
R/W
PLLN3
Bit3
R/W
PLLN2
Bit2
R/W
PLLN1
Bit1
R/W
Reset Value
PLLN0 00000001
Bit0
SFR Address: 0x8E
SFR Page: F
Bits 7–0: PLLN7–0: PLL Multiplier.
These bits select the multiplication factor of the divided PLL reference clock. When set to
any non-zero value, the multiplication factor will be equal to the value in PLLN7-0. When set
to ‘00000000b’, the multiplication factor will be equal to 256.
194
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 14.8. PLL0FLT: PLL Filter
R/W
-
R/W
-
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
PLLICO1 PLLICO0 PLLLP3 PLLLP2 PLLLP1 PLLLP0 00110001
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x8F
SFR Page: F
Bits 7–6: UNUSED: Read = 00b; Write = don’t care.
Bits 5–4: PLLICO1-0: PLL Current-Controlled Oscillator Control Bits.
Selection is based on the desired output frequency, according to the following table:
PLL Output Clock
65–100 MHz
45–80 MHz
PLLICO1-0
00
01
10
11
30–60 MHz
25–50 MHz
Bits 3–0: PLLLP3-0: PLL Loop Filter Control Bits.
Selection is based on the divided PLL reference clock, according to the following table:
Divided PLL Reference Clock
19–30 MHz
PLLLP3-0
0001
12.2–19.5 MHz
7.8–12.5 MHz
0011
0111
5–8 MHz
1111
Table 14.2. PLL Frequency Characteristics
–40 to +85 °C unless otherwise specified
Parameter
Input Frequency
Conditions
Min
5
Typ
Max
30
Units
MHz
MHz
(Divided Reference Frequency)
PLL Output Frequency
25
100*
*Note: The maximum operating frequency of the C8051F124/5/6/7 is 50 MHz
Rev. 1.4
195
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 14.3. PLL Lock Timing Characteristics
–40 to +85 °C unless otherwise specified
Input
Frequency
Multiplier
(Pll0mul)
Pll0flt
Setting
0x0F
0x0F
0x1F
0x1F
0x2F
0x2F
0x3F
0x3F
0x01
0x01
0x11
0x11
0x21
0x21
0x31
0x31
Output
Frequency
100 MHz
65 MHz
80 MHz
45 MHz
60 MHz
30 MHz
50 MHz
25 MHz
100 MHz
50 MHz
75 MHz
50 MHz
50 MHz
25 MHz
50 MHz
25 MHz
Min
Typ
Max
Units
20
13
16
9
12
6
10
5
4
2
3
2
2
202
115
241
116
258
112
263
113
42
33
48
17
42
µs
µs
µs
µs
µs
µs
µs
µs
µs
µs
µs
µs
µs
µs
µs
µs
5 MHz
25 MHz
1
2
1
33
60
25
196
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
NOTES:
Rev. 1.4
197
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
198
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
15. Flash Memory
All devices include either 128 kB (C8051F12x and C8051F130/1) or 64 kB (C8051F132/3) of on-chip,
reprogrammable Flash memory for program code or non-volatile data storage. An additional 256-byte
page of Flash is also included for non-volatile data storage. The Flash memory can be programmed in-sys-
tem through the JTAG interface, or by software using the MOVX write instructions. Once cleared to logic 0,
a Flash bit must be erased to set it back to logic 1. Bytes should be erased (set to 0xFF) before being
reprogrammed. Flash write and erase operations are automatically timed by hardware for proper execu-
tion. During a Flash erase or write, the FLBUSY bit in the FLSTAT register is set to ‘1’ (see SFR Definition
16.5). During this time, instructions that are located in the prefetch buffer or the branch target cache can be
executed, but the processor will stall until the erase or write is completed if instruction data must be fetched
from Flash memory. Interrupts that have been pre-loaded into the branch target cache can also be ser-
viced at this time, if the current code is also executing from the prefetch engine or cache memory. Any
interrupts that are not pre-loaded into cache, or that occur while the core is halted, will be held in a pending
state during the Flash write/erase operation, and serviced in priority order once the Flash operation has
completed. Refer to Table 15.1 for the electrical characteristics of the Flash memory.
15.1. Programming the Flash Memory
The simplest means of programming the Flash memory is through the JTAG interface using programming
tools provided by Silicon Labs or a third party vendor. This is the only means for programming a non-initial-
ized device. For details on the JTAG commands to program Flash memory, see Section “25. JTAG (IEEE
1149.1)” on page 341.
The Flash memory can be programmed from software using the MOVX write instruction with the address
and data byte to be programmed provided as normal operands. Before writing to Flash memory using
MOVX, Flash write operations must be enabled by setting the PSWE Program Store Write Enable bit
(PSCTL.0) to logic 1. This directs the MOVX writes to Flash memory instead of to XRAM, which is the
default target. The PSWE bit remains set until cleared by software. To avoid errant Flash writes, it is rec-
ommended that interrupts be disabled while the PSWE bit is logic 1.
Flash memory is read using the MOVC instruction. MOVX reads are always directed to XRAM, regardless
of the state of PSWE.
On the devices with 128 kB of Flash, the COBANK bits in the PSBANK register (SFR Definition 11.1)
determine which of the upper three Flash banks are mapped to the address range 0x08000 to 0x0FFFF for
Flash writes, reads and erases.
For devices with 64 kB of Flash. the COBANK bits should always remain set to ‘01’ to ensure that Flash
write, erase, and read operations are valid.
NOTE: To ensure the integrity of Flash memory contents, it is strongly recommended that the on-
chip V monitor be enabled by connecting the V monitor enable pin (MONEN) to V and set-
DD
DD
DD
ting the PORSF bit in the RSTSRC register to ‘1’ in any system that writes and/or erases Flash
memory from software. See “Reset Sources” on page 177 for more information.
A write to Flash memory can clear bits but cannot set them; only an erase operation can set bits in Flash.
A byte location to be programmed must be erased before a new value can be written.
Write/Erase timing is automatically controlled by hardware. Note that on the 128 k Flash versions, 1024
bytes beginning at location 0x1FC00 are reserved. Flash writes and erases targeting the reserved area
should be avoided.
Rev. 1.4
199
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 15.1. Flash Electrical Characteristics
= 2.7 to 3.6 V; –40 to +85 °C
V
DD
Parameter
Conditions
C8051F12x and C8051F130/1
C8051F132/3
Min
Typ
131328
65792
100k
12
Max
Units
Bytes
Bytes
Erase/Write
ms
1
2
Flash Size
Flash Size
1
20k
10
Endurance
14
60
Erase Cycle Time
Write Cycle Time
Notes:
40
50
µs
1. Includes 256-byte Scratch Pad Area
2. 1024 Bytes at location 0x1FC00 to 0x1FFFF are reserved.
15.1.1. Non-volatile Data Storage
The Flash memory can be used for non-volatile data storage as well as program code. This allows data
such as calibration coefficients to be calculated and stored at run time. Data is written and erased using the
MOVX write instruction (as described in Section 15.1.2 and Section 15.1.3) and read using the MOVC
instruction. The COBANK bits in register PSBANK (SFR Definition 11.1) control which portion of the Flash
memory is targeted by writes and erases of addresses above 0x07FFF. For devices with 64 kB of Flash.
the COBANK bits should always remain set to ‘01’ to ensure that Flash write, erase, and read operations
are valid.
Two additional 128-byte sectors (256 bytes total) of Flash memory are included for non-volatile data stor-
age. The smaller sector size makes them particularly well suited as general purpose, non-volatile scratch-
pad memory. Even though Flash memory can be written a single byte at a time, an entire sector must be
erased first. In order to change a single byte of a multi-byte data set, the data must be moved to temporary
storage. The 128-byte sector-size facilitates updating data without wasting program memory or RAM
space. The 128-byte sectors are double-mapped over the normal Flash memory for MOVC reads and
MOVX writes only; their addresses range from 0x00 to 0x7F and from 0x80 to 0xFF (see Figure 15.2). To
access the 128-byte sectors, the SFLE bit in PSCTL must be set to logic 1. Code execution from the 128-
byte Scratchpad areas is not permitted. The 128-byte sectors can be erased individually, or both at the
same time. To erase both sectors simultaneously, the address 0x0400 should be targeted during the erase
operation with SFLE set to ‘1’. See Figure 15.1 for the memory map under different COBANK and SFLE
settings.
200
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFLE = 0
COBANK = 0 COBANK = 1 COBANK = 2 COBANK = 3
SFLE = 1
Internal
Address
0xFFFF
Bank 0
Bank 1
Bank 2
Bank 3
Undefined
0x8000
0x7FFF
Bank 0
Bank 0
Bank 0
Bank 0
0x00FF
0x0000
Scratchpad
Areas (2)
128k FLASH devices only.
Figure 15.1. Flash Memory Map for MOVC Read and MOVX Write Operations
15.1.2. Erasing Flash Pages From Software
When erasing Flash memory, an entire page is erased (all bytes in the page are set to 0xFF). The Flash
memory is organized in 1024-byte pages. The 256 bytes of Scratchpad area (addresses 0x20000 to
0x200FF) consists of two 128 byte pages. To erase any Flash page, the FLWE, PSWE, and PSEE bits
must be set to ‘1’, and a byte must be written using a MOVX instruction to any address within that page.
The following is the recommended procedure for erasing a Flash page from software:
Step 1. Disable interrupts.
Step 2. If erasing a page in Bank 1, Bank 2, or Bank 3, set the COBANK bits (PSBANK.5-4) for
the appropriate bank.
Step 3. If erasing a page in the Scratchpad area, set the SFLE bit (PSCTL.2).
Step 4. Set FLWE (FLSCL.0) to enable Flash writes/erases via user software.
Step 5. Set PSEE (PSCTL.1) to enable Flash erases.
Step 6. Set PSWE (PSCTL.0) to redirect MOVX commands to write to Flash.
Step 7. Use the MOVX instruction to write a data byte to any location within the page to be
erased.
Step 8. Clear PSEE to disable Flash erases.
Step 9. Clear the PSWE bit to redirect MOVX commands to the XRAM data space.
Step 10. Clear the FLWE bit, to disable Flash writes/erases.
Step 11. If erasing a page in the Scratchpad area, clear the SFLE bit.
Step 12. Re-enable interrupts.
Rev. 1.4
201
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
15.1.3. Writing Flash Memory From Software
Bytes in Flash memory can be written one byte at a time, or in small blocks. The CHBLKW bit in register
CCH0CN (SFR Definition 16.1) controls whether a single byte or a block of bytes is written to Flash during
a write operation. When CHBLKW is cleared to ‘0’, the Flash will be written one byte at a time. When
CHBLKW is set to ‘1’, the Flash will be written in blocks of four bytes for addresses in code space, or
blocks of two bytes for addresses in the Scratchpad area. Block writes are performed in the same amount
of time as single byte writes, which can save time when storing large amounts of data to Flash memory.
For single-byte writes to Flash, bytes are written individually, and the Flash write is performed after each
MOVX write instruction. The recommended procedure for writing Flash in single bytes is as follows:
Step 1. Disable interrupts.
Step 2. Clear CHBLKW (CCH0CN.0) to select single-byte write mode.
Step 3. If writing to bytes in Bank 1, Bank 2, or Bank 3, set the COBANK bits (PSBANK.5-4) for
the appropriate bank.
Step 4. If writing to bytes in the Scratchpad area, set the SFLE bit (PSCTL.2).
Step 5. Set FLWE (FLSCL.0) to enable Flash writes/erases via user software.
Step 6. Set PSWE (PSCTL.0) to redirect MOVX commands to write to Flash.
Step 7. Use the MOVX instruction to write a data byte to the desired location (repeat as
necessary).
Step 8. Clear the PSWE bit to redirect MOVX commands to the XRAM data space.
Step 9. Clear the FLWE bit, to disable Flash writes/erases.
Step 10. If writing to bytes in the Scratchpad area, clear the SFLE bit.
Step 11. Re-enable interrupts.
For block Flash writes, the Flash write procedure is only performed after the last byte of each block is writ-
ten with the MOVX write instruction. When writing to addresses located in any of the four code banks, a
Flash write block is four bytes long, from addresses ending in 00b to addresses ending in 11b. Writes must
be performed sequentially (i.e. addresses ending in 00b, 01b, 10b, and 11b must be written in order). The
Flash write will be performed following the MOVX write that targets the address ending in 11b. When writ-
ing to addresses located in the Flash Scratchpad area, a Flash block is two bytes long, from addresses
ending in 0b to addresses ending in 1b. The Flash write will be performed following the MOVX write that
targets the address ending in 1b. If any bytes in the block do not need to be updated in Flash, they should
be written to 0xFF. The recommended procedure for writing Flash in blocks is as follows:
Step 1. Disable interrupts.
Step 2. Set CHBLKW (CCH0CN.0) to select block write mode.
Step 3. If writing to bytes in Bank 1, Bank 2, or Bank 3, set the COBANK bits (PSBANK.5-4) for
the appropriate bank.
Step 4. If writing to bytes in the Scratchpad area, set the SFLE bit (PSCTL.2).
Step 5. Set FLWE (FLSCL.0) to enable Flash writes/erases via user software.
Step 6. Set PSWE (PSCTL.0) to redirect MOVX commands to write to Flash.
Step 7. Use the MOVX instruction to write data bytes to the desired block. The data bytes must
be written sequentially, and the last byte written must be the high byte of the block (see
text for details, repeat as necessary).
Step 8. Clear the PSWE bit to redirect MOVX commands to the XRAM data space.
Step 9. Clear the FLWE bit, to disable Flash writes/erases.
Step 10. If writing to bytes in the Scratchpad area, clear the SFLE bit.
Step 11. Re-enable interrupts.
202
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
15.2. Security Options
The CIP-51 provides security options to protect the Flash memory from inadvertent modification by soft-
ware as well as prevent the viewing of proprietary program code and constants. The Program Store Write
Enable (PSCTL.0), Program Store Erase Enable (PSCTL.1), and Flash Write/Erase Enable (FLACL.0) bits
protect the Flash memory from accidental modification by software. These bits must be explicitly set to
logic 1 before software can write or erase the Flash memory. Additional security features prevent proprie-
tary program code and data constants from being read or altered across the JTAG interface or by software
running on the system controller.
A set of security lock bytes protect the Flash program memory from being read or altered across the JTAG
interface. Each bit in a security lock-byte protects one 16k-byte block of memory. Clearing a bit to logic 0 in
the Read Lock Byte prevents the corresponding block of Flash memory from being read across the JTAG
interface. Clearing a bit in the Write/Erase Lock Byte protects the block from JTAG erasures and/or writes.
The Scratchpad area is read or write/erase locked when all bits in the corresponding security byte are
cleared to logic 0.
On the C8051F12x and C8051F130/1, the security lock bytes are located at 0x1FBFE (Write/Erase Lock)
and 0x1FBFF (Read Lock), as shown in Figure 15.2. On the C8051F132/3, the security lock bytes are
located at 0x0FFFE (Write/Erase Lock) and 0x0FFFF (Read Lock), as shown in Figure 15.3. The 1024-
byte sector containing the lock bytes can be written to, but not erased, by software. An attempted read of a
read-locked byte returns undefined data. Debugging code in a read-locked sector is not possible through
the JTAG interface. The lock bits can always be read from and written to logic 0 regardless of the security
setting applied to the block containing the security bytes. This allows additional blocks to be protected after
the block containing the security bytes has been locked.
Important Note: To ensure protection from external access, the block containing the lock bytes
must be Write/Erase locked. On the 128 kB devices (C8051F12x and C8051F130/1), the block con-
taining the security bytes is 0x18000-0x1BFFF, and is locked by clearing bit 7 of the Write/Erase
Lock Byte. On the 64 kB devices (C8051F132/3), the block containing the security bytes is
0x0C000-0x0FFFF, and is locked by clearing bit 3 of the Write/Erase Lock Byte. If the page contain-
ing the security bytes is not Write/Erase locked, it is still possible to erase this page of Flash mem-
ory through the JTAG port and reset the security bytes.
When the page containing the security bytes has been Write/Erase locked, a JTAG full device erase
must be performed to unlock any areas of Flash protected by the security bytes. A JTAG full
device erase is initiated by performing a normal JTAG erase operation on either of the security byte
locations. This operation must be initiated through the JTAG port, and cannot be performed from
firmware running on the device.
Rev. 1.4
203
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Read and Write/Erase Security Bits.
(Bit 7 is MSB.)
SFLE = 0
0x1FFFF
Bit
Memory Block
Reserved
7
6
5
4
3
2
1
0
0x1C000 - 0x1FBFD
0x18000 - 0x1BFFF
0x14000 - 0x17FFF
0x10000 - 0x13FFF
0x0C000 - 0x0FFFF
0x08000 - 0x0BFFF
0x04000 - 0x07FFF
0x00000 - 0x03FFF
0x1FC00
0x1FBFF
Read Lock Byte
0x1FBFE
0x1FBFD
Write/Erase Lock Byte
Flash Access Limit
SFLE = 1
0x00FF
0x0000
Scratchpad Memory
(Data only)
0x00000
Program/Data
Memory Space
Flash Read Lock Byte
Bits7–0: Each bit locks a corresponding block of memory. (Bit7 is MSB).
0: Read operations are locked (disabled) for corresponding block across the JTAG interface.
1: Read operations are unlocked (enabled) for corresponding block across the JTAG inter-
face.
Flash Write/Erase Lock Byte
Bits7–0: Each bit locks a corresponding block of memory.
0: Write/Erase operations are locked (disabled) for corresponding block across the JTAG
interface.
1: Write/Erase operations are unlocked (enabled) for corresponding block across the JTAG
interface.
NOTE: When the highest block is locked, the security bytes may be written but not erased.
Flash access Limit Register (FLACL)
The Flash Access Limit is defined by the setting of the FLACL register, as described in SFR
Definition 15.1. Firmware running at or above this address is prohibited from using the
MOVX and MOVC instructions to read, write, or erase Flash locations below this address.
Figure 15.2. 128 kB Flash Memory Map and Security Bytes
204
Rev. 1.4
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C8051F130/1/2/3
Read and Write/Erase Security Bits.
(Bit 7 is MSB.)
SFLE = 0
0x0FFFF
0x0FFFE
Read Lock Byte
Bit
Memory Block
7
6
5
4
3
2
1
0
N/A
N/A
N/A
Write/Erase Lock Byte
0x0FFFD
N/A
0x0C000 - 0x0FFFF
0x08000 - 0x0BFFF
0x04000 - 0x07FFF
0x00000 - 0x03FFF
Flash Access Limit
SFLE = 1
0x00FF
0x0000
Scratchpad Memory
(Data only)
0x00000
Program/Data
Memory Space
Flash Read Lock Byte
Bits7–0: Each bit locks a corresponding block of memory. (Bit7 is MSB).
0: Read operations are locked (disabled) for corresponding block across the JTAG interface.
1: Read operations are unlocked (enabled) for corresponding block across the JTAG inter-
face.
Flash Write/Erase Lock Byte
Bits7–0: Each bit locks a corresponding block of memory.
0: Write/Erase operations are locked (disabled) for corresponding block across the JTAG
interface.
1: Write/Erase operations are unlocked (enabled) for corresponding block across the JTAG
interface.
NOTE: When the highest block is locked, the security bytes may be written but not erased.
Flash access Limit Register (FLACL)
The Flash Access Limit is defined by the setting of the FLACL register, as described in SFR
Definition 15.1. Firmware running at or above this address is prohibited from using the
MOVX and MOVC instructions to read, write, or erase Flash locations below this address.
Figure 15.3. 64 kB Flash Memory Map and Security Bytes
Rev. 1.4
205
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
The Flash Access Limit security feature (see SFR Definition 15.1) protects proprietary program code and
data from being read by software running on the device. This feature provides support for OEMs that wish
to program the MCU with proprietary value-added firmware before distribution. The value-added firmware
can be protected while allowing additional code to be programmed in remaining program memory space
later.
The Flash Access Limit (FAL) is a 17-bit address that establishes two logical partitions in the program
memory space. The first is an upper partition consisting of all the program memory locations at or above
the FAL address, and the second is a lower partition consisting of all the program memory locations start-
ing at 0x00000 up to (but excluding) the FAL address. Software in the upper partition can execute code in
the lower partition, but is prohibited from reading locations in the lower partition using the MOVC instruc-
tion. (Executing a MOVC instruction from the upper partition with a source address in the lower partition
will return indeterminate data.) Software running in the lower partition can access locations in both the
upper and lower partition without restriction.
The Value-added firmware should be placed in the lower partition. On reset, control is passed to the value-
added firmware via the reset vector. Once the value-added firmware completes its initial execution, it
branches to a predetermined location in the upper partition. If entry points are published, software running
in the upper partition may execute program code in the lower partition, but it cannot read or change the
contents of the lower partition. Parameters may be passed to the program code running in the lower parti-
tion either through the typical method of placing them on the stack or in registers before the call or by plac-
ing them in prescribed memory locations in the upper partition.
The FAL address is specified using the contents of the Flash Access Limit Register. The 8 MSBs of the 17-
bit FAL address are determined by the setting of the FLACL register. Thus, the FAL can be located on 512-
byte boundaries anywhere in program memory space. However, the 1024-byte erase sector size essen-
tially requires that a 1024 boundary be used. The contents of a non-initialized FLACL security byte are
0x00, thereby setting the FAL address to 0x00000 and allowing read access to all locations in program
memory space by default.
SFR Definition 15.1. FLACL: Flash Access Limit
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address:
SFR Address: 0xB7
SFR Page: F
Bits 7–0: FLACL: Flash Access Limit.
This register holds the most significant 8 bits of the 17-bit program memory read/write/erase
limit address. The lower 9 bits of the read/write/erase limit are always set to 0. A write to this
register sets the Flash Access Limit. This register can only be written once after any reset.
Any subsequent writes are ignored until the next reset. To fully protect all addresses
below this limit, bit 0 of FLACL should be set to ‘0’ to align the FAL on a 1024-byte
Flash page boundary.
206
Rev. 1.4
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C8051F130/1/2/3
15.2.1. Summary of Flash Security Options
There are three Flash access methods supported on the C8051F12x and C8051F13x devices; 1) Access-
ing Flash through the JTAG debug interface, 2) Accessing Flash from firmware residing below the Flash
Access Limit, and 3) Accessing Flash from firmware residing at or above the Flash Access Limit.
Accessing Flash through the JTAG debug interface:
1. The Read and Write/Erase Lock bytes (security bytes) provide security for Flash access
through the JTAG interface.
2. Any unlocked page may be read from, written to, or erased.
3. Locked pages cannot be read from, written to, or erased.
4. Reading the security bytes is always permitted.
5. Locking additional pages by writing to the security bytes is always permitted.
6. If the page containing the security bytes is unlocked, it can be directly erased. Doing so will
reset the security bytes and unlock all pages of Flash.
7. If the page containing the security bytes is locked, it cannot be directly erased. To unlock the
page containing the security bytes, a full JTAG device erase is required. A full JTAG
device erase will erase all Flash pages, including the page containing the security bytes and
the security bytes themselves.
8. The Reserved Area cannot be read from, written to, or erased at any time.
Accessing Flash from firmware residing below the Flash Access Limit:
1. The Read and Write/Erase Lock bytes (security bytes) do not restrict Flash access from user
firmware.
2. Any page of Flash except the page containing the security bytes may be read from, written to,
or erased.
3. The page containing the security bytes cannot be erased. Unlocking pages of Flash can
only be performed via the JTAG interface.
4. The page containing the security bytes may be read from or written to. Pages of Flash can be
locked from JTAG access by writing to the security bytes.
5. The Reserved Area cannot be read from, written to, or erased at any time.
Accessing Flash from firmware residing at or above the Flash Access Limit:
1. The Read and Write/Erase Lock bytes (security bytes) do not restrict Flash access from user
firmware.
2. Any page of Flash at or above the Flash Access Limit except the page containing the security
bytes may be read from, written to, or erased.
3. Any page of Flash below the Flash Access Limit cannot be read from, written to, or erased.
4. Code branches to locations below the Flash Access Limit are permitted.
5. The page containing the security bytes cannot be erased. Unlocking pages of Flash can
only be performed via the JTAG interface.
6. The page containing the security bytes may be read from or written to. Pages of Flash can be
locked from JTAG access by writing to the security bytes.
7. The Reserved Area cannot be read from, written to, or erased at any time.
Rev. 1.4
207
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 15.2. FLSCL: Flash Memory Control
R/W
-
R/W
-
R/W
Bit5
R/W
Bit4
R/W
R/W
R/W
R/W
FLWE
Bit0
Reset Value
10000000
SFR Address:
FLRT
Reserved Reserved Reserved
Bit7
Bit6
Bit3
Bit2
Bit1
SFR Address: 0xB7
SFR Page: 0
Bits 7–6: Unused.
Bits 5–4: FLRT: Flash Read Time.
These bits should be programmed to the smallest allowed value, according to the system
clock speed.
00: SYSCLK < 25 MHz.
01: SYSCLK < 50 MHz.
10: SYSCLK < 75 MHz.
11: SYSCLK < 100 MHz.
Bits 3–1: RESERVED. Read = 000b. Must Write 000b.
Bit 0:
FLWE: Flash Write/Erase Enable.
This bit must be set to allow Flash writes/erasures from user software.
0: Flash writes/erases disabled.
1: Flash writes/erases enabled.
Important Note: When changing the FLRT bits to a lower setting (e.g. when changing from a
value of 11b to 00b), cache reads, cache writes, and the prefetch engine should be
disabled using the CCH0CN register (see SFR Definition 16.1).
208
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 15.3. PSCTL: Program Store Read/Write Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
-
-
-
-
-
SFLE
PSEE
PSWE 00000000
SFR
Address:
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x8F
SFR Page: 0
Bits 7–3: UNUSED. Read = 00000b, Write = don't care.
Bit 2:
Bit 1:
Bit 0:
SFLE: Scratchpad Flash Memory Access Enable
When this bit is set, Flash MOVC reads and writes from user software are directed to the
two 128-byte Scratchpad Flash sectors. When SFLE is set to logic 1, Flash accesses out of
the address range 0x00-0xFF should not be attempted (with the exception of address
0x400, which can be used to simultaneously erase both Scratchpad areas). Reads/Writes
out of this range will yield undefined results.
0: Flash access from user software directed to the Program/Data Flash sector.
1: Flash access from user software directed to the two 128 byte Scratchpad sectors.
PSEE: Program Store Erase Enable.
Setting this bit allows an entire page of the Flash program memory to be erased provided
the PSWE bit is also set. After setting this bit, a write to Flash memory using the MOVX
instruction will erase the entire page that contains the location addressed by the MOVX
instruction. The value of the data byte written does not matter. Note: The Flash page con-
taining the Read Lock Byte and Write/Erase Lock Byte cannot be erased by software.
0: Flash program memory erasure disabled.
1: Flash program memory erasure enabled.
PSWE: Program Store Write Enable.
Setting this bit allows writing a byte of data to the Flash program memory using the MOVX
write instruction. The location must be erased prior to writing data.
0: Write to Flash program memory disabled. MOVX write operations target External RAM.
1: Write to Flash program memory enabled. MOVX write operations target Flash memory.
Rev. 1.4
209
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
NOTES:
210
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
16. Branch Target Cache
The C8051F12x and C8051F13x device families incorporate a 63x4 byte branch target cache with a 4-byte
prefetch engine. Because the access time of the Flash memory is 40 Flashns, and the minimum instruction
time is 10ns (C8051F120/1/2/3 and C8051F130/1/2/3) or 20 ns (C8051F124/5/6/7), the branch target
cache and prefetch engine are necessary for full-speed code execution. Instructions are read from Flash
memory four bytes at a time by the prefetch engine, and given to the CIP-51 processor core to execute.
When running linear code (code without any jumps or branches), the prefetch engine alone allows instruc-
tions to be executed at full speed. When a code branch occurs, a search is performed for the branch tar-
get (destination address) in the cache. If the branch target information is found in the cache (called a
“cache hit”), the instruction data is read from the cache and immediately returned to the CIP-51 with no
delay in code execution. If the branch target is not found in the cache (called a “cache miss”), the proces-
sor may be stalled for up to four clock cycles while the next set of four instructions is retrieved from Flash
memory. Each time a cache miss occurs, the requested instruction data is written to the cache if allowed
by the current cache settings. A data flow diagram of the interaction between the CIP-51 and the Branch
Target Cache and Prefetch Engine is shown in Figure 16.1.
Instruction
Data
CIP-51
FLASH
Memory
Prefetch
Engine
Branch Target
Cache
Instruction Address
Figure 16.1. Branch Target Cache Data Flow
16.1. Cache and Prefetch Operation
The branch target cache maintains two sets of memory locations: “slots” and “tags”. A slot is where the
cached instruction data from Flash is stored. Each slot holds four consecutive code bytes. A tag contains
the 15 most significant bits of the corresponding Flash address for each four-byte slot. Thus, instruction
data is always cached along four-byte boundaries in code space. A tag also contains a “valid bit”, which
indicates whether a cache location contains valid instruction data. A special cache location (called the lin-
ear tag and slot), is reserved for use by the prefetch engine. The cache organization is shown in
Figure 16.2. Each time a Flash read is requested, the address is compared with all valid cache tag loca-
tions (including the linear tag). If any of the tag locations match the requested address, the data from that
slot is immediately provided to the CIP-51. If the requested address matches a location that is currently
being read by the prefetch engine, the CIP-51 will be stalled until the read is complete. If a match is not
found, the current prefetch operation is abandoned, and a new prefetch operation is initiated for the
requested instruction data. When the prefetch operation is finished, the CIP-51 begins executing the
instructions that were retrieved, and the prefetch engine begins reading the next four-byte word from Flash
memory. If the newly-fetched data also meets the criteria necessary to be cached, it will be written to the
cache in the slot indicated by the current replacement algorithm.
Rev. 1.4
211
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
The replacement algorithm is selected with the Cache Algorithm bit, CHALGM (CCH0TN.3). When
CHALGM is cleared to ‘0’, the cache will use the rebound algorithm to replace cache locations. The
rebound algorithm replaces locations in order from the beginning of cache memory to the end, and then
from the end of cache memory to the beginning. When CHALGM is set to ‘1’, the cache will use the
pseudo-random algorithm to replace cache locations. The pseudo-random algorithm uses a pseudo-ran-
dom number to determine which cache location to replace. The cache can be manually emptied by writing
a ‘1’ to the CHFLUSH bit (CCH0CN.4).
Valid
Bit
Address
Data
Prefetch Data
VL
LINEAR TAG
LINEAR SLOT
V0
V1
V2
TAG 0
TAG 1
TAG 2
SLOT 0
SLOT 1
SLOT 2
Cache Data
V58
V59
V60
V61
V62
TAG 58
TAG 59
TAG 60
TAG 61
TAG 62
SLOT 58
SLOT 59
SLOT 60
SLOT 61
SLOT 62
A16
A2 A1 A0
0
0
1
1
0
1
0
1
Byte 0
Byte 1
Byte 2
Byte 3
TAG = 15 MSBs of Absolute FLASH Address
SLOT = 4 Instruction
Data Bytes
Figure 16.2. Branch Target Cache Organiztion
16.2. Cache and Prefetch Optimization
By default, the branch target cache is configured to provide code speed improvements for a broad range of
circumstances. In most applications, the cache control registers should be left in their reset states.
Sometimes it is desirable to optimize the execution time of a specific routine or critical timing loop. The
branch target cache includes options to exclude caching of certain types of data, as well as the ability to
pre-load and lock time-critical branch locations to optimize execution speed.
The most basic level of cache control is implemented with the Cache Miss Penalty Threshold bits, CHM-
STH (CCH0TN.1-0). If the processor is stalled during a prefetch operation for more clock cycles than the
number stored in CHMSTH, the requested data will be cached when it becomes available. The CHMSTH
bits are set to zero by default, meaning that any time the processor is stalled, the new data will be cached.
If, for example, CHMSTH is equal to 2, any cache miss causing a delay of 3 or 4 clock cycles will be
cached, while a cache miss causing a delay of 1-2 clock cycles will not be cached.
212
Rev. 1.4
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C8051F130/1/2/3
Certain types of instruction data or certain blocks of code can also be excluded from caching. The destina-
tions of RETI instructions are, by default, excluded from caching. To enable caching of RETI destinations,
the CHRETI bit (CCH0CN.3) can be set to ‘1’. It is generally not beneficial to cache RETI destinations
unless the same instruction is likely to be interrupted repeatedly (such as a code loop that is waiting for an
interrupt to happen). Instructions that are part of an interrupt service routine (ISR) can also be excluded
from caching. By default, ISR instructions are cached, but this can be disabled by clearing the CHISR bit
(CCH0CN.2) to ‘0’. The other information that can be explicitly excluded from caching are the data
returned by MOVC instructions. Clearing the CHMOV bit (CCH0CN.1) to ‘0’ will disable caching of MOVC
data. If MOVC caching is allowed, it can be restricted to only use slot 0 for the MOVC information (exclud-
ing cache push operations). The CHFIXM bit (CCH0TN.2) controls this behavior.
Further cache control can be implemented by disabling all cache writes. Cache writes can be disabled by
clearing the CHWREN bit (CCH0CN.7) to ‘0’. Although normal cache writes (such as those after a cache
miss) are disabled, data can still be written to the cache with a cache push operation. Disabling cache
writes can be used to prevent a non-critical section of code from changing the cache contents. Note that
regardless of the value of CHWREN, a Flash write or erase operation automatically removes the affected
bytes from the cache. Cache reads and the prefetch engine can also be individually disabled. Disabling
cache reads forces all instructions data to execute from Flash memory or from the prefetch engine. To dis-
able cache reads, the CHRDEN bit (CCH0CN.6) can be cleared to ‘0’. Note that when cache reads are
disabled, cache writes will still occur (if CHWREN is set to ‘1’). Disabling the prefetch engine is accom-
plished using the CHPFEN bit (CCH0CN.5). When this bit is cleared to ‘0’, the prefetch engine will be dis-
abled. If both CHPFEN and CHRDEN are ‘0’, code will execute at a fixed rate, as instructions become
available from the Flash memory.
Cache locations can also be pre-loaded and locked with time-critical branch destinations. For example, in
a system with an ISR that must respond as fast as possible, the entry point for the ISR can be locked into
a cache location to minimize the response latency of the ISR. Up to 61 locations can be locked into the
cache at one time. Instructions are locked into cache by enabling cache push operations with the
CHPUSH bit (CCH0LC.7). When CHPUSH is set to ‘1’, a MOVC instruction will cause the four-byte seg-
ment containing the data byte to be written to the cache slot location indicated by CHSLOT (CCH0LC.5-0).
CHSLOT is them decremented to point to the next lockable cache location. This process is called a cache
push operation. Cache locations that are above CHSLOT are “locked”, and cannot be changed by the pro-
cessor core, as shown in Figure 16.3. Cache locations can be unlocked by using a cache pop operation.
A cache pop is performed by writing a ‘1’ to the CHPOP bit (CCH0LC.6). When a cache pop is initiated,
the value of CHSLOT is incremented. This unlocks the most recently locked cache location, but does not
remove the information from the cache. Note that a cache pop should not be initiated if CHSLOT is equal
to 111110b. Doing so may have an adverse effect on cache performance. Important: Although locking
cache location 1 is not explicitly disabled by hardware, the entire cache will be unlocked when
CHSLOT is equal to 000000b. Therefore, cache locations 1 and 0 must remain unlocked at all
times.
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Lock Status
UNLOCKED
UNLOCKED
UNLOCKED
UNLOCKED
TAG 0
TAG 1
SLOT 0
SLOT 1
SLOT 2
Cache Push
Operations
Decrement
CHSLOT
TAG 2
TAG 57
TAG 58
TAG 59
TAG 60
TAG 61
TAG 62
SLOT 57
SLOT 58
SLOT 59
SLOT 60
SLOT 61
SLOT 62
UNLOCKED
UNLOCKED
LOCKED
CHSLOT = 58
LOCKED
Cache Pop
Operations
Increment
CHSLOT
LOCKED
LOCKED
Figure 16.3. Cache Lock Operation
214
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SFR Definition 16.1. CCH0CN: Cache Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
CHWREN CHRDEN CHPFEN CHFLSH CHRETI
CHISR CHMOVC CHBLKW 11100110
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xA1
SFR Page: F
Bit 7:
CHWREN: Cache Write Enable.
This bit enables the processor to write to the cache memory.
0: Cache contents are not allowed to change, except during Flash writes/erasures or cache
locks.
1: Writes to cache memory are allowed.
Bit 6:
Bit 5:
CHRDEN: Cache Read Enable.
This bit enables the processor to read instructions from the cache memory.
0: All instruction data comes from Flash memory or the prefetch engine.
1: Instruction data is obtained from cache (when available).
CHPFEN: Cache Prefetch Enable.
This bit enables the prefetch engine.
0: Prefetch engine is disabled.
1: Prefetch engine is enabled.
Bit 4:
Bit 3:
CHFLSH: Cache Flush.
When written to a ‘1’, this bit clears the cache contents. This bit always reads ‘0’.
CHRETI: Cache RETI Destination Enable.
This bit enables the destination of a RETI address to be cached.
0: Destinations of RETI instructions will not be cached.
1: RETI destinations will be cached.
Bit 2:
CHISR: Cache ISR Enable.
This bit allows instructions which are part of an Interrupt Service Rountine (ISR) to be
cached.
0: Instructions in ISRs will not be loaded into cache memory.
1: Instructions in ISRs can be cached.
Bit 1:
Bit 0:
CHMOVC: Cache MOVC Enable.
This bit allows data requested by a MOVC instruction to be loaded into the cache memory.
0: Data requested by MOVC instructions will not be cached.
1: Data requested by MOVC instructions will be loaded into cache memory.
CHBLKW: Block Write Enable.
This bit allows block writes to Flash memory from software.
0: Each byte of a software Flash write is written individually.
1: Flash bytes are written in groups of four (for code space writes) or two (for scratchpad
writes).
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SFR Definition 16.2. CCH0TN: Cache Tuning
R/W
Bit7
R/W
R/W
Bit5
R/W
Bit4
R/W
R/W
R/W
R/W
Bit0
Reset Value
CHMSCTL
Bit6
CHALGM CHFIXM
CHMSTH
Bit1
00000100
Bit3
Bit2
SFR Address: 0xA2
SFR Page: F
Bits 7–4: CHMSCTL: Cache Miss Penalty Accumulator (Bits 4–1).
These are bits 4-1 of the Cache Miss Penalty Accumulator. To read these bits, they must first
be latched by reading the CHMSCTH bits in the CCH0MA Register (See SFR Definition
16.4).
Bit 3:
Bit 2:
CHALGM: Cache Algorithm Select.
This bit selects the cache replacement algorithm.
0: Cache uses Rebound algorithm.
1: Cache uses Pseudo-random algorithm.
CHFIXM: Cache Fix MOVC Enable.
This bit forces MOVC writes to the cache memory to use slot 0.
0: MOVC data is written according to the current algorithm selected by the CHALGM bit.
1: MOVC data is always written to cache slot 0.
Bits 1–0: CHMSTH: Cache Miss Penalty Threshold.
These bits determine when missed instruction data will be cached.
If data takes longer than CHMSTH clocks to obtain, it will be cached.
SFR Definition 16.3. CCH0LC: Cache Lock Control
R/W
R/W
R
R
R
R
R
R
Reset Value
CHPUSH CHPOP
CHSLOT
00111110
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xA3
SFR Page: F
Bit 7:
CHPUSH: Cache Push Enable.
This bit enables cache push operations, which will lock information in cache slots using
MOVC instructions.
0: Cache push operations are disabled.
1: Cache push operations are enabled. When a MOVC read is executed, the requested 4-
byte segment containing the data is locked into the cache at the location indicated by
CHSLOT, and CHSLOT is decremented.
Note that no more than 61 cache slots should be locked at one time, since the entire cache
will be unlocked when CHSLOT is equal to 0.
Bit 6:
CHPOP: Cache Pop.
Writing a ‘1’ to this bit will increment CHSLOT and then unlock that location. This bit always
reads ‘0’. Note that Cache Pop operations should not be performed while CHSLOT =
111110b. “Pop”ing more Cache slots than have been “Push”ed will have indeterminate
results on the Cache performance.
Bits 5–0: CHSLOT: Cache Slot Pointer.
These read-only bits are the pointer into the cache lock stack. Locations above CHSLOT are
locked, and will not be changed by the processor, except when CHSLOT equals 0.
216
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SFR Definition 16.4. CCH0MA: Cache Miss Accumulator
R
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
CHMSCTH
Bit3
R/W
Bit2
R/W
Bit1
R/W
Reset Value
CHMSOV
Bit7
00000000
Bit0
SFR Address: 0x9A
SFR Page: F
Bit 7:
CHMSOV: Cache Miss Penalty Overflow.
This bit indicates when the Cache Miss Penalty Accumulator has overflowed since it was
last written.
0: The Cache Miss Penalty Accumulator has not overflowed since it was last written.
1: An overflow of the Cache Miss Penalty Accumulator has occurred since it was last written.
Bits 6–0: CHMSCTH: Cache Miss Penalty Accumulator (bits 11–5)
These are bits 11-5 of the Cache Miss Penalty Accumulator. The next four bits (bits 4-1) are
stored in CHMSCTL in the CCH0TN register.
The Cache Miss Penalty Accumulator is incremented every clock cycle that the processor is
delayed due to a cache miss. This is primarily used as a diagnostic feature, when optimizing
code for execution speed.
Writing to CHMSCTH clears the lower 5 bits of the Cache Miss Penalty Accumulator.
Reading from CHMSCTH returns the current value of CHMSTCH, and latches bits 4-1 into
CHMSTCL so that they can be read. Because bit 0 of the Cache Miss Penalty Accumulator
is not available, the Cumulative Miss Penalty is equal to 2 * (CCHMSTCH:CCHMSTCL).
SFR Definition 16.5. FLSTAT: Flash Status
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
-
-
-
-
-
-
-
FLBUSY 00000000
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0x88
SFR Page: F
Bit 7–1: Reserved.
Bit 0: FLBUSY: Flash Busy
This bit indicates when a Flash write or erase operation is in progress.
0: Flash is idle or reading.
1: Flash write/erase operation is currently in progress.
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NOTES:
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17. External Data Memory Interface and On-Chip XRAM
There are 8 kB of on-chip RAM mapped into the external data memory space (XRAM), as well as an Exter-
nal Data Memory Interface which can be used to access off-chip memories and memory-mapped devices
connected to the GPIO ports. The external memory space may be accessed using the external move
instruction (MOVX) and the data pointer (DPTR), or using the MOVX indirect addressing mode using R0 or
R1. If the MOVX instruction is used with an 8-bit address operand (such as @R1), then the high byte of the
16-bit address is provided by the External Memory Interface Control Register (EMI0CN, shown in SFR
Definition 17.1). Note: the MOVX instruction can also be used for writing to the Flash memory. See Sec-
tion “15. Flash Memory” on page 199 for details. The MOVX instruction accesses XRAM by default. The
EMIF can be configured to appear on the lower GPIO Ports (P0–P3) or the upper GPIO Ports (P4–P7).
17.1. Accessing XRAM
The XRAM memory space is accessed using the MOVX instruction. The MOVX instruction has two forms,
both of which use an indirect addressing method. The first method uses the Data Pointer, DPTR, a 16-bit
register which contains the effective address of the XRAM location to be read from or written to. The sec-
ond method uses R0 or R1 in combination with the EMI0CN register to generate the effective XRAM
address. Examples of both of these methods are given below.
17.1.1. 16-Bit MOVX Example
The 16-bit form of the MOVX instruction accesses the memory location pointed to by the contents of the
DPTR register. The following series of instructions reads the value of the byte at address 0x1234 into the
accumulator A:
MOV
MOVX
DPTR, #1234h
A, @DPTR
; load DPTR with 16-bit address to read (0x1234)
; load contents of 0x1234 into accumulator A
The above example uses the 16-bit immediate MOV instruction to set the contents of DPTR. Alternately,
the DPTR can be accessed through the SFR registers DPH, which contains the upper 8-bits of DPTR, and
DPL, which contains the lower 8-bits of DPTR.
17.1.2. 8-Bit MOVX Example
The 8-bit form of the MOVX instruction uses the contents of the EMI0CN SFR to determine the upper 8-bits
of the effective address to be accessed and the contents of R0 or R1 to determine the lower 8-bits of the
effective address to be accessed. The following series of instructions read the contents of the byte at
address 0x1234 into the accumulator A.
MOV
MOV
MOVX
EMI0CN, #12h
R0, #34h
a, @R0
; load high byte of address into EMI0CN
; load low byte of address into R0 (or R1)
; load contents of 0x1234 into accumulator A
17.2. Configuring the External Memory Interface
Configuring the External Memory Interface consists of five steps:
1. Select EMIF on Low Ports (P3, P2, P1, and P0) or High Ports (P7, P6, P5, and P4).
2. Configure the Output Modes of the port pins as either push-pull or open-drain (push-pull is
most common).
3. Configure Port latches to “park” the EMIF pins in a dormant state (usually by setting them to
logic ‘1’).
4. Select Multiplexed mode or Non-multiplexed mode.
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5. Select the memory mode (on-chip only, split mode without bank select, split mode with bank
select, or off-chip only).
6. Set up timing to interface with off-chip memory or peripherals.
Each of these five steps is explained in detail in the following sections. The Port selection, Multiplexed
mode selection, and Mode bits are located in the EMI0CF register shown in SFR Definition 17.2.
17.3. Port Selection and Configuration
The External Memory Interface can appear on Ports 3, 2, 1, and 0 (All Devices) or on Ports 7, 6, 5, and 4
(100-pin TQFP devices only), depending on the state of the PRTSEL bit (EMI0CF.5). If the lower Ports are
selected, the EMIFLE bit (XBR2.1) must be set to a ‘1’ so that the Crossbar will skip over P0.7 (/WR), P0.6
(/RD), and if multiplexed mode is selected P0.5 (ALE). For more information about the configuring the
Crossbar, see Section “18.1. Ports 0 through 3 and the Priority Crossbar Decoder” on page 238.
The External Memory Interface claims the associated Port pins for memory operations ONLY during the
execution of an off-chip MOVX instruction. Once the MOVX instruction has completed, control of the Port
pins reverts to the Port latches or to the Crossbar (on Ports 3, 2, 1, and 0). See Section “18. Port Input/
Output” on page 235 for more information about the Crossbar and Port operation and configuration. The
Port latches should be explicitly configured to ‘park’ the External Memory Interface pins in a dor-
mant state, most commonly by setting them to a logic 1.
During the execution of the MOVX instruction, the External Memory Interface will explicitly disable the driv-
ers on all Port pins that are acting as Inputs (Data[7:0] during a READ operation, for example). The Output
mode of the Port pins (whether the pin is configured as Open-Drain or Push-Pull) is unaffected by the
External Memory Interface operation, and remains controlled by the PnMDOUT registers. In most cases,
the output modes of all EMIF pins should be configured for push-pull mode. See“Configuring the Output
Modes of the Port Pins” on page 239.
SFR Definition 17.1. EMI0CN: External Memory Interface Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
PGSEL7 PGSEL6 PGSEL5 PGSEL4 PGSEL3 PGSEL2 PGSEL1 PGSEL0 00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0xA2
SFR Page: 0
Bits7–0: PGSEL[7:0]: XRAM Page Select Bits.
The XRAM Page Select Bits provide the high byte of the 16-bit external data memory
address when using an 8-bit MOVX command, effectively selecting a 256-byte page of
RAM.
0x00: 0x0000 to 0x00FF
0x01: 0x0100 to 0x01FF
...
0xFE: 0xFE00 to 0xFEFF
0xFF: 0xFF00 to 0xFFFF
220
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SFR Definition 17.2. EMI0CF: External Memory Configuration
R/W
-
R/W
-
R/W
PRTSEL
Bit5
R/W
EMD2
Bit4
R/W
EMD1
Bit3
R/W
EMD0
Bit2
R/W
EALE1
Bit1
R/W
Reset Value
EALE0 00000011
Bit0
Bit7
Bit6
SFR Address: 0xA3
SFR Page:
0
Bits7–6: Unused. Read = 00b. Write = don’t care.
Bit5:
PRTSEL: EMIF Port Select.
0: EMIF active on P0–P3.
1: EMIF active on P4–P7.
Bit4:
EMD2: EMIF Multiplex Mode Select.
0: EMIF operates in multiplexed address/data mode.
1: EMIF operates in non-multiplexed mode (separate address and data pins).
Bits3–2: EMD1-0: EMIF Operating Mode Select.
These bits control the operating mode of the External Memory Interface.
00: Internal Only: MOVX accesses on-chip XRAM only. All effective addresses alias to on-
chip memory space.
01: Split Mode without Bank Select: Accesses below the 8 k boundary are directed on-chip.
Accesses above the 8 k boundary are directed off-chip. 8-bit off-chip MOVX operations use
the current contents of the Address High port latches to resolve upper address byte. Note
that in order to access off-chip space, EMI0CN must be set to a page that is not contained in
the on-chip address space.
10: Split Mode with Bank Select: Accesses below the 8 k boundary are directed on-chip.
Accesses above the 8k boundary are directed off-chip. 8-bit off-chip MOVX operations use
the contents of EMI0CN to determine the high-byte of the address.
11: External Only: MOVX accesses off-chip XRAM only. On-chip XRAM is not visible to the
CPU.
Bits1–0: EALE1–0: ALE Pulse-Width Select Bits (only has effect when EMD2 = 0).
00: ALE high and ALE low pulse width = 1 SYSCLK cycle.
01: ALE high and ALE low pulse width = 2 SYSCLK cycles.
10: ALE high and ALE low pulse width = 3 SYSCLK cycles.
11: ALE high and ALE low pulse width = 4 SYSCLK cycles.
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17.4. Multiplexed and Non-multiplexed Selection
The External Memory Interface is capable of acting in a Multiplexed mode or a Non-multiplexed mode,
depending on the state of the EMD2 (EMI0CF.4) bit.
17.4.1. Multiplexed Configuration
In Multiplexed mode, the Data Bus and the lower 8-bits of the Address Bus share the same Port pins:
AD[7:0]. In this mode, an external latch (74HC373 or equivalent logic gate) is used to hold the lower 8-bits
of the RAM address. The external latch is controlled by the ALE (Address Latch Enable) signal, which is
driven by the External Memory Interface logic. An example of a Multiplexed Configuration is shown in
Figure 17.1.
In Multiplexed mode, the external MOVX operation can be broken into two phases delineated by the state
of the ALE signal. During the first phase, ALE is high and the lower 8-bits of the Address Bus are pre-
sented to AD[7:0]. During this phase, the address latch is configured such that the ‘Q’ outputs reflect the
states of the ‘D’ inputs. When ALE falls, signaling the beginning of the second phase, the address latch
outputs remain fixed and are no longer dependent on the latch inputs. Later in the second phase, the Data
Bus controls the state of the AD[7:0] port at the time /RD or /WR is asserted.
See Section “17.6.2. Multiplexed Mode” on page 230 for more information.
A[15:8]
ADDRESS BUS
74HC373
A[15:8]
A[7:0]
ALE
G
E
M
I
AD[7:0]
ADDRESS/DATA BUS
VDD
D
Q
64K X 8
SRAM
(Optional)
8
I/O[7:0]
F
CE
WE
OE
/WR
/RD
Figure 17.1. Multiplexed Configuration Example
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17.4.2. Non-multiplexed Configuration
In Non-multiplexed mode, the Data Bus and the Address Bus pins are not shared. An example of a Non-
multiplexed Configuration is shown in Figure 17.2. See Section “17.6.1. Non-multiplexed Mode” on
page 227 for more information about Non-multiplexed operation.
A[15:0]
ADDRESS BUS
A[15:0]
E
M
I
VDD
(Optional)
64K X 8
SRAM
I/O[7:0]
8
D[7:0]
DATA BUS
CE
WE
OE
F
/WR
/RD
Figure 17.2. Non-multiplexed Configuration Example
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17.5. Memory Mode Selection
The external data memory space can be configured in one of four modes, shown in Figure 17.3, based on
the EMIF Mode bits in the EMI0CF register (SFR Definition 17.2). These modes are summarized below.
More information about the different modes can be found in Section “SFR Definition 17.3. EMI0TC:
External Memory Timing Control” on page 226.
17.5.1. Internal XRAM Only
When EMI0CF.[3:2] are set to ‘00’, all MOVX instructions will target the internal XRAM space on the
device. Memory accesses to addresses beyond the populated space will wrap on 8 k boundaries. As an
example, the addresses 0x2000 and 0x4000 both evaluate to address 0x0000 in on-chip XRAM space.
•
•
8-bit MOVX operations use the contents of EMI0CN to determine the high-byte of the effective address
and R0 or R1 to determine the low-byte of the effective address.
16-bit MOVX operations use the contents of the 16-bit DPTR to determine the effective address.
17.5.2. Split Mode without Bank Select
When EMI0CF.[3:2] are set to ‘01’, the XRAM memory map is split into two areas, on-chip space and off-
chip space.
•
•
•
Effective addresses below the 8 k boundary will access on-chip XRAM space.
Effective addresses above the 8 k boundary will access off-chip space.
8-bit MOVX operations use the contents of EMI0CN to determine whether the memory access is on-
chip or off-chip. However, in the “No Bank Select” mode, an 8-bit MOVX operation will not drive the
upper 8-bits A[15:8] of the Address Bus during an off-chip access. This allows the user to manipulate
the upper address bits at will by setting the Port state directly via the port latches. This behavior is in
contrast with “Split Mode with Bank Select” described below. The lower 8-bits of the Address Bus
A[7:0] are driven, determined by R0 or R1.
•
16-bit MOVX operations use the contents of DPTR to determine whether the memory access is on-
chip or off-chip, and unlike 8-bit MOVX operations, the full 16-bits of the Address Bus A[15:0] are
driven during the off-chip transaction.
EMI0CF[3:2] = 00
EMI0CF[3:2] = 01
EMI0CF[3:2] = 10
EMI0CF[3:2] = 11
0xFFFF
0xFFFF
0xFFFF
0xFFFF
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM
Off-Chip
Memory
(No Bank Select)
Off-Chip
Memory
(Bank Select)
Off-Chip
Memory
On-Chip XRAM
On-Chip XRAM
0x0000
0x0000
0x0000
0x0000
Figure 17.3. EMIF Operating Modes
224
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17.5.3. Split Mode with Bank Select
When EMI0CF.[3:2] are set to ‘10’, the XRAM memory map is split into two areas, on-chip space and off-
chip space.
•
•
•
Effective addresses below the 8k boundary will access on-chip XRAM space.
Effective addresses above the 8k boundary will access off-chip space.
8-bit MOVX operations use the contents of EMI0CN to determine whether the memory access is on-
chip or off-chip. The upper 8-bits of the Address Bus A[15:8] are determined by EMI0CN, and the lower
8-bits of the Address Bus A[7:0] are determined by R0 or R1. All 16-bits of the Address Bus A[15:0] are
driven in “Bank Select” mode.
•
16-bit MOVX operations use the contents of DPTR to determine whether the memory access is on-
chip or off-chip, and the full 16-bits of the Address Bus A[15:0] are driven during the off-chip transac-
tion.
17.5.4. External Only
When EMI0CF[3:2] are set to ‘11’, all MOVX operations are directed to off-chip space. On-chip XRAM is
not visible to the CPU. This mode is useful for accessing off-chip memory located between 0x0000 and the
8k boundary.
•
8-bit MOVX operations ignore the contents of EMI0CN. The upper Address bits A[15:8] are not driven
(identical behavior to an off-chip access in “Split Mode without Bank Select” described above). This
allows the user to manipulate the upper address bits at will by setting the Port state directly. The lower
8-bits of the effective address A[7:0] are determined by the contents of R0 or R1.
•
16-bit MOVX operations use the contents of DPTR to determine the effective address A[15:0]. The full
16-bits of the Address Bus A[15:0] are driven during the off-chip transaction.
17.6. EMIF Timing
The timing parameters of the External Memory Interface can be configured to enable connection to
devices having different setup and hold time requirements. The Address Setup time, Address Hold time, /
RD and /WR strobe widths, and in multiplexed mode, the width of the ALE pulse are all programmable in
units of SYSCLK periods through EMI0TC, shown in SFR Definition 17.3, and EMI0CF[1:0].
The timing for an off-chip MOVX instruction can be calculated by adding 4 SYSCLK cycles to the timing
parameters defined by the EMI0TC register. Assuming non-multiplexed operation, the minimum execution
time for an off-chip XRAM operation is 5 SYSCLK cycles (1 SYSCLK for /RD or /WR pulse + 4 SYSCLKs).
For multiplexed operations, the Address Latch Enable signal will require a minimum of 2 additional SYS-
CLK cycles. Therefore, the minimum execution time for an off-chip XRAM operation in multiplexed mode
is 7 SYSCLK cycles (2 for /ALE + 1 for /RD or /WR + 4). The programmable setup and hold times default
to the maximum delay settings after a reset. Table 17.1 lists the ac parameters for the External Memory
Interface, and Figure 17.4 through Figure 17.9 show the timing diagrams for the different External Memory
Interface modes and MOVX operations.
Rev. 1.4
225
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 17.3. EMI0TC: External Memory Timing Control
R/W
EAS1
Bit7
R/W
EAS0
Bit6
R/W
ERW3
Bit5
R/W
EWR2
Bit4
R/W
EWR1
Bit3
R/W
EWR0
Bit2
R/W
EAH1
Bit1
R/W
EAH0
Bit0
Reset Value
11111111
SFR Address: 0xA1
SFR Page: 0
Bits7–6: EAS1–0: EMIF Address Setup Time Bits.
00: Address setup time = 0 SYSCLK cycles.
01: Address setup time = 1 SYSCLK cycle.
10: Address setup time = 2 SYSCLK cycles.
11: Address setup time = 3 SYSCLK cycles.
Bits5–2: EWR3–0: EMIF /WR and /RD Pulse-Width Control Bits.
0000: /WR and /RD pulse width = 1 SYSCLK cycle.
0001: /WR and /RD pulse width = 2 SYSCLK cycles.
0010: /WR and /RD pulse width = 3 SYSCLK cycles.
0011: /WR and /RD pulse width = 4 SYSCLK cycles.
0100: /WR and /RD pulse width = 5 SYSCLK cycles.
0101: /WR and /RD pulse width = 6 SYSCLK cycles.
0110: /WR and /RD pulse width = 7 SYSCLK cycles.
0111: /WR and /RD pulse width = 8 SYSCLK cycles.
1000: /WR and /RD pulse width = 9 SYSCLK cycles.
1001: /WR and /RD pulse width = 10 SYSCLK cycles.
1010: /WR and /RD pulse width = 11 SYSCLK cycles.
1011: /WR and /RD pulse width = 12 SYSCLK cycles.
1100: /WR and /RD pulse width = 13 SYSCLK cycles.
1101: /WR and /RD pulse width = 14 SYSCLK cycles.
1110: /WR and /RD pulse width = 15 SYSCLK cycles.
1111: /WR and /RD pulse width = 16 SYSCLK cycles.
Bits1–0: EAH1–0: EMIF Address Hold Time Bits.
00: Address hold time = 0 SYSCLK cycles.
01: Address hold time = 1 SYSCLK cycle.
10: Address hold time = 2 SYSCLK cycles.
11: Address hold time = 3 SYSCLK cycles.
226
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
17.6.1. Non-multiplexed Mode
17.6.1.1.16-bit MOVX: EMI0CF[4:2] = ‘101’, ‘110’, or ‘111’
Nonmuxed 16-bit WRITE
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
P1/P5
P2/P6
P3/P7
EMIF ADDRESS (8 MSBs) from DPH
EMIF ADDRESS (8 LSBs) from DPL
EMIF WRITE DATA
P1/P5
P2/P6
P3/P7
T
T
WDS
WDH
T
T
T
ACS
ACW
ACH
/WR
/RD
P0.7/P4.7
P0.6/P4.6
P0.7/P4.7
P0.6/P4.6
Nonmuxed 16-bit READ
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
P1/P5
P2/P6
P3/P7
EMIF ADDRESS (8 MSBs) from DPH
EMIF ADDRESS (8 LSBs) from DPL
EMIF READ DATA
P1/P5
P2/P6
P3/P7
T
T
RDS
RDH
T
T
T
ACS
ACW
ACH
/RD
P0.6/P4.6
P0.7/P4.7
P0.6/P4.6
P0.7/P4.7
/WR
Figure 17.4. Non-multiplexed 16-bit MOVX Timing
Rev. 1.4
227
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
17.6.1.2.8-bit MOVX without Bank Select: EMI0CF[4:2] = ‘101’ or ‘111’.
Nonmuxed 8-bit WRITE without Bank Select
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
P1/P5
P2/P6
P3/P7
EMIF ADDRESS (8 LSBs) from R0 or R1
EMIF WRITE DATA
P2/P6
P3/P7
T
T
WDS
WDH
T
T
T
ACS
ACW
ACH
/WR
/RD
P0.7/P4.7
P0.6/P4.6
P0.7/P4.7
P0.6/P4.6
Nonmuxed 8-bit READ without Bank Select
P1/P5
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
P2/P6
P3/P7
EMIF ADDRESS (8 LSBs) from R0 or R1
EMIF READ DATA
P2/P6
P3/P7
T
T
RDS
RDH
T
T
T
ACS
ACW
ACH
/RD
P0.6/P4.6
P0.7/P4.7
P0.6/P4.6
P0.7/P4.7
/WR
Figure 17.5. Non-multiplexed 8-bit MOVX without Bank Select Timing
228
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
17.6.1.3.8-bit MOVX with Bank Select: EMI0CF[4:2] = ‘110’.
Nonmuxed 8-bit WRITE with Bank Select
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
P1/P5
P2/P6
P3/P7
EMIF ADDRESS (8 MSBs) from EMI0CN
EMIF ADDRESS (8 LSBs) from R0 or R1
EMIF WRITE DATA
P1/P5
P2/P6
P3/P7
T
T
WDS
WDH
T
T
T
ACS
ACW
ACH
/WR
/RD
P0.7/P4.7
P0.6/P4.6
P0.7/P4.7
P0.6/P4.6
Nonmuxed 8-bit READ with Bank Select
EMIF ADDRESS (8 MSBs) from EMI0CN
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
P1/P5
P2/P6
P3/P7
P1/P5
P2/P6
P3/P7
EMIF ADDRESS (8 LSBs) from R0 or R1
EMIF READ DATA
T
T
RDS
RDH
T
T
T
ACS
ACW
ACH
/RD
P0.6/P4.6
P0.7/P4.7
P0.6/P4.6
P0.7/P4.7
/WR
Figure 17.6. Non-multiplexed 8-bit MOVX with Bank Select Timing
Rev. 1.4
229
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
17.6.2. Multiplexed Mode
17.6.2.1.16-bit MOVX: EMI0CF[4:2] = ‘001’, ‘010’, or ‘011’
Muxed 16-bit WRITE
ADDR[15:8]
AD[7:0]
P2/P6
P3/P7
EMIF ADDRESS (8 MSBs) from DPH
P2/P6
P3/P7
EMIF ADDRESS (8 LSBs) from
DPL
EMIF WRITE DATA
T
T
ALEL
ALEH
ALE
P0.5/P4.5
P0.5/P4.5
T
T
WDS
WDH
T
T
T
ACS
ACW
ACH
/WR
/RD
P0.7/P4.7
P0.6/P4.6
P0.7/P4.7
P0.6/P4.6
Muxed 16-bit READ
ADDR[15:8]
AD[7:0]
P2/P6
P3/P7
EMIF ADDRESS (8 MSBs) from DPH
P2/P6
P3/P7
EMIF ADDRESS (8 LSBs) from
DPL
EMIF READ DATA
T
T
ALEH
ALEL
T
T
RDH
RDS
ALE
P0.5/P4.5
P0.5/P4.5
T
T
T
ACH
ACS
ACW
/RD
P0.6/P4.6
P0.7/P4.7
P0.6/P4.6
P0.7/P4.7
/WR
Figure 17.7. Multiplexed 16-bit MOVX Timing
230
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
17.6.2.2.8-bit MOVX without Bank Select: EMI0CF[4:2] = ‘001’ or ‘011’.
Muxed 8-bit WRITE Without Bank Select
P2/P6
ADDR[15:8]
AD[7:0]
EMIF ADDRESS (8 LSBs) from
R0 or R1
P3/P7
EMIF WRITE DATA
P3/P7
T
T
ALEH
ALEL
ALE
P0.5/P4.5
P0.5/P4.5
T
T
WDS
WDH
T
T
T
ACS
ACW
ACH
/WR
/RD
P0.7/P4.7
P0.6/P4.6
P0.7/P4.7
P0.6/P4.6
Muxed 8-bit READ Without Bank Select
P2/P6
ADDR[15:8]
AD[7:0]
EMIF ADDRESS (8 LSBs) from
R0 or R1
P3/P7
EMIF READ DATA
P3/P7
T
T
ALEL
ALEH
T
T
RDH
RDS
ALE
P0.5/P4.5
P0.5/P4.5
T
T
T
ACS
ACW
ACH
/RD
P0.6/P4.6
P0.7/P4.7
P0.6/P4.6
P0.7/P4.7
/WR
Figure 17.8. Multiplexed 8-bit MOVX without Bank Select Timing
Rev. 1.4
231
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
17.6.2.3.8-bit MOVX with Bank Select: EMI0CF[4:2] = ‘010’.
Muxed 8-bit WRITE with Bank Select
ADDR[15:8]
AD[7:0]
P2/P6
P3/P7
EMIF ADDRESS (8 MSBs) from EMI0CN
P2/P6
P3/P7
EMIF ADDRESS (8 LSBs) from
R0 or R1
EMIF WRITE DATA
T
T
ALEH
ALEL
ALE
P0.5/P4.5
P0.5/P4.5
T
T
WDS
WDH
T
T
T
ACS
ACW
ACH
/WR
/RD
P0.7/P4.7
P0.6/P4.6
P0.7/P4.7
P0.6/P4.6
Muxed 8-bit READ with Bank Select
EMIF ADDRESS (8 MSBs) from EMI0CN
ADDR[15:8]
AD[7:0]
P2/P6
P3/P7
P2/P6
P3/P7
EMIF ADDRESS (8 LSBs) from
R0 or R1
EMIF READ DATA
T
T
ALEL
ALEH
T
T
RDS
RDH
ALE
P0.5/P4.5
P0.5/P4.5
T
T
T
ACH
ACS
ACW
/RD
P0.6/P4.6
P0.7/P4.7
P0.6/P4.6
P0.7/P4.7
/WR
Figure 17.9. Multiplexed 8-bit MOVX with Bank Select Timing
232
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 17.1. AC Parameters for External Memory Interface
Parameter
Description
Min
Max
Units
T
Address/Control Setup Time
0
3 x TSYSCLK
ns
ACS
T
Address/Control Pulse Width
Address/Control Hold Time
Address Latch Enable High Time
Address Latch Enable Low Time
Write Data Setup Time
1 x TSYSCLK 16 x TSYSCLK
ns
ns
ns
ns
ns
ns
ns
ns
ACW
T
0
3 x TSYSCLK
4 x TSYSCLK
4 x TSYSCLK
ACH
T
1 x TSYSCLK
1 x TSYSCLK
ALEH
T
ALEL
T
1 x TSYSCLK 19 x TSYSCLK
WDS
T
Write Data Hold Time
0
20
0
3 x TSYSCLK
WDH
T
Read Data Setup Time
—
—
RDS
T
Read Data Hold Time
RDH
Note: TSYSCLK is equal to one period of the device system clock (SYSCLK).
Rev. 1.4
233
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
NOTES:
234
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
18. Port Input/Output
The devices are fully integrated mixed-signal System on a Chip MCUs with 64 digital I/O pins (100-pin
TQFP packaging) or 32 digital I/O pins (64-pin TQFP packaging), organized as 8-bit Ports. All ports are
both bit- and byte-addressable through their corresponding Port Data registers. All Port pins are 5 V-toler-
ant, and all support configurable Open-Drain or Push-Pull output modes and weak pullups. A block dia-
gram of the Port I/O cell is shown in Figure 18.1. Complete Electrical Specifications for the Port I/O pins
are given in Table 18.1.
/WEAK-PULLUP
VDD
VDD
PUSH-PULL
/PORT-OUTENABLE
(WEAK)
PORT
PAD
PORT-OUTPUT
DGND
Analog Select
(Ports 1, 2, and 3)
ANALOG INPUT
PORT-INPUT
Figure 18.1. Port I/O Cell Block Diagram
Rev. 1.4
235
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 18.1. Port I/O DC Electrical Characteristics
VDD = 2.7 to 3.6 V, –40 to +85 °C unless otherwise specified.
Parameter
Conditions
Min
Typ
Max
Units
IOH = -3 mA, Port I/O Push-Pull
V
DD – 0.7
V
Output High Voltage
IOH = -10 µA, Port I/O Push-Pull
OH = -10 mA, Port I/O Push-Pull
VDD – 0.1
(VOH
)
I
VDD – 0.8
IOL = 8.5 mA
0.6
0.1
V
Output Low Voltage
(VOL
IOL = 10 µA
OL = 25 mA
)
I
1.0
Input High Voltage (VIH)
Input Low Voltage (VIL)
0.7 x VDD
0.3 x
VDD
DGND < Port Pin < VDD, Pin Tri-state
Weak Pullup Off
Weak Pullup On
µA
pF
Input Leakage Current
Input Capacitance
± 1
10
5
236
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
A wide array of digital resources is available through the four lower I/O Ports: P0, P1, P2, and P3. Each of
the pins on P0, P1, P2, and P3, can be defined as a General-Purpose I/O (GPIO) pin or can be controlled
by a digital peripheral or function (like UART0 or /INT1 for example), as shown in Figure 18.2. The system
designer controls which digital functions are assigned pins, limited only by the number of pins available.
This resource assignment flexibility is achieved through the use of a Priority Crossbar Decoder. Note that
the state of a Port I/O pin can always be read from its associated Data register regardless of whether that
pin has been assigned to a digital peripheral or behaves as GPIO. The Port pins on Port 1 can be used as
Analog Inputs to ADC2.
An External Memory Interface which is active during the execution of an off-chip MOVX instruction can be
active on either the lower Ports or the upper Ports. See Section “17. External Data Memory Interface
and On-Chip XRAM” on page 219 for more information about the External Memory Interface.
XBR0, XBR1,
XBR2, P1MDIN
Registers
P0MDOUT, P1MDOUT,
P2MDOUT, P3MDOUT
Registers
2
4
Highest
Priority
UART0
SPI
External
Pins
2
2
7
SMBus
UART1
PCA
Priority
Decoder
P0.0
Highest
Priority
P0
I/O
Cells
8
8
8
8
P0.7
2
Comptr.
Outputs
Digital
Crossbar
P1.0
P1.7
P1
I/O
Cells
T0, T1,
T2, T2EX,
T4,T4EX
/INT0,
8
P2.0
P2.7
/INT1
P2
I/O
Cells
Lowest
Priority
/SYSCLK divided by 1,2,4, or 8
2
CNVSTR0/2
P3.0
P3.7
P3
I/O
Cells
8
Lowest
Priority
P0
(P0.0-P0.7)
8
P1
P2
P3
(P1.0-P1.7)
8
To External
Memory
Interface
(EMIF)
Port
Latches
To ADC2 Input
(‘F12x Only)
(P2.0-P2.7)
8
(P3.0-P3.7)
Figure 18.2. Port I/O Functional Block Diagram
Rev. 1.4
237
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
18.1. Ports 0 through 3 and the Priority Crossbar Decoder
The Priority Crossbar Decoder, or “Crossbar”, allocates and assigns Port pins on Port 0 through Port 3 to
the digital peripherals (UARTs, SMBus, PCA, Timers, etc.) on the device using a priority order. The Port
pins are allocated in order starting with P0.0 and continue through P3.7 if necessary. The digital peripher-
als are assigned Port pins in a priority order which is listed in Figure 18.3, with UART0 having the highest
priority and CNVSTR2 having the lowest priority.
18.1.1. Crossbar Pin Assignment and Allocation
The Crossbar assigns Port pins to a peripheral if the corresponding enable bits of the peripheral are set to
a logic 1 in the Crossbar configuration registers XBR0, XBR1, and XBR2, shown in SFR Definition 18.1,
SFR Definition 18.2, and SFR Definition 18.3. For example, if the UART0EN bit (XBR0.2) is set to a
logic 1, the TX0 and RX0 pins will be mapped to P0.0 and P0.1 respectively.
P0
P1
P2
P3
Crossbar Register Bits
UART0EN: XBR0.2
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
PIN I/O
TX0
●
RX0
●
●
SCK
●
●
●
●
●
●
●
MISO
MOSI
NSS
●
SPI0EN: XBR0.1
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
NSS is not assigned to a port pin when the SPI is placed in 3-wire mode
SDA
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
SMB0EN: XBR0.0
UART1EN: XBR2.2
SCL
●
●
●
●
TX1
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
RX1
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
CEX0
CEX1
CEX2
CEX3
CEX4
CEX5
ECI
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
PCA0ME: XBR0.[5:3]
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
ECI0E: XBR0.6
CP0E: XBR0.7
CP1E: XBR1.0
T0E: XBR1.1
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
CP0
●
●
●
●
●
●
●
●
●
●
●
●
●
CP1
●
●
●
●
●
●
●
●
●
●
●
●
T0
●
●
●
●
●
●
●
●
●
●
●
/INT0
T1
INT0E: XBR1.2
T1E: XBR1.3
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
/INT1
T2
INT1E: XBR1.4
T2E: XBR1.5
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
T2EX
T4
T2EXE: XBR1.6
T4E: XBR2.3
●
●
●
●
●
●
●
●
●
●
●
T4EX
/SYSCLK
CNVSTR0
CNVSTR2
T4EXE: XBR2.4
SYSCKE: XBR1.7
CNVSTE0: XBR2.0
CNVSTE2: XBR2.5
●
●
●
●
●
●
●
●
●
●
AIN2 Inputs/Non-muxed Addr H Muxed Addr H/Non-muxed Addr L Muxed Data/Non-muxed Data
Figure 18.3. Priority Crossbar Decode Table (EMIFLE = 0; P1MDIN = 0xFF)
Because UART0 has the highest priority, its pins will always be mapped to P0.0 and P0.1 when UART0EN
is set to a logic 1. If a digital peripheral’s enable bits are not set to a logic 1, then its ports are not accessi-
ble at the Port pins of the device. Also note that the Crossbar assigns pins to all associated functions when
a serial communication peripheral is selected (i.e. SMBus, SPI, UART). It would be impossible, for exam-
238
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
ple, to assign TX0 to a Port pin without assigning RX0 as well. Each combination of enabled peripherals
results in a unique device pinout.
All Port pins on Ports 0 through 3 that are not allocated by the Crossbar can be accessed as General-Pur-
pose I/O (GPIO) pins by reading and writing the associated Port Data registers (See SFR Definition 18.4,
SFR Definition 18.6, SFR Definition 18.9, and SFR Definition 18.11), a set of SFR’s which are both byte-
and bit-addressable. The output states of Port pins that are allocated by the Crossbar are controlled by the
digital peripheral that is mapped to those pins. Writes to the Port Data registers (or associated Port bits)
will have no effect on the states of these pins.
A Read of a Port Data register (or Port bit) will always return the logic state present at the pin itself, regard-
less of whether the Crossbar has allocated the pin for peripheral use or not. An exception to this occurs
during the execution of a read-modify-write instruction (ANL, ORL, XRL, CPL, INC, DEC, DJNZ, JBC,
CLR, SETB, and the bitwise MOV write operation). During the read cycle of the read-modify-write instruc-
tion, it is the contents of the Port Data register, not the state of the Port pins themselves, which is read.
Note that at clock rates above 50 MHz, when a pin is written and then immediately read (i.e. a write instruc-
tion followed immediately by a read instruction), the propagation delay of the port drivers may cause the
read instruction to return the previous logic level of the pin.
Because the Crossbar registers affect the pinout of the peripherals of the device, they are typically config-
ured in the initialization code of the system before the peripherals themselves are configured. Once config-
ured, the Crossbar registers are typically left alone.
Once the Crossbar registers have been properly configured, the Crossbar is enabled by setting XBARE
(XBR2.4) to a logic 1. Until XBARE is set to a logic 1, the output drivers on Ports 0 through 3 are
explicitly disabled in order to prevent possible contention on the Port pins while the Crossbar reg-
isters and other registers which can affect the device pinout are being written.
The output drivers on Crossbar-assigned input signals (like RX0, for example) are explicitly disabled; thus
the values of the Port Data registers and the PnMDOUT registers have no effect on the states of these
pins.
18.1.2. Configuring the Output Modes of the Port Pins
The output drivers on Ports 0 through 3 remain disabled until the Crossbar is enabled by setting XBARE
(XBR2.4) to a logic 1.
The output mode of each port pin can be configured to be either Open-Drain or Push-Pull. In the Push-Pull
configuration, writing a logic 0 to the associated bit in the Port Data register will cause the Port pin to be
driven to GND, and writing a logic 1 will cause the Port pin to be driven to VDD. In the Open-Drain configu-
ration, writing a logic 0 to the associated bit in the Port Data register will cause the Port pin to be driven to
GND, and a logic 1 will cause the Port pin to assume a high-impedance state. The Open-Drain configura-
tion is useful to prevent contention between devices in systems where the Port pin participates in a shared
interconnection in which multiple outputs are connected to the same physical wire (like the SDA signal on
an SMBus connection).
The output modes of the Port pins on Ports 0 through 3 are determined by the bits in the associated
PnMDOUT registers (See SFR Definition 18.5, SFR Definition 18.8, SFR Definition 18.10, and SFR Defini-
tion 18.12). For example, a logic 1 in P3MDOUT.7 will configure the output mode of P3.7 to Push-Pull; a
logic 0 in P3MDOUT.7 will configure the output mode of P3.7 to Open-Drain. All Port pins default to Open-
Drain output.
Rev. 1.4
239
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
The PnMDOUT registers control the output modes of the port pins regardless of whether the Crossbar has
allocated the Port pin for a digital peripheral or not. The exceptions to this rule are: the Port pins connected
to SDA, SCL, RX0 (if UART0 is in Mode 0), and RX1 (if UART1 is in Mode 0) are always configured as
Open-Drain outputs, regardless of the settings of the associated bits in the PnMDOUT registers.
18.1.3. Configuring Port Pins as Digital Inputs
A Port pin is configured as a digital input by setting its output mode to “Open-Drain” and writing a logic 1 to
the associated bit in the Port Data register. For example, P3.7 is configured as a digital input by setting
P3MDOUT.7 to a logic 0 and P3.7 to a logic 1.
If the Port pin has been assigned to a digital peripheral by the Crossbar and that pin functions as an input
(for example RX0, the UART0 receive pin), then the output drivers on that pin are automatically disabled.
18.1.4. Weak Pullups
By default, each Port pin has an internal weak pullup device enabled which provides a resistive connection
(about 100 k) between the pin and VDD. The weak pullup devices can be globally disabled by writing a
logic 1 to the Weak Pullup Disable bit, (WEAKPUD, XBR2.7). The weak pullup is automatically deactivated
on any pin that is driving a logic 0; that is, an output pin will not contend with its own pullup device. The
weak pullup device can also be explicitly disabled on any Port 1 pin by configuring the pin as an Analog
Input, as described below.
18.1.5. Configuring Port 1 Pins as Analog Inputs
The pins on Port 1 can serve as analog inputs to the ADC2 analog MUX on the C8051F12x devices. A Port
pin is configured as an Analog Input by writing a logic 0 to the associated bit in the PnMDIN registers. All
Port pins default to a Digital Input mode. Configuring a Port pin as an analog input:
1. Disables the digital input path from the pin. This prevents additional power supply current from
being drawn when the voltage at the pin is near VDD / 2. A read of the Port Data bit will return
a logic 0 regardless of the voltage at the Port pin.
2. Disables the weak pullup device on the pin.
3. Causes the Crossbar to “skip over” the pin when allocating Port pins for digital peripherals.
Note that the output drivers on a pin configured as an Analog Input are not explicitly disabled. Therefore,
the associated P1MDOUT bits of pins configured as Analog Inputs should explicitly be set to logic 0
(Open-Drain output mode), and the associated Port1 Data bits should be set to logic 1 (high-impedance).
Also note that it is not required to configure a Port pin as an Analog Input in order to use it as an input to
ADC2, however, it is strongly recommended. See the ADC2 section in this datasheet for further informa-
tion.
240
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
18.1.6. External Memory Interface Pin Assignments
If the External Memory Interface (EMIF) is enabled on the Low ports (Ports 0 through 3), EMIFLE (XBR2.5)
should be set to a logic 1 so that the Crossbar will not assign peripherals to P0.7 (/WR), P0.6 (/RD), and if
the External Memory Interface is in Multiplexed mode, P0.5 (ALE). Figure 18.4 shows an example Cross-
bar Decode Table with EMIFLE=1 and the EMIF in Multiplexed mode. Figure 18.5 shows an example
Crossbar Decode Table with EMIFLE=1 and the EMIF in Non-multiplexed mode.
If the External Memory Interface is enabled on the Low ports and an off-chip MOVX operation occurs, the
External Memory Interface will control the output states of the affected Port pins during the execution
phase of the MOVX instruction, regardless of the settings of the Crossbar registers or the Port Data regis-
ters. The output configuration of the Port pins is not affected by the EMIF operation, except that Read
operations will explicitly disable the output drivers on the Data Bus. See Section “17. External Data Mem-
ory Interface and On-Chip XRAM” on page 219 for more information about the External Memory Inter-
face.
P0
P1
P2
P3
Crossbar Register Bits
UART0EN: XBR0.2
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
PIN I/O
TX0
●
RX0
●
●
SCK
●
●
●
●
●
●
●
MISO
MOSI
NSS
●
SPI0EN: XBR0.1
●
NSS is not assigned to a port pin when the SPI is placed in 3-wire mode
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
SDA
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
SMB0EN: XBR0.0
UART1EN: XBR2.2
SCL
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
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●
●
●
●
TX1
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
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●
●
●
RX1
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
CEX0
CEX1
CEX2
CEX3
CEX4
CEX5
ECI
●
●
●
●
●
●
●
●
●
●
●
●
●
●
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●
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●
●
●
●
●
●
PCA0ME: XBR0.[5:3]
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
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●
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●
●
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●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
ECI0E: XBR0.6
CP0E: XBR0.7
CP1E: XBR1.0
T0E: XBR1.1
●
●
●
●
●
●
●
●
●
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●
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●
●
CP0
●
●
●
●
●
●
●
●
●
●
●
●
●
CP1
●
●
●
●
●
●
●
●
●
●
●
●
T0
●
●
●
●
●
●
●
●
●
●
●
/INT0
T1
INT0E: XBR1.2
T1E: XBR1.3
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
/INT1
T2
INT1E: XBR1.4
T2E: XBR1.5
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
T2EX
T4
T2EXE: XBR1.6
T4E: XBR2.3
●
●
●
●
●
●
●
●
●
●
●
T4EX
/SYSCLK
CNVSTR0
CNVSTR2
T4EXE: XBR2.4
SYSCKE: XBR1.7
CNVSTE0: XBR2.0
CNVSTE2: XBR2.5
●
●
●
●
●
●
●
●
●
AIN2 Inputs/Non-muxed Addr H Muxed Addr H/Non-muxed Addr L Muxed Data/Non-muxed Data
Figure 18.4. Priority Crossbar Decode Table (EMIFLE = 1; EMIF in Multiplexed
Mode; P1MDIN = 0xFF)
Rev. 1.4
241
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
P0
P1
P2
P3
Crossbar Register Bits
UART0EN: XBR0.2
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
PIN I/O
TX0
●
RX0
●
●
SCK
●
●
●
●
●
●
●
MISO
MOSI
NSS
●
SPI0EN: XBR0.1
●
NSS is not assigned to a port pin when the SPI is placed in 3-wire mode
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
SDA
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
SMB0EN: XBR0.0
UART1EN: XBR2.2
SCL
●
●
●
●
●
●
●
●
●
●
●
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●
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TX1
●
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RX1
●
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●
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●
●
●
CEX0
CEX1
CEX2
CEX3
CEX4
CEX5
ECI
●
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●
PCA0ME: XBR0.[5:3]
●
●
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●
ECI0E: XBR0.6
CP0E: XBR0.7
CP1E: XBR1.0
T0E: XBR1.1
●
●
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●
CP0
●
●
●
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●
●
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●
●
●
●
●
●
CP1
●
●
●
●
●
●
●
●
●
●
●
●
T0
●
●
●
●
●
●
●
●
●
●
●
/INT0
T1
INT0E: XBR1.2
T1E: XBR1.3
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
/INT1
T2
INT1E: XBR1.4
T2E: XBR1.5
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
T2EX
T4
T2EXE: XBR1.6
T4E: XBR2.3
●
●
●
●
●
●
●
●
●
●
●
T4EX
/SYSCLK
CNVSTR0
CNVSTR2
T4EXE: XBR2.4
SYSCKE: XBR1.7
CNVSTE0: XBR2.0
CNVSTE2: XBR2.5
●
●
●
●
●
●
●
●
●
●
AIN2 Inputs/Non-muxed Addr H Muxed Addr H/Non-muxed Addr L Muxed Data/Non-muxed Data
Figure 18.5. Priority Crossbar Decode Table (EMIFLE = 1; EMIF in Non-Multiplexed
Mode; P1MDIN = 0xFF)
242
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
18.1.7. Crossbar Pin Assignment Example
In this example (Figure 18.6), we configure the Crossbar to allocate Port pins for UART0, the SMBus,
UART1, /INT0, and /INT1 (8 pins total). Additionally, we configure the External Memory Interface to oper-
ate in Multiplexed mode and to appear on the Low ports. Further, we configure P1.2, P1.3, and P1.4 for
Analog Input mode so that the voltages at these pins can be measured by ADC2. The configuration steps
are as follows:
1. XBR0, XBR1, and XBR2 are set such that UART0EN = 1, SMB0EN = 1, INT0E = 1,
INT1E = 1, and EMIFLE = 1. Thus: XBR0 = 0x05, XBR1 = 0x14, and XBR2 = 0x02.
2. We configure the External Memory Interface to use Multiplexed mode and to appear on the
Low ports. PRTSEL = 0, EMD2 = 0.
3. We configure the desired Port 1 pins to Analog Input mode by setting P1MDIN to 0xE3
(P1.4, P1.3, and P1.2 are Analog Inputs, so their associated P1MDIN bits are set to logic 0).
4. We enable the Crossbar by setting XBARE = 1: XBR2 = 0x42.
-
-
UART0 has the highest priority, so P0.0 is assigned to TX0, and P0.1 is assigned to RX0.
The SMBus is next in priority order, so P0.2 is assigned to SDA, and P0.3 is assigned to
SCL.
-
UART1 is next in priority order, so P0.4 is assigned to TX1. Because the External Memory
Interface is selected on the lower Ports, EMIFLE = 1, which causes the Crossbar to skip
P0.6 (/RD) and P0.7 (/WR). Because the External Memory Interface is configured in Multi-
plexed mode, the Crossbar will also skip P0.5 (ALE). RX1 is assigned to the next non-
skipped pin, which in this case is P1.0.
-
-
/INT0 is next in priority order, so it is assigned to P1.1.
P1MDIN is set to 0xE3, which configures P1.2, P1.3, and P1.4 as Analog Inputs, causing
the Crossbar to skip these pins.
-
-
/INT1 is next in priority order, so it is assigned to the next non-skipped pin, which is P1.5.
The External Memory Interface will drive Ports 2 and 3 (denoted by red dots in
Figure 18.6) during the execution of an off-chip MOVX instruction.
5. We set the UART0 TX pin (TX0, P0.0) and UART1 TX pin (TX1, P0.4) outputs to Push-Pull by
setting P0MDOUT = 0x11.
6. We configure all EMIF-controlled pins to push-pull output mode by setting P0MDOUT |= 0xE0;
P2MDOUT = 0xFF; P3MDOUT = 0xFF.
7. We explicitly disable the output drivers on the 3 Analog Input pins by setting P1MDOUT =
0x00 (configure outputs to Open-Drain) and P1 = 0xFF (a logic 1 selects the high-impedance
state).
Rev. 1.4
243
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
P0
P1
P2
P3
Crossbar Register Bits
UART0EN: XBR0.2
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
PIN I/O
TX0
●
RX0
●
●
SCK
●
●
●
●
●
●
●
MISO
MOSI
NSS
●
SPI0EN: XBR0.1
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
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●
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●
●
●
●
SDA
●
●
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●
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●
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●
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●
●
●
●
●
●
●
SMB0EN: XBR0.0
UART1EN: XBR2.2
SCL
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
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●
●
●
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●
TX1
●
●
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●
●
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●
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●
RX1
●
●
●
●
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●
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●
●
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●
●
●
●
●
●
●
●
●
●
●
CEX0
CEX1
CEX2
CEX3
CEX4
CEX5
ECI
●
●
●
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●
PCA0ME: XBR0.[5:3]
●
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●
ECI0E: XBR0.6
CP0E: XBR0.7
CP1E: XBR1.0
T0E: XBR1.1
●
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CP0
●
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●
CP1
●
●
●
●
●
●
●
●
●
●
●
●
T0
●
●
●
●
●
●
●
●
●
●
●
/INT0
T1
INT0E: XBR1.2
T1E: XBR1.3
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
/INT1
T2
INT1E: XBR1.4
T2E: XBR1.5
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
T2EX
T4
T2EXE: XBR1.6
T4E: XBR2.3
●
●
●
●
●
●
●
●
●
●
●
T4EX
/SYSCLK
CNVSTR0
CNVSTR2
T4EXE: XBR2.4
SYSCKE: XBR1.7
CNVSTE0: XBR2.0
CNVSTE2: XBR2.5
AIN2 Inputs/Non-muxed Addr H Muxed Addr H/Non-muxed Addr L Muxed Data/Non-muxed Data
(EMIFLE = 1; EMIF in Multiplexed Mode; P1MDIN = 0xE3;
XBR0 = 0x05; XBR1 = 0x14; XBR2 = 0x42)
Figure 18.6. Crossbar Example
244
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 18.1. XBR0: Port I/O Crossbar Register 0
R/W
CP0E
Bit7
R/W
ECI0E
Bit6
R/W
Bit5
R/W
PCA0ME
Bit4
R/W
Bit3
R/W
R/W
R/W
Reset Value
UART0EN SPI0EN SMB0EN 00000000
Bit2
Bit1
Bit0
SFR Address: 0xE1
SFR Page: F
Bit7:
CP0E: Comparator 0 Output Enable Bit.
0: CP0 unavailable at Port pin.
1: CP0 routed to Port pin.
Bit6:
ECI0E: PCA0 External Counter Input Enable Bit.
0: PCA0 External Counter Input unavailable at Port pin.
1: PCA0 External Counter Input (ECI0) routed to Port pin.
Bits5–3: PCA0ME: PCA0 Module I/O Enable Bits.
000: All PCA0 I/O unavailable at port pins.
001: CEX0 routed to port pin.
010: CEX0, CEX1 routed to 2 port pins.
011: CEX0, CEX1, and CEX2 routed to 3 port pins.
100: CEX0, CEX1, CEX2, and CEX3 routed to 4 port pins.
101: CEX0, CEX1, CEX2, CEX3, and CEX4 routed to 5 port pins.
110: CEX0, CEX1, CEX2, CEX3, CEX4, and CEX5 routed to 6 port pins.
UART0EN: UART0 I/O Enable Bit.
0: UART0 I/O unavailable at Port pins.
1: UART0 TX routed to P0.0, and RX routed to P0.1.
SPI0EN: SPI0 Bus I/O Enable Bit.
Bit2:
Bit1:
0: SPI0 I/O unavailable at Port pins.
1: SPI0 SCK, MISO, MOSI, and NSS routed to 4 Port pins. Note that the NSS signal is not
assigned to a port pin if the SPI is in 3-wire mode. See Section “17. External Data Memory
Interface and On-Chip XRAM” on page 219 for more information.
SMB0EN: SMBus0 Bus I/O Enable Bit.
Bit0:
0: SMBus0 I/O unavailable at Port pins.
1: SMBus0 SDA and SCL routed to 2 Port pins.
Rev. 1.4
245
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 18.2. XBR1: Port I/O Crossbar Register 1
R/W
R/W
R/W
T2E
Bit5
R/W
INT1E
Bit4
R/W
T1E
Bit3
R/W
INT0E
Bit2
R/W
T0E
Bit1
R/W
Reset Value
SYSCKE T2EXE
CP1E 00000000
Bit0
Bit7
Bit6
SFR Address: 0xE2
SFR Page: F
Bit7:
SYSCKE: /SYSCLK Output Enable Bit.
0: /SYSCLK unavailable at Port pin.
1: /SYSCLK (divided by 1, 2, 4, or 8) routed to Port pin. divide factor is determined by the
CLKDIV1–0 bits in register CLKSEL (See Section “14. Oscillators” on page 185).
T2EXE: T2EX Input Enable Bit.
0: T2EX unavailable at Port pin.
1: T2EX routed to Port pin.
T2E: T2 Input Enable Bit.
0: T2 unavailable at Port pin.
1: T2 routed to Port pin.
INT1E: /INT1 Input Enable Bit.
0: /INT1 unavailable at Port pin.
1: /INT1 routed to Port pin.
T1E: T1 Input Enable Bit.
0: T1 unavailable at Port pin.
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
1: T1 routed to Port pin.
INT0E: /INT0 Input Enable Bit.
0: /INT0 unavailable at Port pin.
1: /INT0 routed to Port pin.
T0E: T0 Input Enable Bit.
0: T0 unavailable at Port pin.
1: T0 routed to Port pin.
CP1E: CP1 Output Enable Bit.
0: CP1 unavailable at Port pin.
1: CP1 routed to Port pin.
246
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 18.3. XBR2: Port I/O Crossbar Register 2
R/W
R/W
R/W
R/W
R/W
T4E
Bit3
R/W
R/W
R/W
Reset Value
WEAKPUD XBARE CNVST2E T4EXE
UART1E EMIFLE CNVST0E 00000000
Bit7
Bit6
Bit5
Bit4
Bit2
Bit1
Bit0
SFR Address: 0xE3
SFR Page: F
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
WEAKPUD: Weak Pullup Disable Bit.
0: Weak pullups globally enabled.
1: Weak pullups globally disabled.
XBARE: Crossbar Enable Bit.
0: Crossbar disabled. All pins on Ports 0, 1, 2, and 3, are forced to Input mode.
1: Crossbar enabled.
CNVST2E: External Convert Start 2 Input Enable Bit.
0: CNVSTR2 unavailable at Port pin.
1: CNVSTR2 routed to Port pin.
T4EXE: T4EX Input Enable Bit.
0: T4EX unavailable at Port pin.
1: T4EX routed to Port pin.
T4E: T4 Input Enable Bit.
0: T4 unavailable at Port pin.
1: T4 routed to Port pin.
UART1E: UART1 I/O Enable Bit.
0: UART1 I/O unavailable at Port pins.
1: UART1 TX and RX routed to 2 Port pins.
EMIFLE: External Memory Interface Low-Port Enable Bit.
0: P0.7, P0.6, and P0.5 functions are determined by the Crossbar or the Port latches.
1: If EMI0CF.4 = ‘0’ (External Memory Interface is in Multiplexed mode)
P0.7 (/WR), P0.6 (/RD), and P0.5 (ALE) are ‘skipped’ by the Crossbar and their
output states are determined by the Port latches and the External Memory Interface.
1: If EMI0CF.4 = ‘1’ (External Memory Interface is in Non-multiplexed mode)
P0.7 (/WR) and P0.6 (/RD) are ‘skipped’ by the Crossbar and their output states are
determined by the Port latches and the External Memory Interface.
CNVST0E: ADC0 External Convert Start Input Enable Bit.
0: CNVST0 for ADC0 unavailable at Port pin.
Bit0:
1: CNVST0 for ADC0 routed to Port pin.
Rev. 1.4
247
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 18.4. P0: Port0 Data
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
P0.7
P0.6
P0.5
P0.4
P0.3
P0.2
P0.1
P0.0
11111111
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0x80
SFR Page: All Pages
Bits7–0: P0.[7:0]: Port0 Output Latch Bits.
(Write - Output appears on I/O pins per XBR0, XBR1, and XBR2 Registers)
0: Logic Low Output.
1: Logic High Output (open if corresponding P0MDOUT.n bit = 0).
(Read - Regardless of XBR0, XBR1, and XBR2 Register settings).
0: P0.n pin is logic low.
1: P0.n pin is logic high.
Note:
P0.7 (/WR), P0.6 (/RD), and P0.5 (ALE) can be driven by the External Data Memory Interface.
See Section “17. External Data Memory Interface and On-Chip XRAM” on page 219 for
more information. See also SFR Definition 18.3 for information about configuring the Crossbar
for External Memory accesses.
SFR Definition 18.5. P0MDOUT: Port0 Output Mode
R/W
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Reset Value
00000000
Bit7
Bit0
SFR Address: 0xA4
SFR Page: F
Bits7–0: P0MDOUT.[7:0]: Port0 Output Mode Bits.
0: Port Pin output mode is configured as Open-Drain.
1: Port Pin output mode is configured as Push-Pull.
Note:
SDA, SCL, and RX0 (when UART0 is in Mode 0) and RX1 (when UART1 is in Mode 0) are
always configured as Open-Drain when they appear on Port pins.
248
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 18.6. P1: Port1 Data
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
P1.7
P1.6
P1.5
P1.4
P1.3
P1.2
P1.1
P1.0
11111111
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0x90
SFR Page: All Pages
Bits7–0: P1.[7:0]: Port1 Output Latch Bits.
(Write - Output appears on I/O pins per XBR0, XBR1, and XBR2 Registers)
0: Logic Low Output.
1: Logic High Output (open if corresponding P1MDOUT.n bit = 0).
(Read - Regardless of XBR0, XBR1, and XBR2 Register settings).
0: P1.n pin is logic low.
1: P1.n pin is logic high.
Notes:
1.On C8051F12x devices, P1.[7:0] can be configured as inputs to ADC2 as AIN2.[7:0], in which
case they are ‘skipped’ by the Crossbar assignment process and their digital input paths are
disabled, depending on P1MDIN (See SFR Definition 18.7). Note that in analog mode, the
output mode of the pin is determined by the Port 1 latch and P1MDOUT (SFR Definition 18.8).
See Section “7. ADC2 (8-Bit ADC, C8051F12x Only)” on page 91 for more information
about ADC2.
2. P1.[7:0] can be driven by the External Data Memory Interface (as Address[15:8] in Non-
multiplexed mode). See Section “17. External Data Memory Interface and On-Chip
XRAM” on page 219 for more information about the External Memory Interface.
SFR Definition 18.7. P1MDIN: Port1 Input Mode
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
11111111
SFR Address: 0xAD
SFR Page: F
Bits7–0: P1MDIN.[7:0]: Port 1 Input Mode Bits.
0: Port Pin is configured in Analog Input mode. The digital input path is disabled (a read from
the Port bit will always return ‘0’). The weak pullup on the pin is disabled.
1: Port Pin is configured in Digital Input mode. A read from the Port bit will return the logic
level at the Pin. When configured as a digital input, the state of the weak pullup for the port
pin is determined by the WEAKPUD bit (XBR2.7, see SFR Definition 18.3).
Rev. 1.4
249
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 18.8. P1MDOUT: Port1 Output Mode
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Reset Value
00000000
Bit0
SFR Address: 0xA5
SFR Page: F
Bits7–0: P1MDOUT.[7:0]: Port1 Output Mode Bits.
0: Port Pin output mode is configured as Open-Drain.
1: Port Pin output mode is configured as Push-Pull.
Note:
SDA, SCL, and RX0 (when UART0 is in Mode 0) and RX1 (when UART1 is in Mode 0) are
always configured as Open-Drain when they appear on Port pins.
SFR Definition 18.9. P2: Port2 Data
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
P2.7
P2.6
P2.5
P2.4
P2.3
P2.2
P2.1
P2.0
11111111
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR
Address:
SFR Page:
0xA0
All Pages
Bits7–0: P2.[7:0]: Port2 Output Latch Bits.
(Write - Output appears on I/O pins per XBR0, XBR1, and XBR2 Registers)
0: Logic Low Output.
1: Logic High Output (open if corresponding P2MDOUT.n bit = 0).
(Read - Regardless of XBR0, XBR1, and XBR2 Register settings).
0: P2.n pin is logic low.
1: P2.n pin is logic high.
Note:
P2.[7:0] can be driven by the External Data Memory Interface (as Address[15:8] in Multiplexed
mode, or as Address[7:0] in Non-multiplexed mode). See Section “17. External Data
Memory Interface and On-Chip XRAM” on page 219 for more information about the
External Memory Interface.
250
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 18.10. P2MDOUT: Port2 Output Mode
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Reset Value
00000000
Bit0
SFR Address: 0xA6
SFR Page: F
Bits7–0: P2MDOUT.[7:0]: Port2 Output Mode Bits.
0: Port Pin output mode is configured as Open-Drain.
1: Port Pin output mode is configured as Push-Pull.
Note:
SDA, SCL, and RX0 (when UART0 is in Mode 0) and RX1 (when UART1 is in Mode 0) are
always configured as Open-Drain when they appear on Port pins.
SFR Definition 18.11. P3: Port3 Data
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
P3.7
P3.6
P3.5
P3.4
P3.3
P3.2
P3.1
P3.0
11111111
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0xB0
SFR Page: All Pages
Bits7–0: P3.[7:0]: Port3 Output Latch Bits.
(Write - Output appears on I/O pins per XBR0, XBR1, and XBR2 Registers)
0: Logic Low Output.
1: Logic High Output (open if corresponding P3MDOUT.n bit = 0).
(Read - Regardless of XBR0, XBR1, and XBR2 Register settings).
0: P3.n pin is logic low.
1: P3.n pin is logic high.
Note:
P3.[7:0] can be driven by the External Data Memory Interface (as AD[7:0] in Multiplexed
mode, or as D[7:0] in Non-multiplexed mode). See Section “17. External Data Memory
Interface and On-Chip XRAM” on page 219 for more information about the External Memory
Interface.
Rev. 1.4
251
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 18.12. P3MDOUT: Port3 Output Mode
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Reset Value
00000000
Bit0
SFR Address: 0xA7
SFR Page: F
Bits7–0: P3MDOUT.[7:0]: Port3 Output Mode Bits.
0: Port Pin output mode is configured as Open-Drain.
1: Port Pin output mode is configured as Push-Pull.
18.2. Ports 4 through 7 (100-pin TQFP devices only)
All Port pins on Ports 4 through 7 can be accessed as General-Purpose I/O (GPIO) pins by reading and
writing the associated Port Data registers (See SFR Definition 18.13, SFR Definition 18.15, SFR Definition
18.17, and SFR Definition 18.19), a set of SFR’s which are both bit and byte-addressable. Note also that
the Port 4, 5, 6, and 7 registers are located on SFR Page F. The SFRPAGE register must be set to 0x0F to
access these Port registers.
A Read of a Port Data register (or Port bit) will always return the logic state present at the pin itself, regard-
less of whether the Crossbar has allocated the pin for peripheral use or not. An exception to this occurs
during the execution of a read-modify-write instruction (ANL, ORL, XRL, CPL, INC, DEC, DJNZ, JBC,
CLR, SETB, and the bitwise MOV write operation). During the read cycle of the read-modify-write instruc-
tion, it is the contents of the Port Data register, not the state of the Port pins themselves, which is read.
Note that at clock rates above 50 MHz, when a pin is written and then immediately read (i.e. a write instruc-
tion followed immediately by a read instruction), the propagation delay of the port drivers may cause the
read instruction to return the previous logic level of the pin.
18.2.1. Configuring Ports which are not Pinned Out
Although P4, P5, P6, and P7 are not brought out to pins on the 64-pin TQFP devices, the Port Data regis-
ters are still present and can be used by software. Because the digital input paths also remain active, it is
recommended that these pins not be left in a ‘floating’ state in order to avoid unnecessary power dissipa-
tion arising from the inputs floating to non-valid logic levels. This condition can be prevented by any of the
following:
1. Leave the weak pullup devices enabled by setting WEAKPUD (XBR2.7) to a logic 0.
2. Configure the output modes of P4, P5, P6, and P7 to “Push-Pull” by writing PnMDOUT = 0xFF.
3. Force the output states of P4, P5, P6, and P7 to logic 0 by writing zeros to the Port Data regis-
ters: P4 = 0x00, P5 = 0x00, P6= 0x00, and P7 = 0x00.
18.2.2. Configuring the Output Modes of the Port Pins
The output mode of each port pin can be configured to be either Open-Drain or Push-Pull. In the Push-Pull
configuration, a logic 0 in the associated bit in the Port Data register will cause the Port pin to be driven to
GND, and a logic 1 will cause the Port pin to be driven to VDD. In the Open-Drain configuration, a logic 0 in
the associated bit in the Port Data register will cause the Port pin to be driven to GND, and a logic 1 will
cause the Port pin to assume a high-impedance state. The Open-Drain configuration is useful to prevent
contention between devices in systems where the Port pin participates in a shared interconnection in
which multiple outputs are connected to the same physical wire.
252
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
The output modes of the Port pins on Ports 4 through 7 are determined by the bits in their respective
PnMDOUT Output Mode Registers. Each bit in PnMDOUT controls the output mode of its corresponding
port pin (see SFR Definition 18.14, SFR Definition 18.16, SFR Definition 18.18, and SFR Definition 18.20).
For example, to place Port pin 4.3 in push-pull mode (digital output), set P4MDOUT.3 to logic 1. All port
pins default to open-drain mode upon device reset.
18.2.3. Configuring Port Pins as Digital Inputs
A Port pin is configured as a digital input by setting its output mode to “Open-Drain” and writing a logic 1 to
the associated bit in the Port Data register. For example, P7.7 is configured as a digital input by setting
P7MDOUT.7 to a logic 0 and P7.7 to a logic 1.
18.2.4. Weak Pullups
By default, each Port pin has an internal weak pullup device enabled which provides a resistive connection
(about 100 k) between the pin and VDD. The weak pullup devices can be globally disabled by writing a
logic 1 to the Weak Pullup Disable bit, (WEAKPUD, XBR2.7). The weak pullup is automatically deactivated
on any pin that is driving a logic 0; that is, an output pin will not contend with its own pullup device.
18.2.5. External Memory Interface
If the External Memory Interface (EMIF) is enabled on the High ports (Ports 4 through 7), EMIFLE
(XBR2.5) should be set to a logic 0.
If the External Memory Interface is enabled on the High ports and an off-chip MOVX operation occurs, the
External Memory Interface will control the output states of the affected Port pins during the execution
phase of the MOVX instruction, regardless of the settings of the Port Data registers. The output configura-
tion of the Port pins is not affected by the EMIF operation, except that Read operations will explicitly dis-
able the output drivers on the Data Bus during the MOVX execution. See Section “17. External Data
Memory Interface and On-Chip XRAM” on page 219 for more information about the External Memory
Interface.
Rev. 1.4
253
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 18.13. P4: Port4 Data
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
P4.7
P4.6
P4.5
P4.4
P4.3
P4.2
P4.1
P4.0
11111111
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0xC8
SFR Page: F
Bits7–0: P4.[7:0]: Port4 Output Latch Bits.
Write - Output appears on I/O pins.
0: Logic Low Output.
1: Logic High Output (Open-Drain if corresponding P4MDOUT.n bit = 0). See SFR Definition
18.14.
Read - Returns states of I/O pins.
0: P4.n pin is logic low.
1: P4.n pin is logic high.
Note:
P4.7 (/WR), P4.6 (/RD), and P4.5 (ALE) can be driven by the External Data Memory Interface.
See Section “17. External Data Memory Interface and On-Chip XRAM” on page 219 for
more information.
SFR Definition 18.14. P4MDOUT: Port4 Output Mode
R/W
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Reset Value
00000000
Bit7
Bit0
SFR Address: 0x9C
SFR Page: F
Bits7–0: P4MDOUT.[7:0]: Port4 Output Mode Bits.
0: Port Pin output mode is configured as Open-Drain.
1: Port Pin output mode is configured as Push-Pull.
254
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 18.15. P5: Port5 Data
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
P5.7
P5.6
P5.5
P5.4
P5.3
P5.2
P5.1
P5.0
11111111
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0xD8
SFR Page: F
Bits7–0: P5.[7:0]: Port5 Output Latch Bits.
Write - Output appears on I/O pins.
0: Logic Low Output.
1: Logic High Output (Open-Drain if corresponding P5MDOUT bit = 0). See SFR Definition
18.16.
Read - Returns states of I/O pins.
0: P5.n pin is logic low.
1: P5.n pin is logic high.
Note:
P5.[7:0] can be driven by the External Data Memory Interface (as Address[15:8] in Non-
multiplexed mode). See Section “17. External Data Memory Interface and On-Chip
XRAM” on page 219 for more information about the External Memory Interface.
SFR Definition 18.16. P5MDOUT: Port5 Output Mode
R/W
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Reset Value
00000000
Bit7
Bit0
SFR Address: 0x9D
SFR Page: F
Bits7–0: P5MDOUT.[7:0]: Port5 Output Mode Bits.
0: Port Pin output mode is configured as Open-Drain.
1: Port Pin output mode is configured as Push-Pull.
Rev. 1.4
255
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 18.17. P6: Port6 Data
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
P6.7
P6.6
P6.5
P6.4
P6.3
P6.2
P6.1
P6.0
11111111
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0xE8
SFR Page: F
Bits7–0: P6.[7:0]: Port6 Output Latch Bits.
Write - Output appears on I/O pins.
0: Logic Low Output.
1: Logic High Output (Open-Drain if corresponding P6MDOUT bit = 0). See SFR Definition
18.18.
Read - Returns states of I/O pins.
0: P6.n pin is logic low.
1: P6.n pin is logic high.
Note:
P6.[7:0] can be driven by the External Data Memory Interface (as Address[15:8] in Multiplexed
mode, or as Address[7:0] in Non-multiplexed mode). See Section “17. External Data
Memory Interface and On-Chip XRAM” on page 219 for more information about the
External Memory Interface.
SFR Definition 18.18. P6MDOUT: Port6 Output Mode
R/W
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Reset Value
00000000
Bit7
Bit0
SFR Address: 0x9E
SFR Page: F
Bits7–0: P6MDOUT.[7:0]: Port6 Output Mode Bits.
0: Port Pin output mode is configured as Open-Drain.
1: Port Pin output mode is configured as Push-Pull.
256
Rev. 1.4
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C8051F130/1/2/3
SFR Definition 18.19. P7: Port7 Data
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
P7.7
P7.6
P7.5
P7.4
P7.3
P7.2
P7.1
P7.0
11111111
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0xF8
SFR Page: F
Bits7–0: P7.[7:0]: Port7 Output Latch Bits.
Write - Output appears on I/O pins.
0: Logic Low Output.
1: Logic High Output (Open-Drain if corresponding P7MDOUT bit = 0). See SFR Definition
18.20.
Read - Returns states of I/O pins.
0: P7.n pin is logic low.
1: P7.n pin is logic high.
Note:
P7.[7:0] can be driven by the External Data Memory Interface (as AD[7:0] in Multiplexed
mode, or as D[7:0] in Non-multiplexed mode). See Section “17. External Data Memory
Interface and On-Chip XRAM” on page 219 for more information about the External Memory
Interface.
SFR Definition 18.20. P7MDOUT: Port7 Output Mode
R/W
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Reset Value
00000000
Bit7
Bit0
SFR Address: 0x9F
SFR Page: F
Bits7–0: P7MDOUT.[7:0]: Port7 Output Mode Bits.
0: Port Pin output mode is configured as Open-Drain.
1: Port Pin output mode is configured as Push-Pull.
Rev. 1.4
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C8051F130/1/2/3
NOTES:
258
Rev. 1.4
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C8051F130/1/2/3
19. System Management Bus / I2C Bus (SMBus0)
The SMBus0 I/O interface is a two-wire, bi-directional serial bus. SMBus0 is compliant with the System
Management Bus Specification, version 1.1, and compatible with the I2C serial bus. Reads and writes to
the interface by the system controller are byte oriented with the SMBus0 interface autonomously control-
ling the serial transfer of the data. A method of extending the clock-low duration is available to accommo-
date devices with different speed capabilities on the same bus.
SMBus0 may operate as a master and/or slave, and may function on a bus with multiple masters. SMBus0
provides control of SDA (serial data), SCL (serial clock) generation and synchronization, arbitration logic,
and START/STOP control and generation.
SFR Bus
SMB0CN
SMB0STA
SMB0CR
B
U
S
Y
E
N
S
M
B
S
T
A
S
T
O
S
I
A
A
F
T
E
T
O
E
S
T
A
7
S
T
A
6
S
T
A
5
S
T
A
4
S
T
A
3
S
T
A
2
S
T
A
1
S
T
A
0
C
R
7
C
R
6
C
R
5
C
R
4
C
R
3
C
R
2
C
R
1
C
R
0
Clock Divide
Logic
SYSCLK
SCL
FILTER
SMBUS CONTROL LOGIC
Arbitration
SMBUS
IRQ
Interrupt
Request
SCL Synchronization
Status Generation
SCL Generation (Master Mode)
IRQ Generation
SCL
Control
N
SDA
Control
Data Path
Control
C
R
O
S
S
B
A
R
Port I/O
B
A
B
A
0000000b
7 MSBs
8
7
SMB0DAT
7 6 5 4 3 2 1 0
SDA
FILTER
8
8
1
0
S
L
V
6
S
L
V
5
S
L
V
4
S
L
V
3
S
L
V
2
S
L
V
1
S
L
V
0
N
G
C
Read
SMB0DAT
Write to
SMB0DAT
SMB0ADR
SFR Bus
Figure 19.1. SMBus0 Block Diagram
Rev. 1.4
259
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Figure 19.2 shows a typical SMBus configuration. The SMBus0 interface will work at any voltage between
3.0 and 5.0 V and different devices on the bus may operate at different voltage levels. The bi-directional
SCL (serial clock) and SDA (serial data) lines must be connected to a positive power supply voltage
through a pullup resistor or similar circuit. Every device connected to the bus must have an open-drain or
open-collector output for both the SCL and SDA lines, so that both are pulled high when the bus is free.
The maximum number of devices on the bus is limited only by the requirement that the rise and fall times
on the bus will not exceed 300 ns and 1000 ns, respectively.
VDD = 5V
VDD = 3V
VDD = 5V
VDD = 3V
Master
Device
Slave
Device 1
Slave
Device 2
SDA
SCL
Figure 19.2. Typical SMBus Configuration
19.1. Supporting Documents
It is assumed the reader is familiar with or has access to the following supporting documents:
1. The I2C-bus and how to use it (including specifications), Philips Semiconductor.
2. The I2C-Bus Specification -- Version 2.0, Philips Semiconductor.
3. System Management Bus Specification -- Version 1.1, SBS Implementers Forum.
19.2. SMBus Protocol
Two types of data transfers are possible: data transfers from a master transmitter to an addressed slave
receiver (WRITE), and data transfers from an addressed slave transmitter to a master receiver (READ).
The master device initiates both types of data transfers and provides the serial clock pulses on SCL. Note:
multiple master devices on the same bus are supported. If two or more masters attempt to initiate a data
transfer simultaneously, an arbitration scheme is employed with a single master always winning the arbitra-
tion. Note that it is not necessary to specify one device as the master in a system; any device who trans-
mits a START and a slave address becomes the master for that transfer.
A typical SMBus transaction consists of a START condition followed by an address byte (Bits7–1: 7-bit
slave address; Bit0: R/W direction bit), one or more bytes of data, and a STOP condition. Each byte that is
received (by a master or slave) must be acknowledged (ACK) with a low SDA during a high SCL (see
Figure 19.3). If the receiving device does not ACK, the transmitting device will read a “not acknowledge”
(NACK), which is a high SDA during a high SCL.
The direction bit (R/W) occupies the least-significant bit position of the address. The direction bit is set to
logic 1 to indicate a "READ" operation and cleared to logic 0 to indicate a "WRITE" operation.
260
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All transactions are initiated by a master, with one or more addressed slave devices as the target. The
master generates the START condition and then transmits the slave address and direction bit. If the trans-
action is a WRITE operation from the master to the slave, the master transmits the data a byte at a time
waiting for an ACK from the slave at the end of each byte. For READ operations, the slave transmits the
data waiting for an ACK from the master at the end of each byte. At the end of the data transfer, the master
generates a STOP condition to terminate the transaction and free the bus. Figure 19.3 illustrates a typical
SMBus transaction.
SCL
SDA
SLA6
SLA5-0
R/W
D7
D6-0
START
Slave Address + R/W
ACK
Data Byte
NACK
STOP
Figure 19.3. SMBus Transaction
19.2.1. Arbitration
A master may start a transfer only if the bus is free. The bus is free after a STOP condition or after the SCL
and SDA lines remain high for a specified time (see Section 19.2.4). In the event that two or more devices
attempt to begin a transfer at the same time, an arbitration scheme is employed to force one master to give
up the bus. The master devices continue transmitting until one attempts a HIGH while the other transmits a
LOW. Since the bus is open-drain, the bus will be pulled LOW. The master attempting the HIGH will detect
a LOW SDA and give up the bus. The winning master continues its transmission without interruption; the
losing master becomes a slave and receives the rest of the transfer. This arbitration scheme is non-
destructive: one device always wins, and no data is lost.
19.2.2. Clock Low Extension
SMBus provides a clock synchronization mechanism, similar to I2C, which allows devices with different
speed capabilities to coexist on the bus. A clock-low extension is used during a transfer in order to allow
slower slave devices to communicate with faster masters. The slave may temporarily hold the SCL line
LOW to extend the clock low period, effectively decreasing the serial clock frequency.
19.2.3. SCL Low Timeout
If the SCL line is held low by a slave device on the bus, no further communication is possible. Furthermore,
the master cannot force the SCL line high to correct the error condition. To solve this problem, the SMBus
protocol specifies that devices participating in a transfer must detect any clock cycle held low longer than
25 ms as a “timeout” condition. Devices that have detected the timeout condition must reset the communi-
cation no later than 10 ms after detecting the timeout condition.
19.2.4. SCL High (SMBus Free) Timeout
The SMBus specification stipulates that if the SCL and SDA lines remain high for more that 50 µs, the bus
is designated as free. If an SMBus device is waiting to generate a Master START, the START will be gen-
erated following the bus free timeout.
Rev. 1.4
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19.3. SMBus Transfer Modes
The SMBus0 interface may be configured to operate as a master and/or a slave. At any particular time, the
interface will be operating in one of the following modes: Master Transmitter, Master Receiver, Slave
Transmitter, or Slave Receiver. See Table 19.1 for transfer mode status decoding using the SMB0STA sta-
tus register. The following mode descriptions illustrate an interrupt-driven SMBus0 application; SMBus0
may alternatively be operated in polled mode.
19.3.1. Master Transmitter Mode
Serial data is transmitted on SDA while the serial clock is output on SCL. SMBus0 generates a START
condition and then transmits the first byte containing the address of the target slave device and the data
direction bit. In this case the data direction bit (R/W) will be logic 0 to indicate a "WRITE" operation. The
SMBus0 interface transmits one or more bytes of serial data, waiting for an acknowledge (ACK) from the
slave after each byte. To indicate the end of the serial transfer, SMBus0 generates a STOP condition.
S
SLA
W
A
Data Byte
A
Data Byte
A
P
Interrupt
Interrupt
Interrupt
Interrupt
S = START
P = STOP
A = ACK
Received by SMBus
Interface
W = WRITE
Transmitted by
SLA = Slave Address
SMBus Interface
Figure 19.4. Typical Master Transmitter Sequence
19.3.2. Master Receiver Mode
Serial data is received on SDA while the serial clock is output on SCL. The SMBus0 interface generates a
START followed by the first data byte containing the address of the target slave and the data direction bit.
In this case the data direction bit (R/W) will be logic 1 to indicate a "READ" operation. The SMBus0 inter-
face receives serial data from the slave and generates the clock on SCL. After each byte is received,
SMBus0 generates an ACK or NACK depending on the state of the AA bit in register SMB0CN. SMBus0
generates a STOP condition to indicate the end of the serial transfer.
S
SLA
R
A
Data Byte
A
Data Byte
N
P
Interrupt
Interrupt
Interrupt
Interrupt
S = START
P = STOP
A = ACK
Received by SMBus
Interface
N = NACK
R = READ
SLA = Slave Address
Transmitted by
SMBus Interface
Figure 19.5. Typical Master Receiver Sequence
262
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C8051F130/1/2/3
19.3.3. Slave Transmitter Mode
Serial data is transmitted on SDA while the serial clock is received on SCL. The SMBus0 interface receives
a START followed by data byte containing the slave address and direction bit. If the received slave address
matches the address held in register SMB0ADR, the SMBus0 interface generates an ACK. SMBus0 will
also ACK if the general call address (0x00) is received and the General Call Address Enable bit
(SMB0ADR.0) is set to logic 1. In this case the data direction bit (R/W) will be logic 1 to indicate a "READ"
operation. The SMBus0 interface receives the clock on SCL and transmits one or more bytes of serial
data, waiting for an ACK from the master after each byte. SMBus0 exits slave mode after receiving a
STOP condition from the master.
Interrupt
S
SLA
R
A
Data Byte
A
Data Byte
N
P
Interrupt
Interrupt
Interrupt
S = START
P = STOP
N = NACK
R = READ
Received by SMBus
Interface
Transmitted by
SMBus Interface
SLA = Slave Address
Figure 19.6. Typical Slave Transmitter Sequence
19.3.4. Slave Receiver Mode
Serial data is received on SDA while the serial clock is received on SCL. The SMBus0 interface receives a
START followed by data byte containing the slave address and direction bit. If the received slave address
matches the address held in register SMB0ADR, the interface generates an ACK. SMBus0 will also ACK if
the general call address (0x00) is received and the General Call Address Enable bit (SMB0ADR.0) is set to
logic 1. In this case the data direction bit (R/W) will be logic 0 to indicate a "WRITE" operation. The
SMBus0 interface receives one or more bytes of serial data; after each byte is received, the interface
transmits an ACK or NACK depending on the state of the AA bit in SMB0CN. SMBus0 exits Slave Receiver
Mode after receiving a STOP condition from the master.
Interrupt
S
SLA
W
A
Data Byte
A
Data Byte
A
P
Interrupt
Interrupt
Interrupt
S = START
P = STOP
A = ACK
Received by SMBus
Interface
W = WRITE
SLA = Slave Address
Transmitted by
SMBus Interface
Figure 19.7. Typical Slave Receiver Sequence
Rev. 1.4
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C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
19.4. SMBus Special Function Registers
The SMBus0 serial interface is accessed and controlled through five SFR’s: SMB0CN Control Register,
SMB0CR Clock Rate Register, SMB0ADR Address Register, SMB0DAT Data Register and SMB0STA Sta-
tus Register. The five special function registers related to the operation of the SMBus0 interface are
described in the following sections.
19.4.1. Control Register
The SMBus0 Control register SMB0CN is used to configure and control the SMBus0 interface. All of the
bits in the register can be read or written by software. Two of the control bits are also affected by the
SMBus0 hardware. The Serial Interrupt flag (SI, SMB0CN.3) is set to logic 1 by the hardware when a valid
serial interrupt condition occurs. It can only be cleared by software. The Stop flag (STO, SMB0CN.4) is set
to logic 1 by software. It is cleared to logic 0 by hardware when a STOP condition is detected on the bus.
Setting the ENSMB flag to logic 1 enables the SMBus0 interface. Clearing the ENSMB flag to logic 0 dis-
ables the SMBus0 interface and removes it from the bus. Momentarily clearing the ENSMB flag and then
resetting it to logic 1 will reset SMBus0 communication. However, ENSMB should not be used to tempo-
rarily remove a device from the bus since the bus state information will be lost. Instead, the Assert
Acknowledge (AA) flag should be used to temporarily remove the device from the bus (see description of
AA flag below).
Setting the Start flag (STA, SMB0CN.5) to logic 1 will put SMBus0 in a master mode. If the bus is free,
SMBus0 will generate a START condition. If the bus is not free, SMBus0 waits for a STOP condition to free
the bus and then generates a START condition after a 5 µs delay per the SMB0CR value (In accordance
with the SMBus protocol, the SMBus0 interface also considers the bus free if the bus is idle for 50 µs and
no STOP condition was recognized). If STA is set to logic 1 while SMBus0 is in master mode and one or
more bytes have been transferred, a repeated START condition will be generated.
When the Stop flag (STO, SMB0CN.4) is set to logic 1 while the SMBus0 interface is in master mode, the
interface generates a STOP condition. In a slave mode, the STO flag may be used to recover from an error
condition. In this case, a STOP condition is not generated on the bus, but the SMBus hardware behaves
as if a STOP condition has been received and enters the "not addressed" slave receiver mode. Note that
this simulated STOP will not cause the bus to appear free to SMBus0. The bus will remain occupied until a
STOP appears on the bus or a Bus Free Timeout occurs. Hardware automatically clears the STO flag to
logic 0 when a STOP condition is detected on the bus.
The Serial Interrupt flag (SI, SMB0CN.3) is set to logic 1 by hardware when the SMBus0 interface enters
one of 27 possible states. If interrupts are enabled for the SMBus0 interface, an interrupt request is gener-
ated when the SI flag is set. The SI flag must be cleared by software.
Important Note: If SI is set to logic 1 while the SCL line is low, the clock-low period of the serial clock will
be stretched and the serial transfer is suspended until SI is cleared to logic 0. A high level on SCL is not
affected by the setting of the SI flag.
The Assert Acknowledge flag (AA, SMB0CN.2) is used to set the level of the SDA line during the acknowl-
edge clock cycle on the SCL line. Setting the AA flag to logic 1 will cause an ACK (low level on SDA) to be
sent during the acknowledge cycle if the device has been addressed. Setting the AA flag to logic 0 will
cause a NACK (high level on SDA) to be sent during acknowledge cycle. After the transmission of a byte in
slave mode, the slave can be temporarily removed from the bus by clearing the AA flag. The slave's own
address and general call address will be ignored. To resume operation on the bus, the AA flag must be
reset to logic 1 to allow the slave's address to be recognized.
264
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Setting the SMBus0 Free Timer Enable bit (FTE, SMB0CN.1) to logic 1 enables the timer in SMB0CR.
When SCL goes high, the timer in SMB0CR counts up. A timer overflow indicates a free bus timeout: if
SMBus0 is waiting to generate a START, it will do so after this timeout. The bus free period should be less
than 50 µs (see SFR Definition 19.2, SMBus0 Clock Rate Register).
When the TOE bit in SMB0CN is set to logic 1, Timer 3 is used to detect SCL low timeouts. If Timer 3 is
enabled (see Section “23.2. Timer 2, Timer 3, and Timer 4” on page 317), Timer 3 is forced to reload
when SCL is high, and forced to count when SCL is low. With Timer 3 enabled and configured to overflow
after 25 ms (and TOE set), a Timer 3 overflow indicates a SCL low timeout; the Timer 3 interrupt service
routine can then be used to reset SMBus0 communication in the event of an SCL low timeout.
Rev. 1.4
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SFR Definition 19.1. SMB0CN: SMBus0 Control
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
BUSY
ENSMB
STA
STO
SI
AA
FTE
TOE
00000000
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0xC0
SFR Page: 0
Bit7:
BUSY: Busy Status Flag.
0: SMBus0 is free
1: SMBus0 is busy
Bit6:
Bit5:
ENSMB: SMBus Enable.
This bit enables/disables the SMBus serial interface.
0: SMBus0 disabled.
1: SMBus0 enabled.
STA: SMBus Start Flag.
0: No START condition is transmitted.
1: When operating as a master, a START condition is transmitted if the bus is free. (If the
bus is not free, the START is transmitted after a STOP is received.) If STA is set after one or
more bytes have been transmitted or received and before a STOP is received, a repeated
START condition is transmitted.
Bit4:
STO: SMBus Stop Flag.
0: No STOP condition is transmitted.
1: Setting STO to logic 1 causes a STOP condition to be transmitted. When a STOP condi-
tion is received, hardware clears STO to logic 0. If both STA and STO are set, a STOP con-
dition is transmitted followed by a START condition. In slave mode, setting the STO flag
causes SMBus to behave as if a STOP condition was received.
SI: SMBus Serial Interrupt Flag.
This bit is set by hardware when one of 27 possible SMBus0 states is entered. (Status code
0xF8 does not cause SI to be set.) When the SI interrupt is enabled, setting this bit causes
the CPU to vector to the SMBus interrupt service routine. This bit is not automatically
cleared by hardware and must be cleared by software.
Bit3:
Bit2:
AA: SMBus Assert Acknowledge Flag.
This bit defines the type of acknowledge returned during the acknowledge cycle on the SCL
line.
0: A "not acknowledge" (high level on SDA) is returned during the acknowledge cycle.
1: An "acknowledge" (low level on SDA) is returned during the acknowledge cycle.
FTE: SMBus Free Timer Enable Bit
0: No timeout when SCL is high
1: Timeout when SCL high time exceeds limit specified by the SMB0CR value.
TOE: SMBus Timeout Enable Bit
Bit1:
Bit0:
0: No timeout when SCL is low.
1: Timeout when SCL low time exceeds limit specified by Timer 3, if enabled.
266
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19.4.2. Clock Rate Register
SFR Definition 19.2. SMB0CR: SMBus0 Clock Rate
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Reset Value
00000000
Bit0
SFR Address: 0xCF
SFR Page: 0
Bits7–0: SMB0CR.[7:0]: SMBus0 Clock Rate Preset
The SMB0CR Clock Rate register controls the frequency of the serial clock SCL in master
mode. The 8-bit word stored in the SMB0CR Register preloads a dedicated 8-bit timer. The
timer counts up, and when it rolls over to 0x00, the SCL logic state toggles.
The SMB0CR setting should be bounded by the following equation , where SMB0CR is the
unsigned 8-bit value in register SMB0CR, and SYSCLK is the system clock frequency in
MHz:
SYSCLK
---------------------
SMB0CR 288 – 0.85
1.125
The resulting SCL signal high and low times are given by the following equations, where
SYSCLK is the system clock frequency in Hz:
TLOW = 4 256 – SMB0CR SYSCLK
THIGH 4 258 – SMB0CR SYSCLK + 625ns
Using the same value of SMB0CR from above, the Bus Free Timeout period is given in the
following equation:
4 256 – SMB0CR + 1
--------------------------------------------------------------
TBFT 10
SYSCLK
Rev. 1.4
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19.4.3. Data Register
The SMBus0 Data register SMB0DAT holds a byte of serial data to be transmitted or one that has just
been received. Software can read or write to this register while the SI flag is set to logic 1; software should
not attempt to access the SMB0DAT register when the SMBus is enabled and the SI flag reads logic 0
since the hardware may be in the process of shifting a byte of data in or out of the register.
Data in SMB0DAT is always shifted out MSB first. After a byte has been received, the first bit of received
data is located at the MSB of SMB0DAT. While data is being shifted out, data on the bus is simultaneously
being shifted in. Therefore, SMB0DAT always contains the last data byte present on the bus. In the event
of lost arbitration, the transition from master transmitter to slave receiver is made with the correct data in
SMB0DAT.
SFR Definition 19.3. SMB0DAT: SMBus0 Data
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address: 0xC2
SFR Page: 0
Bits7–0: SMB0DAT: SMBus0 Data.
The SMB0DAT register contains a byte of data to be transmitted on the SMBus0 serial inter-
face or a byte that has just been received on the SMBus0 serial interface. The CPU can
read from or write to this register whenever the SI serial interrupt flag (SMB0CN.3) is set to
logic 1. When the SI flag is not set, the system may be in the process of shifting data and the
CPU should not attempt to access this register.
19.4.4. Address Register
The SMB0ADR Address register holds the slave address for the SMBus0 interface. In slave mode, the
seven most-significant bits hold the 7-bit slave address. The least significant bit (Bit0) is used to enable the
recognition of the general call address (0x00). If Bit0 is set to logic 1, the general call address will be recog-
nized. Otherwise, the general call address is ignored. The contents of this register are ignored when
SMBus0 is operating in master mode.
268
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SFR Definition 19.4. SMB0ADR: SMBus0 Address
R/W
SLV6
Bit7
R/W
SLV5
Bit6
R/W
SLV4
Bit5
R/W
SLV3
Bit4
R/W
SLV2
Bit3
R/W
SLV1
Bit2
R/W
SLV0
Bit1
R/W
GC
Bit0
Reset Value
00000000
SFR Address:
SFR Page:
0xC3
0
Bits7–1: SLV6–SLV0: SMBus0 Slave Address.
These bits are loaded with the 7-bit slave address to which SMBus0 will respond when oper-
ating as a slave transmitter or slave receiver. SLV6 is the most significant bit of the address
and corresponds to the first bit of the address byte received.
Bit0:
GC: General Call Address Enable.
This bit is used to enable general call address (0x00) recognition.
0: General call address is ignored.
1: General call address is recognized.
19.4.5. Status Register
The SMB0STA Status register holds an 8-bit status code indicating the current state of the SMBus0 inter-
face. There are 28 possible SMBus0 states, each with a corresponding unique status code. The five most
significant bits of the status code vary while the three least-significant bits of a valid status code are fixed at
zero when SI = ‘1’. Therefore, all possible status codes are multiples of eight. This facilitates the use of sta-
tus codes in software as an index used to branch to appropriate service routines (allowing 8 bytes of code
to service the state or jump to a more extensive service routine).
For the purposes of user software, the contents of the SMB0STA register is only defined when the SI flag is
logic 1. Software should never write to the SMB0STA register; doing so will yield indeterminate results. The
28 SMBus0 states, along with their corresponding status codes, are given in Table 1.1.
SFR Definition 19.5. SMB0STA: SMBus0 Status
R/W
STA7
Bit7
R/W
STA6
Bit6
R/W
STA5
Bit5
R/W
STA4
Bit4
R/W
STA3
Bit3
R/W
STA2
Bit2
R/W
STA1
Bit1
R/W
STA0
Bit0
Reset Value
11111000
SFR Address: 0xC1
SFR Page: 0
Bits7–3: STA7–STA3: SMBus0 Status Code.
These bits contain the SMBus0 Status Code. There are 28 possible status codes; each sta-
tus code corresponds to a single SMBus state. A valid status code is present in SMB0STA
when the SI flag (SMB0CN.3) is set to logic 1. The content of SMB0STA is not defined when
the SI flag is logic 0. Writing to the SMB0STA register at any time will yield indeterminate
results.
Bits2–0: STA2–STA0: The three least significant bits of SMB0STA are always read as logic 0 when
the SI flag is logic 1.
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Table 19.1. SMB0STA Status Codes and States
Status
Code
Mode
SMBus State
Typical Action
0x08
0x10
0x18
0x20
START condition transmitted.
Load SMB0DAT with Slave Address +
R/W. Clear STA.
Repeated START condition transmitted.
Load SMB0DAT with Slave Address +
R/W. Clear STA.
Slave Address + W transmitted. ACK
received.
Load SMB0DAT with data to be transmit-
ted.
Slave Address + W transmitted. NACK
received.
Acknowledge poll to retry. Set STO +
STA.
1) Load SMB0DAT with next byte, OR
2) Set STO, OR
3) Clear STO then set STA for repeated
START.
0x28
0x30
Data byte transmitted. ACK received.
Data byte transmitted. NACK received.
Arbitration Lost.
1) Retry transfer OR
2) Set STO.
0x38
0x40
Save current data.
Slave Address + R transmitted. ACK received. If only receiving one byte, clear AA (send
NACK after received byte). Wait for
received data.
0x48
0x50
0x58
Slave Address + R transmitted. NACK
received.
Acknowledge poll to retry. Set STO +
STA.
Data byte received. ACK transmitted.
Read SMB0DAT. Wait for next byte. If
next byte is last byte, clear AA.
Data byte received. NACK transmitted.
Set STO.
270
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Table 19.1. SMB0STA Status Codes and States (Continued)
Status
Code
Mode
SMBus State
Typical Action
0x60
Own slave address + W received. ACK trans-
mitted.
Wait for data.
0x68
Arbitration lost in sending SLA + R/W as mas-
Save current data for retry when bus is
ter. Own address + W received. ACK transmit- free. Wait for data.
ted.
0x70
0x78
General call address received. ACK transmit-
ted.
Wait for data.
Arbitration lost in sending SLA + R/W as mas-
ter. General call address received. ACK trans-
mitted.
Save current data for retry when bus is
free.
0x80
Data byte received. ACK transmitted.
Read SMB0DAT. Wait for next byte or
STOP.
0x88
0x90
Data byte received. NACK transmitted.
Set STO to reset SMBus.
Data byte received after general call address.
ACK transmitted.
Read SMB0DAT. Wait for next byte or
STOP.
0x98
Data byte received after general call address.
NACK transmitted.
Set STO to reset SMBus.
0xA0
0xA8
0xB0
STOP or repeated START received.
No action necessary.
Own address + R received. ACK transmitted.
Load SMB0DAT with data to transmit.
Arbitration lost in transmitting SLA + R/W as
master. Own address + R received. ACK
transmitted.
Save current data for retry when bus is
free. Load SMB0DAT with data to trans-
mit.
0xB8
0xC0
0xC8
Data byte transmitted. ACK received.
Data byte transmitted. NACK received.
Load SMB0DAT with data to transmit.
Wait for STOP.
Last data byte transmitted (AA=0). ACK
received.
Set STO to reset SMBus.
0xD0
SCL Clock High Timer per SMB0CR timed out Set STO to reset SMBus.
0x00
0xF8
Bus Error (illegal START or STOP)
Idle
Set STO to reset SMBus.
State does not set SI.
Rev. 1.4
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NOTES:
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20. Enhanced Serial Peripheral Interface (SPI0)
The Enhanced Serial Peripheral Interface (SPI0) provides access to a flexible, full-duplex synchronous
serial bus. SPI0 can operate as a master or slave device in both 3-wire or 4-wire modes, and supports mul-
tiple masters and slaves on a single SPI bus. The slave-select (NSS) signal can be configured as an input
to select SPI0 in slave mode, or to disable Master Mode operation in a multi-master environment, avoiding
contention on the SPI bus when more than one master attempts simultaneous data transfers. NSS can
also be configured as a chip-select output in master mode, or disabled for 3-wire operation. Additional gen-
eral purpose port I/O pins can be used to select multiple slave devices in master mode.
SFR Bus
SPI0CKR
SPI0CFG
SPI0CN
Clock Divide
Logic
SYSCLK
SPI CONTROL LOGIC
SPI IRQ
Data Path
Control
Pin Interface
Control
MOSI
Tx Data
C
R
O
S
S
B
A
R
SPI0DAT
SCK
MISO
NSS
Transmit Data Buffer
Pin
Control
Logic
Port I/O
Shift Register
Rx Data
7 6 5 4 3 2 1 0
Receive Data Buffer
Read
SPI0DAT
Write
SPI0DAT
SFR Bus
Figure 20.1. SPI Block Diagram
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20.1. Signal Descriptions
The four signals used by SPI0 (MOSI, MISO, SCK, NSS) are described below.
20.1.1. Master Out, Slave In (MOSI)
The master-out, slave-in (MOSI) signal is an output from a master device and an input to slave devices. It
is used to serially transfer data from the master to the slave. This signal is an output when SPI0 is operat-
ing as a master and an input when SPI0 is operating as a slave. Data is transferred most-significant bit
first. When configured as a master, MOSI is driven by the MSB of the shift register in both 3- and 4-wire
mode.
20.1.2. Master In, Slave Out (MISO)
The master-in, slave-out (MISO) signal is an output from a slave device and an input to the master device.
It is used to serially transfer data from the slave to the master. This signal is an input when SPI0 is operat-
ing as a master and an output when SPI0 is operating as a slave. Data is transferred most-significant bit
first. The MISO pin is placed in a high-impedance state when the SPI module is disabled and when the SPI
operates in 4-wire mode as a slave that is not selected. When acting as a slave in 3-wire mode, MISO is
always driven by the MSB of the shift register.
20.1.3. Serial Clock (SCK)
The serial clock (SCK) signal is an output from the master device and an input to slave devices. It is used
to synchronize the transfer of data between the master and slave on the MOSI and MISO lines. SPI0 gen-
erates this signal when operating as a master. The SCK signal is ignored by a SPI slave when the slave is
not selected (NSS = 1) in 4-wire slave mode.
20.1.4. Slave Select (NSS)
The function of the slave-select (NSS) signal is dependent on the setting of the NSSMD1 and NSSMD0
bits in the SPI0CN register. There are three possible modes that can be selected with these bits:
1. NSSMD[1:0] = 00: 3-Wire Master or 3-Wire Slave Mode: SPI0 operates in 3-wire mode, and
NSS is disabled. When operating as a slave device, SPI0 is always selected in 3-wire mode.
Since no select signal is present, SPI0 must be the only slave on the bus in 3-wire mode. This
is intended for point-to-point communication between a master and one slave.
2. NSSMD[1:0] = 01: 4-Wire Slave or Multi-Master Mode: SPI0 operates in 4-wire mode, and
NSS is enabled as an input. When operating as a slave, NSS selects the SPI0 device. When
operating as a master, a 1-to-0 transition of the NSS signal disables the master function of
SPI0 so that multiple master devices can be used on the same SPI bus.
3. NSSMD[1:0] = 1x: 4-Wire Master Mode: SPI0 operates in 4-wire mode, and NSS is enabled as
an output. The setting of NSSMD0 determines what logic level the NSS pin will output. This
configuration should only be used when operating SPI0 as a master device.
See Figure 20.2, Figure 20.3, and Figure 20.4 for typical connection diagrams of the various operational
modes. Note that the setting of NSSMD bits affects the pinout of the device. When in 3-wire master or
3-wire slave mode, the NSS pin will not be mapped by the crossbar. In all other modes, the NSS signal will
be mapped to a pin on the device. See Section “18. Port Input/Output” on page 235 for general purpose
port I/O and crossbar information.
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20.2. SPI0 Master Mode Operation
A SPI master device initiates all data transfers on a SPI bus. SPI0 is placed in master mode by setting the
Master Enable flag (MSTEN, SPI0CN.6). Writing a byte of data to the SPI0 data register (SPI0DAT) when
in master mode writes to the transmit buffer. If the SPI shift register is empty, the byte in the transmit buffer
is moved to the shift register, and a data transfer begins. The SPI0 master immediately shifts out the data
serially on the MOSI line while providing the serial clock on SCK. The SPIF (SPI0CN.7) flag is set to logic
1 at the end of the transfer. If interrupts are enabled, an interrupt request is generated when the SPIF flag
is set. While the SPI0 master transfers data to a slave on the MOSI line, the addressed SPI slave device
simultaneously transfers the contents of its shift register to the SPI master on the MISO line in a full-duplex
operation. Therefore, the SPIF flag serves as both a transmit-complete and receive-data-ready flag. The
data byte received from the slave is transferred MSB-first into the master's shift register. When a byte is
fully shifted into the register, it is moved to the receive buffer where it can be read by the processor by
reading SPI0DAT.
When configured as a master, SPI0 can operate in one of three different modes: multi-master mode, 3-wire
single-master mode, and 4-wire single-master mode. The default, multi-master mode is active when
NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In this mode, NSS is an input to the device, and
is used to disable the master SPI0 when another master is accessing the bus. When NSS is pulled low in
this mode, MSTEN (SPI0CN.6) and SPIEN (SPI0CN.0) are set to 0 to disable the SPI master device, and
a Mode Fault is generated (MODF, SPI0CN.5 = 1). Mode Fault will generate an interrupt if enabled. SPI0
must be manually re-enabled in software under these circumstances. In multi-master systems, devices will
typically default to being slave devices while they are not acting as the system master device. In multi-mas-
ter mode, slave devices can be addressed individually (if needed) using general-purpose I/O pins.
Figure 20.2 shows a connection diagram between two master devices in multiple-master mode.
3-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. In this
mode, NSS is not used, and is not mapped to an external port pin through the crossbar. Any slave devices
that must be addressed in this mode should be selected using general-purpose I/O pins. Figure 20.3
shows a connection diagram between a master device in 3-wire master mode and a slave device.
4-wire single-master mode is active when NSSMD1 (SPI0CN.3) = 1. In this mode, NSS is configured as an
output pin, and can be used as a slave-select signal for a single SPI device. In this mode, the output value
of NSS is controlled (in software) with the bit NSSMD0 (SPI0CN.2). Additional slave devices can be
addressed using general-purpose I/O pins. Figure 20.4 shows a connection diagram for a master device in
4-wire master mode and two slave devices.
Rev. 1.4
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NSS
GPIO
MISO
MOSI
SCK
MISO
Master
Master
MOSI
Device 1
Device 2
SCK
GPIO
NSS
Figure 20.2. Multiple-Master Mode Connection Diagram
Master
Device
Slave
Device
MISO
MOSI
SCK
MISO
MOSI
SCK
Figure 20.3. 3-Wire Single Master and Slave Mode Connection Diagram
MISO
MOSI
SCK
MISO
MOSI
SCK
Master
Device
Slave
Device
NSS
NSS
GPIO
MISO
MOSI
SCK
Slave
Device
NSS
Figure 20.4. 4-Wire Single Master and Slave Mode Connection Diagram
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20.3. SPI0 Slave Mode Operation
When SPI0 is enabled and not configured as a master, it will operate as a SPI slave. As a slave, bytes are
shifted in through the MOSI pin and out through the MISO pin by a master device controlling the SCK sig-
nal. A bit counter in the SPI0 logic counts SCK edges. When 8 bits have been shifted through the shift reg-
ister, the SPIF flag is set to logic 1, and the byte is copied into the receive buffer. Data is read from the
receive buffer by reading SPI0DAT. A slave device cannot initiate transfers. Data to be transferred to the
master device is pre-loaded into the shift register by writing to SPI0DAT. Writes to SPI0DAT are double-
buffered, and are placed in the transmit buffer first. If the shift register is empty, the contents of the transmit
buffer will immediately be transferred into the shift register. When the shift register already contains data,
the SPI will load the shift register with the transmit buffer’s contents after the last SCK edge of the next (or
current) SPI transfer.
When configured as a slave, SPI0 can be configured for 4-wire or 3-wire operation. The default, 4-wire
slave mode, is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In 4-wire mode, the
NSS signal is routed to a port pin and configured as a digital input. SPI0 is enabled when NSS is logic 0,
and disabled when NSS is logic 1. The bit counter is reset on a falling edge of NSS. Note that the NSS sig-
nal must be driven low at least 2 system clocks before the first active edge of SCK for each byte transfer.
Figure 20.4 shows a connection diagram between two slave devices in 4-wire slave mode and a master
device.
3-wire slave mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. NSS is not
used in this mode, and is not mapped to an external port pin through the crossbar. Since there is no way of
uniquely addressing the device in 3-wire slave mode, SPI0 must be the only slave device present on the
bus. It is important to note that in 3-wire slave mode there is no external means of resetting the bit counter
that determines when a full byte has been received. The bit counter can only be reset by disabling and re-
enabling SPI0 with the SPIEN bit. Figure 20.3 shows a connection diagram between a slave device in 3-
wire slave mode and a master device.
20.4. SPI0 Interrupt Sources
When SPI0 interrupts are enabled, the following four flags will generate an interrupt when they are set to
logic 1:
Note that all of the following bits must be cleared by software.
1. The SPI Interrupt Flag, SPIF (SPI0CN.7) is set to logic 1 at the end of each byte transfer. This
flag can occur in all SPI0 modes.
2. The Write Collision Flag, WCOL (SPI0CN.6) is set to logic 1 if a write to SPI0DAT is attempted
when the transmit buffer has not been emptied to the SPI shift register. When this occurs, the
write to SPI0DAT will be ignored, and the transmit buffer will not be written.This flag can occur
in all SPI0 modes.
3. The Mode Fault Flag MODF (SPI0CN.5) is set to logic 1 when SPI0 is configured as a master,
and for multi-master mode and the NSS pin is pulled low. When a Mode Fault occurs, the
MSTEN and SPIEN bits in SPI0CN are set to logic 0 to disable SPI0 and allow another master
device to access the bus.
4. The Receive Overrun Flag RXOVRN (SPI0CN.4) is set to logic 1 when configured as a slave,
and a transfer is completed and the receive buffer still holds an unread byte from a previous
transfer. The new byte is not transferred to the receive buffer, allowing the previously received
data byte to be read. The data byte which caused the overrun is lost.
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20.5. Serial Clock Timing
Four combinations of serial clock phase and polarity can be selected using the clock control bits in the
SPI0 Configuration Register (SPI0CFG). The CKPHA bit (SPI0CFG.5) selects one of two clock phases
(edge used to latch the data). The CKPOL bit (SPI0CFG.4) selects between an active-high or active-low
clock. Both master and slave devices must be configured to use the same clock phase and polarity. SPI0
should be disabled (by clearing the SPIEN bit, SPI0CN.0) when changing the clock phase or polarity. The
clock and data line relationships for master mode are shown in Figure 20.5. For slave mode, the clock and
data relationships are shown in Figure 20.6 and Figure 20.7. Note that CKPHA must be set to ‘0’ on both
the master and slave SPI when communicating between two of the following devices: C8051F04x,
C8051F06x, C8051F12x/13x, C8051F31x, C8051F32x, and C8051F33x
The SPI0 Clock Rate Register (SPI0CKR) as shown in SFR Definition 20.3 controls the master mode
serial clock frequency. This register is ignored when operating in slave mode. When the SPI is configured
as a master, the maximum data transfer rate (bits/sec) is one-half the system clock frequency or 12.5 MHz,
whichever is slower. When the SPI is configured as a slave, the maximum data transfer rate (bits/sec) for
full-duplex operation is 1/10 the system clock frequency, provided that the master issues SCK, NSS (in 4-
wire slave mode), and the serial input data synchronously with the slave’s system clock. If the master
issues SCK, NSS, and the serial input data asynchronously, the maximum data transfer rate (bits/sec)
must be less than 1/10 the system clock frequency. In the special case where the master only wants to
transmit data to the slave and does not need to receive data from the slave (i.e. half-duplex operation), the
SPI slave can receive data at a maximum data transfer rate (bits/sec) of 1/4 the system clock frequency.
This is provided that the master issues SCK, NSS, and the serial input data synchronously with the slave’s
system clock.
SCK
(CKPOL=0, CKPHA=0)
SCK
(CKPOL=0, CKPHA=1)
SCK
(CKPOL=1, CKPHA=0)
SCK
(CKPOL=1, CKPHA=1)
MISO/MOSI
MSB
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
NSS (Must Remain High
in Multi-Master Mode)
Figure 20.5. Master Mode Data/Clock Timing
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SCK
(CKPOL=0, CKPHA=0)
SCK
(CKPOL=1, CKPHA=0)
MOSI
MSB
MSB
Bit 6
Bit 6
Bit 5
Bit 5
Bit 4
Bit 4
Bit 3
Bit 3
Bit 2
Bit 2
Bit 1
Bit 1
Bit 0
Bit 0
MISO
NSS (4-Wire Mode)
Figure 20.6. Slave Mode Data/Clock Timing (CKPHA = 0)
SCK
(CKPOL=0, CKPHA=1)
SCK
(CKPOL=1, CKPHA=1)
MOSI
MSB
MSB
Bit 6
Bit 6
Bit 5
Bit 5
Bit 4
Bit 4
Bit 3
Bit 3
Bit 2
Bit 2
Bit 1
Bit 1
Bit 0
Bit 0
MISO
NSS (4-Wire Mode)
Figure 20.7. Slave Mode Data/Clock Timing (CKPHA = 1)
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20.6. SPI Special Function Registers
SPI0 is accessed and controlled through four special function registers in the system controller: SPI0CN
Control Register, SPI0DAT Data Register, SPI0CFG Configuration Register, and SPI0CKR Clock Rate
Register. The four special function registers related to the operation of the SPI0 Bus are described in the
following figures.
SFR Definition 20.1. SPI0CFG: SPI0 Configuration
R
R/W
R/W
CKPHA
Bit5
R/W
R
R
R
R
Reset Value
SPIBSY MSTEN
CKPOL SLVSEL
NSSIN
Bit2
SRMT
Bit1
RXBMT 00000111
Bit7
Bit6
Bit4
Bit3
Bit0
SFR Address: 0x9A
SFR Page: 0
Bit 7:
SPIBSY: SPI Busy (read only).
This bit is set to logic 1 when a SPI transfer is in progress (Master or slave Mode).
MSTEN: Master Mode Enable.
0: Disable master mode. Operate in slave mode.
1: Enable master mode. Operate as a master.
CKPHA: SPI0 Clock Phase.
Bit 6:
Bit 5:
This bit controls the SPI0 clock phase.
0: Data centered on first edge of SCK period.*
1: Data centered on second edge of SCK period.*
Bit 4:
Bit 3:
CKPOL: SPI0 Clock Polarity.
This bit controls the SPI0 clock polarity.
0: SCK line low in idle state.
1: SCK line high in idle state.
SLVSEL: Slave Selected Flag (read only).
This bit is set to logic 1 whenever the NSS pin is low indicating SPI0 is the selected slave. It
is cleared to logic 0 when NSS is high (slave not selected). This bit does not indicate the
instantaneous value at the NSS pin, but rather a de-glitched version of the pin input.
NSSIN: NSS Instantaneous Pin Input (read only).
This bit mimics the instantaneous value that is present on the NSS port pin at the time that
the register is read. This input is not de-glitched.
SRMT: Shift Register Empty (Valid in Slave Mode, read only).
This bit will be set to logic 1 when all data has been transferred in/out of the shift register,
and there is no new information available to read from the transmit buffer or write to the
receive buffer. It returns to logic 0 when a data byte is transferred to the shift register from
the transmit buffer or by a transition on SCK.
Bit 2:
Bit 1:
NOTE: SRMT = 1 when in Master Mode.
Bit 0:
RXBMT: Receive Buffer Empty (Valid in Slave Mode, read only).
This bit will be set to logic 1 when the receive buffer has been read and contains no new
information. If there is new information available in the receive buffer that has not been read,
this bit will return to logic 0.
NOTE: RXBMT = 1 when in Master Mode.
*Note:
In slave mode, data on MOSI is sampled in the center of each data bit. In master mode, data
on MISO is sampled one SYSCLK before the end of each data bit, to provide maximum
settling time for the slave device. See Table 20.1 for timing parameters.
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SFR Definition 20.2. SPI0CN: SPI0 Control
R/W
R/W
R/W
R/W
R/W
R/W
R
R/W
Reset Value
SPIF
WCOL
MODF RXOVRN NSSMD1 NSSMD0 TXBMT
SPIEN 00000110
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0xF8
SFR Page: 0
Bit 7:
SPIF: SPI0 Interrupt Flag.
This bit is set to logic 1 by hardware at the end of a data transfer. If interrupts are enabled,
setting this bit causes the CPU to vector to the SPI0 interrupt service routine. This bit is not
automatically cleared by hardware. It must be cleared by software.
WCOL: Write Collision Flag.
This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) to indicate a write to
the SPI0 data register was attempted while a data transfer was in progress. It must be
cleared by software.
Bit 6:
Bit 5:
Bit 4:
MODF: Mode Fault Flag.
This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when a master mode
collision is detected (NSS is low, MSTEN = 1, and NSSMD[1:0] = 01). This bit is not auto-
matically cleared by hardware. It must be cleared by software.
RXOVRN: Receive Overrun Flag (Slave Mode only).
This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when the receive
buffer still holds unread data from a previous transfer and the last bit of the current transfer is
shifted into the SPI0 shift register. This bit is not automatically cleared by hardware. It must
be cleared by software.
Bits 3–2: NSSMD1–NSSMD0: Slave Select Mode.
Selects between the following NSS operation modes:
(See Section “20.2. SPI0 Master Mode Operation” on page 275 and Section “20.3. SPI0
Slave Mode Operation” on page 277).
00: 3-Wire Slave or 3-wire Master Mode. NSS signal is not routed to a port pin.
01: 4-Wire Slave or Multi-Master Mode (Default). NSS is always an input to the device.
1x: 4-Wire Single-Master Mode. NSS signal is mapped as an output from the device and will
assume the value of NSSMD0.
Bit 1:
Bit 0:
TXBMT: Transmit Buffer Empty.
This bit will be set to logic 0 when new data has been written to the transmit buffer. When
data in the transmit buffer is transferred to the SPI shift register, this bit will be set to logic 1,
indicating that it is safe to write a new byte to the transmit buffer.
SPIEN: SPI0 Enable.
This bit enables/disables the SPI.
0: SPI disabled.
1: SPI enabled.
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SFR Definition 20.3. SPI0CKR: SPI0 Clock Rate
R/W
SCR7
Bit7
R/W
SCR6
Bit6
R/W
SCR5
Bit5
R/W
SCR4
Bit4
R/W
SCR3
Bit3
R/W
SCR2
Bit2
R/W
SCR1
Bit1
R/W
Reset Value
SCR0 00000000
Bit0
SFR Address: 0x9D
SFR Page: 0
Bits 7–0: SCR7–SCR0: SPI0 Clock Rate.
These bits determine the frequency of the SCK output when the SPI0 module is configured
for master mode operation. The SCK clock frequency is a divided version of the system
clock, and is given in the following equation, where SYSCLK is the system clock frequency
and SPI0CKR is the 8-bit value held in the SPI0CKR register.
SYSCLK
2 SPI0CKR + 1
----------------------------------------------
=
fSCK
for 0 <= SPI0CKR <= 255
Example: If SYSCLK = 2 MHz and SPI0CKR = 0x04,
2000000
2 4 + 1
-------------------------
=
fSCK
fSCK = 200kHz
SFR Definition 20.4. SPI0DAT: SPI0 Data
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address: 0x9B
SFR Page: 0
Bits 7–0: SPI0DAT: SPI0 Transmit and Receive Data.
The SPI0DAT register is used to transmit and receive SPI0 data. Writing data to SPI0DAT
places the data into the transmit buffer and initiates a transfer when in Master Mode. A read
of SPI0DAT returns the contents of the receive buffer.
282
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SCK*
T
T
MCKL
MCKH
T
T
MIS
MIH
MISO
MOSI
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 20.8. SPI Master Timing (CKPHA = 0)
SCK*
T
T
MCKL
MCKH
T
T
MIH
MIS
MISO
MOSI
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 20.9. SPI Master Timing (CKPHA = 1)
Rev. 1.4
283
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C8051F130/1/2/3
NSS
T
T
T
SD
SE
CKL
SCK*
T
CKH
T
T
SIH
SIS
MOSI
MISO
T
T
T
SDZ
SEZ
SOH
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 20.10. SPI Slave Timing (CKPHA = 0)
NSS
T
T
T
SD
SE
CKL
SCK*
T
CKH
T
T
SIH
SIS
MOSI
T
T
T
SDZ
T
SOH
SLH
SEZ
MISO
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
Figure 20.11. SPI Slave Timing (CKPHA = 1)
284
Rev. 1.4
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C8051F130/1/2/3
Table 20.1. SPI Slave Timing Parameters
Parameter
Description
Min
Max
Units
Master Mode Timing* (See Figure 20.8 and Figure 20.9)
T
1 x TSYSCLK
1 x TSYSCLK
1 x TSYSCLK + 20
0
SCK High Time
ns
ns
ns
ns
MCKH
T
SCK Low Time
MCKL
T
MISO Valid to SCK Shift Edge
SCK Shift Edge to MISO Change
MIS
T
MIH
Slave Mode Timing* (See Figure 20.10 and Figure 20.11)
T
2 x TSYSCLK
2 x TSYSCLK
NSS Falling to First SCK Edge
Last SCK Edge to NSS Rising
NSS Falling to MISO Valid
NSS Rising to MISO High-Z
SCK High Time
ns
ns
ns
ns
ns
ns
ns
ns
ns
SE
T
SD
T
4 x TSYSCLK
4 x TSYSCLK
SEZ
T
SDZ
T
5 x TSYSCLK
5 x TSYSCLK
2 x TSYSCLK
2 x TSYSCLK
CKH
T
SCK Low Time
CKL
T
MOSI Valid to SCK Sample Edge
SCK Sample Edge to MOSI Change
SCK Shift Edge to MISO Change
SIS
T
SIH
T
4 x TSYSCLK
8 x TSYSCLK
SOH
Last SCK Edge to MISO Change
(CKPHA = 1 ONLY)
T
6 x TSYSCLK
ns
SLH
*Note: TSYSCLK is equal to one period of the device system clock (SYSCLK).
Rev. 1.4
285
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
NOTES:
286
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
21. UART0
UART0 is an enhanced serial port with frame error detection and address recognition hardware. UART0
may operate in full-duplex asynchronous or half-duplex synchronous modes, and mutiproccessor commu-
nication is fully supported. Receive data is buffered in a holding register, allowing UART0 to start reception
of a second incoming data byte before software has finished reading the previous data byte. A Receive
Overrun bit indicates when new received data is latched into the receive buffer before the previously
received byte has been read.
UART0 is accessed via its associated SFR’s, Serial Control (SCON0) and Serial Data Buffer (SBUF0). The
single SBUF0 location provides access to both transmit and receive registers. Reading SCON0 accesses
the Receive register and writing SCON0 accesses the Transmit register.
UART0 may be operated in polled or interrupt mode. UART0 has two sources of interrupts: a Transmit
Interrupt flag, TI0 (SCON0.1) set when transmission of a data byte is complete, and a Receive Interrupt
flag, RI0 (SCON0.0) set when reception of a data byte is complete. UART0 interrupt flags are not cleared
by hardware when the CPU vectors to the interrupt service routine; they must be cleared manually by soft-
ware. This allows software to determine the cause of the UART0 interrupt (transmit complete or receive
complete).
SFR Bus
Write to
SBUF0
TB80
SET
D
Q
SBUF0
TX0
CLR
Crossbar
SSTA0
F
E
0
R
X
O
V
0
T
X
C
O
L
S
M
O
D
0
S
0
T
C
L
S
0
T
C
L
S
0
R
C
L
S
0
R
C
L
Zero Detector
0
K
1
K
1
K
1
K
1
Shift
Stop Bit
Gen.
Data
Tx Control
Start
Tx Clock
Send
Tx IRQ
TI0
RI0
SCON0
UART0
Baud Rate Generation
Logic
S
M
0
S
M
1
S
M
2
R
E
N
0
T
B
8
0
R
B
8
T
I
0
R
I
0
Serial Port
(UART0) Interrupt
0
0
0
0
EN
Rx IRQ
Rx Clock
Start
Load
SBUF
Rx Control
Address
Match
Port I/O
Shift
0x1FF
Frame Error
Detection
Input Shift Register
(9 bits)
Load
SBUF0
RB80
SADDR0
SADEN0
SBUF0
Match Detect
Read
SBUF0
SFR Bus
RX0
Crossbar
Figure 21.1. UART0 Block Diagram
Rev. 1.4
287
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
21.1. UART0 Operational Modes
UART0 provides four operating modes (one synchronous and three asynchronous) selected by setting
configuration bits in the SCON0 register. These four modes offer different baud rates and communication
protocols. The four modes are summarized in Table 21.1.
Table 21.1. UART0 Modes
Mode
Synchronization
Synchronous
Asynchronous
Asynchronous
Asynchronous
Baud Clock
SYSCLK / 12
Timer 1, 2, 3, or 4 Overflow
SYSCLK / 32 or SYSCLK / 64
Timer 1, 2, 3, or 4 Overflow
Data Bits
Start/Stop Bits
None
1 Start, 1 Stop
1 Start, 1 Stop
1 Start, 1 Stop
0
1
2
3
8
8
9
9
21.1.1. Mode 0: Synchronous Mode
Mode 0 provides synchronous, half-duplex communication. Serial data is transmitted and received on the
RX0 pin. The TX0 pin provides the shift clock for both transmit and receive. The MCU must be the master
since it generates the shift clock for transmission in both directions (see the interconnect diagram in
Figure 21.3).
Data transmission begins when an instruction writes a data byte to the SBUF0 register. Eight data bits are
transferred LSB first (see the timing diagram in Figure 21.2), and the TI0 Transmit Interrupt Flag
(SCON0.1) is set at the end of the eighth bit time. Data reception begins when the REN0 Receive Enable
bit (SCON0.4) is set to logic 1 and the RI0 Receive Interrupt Flag (SCON0.0) is cleared. One cycle after
the eighth bit is shifted in, the RI0 flag is set and reception stops until software clears the RI0 bit. An inter-
rupt will occur if enabled when either TI0 or RI0 are set.
The Mode 0 baud rate is SYSCLK / 12. RX0 is forced to open-drain in Mode 0, and an external pullup will
typically be required.
MODE 0 TRANSMIT
D0
D1
D2
D3
D4
D5
D6
D7
RX (data out)
TX (clk out)
MODE 0 RECEIVE
D0
D1
D2
D3
D4
D5
D6
D7
RX (data in)
TX (clk out)
Figure 21.2. UART0 Mode 0 Timing Diagram
TX
RX
CLK
Shift
Reg.
C8051Fxxx
DATA
8 Extra Outputs
Figure 21.3. UART0 Mode 0 Interconnect
288
Rev. 1.4
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C8051F130/1/2/3
21.1.2. Mode 1: 8-Bit UART, Variable Baud Rate
Mode 1 provides standard asynchronous, full duplex communication using a total of 10 bits per data byte:
one start bit, eight data bits (LSB first), and one stop bit. Data are transmitted from the TX0 pin and
received at the RX0 pin. On receive, the eight data bits are stored in SBUF0 and the stop bit goes into
RB80 (SCON0.2).
Data transmission begins when an instruction writes a data byte to the SBUF0 register. The TI0 Transmit
Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data
reception can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to logic 1. After the stop
bit is received, the data byte will be loaded into the SBUF0 receive register if the following conditions are
met: RI0 must be logic 0, and if SM20 is logic 1, the stop bit must be logic 1.
If these conditions are met, the eight bits of data is stored in SBUF0, the stop bit is stored in RB80 and the
RI0 flag is set. If these conditions are not met, SBUF0 and RB80 will not be loaded and the RI0 flag will not
be set. An interrupt will occur if enabled when either TI0 or RI0 are set.
MARK
START
BIT
STOP
BIT
D0
D1
D2
D3
D4
D5
D6
D7
SPACE
BIT TIMES
BIT SAMPLING
Figure 21.4. UART0 Mode 1 Timing Diagram
The baud rate generated in Mode 1 is a function of timer overflow. UART0 can use Timer 1 operating in 8-
Bit Auto-Reload Mode, or Timer 2, 3, or 4 operating in Auto-reload Mode to generate the baud rate (note
that the TX and RX clocks are selected separately). On each timer overflow event (a rollover from all ones
- (0xFF for Timer 1, 0xFFFF for Timer 2, 3, or 4) - to zero) a clock is sent to the baud rate logic.
Timers 1, 2, 3, or 4 are selected as the baud rate source with bits in the SSTA0 register (see SFR Defini-
tion 21.2). The transmit baud rate clock is selected using the S0TCLK1 and S0TCLK0 bits, and the receive
baud rate clock is selected using the S0RCLK1 and S0RCLK0 bits.
When Timer 1 is selected as a baud rate source, the SMOD0 bit (SSTA0.4) selects whether or not to divide
the Timer 1 overflow rate by two. On reset, the SMOD0 bit is logic 0, thus selecting the lower speed baud
rate by default. The SMOD0 bit affects the baud rate generated by Timer 1 as shown in Equation 21.1.
The Mode 1 baud rate equations are shown below, where T1M is bit4 of register CKCON, TH1 is the 8-bit
reload register for Timer 1, and [RCAPnH , RCAPnL] is the 16-bit reload register for Timer 2, 3, or 4.
Equation 21.1. Mode 1 Baud Rate using Timer 1
When SMOD0 = 0:
Mode1_BaudRate = 1 32 Timer1_OverflowRate
When SMOD0 = 1:
Mode1_BaudRate = 1 16 Timer1_OverflowRate
Rev. 1.4
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C8051F130/1/2/3
The Timer 1 overflow rate is determined by the Timer 1 clock source (T1CLK) and reload value (TH1). The
frequency of T1CLK is selected as described in Section “23.1. Timer 0 and Timer 1” on page 309. The
Timer 1 overflow rate is calculated as shown in Equation 21.2.
Equation 21.2. Timer 1 Overflow Rate
Timer1_OverflowRate = T1CLK 256 – TH1
When Timers 2, 3, or 4 are selected as a baud rate source, the baud rate is generated as shown in
Equation 21.3.
Equation 21.3. Mode 1 Baud Rate using Timer 2, 3, or 4
Mode1_BaudRate = 1 16 Timer234_OverflowRate
The overflow rate for Timer 2, 3, or 4 is determined by the clock source for the timer (TnCLK) and the 16-
bit reload value stored in the RCAPn register (n = 2, 3, or 4), as shown in Equation 21.4.
Equation 21.4. Timer 2, 3, or 4 Overflow Rate
Timer234_OverflowRate = TnCLK 65536 – RCAPn
290
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21.1.3. Mode 2: 9-Bit UART, Fixed Baud Rate
Mode 2 provides asynchronous, full-duplex communication using a total of eleven bits per data byte: a start
bit, 8 data bits (LSB first), a programmable ninth data bit, and a stop bit. Mode 2 supports multiprocessor
communications and hardware address recognition (see Section 21.2). On transmit, the ninth data bit is
determined by the value in TB80 (SCON0.3). It can be assigned the value of the parity flag P in the PSW or
used in multiprocessor communications. On receive, the ninth data bit goes into RB80 (SCON0.2) and the
stop bit is ignored.
Data transmission begins when an instruction writes a data byte to the SBUF0 register. The TI0 Transmit
Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data
reception can begin any time after the REN0 Receive Enable bit (SCON0.4) is set to logic 1. After the stop
bit is received, the data byte will be loaded into the SBUF0 receive register if RI0 is logic 0 and one of the
following requirements are met:
1. SM20 is logic 0
2. SM20 is logic 1, the received 9th bit is logic 1, and the received address matches the UART0
address as described in Section 21.2.
If the above conditions are satisfied, the eight bits of data are stored in SBUF0, the ninth bit is stored in
RB80 and the RI0 flag is set. If these conditions are not met, SBUF0 and RB80 will not be loaded and the
RI0 flag will not be set. An interrupt will occur if enabled when either TI0 or RI0 are set.
The baud rate in Mode 2 is either SYSCLK / 32 or SYSCLK / 64, according to the value of the SMOD0 bit
in register SSTA0.
Equation 21.5. Mode 2 Baud Rate
SYSCLK
BaudRate = 2SMOD0
---------------------
64
MARK
START
BIT
STOP
BIT
D0
D1
D2
D3
D4
D5
D6
D7
D8
SPACE
BIT TIMES
BIT SAMPLING
Figure 21.5. UART0 Modes 2 and 3 Timing Diagram
Rev. 1.4
291
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
TX
RX
RS-232
LEVEL
XLTR
RS-232
C8051Fxxx
OR
TX
RX
TX
RX
MCU
C8051Fxxx
Figure 21.6. UART0 Modes 1, 2, and 3 Interconnect Diagram
21.1.4. Mode 3: 9-Bit UART, Variable Baud Rate
Mode 3 uses the Mode 2 transmission protocol with the Mode 1 baud rate generation. Mode 3 operation
transmits 11 bits: a start bit, 8 data bits (LSB first), a programmable ninth data bit, and a stop bit. The baud
rate is derived from Timer 1 or Timer 2, 3, or 4 overflows, as defined by Equation 21.1 and Equation 21.3.
Multiprocessor communications and hardware address recognition are supported, as described in Section
21.2.
292
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21.2. Multiprocessor Communications
Modes 2 and 3 support multiprocessor communication between a master processor and one or more slave
processors by special use of the ninth data bit and the built-in UART0 address recognition hardware. When
a master processor wants to transmit to one or more slaves, it first sends an address byte to select the tar-
get(s). An address byte differs from a data byte in that its ninth bit is logic 1; in a data byte, the ninth bit is
always set to logic 0. UART0 will recognize as “valid” (i.e., capable of causing an interrupt) two types of
addresses: (1) a masked address and (2) a broadcast address at any given time. Both are described
below.
21.2.1. Configuration of a Masked Address
The UART0 address is configured via two SFR’s: SADDR0 (Serial Address) and SADEN0 (Serial Address
Enable). SADEN0 sets the bit mask for the address held in SADDR0: bits set to logic 1 in SADEN0 corre-
spond to bits in SADDR0 that are checked against the received address byte; bits set to logic 0 in SADEN0
correspond to “don’t care” bits in SADDR0.
Example 1, SLAVE #1
Example 2, SLAVE #2
Example 3, SLAVE #3
SADDR0
SADEN0
= 00110101
= 00001111
SADDR0
SADEN0
= 00110101
= 11110011
SADDR0
SADEN0
= 00110101
= 11000000
UART0 Address = xxxx0101
UART0 Address = 0011xx01
UART0 Address = 00xxxxxx
Setting the SM20 bit (SCON0.5) configures UART0 such that when a stop bit is received, UART0 will gen-
erate an interrupt only if the ninth bit is logic 1 (RB80 = ‘1’) and the received data byte matches the UART0
slave address. Following the received address interrupt, the slave will clear its SM20 bit to enable interrupts
on the reception of the following data byte(s). Once the entire message is received, the addressed slave
resets its SM20 bit to ignore all transmissions until it receives the next address byte. While SM20 is logic 1,
UART0 ignores all bytes that do not match the UART0 address and include a ninth bit that is logic 1.
21.2.2. Broadcast Addressing
Multiple addresses can be assigned to a single slave and/or a single address can be assigned to multiple
slaves, thereby enabling "broadcast" transmissions to more than one slave simultaneously. The broadcast
address is the logical OR of registers SADDR0 and SADEN0, and ‘0’s of the result are treated as “don’t
cares”. Typically a broadcast address of 0xFF (hexadecimal) is acknowledged by all slaves, assuming
“don’t care” bits as ‘1’s. The master processor can be configured to receive all transmissions or a protocol
can be implemented such that the master/slave role is temporarily reversed to enable half-duplex trans-
mission between the original master and slave(s)..
Example 4, SLAVE #1
Example 5, SLAVE #2
Example 6, SLAVE #3
SADDR0
SADEN0
= 00110101
= 00001111
SADDR0
SADEN0
= 00110101
= 11110011
SADDR0
SADEN0
= 00110101
= 11000000
Broadcast Address = 00111111
Broadcast Address = 11110111
Broadcast Address = 11110101
Where all ZEROES in the Broadcast address are don’t cares.
Note in the above examples 4, 5, and 6, each slave would recognize as “valid” an address of 0xFF as a
broadcast address. Also note that examples 4, 5, and 6 uses the same SADDR0 and SADEN0 register
values as shown in the examples 1, 2, and 3 respectively (slaves #1, 2, and 3). Thus, a master could
address each slave device individually using a masked address, and also broadcast to all three slave
devices. For example, if a Master were to send an address “11110101”, only slave #1 would recognize the
address as valid. If a master were to then send an address of “11111111”, all three slave devices would rec-
ognize the address as a valid broadcast address.
Rev. 1.4
293
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Master
Device
Slave
Device
Slave
Device
Slave
Device
+5V
RX
TX
RX
TX
RX
TX
RX
TX
Figure 21.7. UART Multi-Processor Mode Interconnect Diagram
21.3. Frame and Transmission Error Detection
All Modes:
The Transmit Collision bit (TXCOL0 bit in register SSTA0) reads ‘1’ if user software writes data to the
SBUF0 register while a transmit is in progress.
Modes 1, 2, and 3:
The Receive Overrun bit (RXOV0 in register SSTA0) reads ‘1’ if a new data byte is latched into the receive
buffer before software has read the previous byte. The Frame Error bit (FE0 in register SSTA0) reads ‘1’ if
an invalid (low) STOP bit is detected.
294
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C8051F130/1/2/3
Table 21.2. Oscillator Frequencies for Standard Baud Rates
Timer 2, 3, or
4 Reload
Value
Timer 1 Reload
System Clock
Frequency (MHz)
2
Divide Factor
Resulting Baud Rate (Hz)
1
Value
100.0
99.5328
50.0
864
864
0xCA
0xCA
0xE5
0xE5
0xF3
0xF4
0xF6
0xFA
0xFE
0xFF
0x27
0x28
0x93
0x94
0xCC
0xD0
0xD8
0xE8
0xF8
0xFC
-
0xFFCA
0xFFCA
0xFFE5
0xFFE5
0xFFF3
0xFFF4
0xFFF6
0xFFFA
0xFFFE
0xFFFF
0xFF27
0xFF28
0xFF93
0xFF94
0xFFCC
0xFFD0
0xFFD8
0xFFE8
0xFFF8
0xFFFC
0xFD75
0xFD78
0xFEBA
0xFEBC
0xFF64
0xFF70
0xFF88
0xFFB8
0xFFE8
0xFFF4
115200 (115741)
115200
432
115200 (115741)
115200
49.7664
24.0
432
208
115200 (115384)
115200
22.1184
18.432
11.0592
3.6864
1.8432
100.0
192
160
115200
96
115200
32
115200
16
115200
3472
3456
1744
1728
832
28800 (28802)
28800
99.5328
50.0
28800 (28670)
28800
49.7664
24.0
28800 (28846)
28800
22.1184
18.432
11.0592
3.6864
1.8432
100.0
768
640
28800
348
28800
128
28800
64
28800
10416
10368
5216
5184
2496
2304
1920
1152
384
9600 (9601)
9600
99.5328
50.0
-
-
9600 (9586)
9600
49.7664
24.0
-
0x64
0x70
0x88
0xB8
0xE8
0xF4
9600 (9615)
9600
22.1184
18.432
11.0592
3.6864
1.8432
9600
9600
9600
192
9600
Notes:
1. Assumes SMOD0 = 1 and T1M = 1.
2. Numbers in parenthesis show the actual baud rate.
Rev. 1.4
295
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 21.1. SCON0: UART0 Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
SM00
SM10
SM20
REN0
TB80
RB80
TI0
RI0
00000000
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0x98
SFR Page: 0
Bits7–6: SM00–SM10: Serial Port Operation Mode:
Write:
When written, these bits select the Serial Port Operation Mode as follows:
SM00
SM10
Mode
0
0
1
1
0
1
0
1
Mode 0: Synchronous Mode
Mode 1: 8-Bit UART, Variable Baud Rate
Mode 2: 9-Bit UART, Fixed Baud Rate
Mode 3: 9-Bit UART, Variable Baud Rate
Reading these bits returns the current UART0 mode as defined above.
SM20: Multiprocessor Communication Enable.
Bit5:
The function of this bit is dependent on the Serial Port Operation Mode.
Mode 0: No effect
Mode 1: Checks for valid stop bit.
0: Logic level of stop bit is ignored.
1: RI0 will only be activated if stop bit is logic level 1.
Mode 2 and 3: Multiprocessor Communications Enable.
0: Logic level of ninth bit is ignored.
1: RI0 is set and an interrupt is generated only when the ninth bit is logic 1 and the
received address matches the UART0 address or the broadcast address.
REN0: Receive Enable.
Bit4:
This bit enables/disables the UART0 receiver.
0: UART0 reception disabled.
1: UART0 reception enabled.
Bit3:
Bit2:
TB80: Ninth Transmission Bit.
The logic level of this bit will be assigned to the ninth transmission bit in Modes 2 and 3. It is
not used in Modes 0 and 1. Set or cleared by software as required.
RB80: Ninth Receive Bit.
The bit is assigned the logic level of the ninth bit received in Modes 2 and 3. In Mode 1, if
SM20 is logic 0, RB80 is assigned the logic level of the received stop bit. RB8 is not used in
Mode 0.
Bit1:
Bit0:
TI0: Transmit Interrupt Flag.
Set by hardware when a byte of data has been transmitted by UART0 (after the 8th bit in
Mode 0, or at the beginning of the stop bit in other modes). When the UART0 interrupt is
enabled, setting this bit causes the CPU to vector to the UART0 interrupt service routine.
This bit must be cleared manually by software
RI0: Receive Interrupt Flag.
Set by hardware when a byte of data has been received by UART0 (as selected by the
SM20 bit). When the UART0 interrupt is enabled, setting this bit causes the CPU to vector
to the UART0 interrupt service routine. This bit must be cleared manually by software.
296
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C8051F130/1/2/3
SFR Definition 21.2. SSTA0: UART0 Status and Clock Selection
R/W
FE0
Bit7
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
RXOV0 TXCOL0 SMOD0 S0TCLK1 S0TCLK0 S0RCLK1 S0RCLK0 00000000
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
SFR Address: 0x91
SFR Page: 0
Bit7:
FE0: Frame Error Flag.*
This flag indicates if an invalid (low) STOP bit is detected.
0: Frame Error has not been detected
1: Frame Error has been detected.
Bit6:
Bit5:
Bit4:
RXOV0: Receive Overrun Flag.*
This flag indicates new data has been latched into the receive buffer before software has
read the previous byte.
0: Receive overrun has not been detected.
1: Receive Overrun has been detected.
TXCOL0: Transmit Collision Flag.*
This flag indicates user software has written to the SBUF0 register while a transmission is
in progress.
0: Transmission Collision has not been detected.
1: Transmission Collision has been detected.
SMOD0: UART0 Baud Rate Doubler Enable.
This bit enables/disables the divide-by-two function of the UART0 baud rate logic for config-
urations described in the UART0 section.
0: UART0 baud rate divide-by-two enabled.
1: UART0 baud rate divide-by-two disabled.
Bits3–2: UART0 Transmit Baud Rate Clock Selection Bits
.
S0TCLK1 S0TCLK0
Serial Transmit Baud Rate Clock Source
0
0
1
1
0
1
0
1
Timer 1 generates UART0 TX Baud Rate
Timer 2 Overflow generates UART0 TX baud rate
Timer 3 Overflow generates UART0 TX baud rate
Timer 4 Overflow generates UART0 TX baud rate
Bits1–0: UART0 Receive Baud Rate Clock Selection Bits
S0RCLK1 S0RCLK0
Serial Receive Baud Rate Clock Source
0
0
1
1
0
1
0
1
Timer 1 generates UART0 RX Baud Rate
Timer 2 Overflow generates UART0 RX baud rate
Timer 3 Overflow generates UART0 RX baud rate
Timer 4 Overflow generates UART0 RX baud rate
*Note:
FE0, RXOV0, and TXCOL0 are flags only, and no interrupt is generated by these conditions.
Rev. 1.4
297
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 21.3. SBUF0: UART0 Data Buffer
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address: 0x99
SFR Page: 0
Bits7–0: SBUF0.[7:0]: UART0 Buffer Bits 7–0 (MSB–LSB)
This is actually two registers; a transmit and a receive buffer register. When data is moved
to SBUF0, it goes to the transmit buffer and is held for serial transmission. Moving a byte to
SBUF0 is what initiates the transmission. When data is moved from SBUF0, it comes from
the receive buffer.
SFR Definition 21.4. SADDR0: UART0 Slave Address
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Reset Value
00000000
Bit0
SFR Address: 0xA9
SFR Page: 0
Bits7–0: SADDR0.[7:0]: UART0 Slave Address
The contents of this register are used to define the UART0 slave address. Register SADEN0
is a bit mask to determine which bits of SADDR0 are checked against a received address:
corresponding bits set to logic 1 in SADEN0 are checked; corresponding bits set to logic 0
are “don’t cares”.
SFR Definition 21.5. SADEN0: UART0 Slave Address Enable
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Reset Value
00000000
Bit0
SFR Address: 0xB9
SFR Page: 0
Bits7–0: SADEN0.[7:0]: UART0 Slave Address Enable
Bits in this register enable corresponding bits in register SADDR0 to determine the UART0
slave address.
0: Corresponding bit in SADDR0 is a “don’t care”.
1: Corresponding bit in SADDR0 is checked against a received address.
298
Rev. 1.4
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C8051F130/1/2/3
22. UART1
UART1 is an asynchronous, full duplex serial port offering modes 1 and 3 of the standard 8051 UART.
Enhanced baud rate support allows a wide range of clock sources to generate standard baud rates (details
in Section “22.1. Enhanced Baud Rate Generation” on page 300). Received data buffering allows
UART1 to start reception of a second incoming data byte before software has finished reading the previous
data byte.
UART1 has two associated SFRs: Serial Control Register 1 (SCON1) and Serial Data Buffer 1 (SBUF1).
The single SBUF1 location provides access to both transmit and receive registers. Reading SBUF1
accesses the buffered Receive register; writing SBUF1 accesses the Transmit register.
With UART1 interrupts enabled, an interrupt is generated each time a transmit is completed (TI1 is set in
SCON1), or a data byte has been received (RI1 is set in SCON1). The UART1 interrupt flags are not
cleared by hardware when the CPU vectors to the interrupt service routine. They must be cleared manually
by software, allowing software to determine the cause of the UART1 interrupt (transmit complete or receive
complete).
SFR Bus
Write to
SBUF1
TB81
SBUF1
SET
(TX Shift)
D
Q
TX1
CLR
Crossbar
Zero Detector
Stop Bit
Shift
Data
Start
Tx Control
Tx Clock
Send
Tx IRQ
SCON1
TI1
UART1 Baud
Rate Generator
Serial
Port
Interrupt
Port I/O
RI1
Rx IRQ
Rx Clock
Rx Control
Load
SBUF1
Start
Shift
0x1FF
RB81
Input Shift Register
(9 bits)
Load SBUF1
SBUF1
(RX Latch)
Read
SBUF1
SFR Bus
RX1
Crossbar
Figure 22.1. UART1 Block Diagram
Rev. 1.4
299
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
22.1. Enhanced Baud Rate Generation
The UART1 baud rate is generated by Timer 1 in 8-bit auto-reload mode. The TX clock is generated by
TL1; the RX clock is generated by a copy of TL1 (shown as RX Timer in Figure 22.2), which is not user-
accessible. Both TX and RX Timer overflows are divided by two to generate the TX and RX baud rates.
The RX Timer runs when Timer 1 is enabled, and uses the same reload value (TH1). However, an
RX Timer reload is forced when a START condition is detected on the RX pin. This allows a receive to
begin any time a START is detected, independent of the TX Timer state.
Timer 1
TL1
UART1
Overflow
TX Clock
2
TH1
Start
Detected
Overflow
RX Clock
RX Timer
2
Figure 22.2. UART1 Baud Rate Logic
Timer 1 should be configured for Mode 2, 8-bit auto-reload (see Section “23.1.3. Mode 2: 8-bit Counter/
Timer with Auto-Reload” on page 311). The Timer 1 reload value should be set so that overflows will
occur at two times the desired baud rate. Note that Timer 1 may be clocked by one of five sources: SYS-
CLK, SYSCLK / 4, SYSCLK / 12, SYSCLK / 48, or the external oscillator clock / 8. For any given Timer 1
clock source, the UART1 baud rate is determined by Equation 22.1.
Equation 22.1. UART1 Baud Rate
T1CLK
------------------------------ --
1
UARTBaudRate =
256 – T1H 2
Where T1CLK is the frequency of the clock supplied to Timer 1, and T1H is the high byte of Timer 1 (reload
value). Timer 1 clock frequency is selected as described in Section “23.1. Timer 0 and Timer 1” on
page 309. A quick reference for typical baud rates and system clock frequencies is given in Table 22.1
through Table 22.5. Note that the internal oscillator or PLL may still generate the system clock when the
external oscillator is driving Timer 1 (see Section “23.1. Timer 0 and Timer 1” on page 309 for more
details).
300
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C8051F130/1/2/3
22.2. Operational Modes
UART1 provides standard asynchronous, full duplex communication. The UART mode (8-bit or 9-bit) is
selected by the S1MODE bit (SCON1.7). Typical UART connection options are shown below.
TX
RS-232
RS-232
LEVEL
C8051Fxxx
RX
XLTR
OR
TX
RX
TX
RX
MCU
C8051Fxxx
Figure 22.3. UART Interconnect Diagram
22.2.1. 8-Bit UART
8-Bit UART mode uses a total of 10 bits per data byte: one start bit, eight data bits (LSB first), and one stop
bit. Data are transmitted LSB first from the TX1 pin and received at the RX1 pin. On receive, the eight data
bits are stored in SBUF1 and the stop bit goes into RB81 (SCON1.2).
Data transmission begins when software writes a data byte to the SBUF1 register. The TI1 Transmit Inter-
rupt Flag (SCON1.1) is set at the end of the transmission (the beginning of the stop-bit time). Data recep-
tion can begin any time after the REN1 Receive Enable bit (SCON1.4) is set to logic 1. After the stop bit is
received, the data byte will be loaded into the SBUF1 receive register if the following conditions are met:
RI1 must be logic 0, and if MCE1 is logic 1, the stop bit must be logic 1. In the event of a receive data over-
run, the first received 8 bits are latched into the SBUF1 receive register and the following overrun data bits
are lost.
If these conditions are met, the eight bits of data is stored in SBUF1, the stop bit is stored in RB81 and the
RI1 flag is set. If these conditions are not met, SBUF1 and RB81 will not be loaded and the RI1 flag will not
be set. An interrupt will occur if enabled when either TI1 or RI1 is set.
MARK
START
BIT
STOP
BIT
D0
D1
D2
D3
D4
D5
D6
D7
SPACE
BIT TIMES
BIT SAMPLING
Figure 22.4. 8-Bit UART Timing Diagram
Rev. 1.4
301
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
22.2.2. 9-Bit UART
9-bit UART mode uses a total of eleven bits per data byte: a start bit, 8 data bits (LSB first), a programma-
ble ninth data bit, and a stop bit. The state of the ninth transmit data bit is determined by the value in TB81
(SCON1.3), which is assigned by user software. It can be assigned the value of the parity flag (bit P in reg-
ister PSW) for error detection, or used in multiprocessor communications. On receive, the ninth data bit
goes into RB81 (SCON1.2) and the stop bit is ignored.
Data transmission begins when an instruction writes a data byte to the SBUF1 register. The TI1 Transmit
Interrupt Flag (SCON1.1) is set at the end of the transmission (the beginning of the stop-bit time). Data
reception can begin any time after the REN1 Receive Enable bit (SCON1.4) is set to ‘1’. After the stop bit
is received, the data byte will be loaded into the SBUF1 receive register if the following conditions are met:
(1) RI1 must be logic 0, and (2) if MCE1 is logic 1, the 9th bit must be logic 1 (when MCE1 is logic 0, the
state of the ninth data bit is unimportant). If these conditions are met, the eight bits of data are stored in
SBUF1, the ninth bit is stored in RB81, and the RI1 flag is set to ‘1’. If the above conditions are not met,
SBUF1 and RB81 will not be loaded and the RI1 flag will not be set to ‘1’. A UART1 interrupt will occur if
enabled when either TI1 or RI1 is set to ‘1’.
MARK
START
BIT
STOP
BIT
D0
D1
D2
D3
D4
D5
D6
D7
D8
SPACE
BIT TIMES
BIT SAMPLING
Figure 22.5. 9-Bit UART Timing Diagram
302
Rev. 1.4
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C8051F130/1/2/3
22.3. Multiprocessor Communications
9-Bit UART mode supports multiprocessor communication between a master processor and one or more
slave processors by special use of the ninth data bit. When a master processor wants to transmit to one or
more slaves, it first sends an address byte to select the target(s). An address byte differs from a data byte
in that its ninth bit is logic 1; in a data byte, the ninth bit is always set to logic 0.
Setting the MCE1 bit (SCON.5) of a slave processor configures its UART such that when a stop bit is
received, the UART will generate an interrupt only if the ninth bit is logic one (RB81 = 1) signifying an
address byte has been received. In the UART interrupt handler, software should compare the received
address with the slave's own assigned 8-bit address. If the addresses match, the slave should clear its
MCE1 bit to enable interrupts on the reception of the following data byte(s). Slaves that weren't addressed
leave their MCE1 bits set and do not generate interrupts on the reception of the following data bytes,
thereby ignoring the data. Once the entire message is received, the addressed slave should reset its
MCE1 bit to ignore all transmissions until it receives the next address byte.
Multiple addresses can be assigned to a single slave and/or a single address can be assigned to multiple
slaves, thereby enabling "broadcast" transmissions to more than one slave simultaneously. The master
processor can be configured to receive all transmissions or a protocol can be implemented such that the
master/slave role is temporarily reversed to enable half-duplex transmission between the original master
and slave(s).
Master
Device
Slave
Device
Slave
Device
Slave
Device
+5V
RX
TX
RX
TX
RX
TX
RX
TX
Figure 22.6. UART Multi-Processor Mode Interconnect Diagram
Rev. 1.4
303
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 22.1. SCON1: Serial Port 1 Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
S1MODE
-
MCE1
REN1
TB81
RB81
TI1
RI1
01000000
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0x98
SFR Page: 1
Bit7:
S1MODE: Serial Port 1 Operation Mode.
This bit selects the UART1 Operation Mode.
0: Mode 0: 8-bit UART with Variable Baud Rate
1: Mode 1: 9-bit UART with Variable Baud Rate
UNUSED. Read = 1b. Write = don’t care.
MCE1: Multiprocessor Communication Enable.
Bit6:
Bit5:
The function of this bit is dependent on the Serial Port 0 Operation Mode.
Mode 0: Checks for valid stop bit.
0: Logic level of stop bit is ignored.
1: RI1 will only be activated if stop bit is logic level 1.
Mode 1: Multiprocessor Communications Enable.
0: Logic level of ninth bit is ignored.
1: RI1 is set and an interrupt is generated only when the ninth bit is logic 1.
REN1: Receive Enable.
Bit4:
This bit enables/disables the UART receiver.
0: UART1 reception disabled.
1: UART1 reception enabled.
Bit3:
Bit2:
Bit1:
TB81: Ninth Transmission Bit.
The logic level of this bit will be assigned to the ninth transmission bit in 9-bit UART Mode. It
is not used in 8-bit UART Mode. Set or cleared by software as required.
RB81: Ninth Receive Bit.
RB81 is assigned the value of the STOP bit in Mode 0; it is assigned the value of the 9th
data bit in Mode 1.
TI1: Transmit Interrupt Flag.
Set by hardware when a byte of data has been transmitted by UART1 (after the 8th bit in 8-
bit UART Mode, or at the beginning of the STOP bit in 9-bit UART Mode). When the UART1
interrupt is enabled, setting this bit causes the CPU to vector to the UART1 interrupt service
routine. This bit must be cleared manually by software
RI1: Receive Interrupt Flag.
Bit0:
Set to ‘1’ by hardware when a byte of data has been received by UART1 (set at the STOP bit
sampling time). When the UART1 interrupt is enabled, setting this bit to ‘1’ causes the CPU
to vector to the UART1 interrupt service routine. This bit must be cleared manually by soft-
ware.
304
Rev. 1.4
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C8051F130/1/2/3
SFR Definition 22.2. SBUF1: Serial (UART1) Port Data Buffer
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Reset Value
00000000
Bit0
SFR Address: 0x99
SFR Page: 1
Bits7–0: SBUF1[7:0]: Serial Data Buffer Bits 7-0 (MSB-LSB)
This SFR accesses two registers; a transmit shift register and a receive latch register. When
data is written to SBUF1, it goes to the transmit shift register and is held for serial transmis-
sion. Writing a byte to SBUF1 is what initiates the transmission. A read of SBUF1 returns the
contents of the receive latch.
Table 22.1. Timer Settings for Standard Baud Rates Using The Internal 24.5 MHz
Oscillator
Frequency: 24.5 MHz
Target
Baud Rate
(bps)
230400
115200
57600
Baud Rate
% Error
Oscilla- Timer Clock
SCA1-SCA0
(pre-scale
T1M*
Timer 1
Reload
Value (hex)
0xCB
tor Divide
Factor
106
Source
select)*
XX
XX
XX
01
-0.32%
-0.32%
0.15%
-0.32%
0.15%
-0.32%
-0.32%
0.15%
SYSCLK
SYSCLK
1
1
1
0
0
0
0
0
212
0x96
0x2B
0x96
0xB9
0x96
0x96
0x2B
426
SYSCLK
28800
14400
9600
2400
848
SYSCLK / 4
SYSCLK / 12
SYSCLK / 12
SYSCLK / 48
SYSCLK / 48
1704
2544
10176
20448
00
00
10
10
1200
X = Don’t care
*Note: SCA1-SCA0 and T1M bit definitions can be found in Section 23.1.
Rev. 1.4
305
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 22.2. Timer Settings for Standard Baud Rates Using an External 25.0 MHz
Oscillator
Frequency: 25.0 MHz
Target
Baud Rate
(bps)
230400
115200
57600
28800
14400
9600
Baud Rate
% Error
Oscilla- Timer Clock
SCA1-SCA0
(pre-scale
T1M*
Timer 1
Reload
Value (hex)
0xCA
tor Divide
Factor
108
Source
select)*
XX
XX
XX
01
-0.47%
0.45%
-0.01%
0.45%
-0.01%
0.15%
0.45%
-0.01%
-0.47%
-0.47%
0.45%
SYSCLK
SYSCLK
1
1
1
0
0
0
0
0
0
0
0
218
0x93
0x27
0x93
0x27
0x5D
0x93
0x27
0xE5
434
SYSCLK
872
SYSCLK / 4
SYSCLK / 4
EXTCLK / 8
SYSCLK / 48
SYSCLK / 48
EXTCLK / 8
EXTCLK / 8
EXTCLK / 8
1736
2608
10464
20832
432
01
11
10
10
11
11
11
2400
1200
57600
28800
14400
864
1744
0xCA
0x93
9600
0.15%
2608
EXTCLK / 8
11
0
0x5D
X = Don’t care
*Note: SCA1-SCA0 and T1M bit definitions can be found in Section 23.1.
Table 22.3. Timer Settings for Standard Baud Rates Using an External 22.1184 MHz
Oscillator
Frequency: 22.1184 MHz
Target
Baud Rate
(bps)
230400
115200
57600
Baud Rate
% Error
Oscilla- Timer Clock
SCA1-SCA0
(pre-scale
T1M*
Timer 1
Reload
Value (hex)
0xD0
tor Divide
Factor
96
Source
select)*
XX
XX
XX
00
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
0.00%
SYSCLK
SYSCLK
1
1
1
0
0
0
0
0
0
0
0
0
0
0
192
0xA0
0x40
0xE0
0xC0
0xA0
0xA0
0x40
0xFA
0xF4
0xE8
0xD0
0xA0
384
SYSCLK
28800
14400
9600
2400
768
SYSCLK / 12
SYSCLK / 12
SYSCLK / 12
SYSCLK / 48
SYSCLK / 48
EXTCLK / 8
EXTCLK / 8
EXTCLK / 8
EXTCLK / 8
EXTCLK / 8
EXTCLK / 8
1536
2304
9216
18432
96
192
384
768
1536
2304
00
00
10
10
11
11
11
11
1200
230400
115200
57600
28800
14400
11
11
9600
0x70
X = Don’t care
*Note: SCA1-SCA0 and T1M bit definitions can be found in Section 23.1.
306
Rev. 1.4
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C8051F130/1/2/3
Table 22.4. Timer Settings for Standard Baud Rates Using the PLL
Frequency: 50.0 MHz
Target
Baud Rate
(bps)
230400
115200
57600
Baud Rate
% Error
Oscilla- Timer Clock
SCA1-SCA0
(pre-scale
T1M*
Timer 1
Reload
Value (hex)
0x93
tor Divide
Factor
218
Source
select)*
0.45%
-0.01%
0.45%
-0.01%
0.22%
-0.01%
-0.01%
SYSCLK
SYSCLK
XX
XX
01
01
00
00
10
1
1
0
0
0
0
0
434
0x27
0x93
0x27
0x6F
0x27
0x27
872
1736
3480
5208
SYSCLK / 4
SYSCLK / 4
SYSCLK / 12
SYSCLK / 12
SYSCLK / 48
28800
14400
9600
2400
20832
X = Don’t care
*Note: SCA1-SCA0 and T1M bit definitions can be found in Section 23.1.
Table 22.5. Timer Settings for Standard Baud Rates Using the PLL
Frequency: 100.0 MHz
Target
Baud Rate
(bps)
230400
115200
57600
Baud Rate
% Error
Oscilla- Timer Clock
SCA1-SCA0
(pre-scale
T1M*
Timer 1
Reload
Value (hex)
0x27
tor Divide
Factor
434
Source
select)*
-0.01%
0.45%
-0.01%
0.22%
-0.47%
0.45%
SYSCLK
XX
01
01
00
10
10
1
0
0
0
0
0
872
1736
3480
6912
SYSCLK / 4
SYSCLK / 4
SYSCLK / 12
SYSCLK / 48
SYSCLK / 48
0x93
0x27
0x6F
0xB8
28800
14400
9600
10464
0x93
X = Don’t care
*Note: SCA1-SCA0 and T1M bit definitions can be found in Section 23.1.
Rev. 1.4
307
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
NOTES:
308
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
23. Timers
Each MCU includes 5 counter/timers: Timer 0 and Timer 1 are 16-bit counter/timers compatible with those
found in the standard 8051. Timer 2, Timer 3, and Timer 4 are 16-bit auto-reload and capture counter/tim-
ers for use with the ADCs, DACs, square-wave generation, or for general-purpose use. These timers can
be used to measure time intervals, count external events and generate periodic interrupt requests. Timer 0
and Timer 1 are nearly identical and have four primary modes of operation. Timer 3 offers 16-bit auto-
reload and capture. Timers 2 and 4 are identical, and offer not only 16-bit auto-reload and capture, but
have the ability to produce a 50% duty-cycle square-wave (toggle output) at an external port pin.
Timer 0 and Timer 1 Modes:
13-bit counter/timer
16-bit counter/timer
8-bit counter/timer with auto-reload
Two 8-bit counter/timers (Timer 0 only)
Timer 2, 3 and 4 Modes:
16-bit counter/timer with auto-reload
16-bit counter/timer with capture
Toggle Output (Timer 2 and 4 only)
Timers 0 and 1 may be clocked by one of five sources, determined by the Timer Mode Select bits (T1M-
T0M) and the Clock Scale bits (SCA1-SCA0). The Clock Scale bits define a pre-scaled clock by which
Timer 0 and/or Timer 1 may be clocked (See SFR Definition 23.3 for pre-scaled clock selection). Timers 0
and 1 can be configured to use either the pre-scaled clock signal or the system clock directly. Timers 2, 3,
and 4 may be clocked by the system clock, the system clock divided by 12, or the external oscillator clock
source divided by 8.
Timer 0 and Timer 1 may also be operated as counters. When functioning as a counter, a counter/timer
register is incremented on each high-to-low transition at the selected input pin. Events with a frequency of
up to one-fourth the system clock's frequency can be counted. The input signal need not be periodic, but it
should be held at a given logic level for at least two full system clock cycles to ensure the level is properly
sampled.
23.1. Timer 0 and Timer 1
Each timer is implemented as a 16-bit register accessed as two separate 8-bit SFRs: a low byte (TL0 or
TL1) and a high byte (TH0 or TH1). The Counter/Timer Control register (TCON) is used to enable Timer 0
and Timer 1 as well as indicate their status. Timer 0 interrupts can be enabled by setting the ET0 bit in the
IE register (Section “11.3.5. Interrupt Register Descriptions” on page 157); Timer 1 interrupts can be
enabled by setting the ET1 bit in the IE register (Section 11.3.5). Both counter/timers operate in one of
four primary modes selected by setting the Mode Select bits T1M1–T0M0 in the Counter/Timer Mode reg-
ister (TMOD). Both timers can be configured independently.
23.1.1. Mode 0: 13-bit Counter/Timer
Timer 0 and Timer 1 operate as 13-bit counter/timers in Mode 0. The following describes the configuration
and operation of Timer 0. However, both timers operate identically, and Timer 1 is configured in the same
manner as described for Timer 0.
The TH0 register holds the eight MSBs of the 13-bit counter/timer. TL0 holds the five LSBs in bit positions
TL0.4–TL0.0. The three upper bits of TL0 (TL0.7–TL0.5) are indeterminate and should be masked out or
ignored when reading the TL0 register. As the 13-bit timer register increments and overflows from 0x1FFF
(all ones) to 0x0000, the timer overflow flag TF0 (TCON.5) is set and an interrupt will occur if Timer 0 inter-
rupts are enabled.
Rev. 1.4
309
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
The C/T0 bit (TMOD.2) selects the counter/timer's clock source. When C/T0 is set to logic 1, high-to-low
transitions at the selected Timer 0 input pin (T0) increment the timer register (Refer to Section
“18.1. Ports 0 through 3 and the Priority Crossbar Decoder” on page 238 for information on selecting
and configuring external I/O pins). Clearing C/T selects the clock defined by the T0M bit (CKCON.3). When
T0M is set, Timer 0 is clocked by the system clock. When T0M is cleared, Timer 0 is clocked by the source
selected by the Clock Scale bits in CKCON (see SFR Definition 23.3).
Setting the TR0 bit (TCON.4) enables the timer when either GATE0 (TMOD.3) is logic 0 or the input signal
/INT0 is logic-level 1. Setting GATE0 to ‘1’ allows the timer to be controlled by the external input signal /
INT0 (see Section “11.3.5. Interrupt Register Descriptions” on page 157), facilitating pulse width mea-
surements.
TR0
0
1
1
1
GATE0
/INT0
Counter/Timer
Disabled
X
0
1
1
X
X
0
1
Enabled
Disabled
Enabled
X = Don't Care
Setting TR0 does not force the timer to reset. The timer registers should be loaded with the desired initial
value before the timer is enabled.
TL1 and TH1 form the 13-bit register for Timer 1 in the same manner as described above for TL0 and TH0.
Timer 1 is configured and controlled using the relevant TCON and TMOD bits just as with Timer 0. The
input signal /INT1 is used with Timer 1.
CKCON
T T S S
1 0 C C
M M A A
1 0
TMOD
G C T T G C T T
A
/
1
1 A
/ 0 0
T T M M T T M M
E 1
1
1
0 E 0
0
1 0
Pre-scaled Clock
SYSCLK
0
1
0
1
TF1
TR1
TF0
TR0
IE1
IT1
T0
Interrupt
TCLK
TL0
(5 bits)
TH0
(8 bits)
TR0
GATE0
IE0
IT0
Crossbar
/INT0
Figure 23.1. T0 Mode 0 Block Diagram
310
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
23.1.2. Mode 1: 16-bit Counter/Timer
Mode 1 operation is the same as Mode 0, except that the counter/timer registers use all 16 bits. The coun-
ter/timers are enabled and configured in Mode 1 in the same manner as for Mode 0.
23.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload
Mode 2 configures Timer 0 or Timer 1 to operate as 8-bit counter/timers with automatic reload of the start
value. TL0 holds the count and TH0 holds the reload value. When the counter in TL0 overflows from 0xFF
to 0x00, the timer overflow flag TF0 (TCON.5) is set and the counter in TL0 is reloaded from TH0. If Timer
0 interrupts are enabled, an interrupt will occur when the TF0 flag is set. The reload value in TH0 is not
changed. TL0 must be initialized to the desired value before enabling the timer for the first count to be cor-
rect. When in Mode 2, Timer 1 operates identically to Timer 0.
Both counter/timers are enabled and configured in Mode 2 in the same manner as Mode 0. Setting the
TR0 bit (TCON.4) enables the timer when either GATE0 (TMOD.3) is logic 0 or when the input signal /INT0
is low
.
CKCON
T T S S
1 0 C C
M M A A
1 0
TMOD
G C T T G C T T
/ 1 1 A / 0 0
T T M M T T M M
E 1 1 0 E 0 1 0
A
1
0
Pre-scaled Clock
SYSCLK
0
1
0
1
T0
TF1
TR1
TF0
TR0
IE1
IT1
TCLK
TL0
(8 bits)
Interrupt
TR0
IE0
IT0
Crossbar
GATE0
TH0
Reload
(8 bits)
/INT0
Figure 23.2. T0 Mode 2 Block Diagram
Rev. 1.4
311
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
23.1.4. Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)
In Mode 3, Timer 0 is configured as two separate 8-bit counter/timers held in TL0 and TH0. The counter/
timer in TL0 is controlled using the Timer 0 control/status bits in TCON and TMOD: TR0, C/T0, GATE0 and
TF0. TL0 can use either the system clock or an external input signal as its timebase. The TH0 register is
restricted to a timer function sourced by the system clock or prescaled clock. TH0 is enabled using the
Timer 1 run control bit TR1. TH0 sets the Timer 1 overflow flag TF1 on overflow and thus controls the
Timer 1 interrupt.
Timer 1 is inactive in Mode 3. When Timer 0 is operating in Mode 3, Timer 1 can be operated in Modes 0,
1 or 2, but cannot be clocked by external signals nor set the TF1 flag and generate an interrupt. However,
the Timer 1 overflow can be used to generate baud rates for the SMBus and/or UART, and/or initiate ADC
conversions. While Timer 0 is operating in Mode 3, Timer 1 run control is handled through its mode set-
tings. To run Timer 1 while Timer 0 is in Mode 3, set the Timer 1 Mode as 0, 1, or 2. To disable Timer 1,
configure it for Mode 3.
CKCON
T T S S
1 0 C C
M M A A
1 0
TMOD
G C T T G C T T
/ 1 1 A / 0 0
T T M M T T M M
E 1 1 0 E 0 1 0
A
1
0
Pre-scaled Clock
SYSCLK
0
1
TH0
(8 bits)
TR1
Interrupt
Interrupt
TF1
TR1
TF0
TR0
IE1
0
IT1
IE0
IT0
1
T0
TL0
(8 bits)
TR0
Crossbar
GATE0
/INT0
Figure 23.3. T0 Mode 3 Block Diagram
312
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 23.1. TCON: Timer Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
00000000
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: 0x88
SFR Page: 0
Bit7:
TF1: Timer 1 Overflow Flag.
Set by hardware when Timer 1 overflows. This flag can be cleared by software but is auto-
matically cleared when the CPU vectors to the Timer 1 interrupt service routine.
0: No Timer 1 overflow detected.
1: Timer 1 has overflowed.
Bit6:
Bit5:
TR1: Timer 1 Run Control.
0: Timer 1 disabled.
1: Timer 1 enabled.
TF0: Timer 0 Overflow Flag.
Set by hardware when Timer 0 overflows. This flag can be cleared by software but is auto-
matically cleared when the CPU vectors to the Timer 0 interrupt service routine.
0: No Timer 0 overflow detected.
1: Timer 0 has overflowed.
Bit4:
Bit3:
TR0: Timer 0 Run Control.
0: Timer 0 disabled.
1: Timer 0 enabled.
IE1: External Interrupt 1.
This flag is set by hardware when an edge/level of type defined by IT1 is detected. It can be
cleared by software but is automatically cleared when the CPU vectors to the External Inter-
rupt 1 service routine if IT1 = 1. This flag is the inverse of the /INT1 signal.
IT1: Interrupt 1 Type Select.
Bit2:
This bit selects whether the configured /INT1 interrupt will be falling-edge sensitive or
active-low.
0: /INT1 is level triggered, active-low.
1: /INT1 is edge triggered, falling-edge.
Bit1:
Bit0:
IE0: External Interrupt 0.
This flag is set by hardware when an edge/level of type defined by IT0 is detected. It can be
cleared by software but is automatically cleared when the CPU vectors to the External Inter-
rupt 0 service routine if IT0 = 1. This flag is the inverse of the /INT0 signal.
IT0: Interrupt 0 Type Select.
This bit selects whether the configured /INT0 interrupt will be falling-edge sensitive or
active-low.
0: /INT0 is level triggered, active logic-low.
1: /INT0 is edge triggered, falling-edge.
Rev. 1.4
313
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 23.2. TMOD: Timer Mode
R/W
GATE1
Bit7
R/W
C/T1
Bit6
R/W
T1M1
Bit5
R/W
T1M0
Bit4
R/W
GATE0
Bit3
R/W
C/T0
Bit2
R/W
T0M1
Bit1
R/W
T0M0
Bit0
Reset Value
00000000
SFR Address: 0x89
SFR Page: 0
Bit7:
GATE1: Timer 1 Gate Control.
0: Timer 1 enabled when TR1 = 1 irrespective of /INT1 logic level.
1: Timer 1 enabled only when TR1 = 1 AND /INT1 = logic 1.
C/T1: Counter/Timer 1 Select.
Bit6:
0: Timer Function: Timer 1 incremented by clock defined by T1M bit (CKCON.4).
1: Counter Function: Timer 1 incremented by high-to-low transitions on external input pin
(T1).
Bits5–4: T1M1–T1M0: Timer 1 Mode Select.
These bits select the Timer 1 operation mode.
T1M1
T1M0
Mode
0
0
1
1
0
1
0
1
Mode 0: 13-bit counter/timer
Mode 1: 16-bit counter/timer
Mode 2: 8-bit counter/timer with auto-reload
Mode 3: Timer 1 inactive
Bit3:
Bit2:
GATE0: Timer 0 Gate Control.
0: Timer 0 enabled when TR0 = 1 irrespective of /INT0 logic level.
1: Timer 0 enabled only when TR0 = 1 AND /INT0 = logic 1.
C/T0: Counter/Timer Select.
0: Timer Function: Timer 0 incremented by clock defined by T0M bit (CKCON.3).
1: Counter Function: Timer 0 incremented by high-to-low transitions on external input pin
(T0).
Bits1–0: T0M1–T0M0: Timer 0 Mode Select.
These bits select the Timer 0 operation mode.
T0M1
T0M0
Mode
0
0
1
1
0
1
0
1
Mode 0: 13-bit counter/timer
Mode 1: 16-bit counter/timer
Mode 2: 8-bit counter/timer with auto-reload
Mode 3: Two 8-bit counter/timers
314
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 23.3. CKCON: Clock Control
R/W
-
R/W
-
R/W
-
R/W
T1M
Bit4
R/W
T0M
Bit3
R/W
-
R/W
SCA1
Bit1
R/W
Reset Value
SCA0 00000000
Bit0
Bit7
Bit6
Bit5
Bit2
SFR Address: 0x8E
SFR Page: 0
Bits7–5: UNUSED. Read = 000b, Write = don’t care.
Bit4:
T1M: Timer 1 Clock Select.
This select the clock source supplied to Timer 1. T1M is ignored when C/T1 is set to logic 1.
0: Timer 1 uses the clock defined by the prescale bits, SCA1–SCA0.
1: Timer 1 uses the system clock.
Bit3:
T0M: Timer 0 Clock Select.
This bit selects the clock source supplied to Timer 0. T0M is ignored when C/T0 is set to
logic 1.
0: Counter/Timer 0 uses the clock defined by the prescale bits, SCA1-SCA0.
1: Counter/Timer 0 uses the system clock.
Bit2:
UNUSED. Read = 0b, Write = don’t care.
Bits1–0: SCA1–SCA0: Timer 0/1 Prescale Bits
These bits control the division of the clock supplied to Timer 0 and/or Timer 1 if configured
to use prescaled clock inputs.
SCA1
SCA0
Prescaled Clock
0
0
1
1
0
1
0
1
System clock divided by 12
System clock divided by 4
System clock divided by 48
External clock divided by 8*
*Note: External clock divided by 8 is synchronized with the system
clock, and external clock must be less than or equal to the
system clock frequency to operate the timer in this mode.
SFR Definition 23.4. TL0: Timer 0 Low Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address: 0x8A
SFR Page: 0
Bits 7–0: TL0: Timer 0 Low Byte.
The TL0 register is the low byte of the 16-bit Timer 0.
Rev. 1.4
315
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 23.5. TL1: Timer 1 Low Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address: 0x8B
SFR Page: 0
Bits 7–0: TL1: Timer 1 Low Byte.
The TL1 register is the low byte of the 16-bit Timer 1.
SFR Definition 23.6. TH0: Timer 0 High Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address: 0x8C
SFR Page: 0
Bits 7–0: TH0: Timer 0 High Byte.
The TH0 register is the high byte of the 16-bit Timer 0.
SFR Definition 23.7. TH1: Timer 1 High Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address: 0x8D
SFR Page: 0
Bits 7–0: TH1: Timer 1 High Byte.
The TH1 register is the high byte of the 16-bit Timer 1.
316
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
23.2. Timer 2, Timer 3, and Timer 4
Timers 2, 3, and 4 are 16-bit counter/timers, each formed by two 8-bit SFR’s: TMRnL (low byte) and
TMRnH (high byte) where n = 2, 3, and 4 for timers 2, 3, and 4 respectively. Timers 2 and 4 feature auto-
reload, capture, and toggle output modes with the ability to count up or down. Timer 3 features auto-reload
and capture modes, with the ability to count up or down. Capture Mode and Auto-reload mode are selected
using bits in the Timer 2, 3, and 4 Control registers (TMRnCN). Toggle output mode is selected using the
Timer 2 or 4 Configuration registers (TMRnCF). These timers may also be used to generate a square-
wave at an external pin. As with Timers 0 and 1, Timers 2, 3, and 4 can use either the system clock
(divided by one, two, or twelve), external clock (divided by eight) or transitions on an external input pin as
its clock source. Timer 2 and 3 can be used to start an ADC Data Conversion and Timers 2, 3, and 4 can
schedule DAC outputs. Timers 1, 2, 3, or 4 may be used to generate baud rates for UART 0. Only Timer 1
can be used to generate baud rates for UART 1.
The Counter/Timer Select bit C/Tn bit (TMRnCN.1) configures the peripheral as a counter or timer. Clear-
ing C/Tn configures the Timer to be in a timer mode (i.e., the system clock or transitions on an external pin
as the input for the timer). When C/Tn is set to 1, the timer is configured as a counter (i.e., high-to-low tran-
sitions at the Tn input pin increment (or decrement) the counter/timer register. Timer 3 and Timer 2 share
the T2 input pin. Refer to Section “18.1. Ports 0 through 3 and the Priority Crossbar Decoder” on
page 238 for information on selecting and configuring external I/O pins for digital peripherals, such as the
Tn pin.
Timer 2, 3, and 4 can use either SYSCLK, SYSCLK divided by 2, SYSCLK divided by 12, an external clock
divided by 8, or high-to-low transitions on the Tn input pin as its clock source when operating in Counter/
Timer with Capture mode. Clearing the C/Tn bit (TMRnCN.1) selects the system clock/external clock as
the input for the timer. The Timer Clock Select bits TnM0 and TnM1 in TMRnCF can be used to select the
system clock undivided, system clock divided by two, system clock divided by 12, or an external clock pro-
vided at the XTAL1/XTAL2 pins divided by 8 (see SFR Definition 23.13). When C/Tn is set to logic 1, a
high-to-low transition at the Tn input pin increments the counter/timer register (i.e., configured as a coun-
ter).
23.2.1. Configuring Timer 2, 3, and 4 to Count Down
Timers 2, 3, and 4 have the ability to count down. When the timer’s Decrement Enable Bit (DCENn) in the
Timer Configuration Register (See SFR Definition 23.13) is set to ‘1’, the timer can then count up or down.
When DCENn = 1, the direction of the timer’s count is controlled by the TnEX pin’s logic level (Timer 3
shares the T2EX pin with Timer 2). When TnEX = 1, the counter/timer will count up; when TnEX = 0, the
counter/timer will count down. To use this feature, TnEX must be enabled in the digital crossbar and config-
ured as a digital input.
Note: When DCENn = 1, other functions of the TnEX input (i.e., capture and auto-reload) are not
available. TnEX will only control the direction of the timer when DCENn = 1.
Rev. 1.4
317
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
23.2.2. Capture Mode
In Capture Mode, Timer 2, 3, and 4 will operate as a 16-bit counter/timer with capture facility. When the
Timer External Enable bit (found in the TMRnCN register) is set to ‘1’, a high-to-low transition on the TnEX
input pin (Timer 3 shares the T2EX pin with Timer 2) causes the 16-bit value in the associated timer (THn,
TLn) to be loaded into the capture registers (RCAPnH, RCAPnL). If a capture is triggered in the counter/
timer, the Timer External Flag (TMRnCN.6) will be set to ‘1’ and an interrupt will occur if the interrupt is
enabled. See Section “11.3. Interrupt Handler” on page 154 for further information concerning the con-
figuration of interrupt sources.
As the 16-bit timer register increments and overflows TMRnH:TMRnL, the TFn Timer Overflow/Underflow
Flag (TMRnCN.7) is set to ‘1’ and an interrupt will occur if the interrupt is enabled. The timer can be config-
ured to count down by setting the Decrement Enable Bit (TMRnCF.0) to ‘1’. This will cause the timer to
decrement with every timer clock/count event and underflow when the timer transitions from 0x0000 to
0xFFFF. Just as in overflows, the Overflow/Underflow Flag (TFn) will be set to ‘1’, and an interrupt will
occur if enabled.
Counter/Timer with Capture mode is selected by setting the Capture/Reload Select bit CP/RLn
(TMRnCN.0) and the Timer 2, 3, and 4 Run Control bit TRn (TMRnCN.2) to logic 1. The Timer 2, 3, and 4
respective External Enable EXENn (TMRnCN.3) must also be set to logic 1 to enable captures. If EXENn
is cleared, transitions on TnEX will be ignored.
TMRnCF
T T T T D
n n O n C
M M G O E
1 0 n E n
Toggle Logic
0
2
Tn
(Port Pin)
0xFF
0xFF
SYSCLK
12
1
External Clock
(XTAL1)
0
1
8
TMRnL
RCAPnL
TMRnH
RCAPnH
TCLK
CP/RLn
C/Tn
Crossbar
Tn
TRn
EXENn
TRn
EXENn
Crossbar
Interrupt
EXFn
TFn
TnE
X
Figure 23.4. T2, 3, and 4 Capture Mode Block Diagram
318
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
23.2.3. Auto-Reload Mode
In Auto-Reload Mode, the counter/timer can be configured to count up or down and cause an interrupt/flag
to occur upon an overflow/underflow event. When counting up, the counter/timer will set its overflow/under-
flow flag (TFn) and cause an interrupt (if enabled) upon overflow/underflow, and the values in the Reload/
Capture Registers (RCAPnH and RCAPnL) are loaded into the timer and the timer is restarted. When the
Timer External Enable Bit (EXENn) bit is set to ‘1’ and the Decrement Enable Bit (DCENn) is ‘0’, a falling
edge (‘1’-to-‘0’ transition) on the TnEX pin will cause a timer reload. Note that timer overflows will also
cause auto-reloads. When DCENn is set to ‘1’, the state of the TnEX pin controls whether the counter/timer
counts up (increments) or down (decrements), and will not cause an auto-reload or interrupt event (Timer 3
shares the T2EX pin with Timer 2). See Section 23.2.1 for information concerning configuration of a timer
to count down.
When counting down, the counter/timer will set its overflow/underflow flag (TFn) and cause an interrupt (if
enabled) when the value in the TMRnH and TMRnL registers matches the 16-bit value in the Reload/Cap-
ture Registers (RCAPnH and RCAPnL). This is considered an underflow event, and will cause the timer to
load the value 0xFFFF. The timer is automatically restarted when an underflow occurs.
Counter/Timer with Auto-Reload mode is selected by clearing the CP/RLn bit. Setting TRn to logic 1
enables and starts the timer.
In Auto-Reload Mode, the External Flag (EXFn) toggles upon every overflow or underflow and does not
cause an interrupt. The EXFn flag can be used as the most significant bit (MSB) of a 17-bit counter.
.
TMRnCF
D
E
C
T T T T
n n O n
M M G O
E
1 0 n E
n
Toggle Logic
0
2
Tn
(Port Pin)
0xFF
0xFF
1
SYSCLK
12
External Clock
(XTAL1)
0
1
8
OVF
TMRnL
RCAPnL
TMRnH
RCAPnH
TCLK
CP/RLn
C/Tn
TRn
EXENn
Tn
Crossbar
TRn
EXENn
Interrupt
EXFn
TFn
Reload
Crossbar
TnE
X
Figure 23.5. Tn Auto-reload (T2,3,4) and Toggle Mode (T2,4) Block Diagram
Rev. 1.4
319
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
23.2.4. Toggle Output Mode (Timer 2 and Timer 4 Only)
Timers 2 and 4 have the capability to toggle the state of their respective output port pins (T2 or T4) to pro-
duce a 50% duty cycle waveform output. The port pin state will change upon the overflow or underflow of
the respective timer (depending on whether the timer is counting up or down). The toggle frequency is
determined by the clock source of the timer and the values loaded into RCAPnH and RCAPnL. When
counting DOWN, the auto-reload value for the timer is 0xFFFF, and underflow will occur when the value in
the timer matches the value stored in RCAPnH:RCAPnL. When counting UP, the auto-reload value for the
timer is RCAPnH:RCAPnL, and overflow will occur when the value in the timer transitions from 0xFFFF to
the reload value.
To output a square wave, the timer is placed in reload mode (the Capture/Reload Select Bit in TMRnCN
and the Timer/Counter Select Bit in TMRnCN are cleared to ‘0’). The timer output is enabled by setting the
Timer Output Enable Bit in TMRnCF to ‘1’. The timer should be configured via the timer clock source and
reload/underflow values such that the timer overflow/underflows at 1/2 the desired output frequency. The
port pin assigned by the crossbar as the timer’s output pin should be configured as a digital output (see
Section “18. Port Input/Output” on page 235). Setting the timer’s Run Bit (TRn) to ‘1’ will start the toggle
of the pin. A Read/Write of the Timer’s Toggle Output State Bit (TMRnCF.2) is used to read the state of the
toggle output, or to force a value of the output. This is useful when it is desired to start the toggle of a pin in
a known state, or to force the pin into a desired state when the toggle mode is halted.
Equation 23.1. Square Wave Frequency (Timer 2 and Timer 4 Only)
F
TCLK
------------------------------------------------------
F
=
sq
2 65536 – RCAPn
320
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 23.8. TMRnCN: Timer 2, 3, and 4 Control
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
TFn
EXFn
-
-
EXENn
TRn
C/Tn
CP/RLn 00000000
Bit
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Addressable
SFR Address: TMR2CN:0xC8;TMR3CN:0xC8;TMR4CN:0xC8
SFR Page: TMR2CN: page 0;TMR3CN: page 1;TMR4CN: page 2
Bit7:
Bit6:
TFn: Timer 2, 3, and 4 Overflow/Underflow Flag.
Set by hardware when either the Timer overflows from 0xFFFF to 0x0000, underflows from
the value placed in RCAPnH:RCAPnL to 0xFFFF (in Auto-reload Mode), or underflows from
0x0000 to 0xFFFF (in Capture Mode). When the Timer interrupt is enabled, setting this bit
causes the CPU to vector to the Timer interrupt service routine. This bit is not automatically
cleared by hardware and must be cleared by software.
EXFn: Timer 2, 3, or 4 External Flag.
Set by hardware when either a capture or reload is caused by a high-to-low transition on the
TnEX input pin and EXENn is logic 1. When the Timer interrupt is enabled, setting this bit
causes the CPU to vector to the Timer Interrupt service routine. This bit is not automatically
cleared by hardware and must be cleared by software.
Bit5–4: Reserved.
Bit3:
EXENn: Timer 2, 3, and 4 External Enable.
Enables high-to-low transitions on TnEX to trigger captures, reloads, and control the direc-
tion of the timer/counter (up or down count). If DCENn = 1, TnEX will determine if the timer
counts up or down when in Auto-reload Mode. If EXENn = 1, TnEX should be configured as
a digital input.
0: Transitions on the TnEX pin are ignored.
1: Transitions on the TnEX pin cause capture, reload, or control the direction of timer count
(up or down) as follows:
Capture Mode: ‘1’-to-’0’ Transition on TnEX pin causes RCAPnH:RCAPnL to capture timer
value.
Auto-Reload Mode:
DCENn = 0: ‘1’-to-’0’ transition causes reload of timer and sets the EXFn Flag.
DCENn = 1: TnEX logic level controls direction of timer (up or down).
TRn: Timer 2, 3, and 4 Run Control.
This bit enables/disables the respective Timer.
0: Timer disabled.
1: Timer enabled and running/counting.
C/Tn: Counter/Timer Select.
0: Timer Function: Timer incremented by clock defined by TnM1:TnM0
(TMRnCF.4:TMRnCF.3).
1: Counter Function: Timer incremented by high-to-low transitions on external input pin.
CP/RLn: Capture/Reload Select.
Bit2:
Bit1:
Bit0:
This bit selects whether the Timer functions in capture or auto-reload mode.
0: Timer is in Auto-Reload Mode.
1: Timer is in Capture Mode.
Note:
Timer 3 and Timer 2 share the T2 and T2EX pins.
Rev. 1.4
321
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 23.9. TMRnCF: Timer 2, 3, and 4 Configuration
R/W
TnM1
Bit4
R/W
TnM0
Bit3
R/W
TOGn
Bit2
R/W
TnOE
Bit1
R/W
Reset Value
-
-
-
DCENn 00000000
Bit7
Bit6
Bit5
Bit0
SFR Address: TMR2CF:0xC9;TMR3CF:0xC9;TMR4CF:0xC9
SFR Page TMR2CF: page 0;TMR3CF: page 1;TMR4CF: Page 2
Bit7–5: Reserved.
Bit4–3: TnM1 and TnM0: Timer Clock Mode Select Bits.
Bits used to select the Timer clock source. The sources can be the System Clock
(SYSCLK), SYSCLK divided by 2 or 12, or the external clock divided by 8. Clock source is
selected as follows:
00: SYSCLK/12
01: SYSCLK
10: EXTERNAL CLOCK/8 (Synchronized to the System Clock)
11: SYSCLK/2
Bit2:
Bit1:
TOGn: Toggle output state bit.
When timer is used to toggle a port pin, this bit can be used to read the state of the output, or
can be written to in order to force the state of the output (Timer 2 and Timer 4 Only).
TnOE: Timer output enable bit.
This bit enables the timer to output a 50% duty cycle output to the timer’s assigned external
port pin.
NOTE: A timer is configured for Square Wave Output as follows:
CP/RLn= 0
C/Tn = 0
TnOE = 1
Load RCAPnH:RCAPnL (See “Square Wave Frequency (Timer 2 and Timer 4 Only)” on
page 320.)
Configure Port Pin to output squarewave (See Section “18. Port Input/Output” on
page 235)
0: Output of toggle mode not available at Timers’s assigned port pin.
1: Output of toggle mode available at Timers’s assigned port pin.
DCENn: Decrement Enable Bit.
Bit0:
This bit enables the timer to count up or down as determined by the state of TnEX.
0: Timer will count up, regardless of the state of TnEX.
1: Timer will count up or down depending on the state of TnEX as follows:
if TnEX = 0, the timer counts DOWN.
if TnEX = 1, the timer counts UP.
Note:
Timer 3 and Timer 2 share the T2 and T2EX pins.
322
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 23.10. RCAPnL: Timer 2, 3, and 4 Capture Register Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
SFR Address: RCAP2L: 0xCA; RCAP3L: 0xCA; RCAP4L: 0xCA
SFR Page: RCAP2L: page 0; RCAP3L: page 1; RCAP4L: page 2
Bits 7–0: RCAP2, 3, and 4L: Timer 2, 3, and 4 Capture Register Low Byte.
The RCAP2, 3, and 4L register captures the low byte of Timer 2, 3, and 4 when Timer 2, 3,
and 4 is configured in capture mode. When Timer 2, 3, and 4 is configured in auto-reload
mode, it holds the low byte of the reload value.
SFR Definition 23.11. RCAPnH: Timer 2, 3, and 4 Capture Register High Byte
R/W
R/W
R/W
R/W
R/W
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
SFR Address: RCAP2H: 0xCB; RCAP3H: 0xCB; RCAP4H: 0xCB
SFR Page: RCAP2H: page 0; RCAP3H: page 1; RCAP4H: page 2
Bits 7–0: RCAP2, 3, and 4H: Timer 2, 3, and 4 Capture Register High Byte.
The RCAP2, 3, and 4H register captures the high byte of Timer 2, 3, and 4 when Timer 2, 3,
and 4 is configured in capture mode. When Timer 2, 3, and 4 is configured in auto-reload
mode, it holds the high byte of the reload value.
SFR Definition 23.12. TMRnL: Timer 2, 3, and 4 Low Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address: TMR2L: 0xCC; TMR3L: 0xCC; TMR4L: 0xCC
SFR Page: TMR2L: page 0; TMR3L: page 1; TMR4L: page 2
Bits 7–0: TL2, 3, and 4: Timer 2, 3, and 4 Low Byte.
The TL2, 3, and 4 register contains the low byte of the 16-bit Timer 2, 3, and 4
Rev. 1.4
323
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
SFR Definition 23.13. TMRnH Timer 2, 3, and 4 High Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Bit0
Reset Value
00000000
SFR Address: TMR2H: 0xCD; TMR3H: 0xCD; TMR4H: 0xCD
SFR Page: TMR2H: page 0; TMR3H: page 1; TMR4H: page 2
Bits 7–0: TH2, 3, and 4: Timer 2, 3, and 4 High Byte.
The TH2, 3, and 4 register contains the high byte of the 16-bit Timer 2, 3, and 4
324
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
24. Programmable Counter Array
The Programmable Counter Array (PCA0) provides enhanced timer functionality while requiring less CPU
intervention than the standard 8051 counter/timers. PCA0 consists of a dedicated 16-bit counter/timer and
six 16-bit capture/compare modules. Each capture/compare module has its own associated I/O line
(CEXn) which is routed through the Crossbar to Port I/O when enabled (See Section “18.1. Ports 0
through 3 and the Priority Crossbar Decoder” on page 238). The counter/timer is driven by a program-
mable timebase that can select between six inputs as its source: system clock, system clock divided by
four, system clock divided by twelve, the external oscillator clock source divided by 8, Timer 0 overflow, or
an external clock signal on the ECI line. Each capture/compare module may be configured to operate inde-
pendently in one of six modes: Edge-Triggered Capture, Software Timer, High-Speed Output, Frequency
Output, 8-Bit PWM, or 16-Bit PWM (each is described in Section 24.2). The PCA is configured and con-
trolled through the system controller's Special Function Registers. The basic PCA block diagram is shown
in Figure 24.1.
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
PCA
16-Bit Counter/Timer
CLOCK
MUX
ECI
SYSCLK
External Clock/8
Capture/Compare
Module 0
Capture/Compare
Module 1
Capture/Compare
Module 2
Capture/Compare
Module 3
Capture/Compare
Module 4
Capture/Compare
Module 5
Crossbar
Port I/O
Figure 24.1. PCA Block Diagram
Rev. 1.4
325
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
24.1. PCA Counter/Timer
The 16-bit PCA counter/timer consists of two 8-bit SFRs: PCA0L and PCA0H. PCA0H is the high byte
(MSB) of the 16-bit counter/timer and PCA0L is the low byte (LSB). Reading PCA0L automatically latches
the value of PCA0H into a “snapshot” register; the following PCA0H read accesses this “snapshot” register.
Reading the PCA0L Register first guarantees an accurate reading of the entire 16-bit PCA0 counter. Read-
ing PCA0H or PCA0L does not disturb the counter operation. The CPS2–CPS0 bits in the PCA0MD regis-
ter select the timebase for the counter/timer as shown in Table 24.1.
When the counter/timer overflows from 0xFFFF to 0x0000, the Counter Overflow Flag (CF) in PCA0MD is
set to logic 1 and an interrupt request is generated if CF interrupts are enabled. Setting the ECF bit in
PCA0MD to logic 1 enables the CF flag to generate an interrupt request. The CF bit is not automatically
cleared by hardware when the CPU vectors to the interrupt service routine, and must be cleared by soft-
ware (Note: PCA0 interrupts must be globally enabled before CF interrupts are recognized. PCA0 inter-
rupts are globally enabled by setting the EA bit (IE.7) and the EPCA0 bit in EIE1 to logic 1). Clearing the
CIDL bit in the PCA0MD register allows the PCA to continue normal operation while the CPU is in Idle
mode.
Table 24.1. PCA Timebase Input Options
CPS2
CPS1
CPS0
Timebase
0
0
0
0
1
1
0
0
1
1
0
0
0
1
0
1
0
1
System clock divided by 12
System clock divided by 4
Timer 0 overflow
High-to-low transitions on ECI (max rate = system clock divided by 4)
System clock
External oscillator source divided by 8*
*Note: External clock divided by 8 is synchronized with the system clock.
IDLE
PCA0MD
PCA0CN
C
I
D
L
W W C C C E
D D P P P C
T L S S S F
E C 2 1 0
K
C C C C C C C C
F R C C C C C C
F F F F F F
5 4 3 2 1 0
To SFR Bus
PCA0L
read
Snapshot
Register
SYSCLK/12
SYSCLK/4
000
001
010
011
100
101
Timer 0 Overflow
ECI
0
Overflow
To PCA Interrupt System
PCA0H
PCA0L
1
SYSCLK
CF
External Clock/8
To PCA Modules
Figure 24.2. PCA Counter/Timer Block Diagram
326
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Important Note About the PCA0CN Register: If the main PCA counter (PCA0H : PCA0L) overflows dur-
ing the execution phase of a read-modify-write instruction (bit-wise SETB or CLR, ANL, ORL, XRL) that
targets the PCA0CN register, the CF (Counter Overflow) bit will not be set. If the CF flag is used by soft-
ware to keep track of counter overflows, the following steps should be taken when performing a bit-wise
operation on the PCA0CN register:
Step 1. Disable global interrupts.
Step 2. Read PCA0L. This will latch the value of PCA0H.
Step 3. Read PCA0H, saving the value.
Step 4. Execute the bit-wise operation on CCFn (for example, CLR CCF0, or CCF0 = 0;).
Step 5. Read PCA0L.
Step 6. Read PCA0H, saving the value.
Step 7. If the value of PCA0H read in Step 3 is 0xFF and the value for PCA0H read in Step 6 is
0x00, then manually set the CF bit in software (for example, SETB CF, or CF = 1;).
Step 8. Re-enable interrupts.
Rev. 1.4
327
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
24.2. Capture/Compare Modules
Each module can be configured to operate independently in one of six operation modes: Edge-triggered
Capture, Software Timer, High Speed Output, Frequency Output, 8-Bit Pulse Width Modulator, or 16-Bit
Pulse Width Modulator. Each module has Special Function Registers (SFRs) associated with it in the CIP-
51 system controller. These registers are used to exchange data with a module and configure the module's
mode of operation.
Table 24.2 summarizes the bit settings in the PCA0CPMn registers used to select the PCA0 capture/com-
pare module’s operating modes. Setting the ECCFn bit in a PCA0CPMn register enables the module's
CCFn interrupt. Note: PCA0 interrupts must be globally enabled before individual CCFn interrupts are rec-
ognized. PCA0 interrupts are globally enabled by setting the EA bit (IE.7) and the EPCA0 bit (EIE1.3) to
logic 1. See Figure 24.3 for details on the PCA interrupt configuration.
(for n = 0 to 5)
PCA0CPMn
PCA0CN
PCA0MD
C C C E
P
W
M
1
6
n
E C C M T
C A A A O
O P P T G
M P N n n
n n n
P
W
M
n
E
C
C
F
n
C C C C C C C C
F R C C C C C C
F F F F F F
C
I
D
L
P P P C
S S S F
2 1 0
5 4 3 2 1 0
0
1
PCA Counter/
Timer Overflow
ECCF0
ECCF1
ECCF2
ECCF3
ECCF4
EPCA0
(EIE.3)
EA
(IE.7)
0
1
PCA Module 0
(CCF0)
Interrupt
Priority
Decoder
0
1
0
1
0
1
PCA Module 1
(CCF1)
0
1
PCA Module 2
(CCF2)
0
1
PCA Module 3
(CCF3)
0
1
PCA Module 4
(CCF4)
ECCF5
0
1
PCA Module 5
(CCF5)
Figure 24.3. PCA Interrupt Block Diagram
328
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Table 24.2. PCA0CPM Register Settings for PCA Capture/Compare Modules
PWM16 ECOM CAPP CAPN MAT TOG PWM ECCF
Operation Mode
Capture triggered by positive edge
on CEXn
X
X
X
X
X
X
1
0
1
0
1
1
0
0
0
0
0
0
0
0
0
X
X
X
Capture triggered by negative
edge on CEXn
Capture triggered by transition on
CEXn
X
X
X
0
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
1
1
0
0
0
0
1
1
1
X
X
X
0
Software Timer
High Speed Output
Frequency Output
8-Bit Pulse Width Modulator
16-Bit Pulse Width Modulator
1
0
X = Don’t Care
24.2.1. Edge-triggered Capture Mode
In this mode, a valid transition on the CEXn pin causes PCA0 to capture the value of the PCA0 counter/
timer and load it into the corresponding module's 16-bit capture/compare register (PCA0CPLn and
PCA0CPHn). The CAPPn and CAPNn bits in the PCA0CPMn register are used to select the type of transi-
tion that triggers the capture: low-to-high transition (positive edge), high-to-low transition (negative edge),
or either transition (positive or negative edge). When a capture occurs, the Capture/Compare Flag (CCFn)
in PCA0CN is set to logic 1 and an interrupt request is generated if CCF interrupts are enabled. The CCFn
bit is not automatically cleared by hardware when the CPU vectors to the interrupt service routine, and
must be cleared by software.
PCA Interrupt
PCA0CPMn
PCA0CN
P
W
M
1
E C C M T
C A A A O
O P P T G
M P N n n
n n n
P
W
M
n
E
C
C
F
n
C C C C C C C C
F R C C C C C C
F F F F F F
5 4 3 2 1 0
6
n
PCA0CPLn
PCA0CPHn
0
1
CEXn
Capture
Port I/O
Crossbar
0
1
PCA
Timebase
PCA0L
PCA0H
Figure 24.4. PCA Capture Mode Diagram
Note: The signal at CEXn must be high or low for at least 2 system clock cycles in order to be valid.
Rev. 1.4
329
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
24.2.2. Software Timer (Compare) Mode
In Software Timer mode, the PCA0 counter/timer is compared to the module's 16-bit capture/compare reg-
ister (PCA0CPHn and PCA0CPLn). When a match occurs, the Capture/Compare Flag (CCFn) in PCA0CN
is set to logic 1 and an interrupt request is generated if CCF interrupts are enabled. The CCFn bit is not
automatically cleared by hardware when the CPU vectors to the interrupt service routine, and must be
cleared by software. Setting the ECOMn and MATn bits in the PCA0CPMn register enables Software
Timer mode.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Write to
0
PCA0CPLn
ENB
Reset
PCA
Write to
PCA0CPHn
Interrupt
ENB
1
PCA0CPMn
PCA0CN
P
W
M
1
6
n
E C C M T
C A A A O
O P P T G
M P N n n
n n n
P
W
M
n
E
C
C
F
n
C C C C C C C C
F R C C C C C C
F F F F F F
PCA0CPLn
PCA0CPHn
5 4 3 2 1 0
x
0 0
0 0
x
0
1
Enable
Match
16-bit Comparator
PCA
Timebase
PCA0L
PCA0H
Figure 24.5. PCA Software Timer Mode Diagram
330
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
24.2.3. High Speed Output Mode
In High Speed Output mode, a module’s associated CEXn pin is toggled each time a match occurs
between the PCA Counter and the module's 16-bit capture/compare register (PCA0CPHn and
PCA0CPLn) Setting the TOGn, MATn, and ECOMn bits in the PCA0CPMn register enables the High-
Speed Output mode.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Write to
0
PCA0CPLn
ENB
Reset
PCA0CPMn
Write to
PCA0CPHn
P
W
M
1
E C C M T
C A A A O
O P P T G
M P N n n
n n n
P
W
M
n
E
C
C
F
n
ENB
1
6
n
PCA
Interrupt
x
0 0
0
x
PCA0CN
C C C C C C C C
F R C C C C C C
F F F F F F
PCA0CPLn
PCA0CPHn
5 4 3 2 1 0
0
1
Enable
Match
16-bit Comparator
TOGn
Toggle
0
CEXn
Crossbar
Port I/O
1
PCA
Timebase
PCA0L
PCA0H
Figure 24.6. PCA High Speed Output Mode Diagram
Rev. 1.4
331
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
24.2.4. Frequency Output Mode
Frequency Output Mode produces a programmable-frequency square wave on the module’s associated
CEXn pin. The capture/compare module high byte holds the number of PCA clocks to count before the out-
put is toggled. The frequency of the square wave is then defined by Equation 24.1.
Equation 24.1. Square Wave Frequency Output
FPCA
----------------------------------------
=
Fsqr
2 PCA0CPHn
Note: A value of 0x00 in the PCA0CPHn register is equal to 256 for this equation.
Where F
is the frequency of the clock selected by the CPS2–0 bits in the PCA mode register,
PCA
PCA0MD. The lower byte of the capture/compare module is compared to the PCA0 counter low byte; on a
match, CEXn is toggled and the offset held in the high byte is added to the matched value in PCA0CPLn.
Frequency Output Mode is enabled by setting the ECOMn, TOGn, and PWMn bits in the PCA0CPMn reg-
ister.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
PCA0CPMn
P
W
M
1
6
n
E C C M T
C A A A O
O P P T G
M P N n n
n n n
P
W
M
n
E
C
C
F
n
PCA0CPLn
8-bit Adder
PCA0CPHn
Adder
Enable
TOGn
0
0 0 0 1
0
Toggle
0
CEXn
8-bit
Comparator
match
Enable
Crossbar
Port I/O
1
PCA Timebase
PCA0L
Figure 24.7. PCA Frequency Output Mode
332
Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
24.2.5. 8-Bit Pulse Width Modulator Mode
Each module can be used independently to generate pulse width modulated (PWM) outputs on its associ-
ated CEXn pin. The frequency of the output is dependent on the timebase for the PCA0 counter/timer. The
duty cycle of the PWM output signal is varied using the module's PCA0CPLn capture/compare register.
When the value in the low byte of the PCA0 counter/timer (PCA0L) is equal to the value in PCA0CPLn, the
output on the CEXn pin will be high. When the count value in PCA0L overflows, the CEXn output will be
low (see Figure 24.8). Also, when the counter/timer low byte (PCA0L) overflows from 0xFF to 0x00,
PCA0CPLn is reloaded automatically with the value stored in the counter/timer's high byte (PCA0H) with-
out software intervention. Setting the ECOMn and PWMn bits in the PCA0CPMn register enables 8-Bit
Pulse Width Modulator mode. The duty cycle for 8-Bit PWM Mode is given by Equation 24.2.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Equation 24.2. 8-Bit PWM Duty Cycle
256 – PCA0CPHn
---------------------------------------------------
256
DutyCycle =
PCA0CPHn
PCA0CPMn
P
W
M
1
E C C M T
C A A A O
O P P T G
M P N n n
n n n
P
W
M
n
E
C
C
F
n
PCA0CPLn
6
n
0
0 0 0 0
0
SET
8-bit
Comparator
match
CEXn
Enable
S
R
Q
Q
Crossbar
Port I/O
CLR
PCA Timebase
PCA0L
Overflow
Figure 24.8. PCA 8-Bit PWM Mode Diagram
Rev. 1.4
333
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
24.2.6. 16-Bit Pulse Width Modulator Mode
Each PCA0 module may also be operated in 16-Bit PWM mode. In this mode, the 16-bit capture/compare
module defines the number of PCA0 clocks for the low time of the PWM signal. When the PCA0 counter
matches the module contents, the output on CEXn is asserted high; when the counter overflows, CEXn is
asserted low. To output a varying duty cycle, new value writes should be synchronized with PCA0 CCFn
match interrupts. 16-Bit PWM Mode is enabled by setting the ECOMn, PWMn, and PWM16n bits in the
PCA0CPMn register. For a varying duty cycle, CCFn should also be set to logic 1 to enable match inter-
rupts. The duty cycle for 16-Bit PWM Mode is given by Equation 24.3.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
Compare registers, the low byte should always be written first. Writing to PCA0CPLn clears the ECOMn bit
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Equation 24.3. 16-Bit PWM Duty Cycle
65536 – PCA0CPn
----------------------------------------------------
65536
DutyCycle =
PCA0CPMn
P
W
M
1
E C C M T
C A A A O
O P P T G
M P N n n
n n n
P
W
M
n
E
C
C
F
n
PCA0CPHn
PCA0CPLn
6
n
1
0 0 0 0
0
SET
match
CEXn
Enable
16-bit Comparator
S
R
Q
Q
Crossbar
Port I/O
CLR
PCA Timebase
PCA0H
PCA0L
Overflow
Figure 24.9. PCA 16-Bit PWM Mode
334
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24.3. Register Descriptions for PCA0
Following are detailed descriptions of the special function registers related to the operation of PCA0.
SFR Definition 24.1. PCA0CN: PCA Control
R/W
CF
Bit7
R/W
CR
Bit6
R/W
CCF5
Bit5
R/W
CCF4
Bit4
R/W
CCF3
Bit3
R/W
CCF2
Bit2
R/W
CCF1
Bit1
R/W
CCF0
Bit0
Reset Value
00000000
SFR Address: 0xD8
SFR Page: 0
Bit7:
CF: PCA Counter/Timer Overflow Flag.
Set by hardware when the PCA0 Counter/Timer overflows from 0xFFFF to 0x0000. When
the Counter/Timer Overflow (CF) interrupt is enabled, setting this bit causes the CPU to vec-
tor to the CF interrupt service routine. This bit is not automatically cleared by hardware and
must be cleared by software.
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
CR: PCA0 Counter/Timer Run Control.
This bit enables/disables the PCA0 Counter/Timer.
0: PCA0 Counter/Timer disabled.
1: PCA0 Counter/Timer enabled.
CCF5: PCA0 Module 5 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF interrupt is
enabled, setting this bit causes the CPU to vector to the CCF interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
CCF4: PCA0 Module 4 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF interrupt is
enabled, setting this bit causes the CPU to vector to the CCF interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
CCF3: PCA0 Module 3 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF interrupt is
enabled, setting this bit causes the CPU to vector to the CCF interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
CCF2: PCA0 Module 2 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF interrupt is
enabled, setting this bit causes the CPU to vector to the CCF interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
CCF1: PCA0 Module 1 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF interrupt is
enabled, setting this bit causes the CPU to vector to the CCF interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
CCF0: PCA0 Module 0 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF interrupt is
enabled, setting this bit causes the CPU to vector to the CCF interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
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SFR Definition 24.2. PCA0MD: PCA0 Mode
R/W
CIDL
Bit7
R/W
-
R/W
-
R/W
-
R/W
CPS2
Bit3
R/W
CPS1
Bit2
R/W
CPS0
Bit1
R/W
ECF
Bit0
Reset Value
00000000
Bit6
Bit5
Bit4
SFR Address: 0xD9
SFR Page: 0
Bit7:
CIDL: PCA0 Counter/Timer Idle Control.
Specifies PCA0 behavior when CPU is in Idle Mode.
0: PCA0 continues to function normally while the system controller is in Idle Mode.
1: PCA0 operation is suspended while the system controller is in Idle Mode.
Bits6–4: UNUSED. Read = 000b, Write = don't care.
Bits3–1: CPS2-CPS0: PCA0 Counter/Timer Pulse Select.
These bits select the timebase source for the PCA0 counter
CPS2 CPS1 CPS0
Timebase
0
0
0
0
0
1
0
1
0
System clock divided by 12
System clock divided by 4
Timer 0 overflow
High-to-low transitions on ECI (max rate = system clock
divided by 4)
0
1
1
1
1
1
1
0
0
1
1
0
1
0
1
System clock
External clock divided by 8 (synchronized with system clock)
Reserved
Reserved
Bit0:
ECF: PCA Counter/Timer Overflow Interrupt Enable.
This bit sets the masking of the PCA0 Counter/Timer Overflow (CF) interrupt.
0: Disable the CF interrupt.
1: Enable a PCA0 Counter/Timer Overflow interrupt request when CF (PCA0CN.7) is set.
336
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SFR Definition 24.3. PCA0CPMn: PCA0 Capture/Compare Mode
R/W
R/W
R/W
CAPPn
Bit5
R/W
CAPNn
Bit4
R/W
MATn
Bit3
R/W
TOGn
Bit2
R/W
PWMn
Bit1
R/W
Reset Value
PWM16n ECOMn
ECCFn 00000000
Bit0
Bit7
Bit6
SFR PCA0CPM0: 0xDA, PCA0CPM1: 0xDB, PCA0CPM2: 0xDC, PCA0CPM3: 0xDD, PCA0CPM4: 0xDE,
Address: PCA0CPM5: 0xDF
PCA0CPM0: page 0, PCA0CPM1: page 0, PCA0CPM2: page 0, PCA0CPM3: 0, PCA0CPM4: page 0,
SFR Page:
PCA0CPM5: page 0
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
PWM16n: 16-bit Pulse Width Modulation Enable
This bit selects 16-bit mode when Pulse Width Modulation mode is enabled (PWMn = 1).
0: 8-bit PWM selected.
1: 16-bit PWM selected.
ECOMn: Comparator Function Enable.
This bit enables/disables the comparator function for PCA0 module n.
0: Disabled.
1: Enabled.
CAPPn: Capture Positive Function Enable.
This bit enables/disables the positive edge capture for PCA0 module n.
0: Disabled.
1: Enabled.
CAPNn: Capture Negative Function Enable.
This bit enables/disables the negative edge capture for PCA0 module n.
0: Disabled.
1: Enabled.
MATn: Match Function Enable.
This bit enables/disables the match function for PCA0 module n. When enabled, matches of
the PCA0 counter with a module's capture/compare register cause the CCFn bit in PCA0MD
register to be set to logic 1.
0: Disabled.
1: Enabled.
Bit2:
Bit1:
Bit0:
TOGn: Toggle Function Enable.
This bit enables/disables the toggle function for PCA0 module n. When enabled, matches of
the PCA0 counter with a module's capture/compare register cause the logic level on the
CEXn pin to toggle. If the PWMn bit is also set to logic 1, the module operates in Frequency
Output Mode.
0: Disabled.
1: Enabled.
PWMn: Pulse Width Modulation Mode Enable.
This bit enables/disables the PWM function for PCA0 module n. When enabled, a pulse
width modulated signal is output on the CEXn pin. 8-bit PWM is used if PWM16n is logic 0;
16-bit mode is used if PWM16n logic 1. If the TOGn bit is also set, the module operates in
Frequency Output Mode.
0: Disabled.
1: Enabled.
ECCFn: Capture/Compare Flag Interrupt Enable.
This bit sets the masking of the Capture/Compare Flag (CCFn) interrupt.
0: Disable CCFn interrupts.
1: Enable a Capture/Compare Flag interrupt request when CCFn is set.
Rev. 1.4
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SFR Definition 24.4. PCA0L: PCA0 Counter/Timer Low Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Reset Value
00000000
Bit0
SFR Address: 0xF9
SFR Page: 0
Bits 7–0: PCA0L: PCA0 Counter/Timer Low Byte.
The PCA0L register holds the low byte (LSB) of the 16-bit PCA0 Counter/Timer.
SFR Definition 24.5. PCA0H: PCA0 Counter/Timer High Byte
R/W
Bit7
R/W
Bit6
R/W
Bit5
R/W
Bit4
R/W
Bit3
R/W
Bit2
R/W
Bit1
R/W
Reset Value
00000000
Bit0
SFR Address: 0xFA
SFR Page: 0
Bits 7–0: PCA0H: PCA0 Counter/Timer High Byte.
The PCA0H register holds the high byte (MSB) of the 16-bit PCA0 Counter/Timer.
SFR Definition 24.6. PCA0CPLn: PCA0 Capture Module Low Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
PCA0CPL0: 0xFB, PCA0CPL1: 0xFD, PCA0CPL2: 0xE9, PCA0CPL3: 0xEB, PCA0CPL4: 0xED, PCA0CPL5:
0xE1
SFR Address:
PCA0CPL0: page 0, PCA0CPL1: page 0, PCA0CPL2: page 0, PCA0CPL3: page 0, PCA0CPL4: page 0,
PCA0CPL5: page 0
SFR Page:
Bits7–0: PCA0CPLn: PCA0 Capture Module Low Byte.
The PCA0CPLn register holds the low byte (LSB) of the 16-bit capture module n.
338
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SFR Definition 24.7. PCA0CPHn: PCA0 Capture Module High Byte
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Value
00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
PCA0CPH0: 0xFC, PCA0CPH1: 0xFD, PCA0CPH2: 0xEA, PCA0CPH3: 0xEC, PCA0CPH4: 0xEE, PCA0CPH5:
0xE2
SFR Address:
PCA0CPH0: page 0, PCA0CPH1: page 0, PCA0CPH2: page 0, PCA0CPH3: page 0, PCA0CPH4: page 0,
PCA0CPH5: page 0
SFR Page:
Bits7–0: PCA0CPHn: PCA0 Capture Module High Byte.
The PCA0CPHn register holds the high byte (MSB) of the 16-bit capture module n.
Rev. 1.4
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NOTES:
340
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25. JTAG (IEEE 1149.1)
Each MCU has an on-chip JTAG interface and logic to support boundary scan for production and in-sys-
tem testing, Flash read/write operations, and non-intrusive in-circuit debug. The JTAG interface is fully
compliant with the IEEE 1149.1 specification. Refer to this specification for detailed descriptions of the Test
Interface and Boundary-Scan Architecture. Access of the JTAG Instruction Register (IR) and Data Regis-
ters (DR) are as described in the Test Access Port and Operation of the IEEE 1149.1 specification.
The JTAG interface is accessed via four dedicated pins on the MCU: TCK, TMS, TDI, and TDO.
Through the 16-bit JTAG Instruction Register (IR), any of the eight instructions shown in Figure 25.1 can
be commanded. There are three DR’s associated with JTAG Boundary-Scan, and four associated with
Flash read/write operations on the MCU.
JTAG Register Definition 25.1. IR: JTAG Instruction Register
Reset Value
0x0000
Bit15
Bit0
IR Value Instruction
Description
Selects the Boundary Data Register for control and observability of all
device pins
Selects the Boundary Data Register for observability and presetting the
scan-path latches
Selects device ID Register
Selects Bypass Data Register
0x0000
0x0002
EXTEST
SAMPLE/
PRELOAD
IDCODE
0x0004
0xFFFF
BYPASS
Selects FLASHCON Register to control how the interface logic responds
to reads and writes to the FLASHDAT Register
0x0082 Flash Control
0x0083
Flash Data Selects FLASHDAT Register for reads and writes to the Flash memory
Selects FLASHADR Register which holds the address of all Flash read,
write, and erase operations
0x0084 Flash Address
Selects FLASHSCL Register which controls the Flash one-shot timer and
read-always enable
0x0085
Flash Scale
Rev. 1.4
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25.1. Boundary Scan
The DR in the Boundary Scan path is an 134-bit shift register. The Boundary DR provides control and
observability of all the device pins as well as the SFR bus and Weak Pullup feature via the EXTEST and
SAMPLE commands.
Table 25.1. Boundary Data Register Bit Definitions
EXTEST provides access to both capture and update actions, while Sample only performs a capture.
Bit
Action Target
0
Capture Reset Enable from MCU (64-pin TQFP devices)
Update
Capture
Update
Capture
Update
Capture
Update
Reset Enable to RST pin (64-pin TQFP devices)
Reset input from RST pin (64-pin TQFP devices)
Reset output to RST pin (64-pin TQFP devices)
Reset Enable from MCU (100-pin TQFP devices)
Reset Enable to RST pin (100-pin TQFP devices)
Reset input from RST pin (100-pin TQFP devices)
Reset output to RST pin (100-pin TQFP devices)
1
2
3
4
5
Capture External Clock from XTAL1 pin
Update Not used
Capture Weak pullup enable from MCU
Update Weak pullup enable to Port Pins
6, 8, 10, 12, 14, Capture P0.n output enable from MCU (e.g. Bit6=P0.0, Bit8=P0.1, etc.)
16, 18, 20
7, 9, 11, 13, 15, Capture P0.n input from pin (e.g. Bit7=P0.0, Bit9=P0.1, etc.)
17, 19, 21
22, 24, 26, 28, 30, Capture P1.n output enable from MCU
32, 34, 36
23, 25, 27, 29, 31, Capture P1.n input from pin
33, 35, 37
38, 40, 42, 44, 46, Capture P2.n output enable from MCU
48, 50, 52
39, 41, 43, 45, 47, Capture P2.n input from pin
49, 51, 53
54, 56, 58, 60, 62, Capture P3.n output enable from MCU
64, 66, 68
55, 57, 59, 61, 63, Capture P3.n input from pin
65, 67, 69
70, 72, 74, 76, 78, Capture P4.n output enable from MCU
80, 82, 84
71, 73, 75, 77, 79, Capture P4.n input from pin
81, 83, 85
86, 88, 90, 92, 94, Capture P5.n output enable from MCU
96, 98, 100
87, 89, 91, 93, 95, Capture P5.n input from pin
Update P0.n output enable to pin (e.g. Bit6=P0.0oe, Bit8=P0.1oe, etc.)
Update P0.n output to pin (e.g. Bit7=P0.0, Bit9=P0.1, etc.)
Update P1.n output enable to pin
Update P1.n output to pin
Update P2.n output enable to pin
Update P2.n output to pin
Update P3.n output enable to pin
Update P3.n output to pin
Update P4.n output enable to pin
Update P4.n output to pin
Update P5.n output enable to pin
97, 99, 101
Update P5.n output to pin
102, 104, 106,
108, 110, 112, 114,
116
Capture P6.n output enable from MCU
Update P6.n output enable to pin
342
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Table 25.1. Boundary Data Register Bit Definitions (Continued)
Bit
Action Target
103, 105, 107,
109, 111, 113, 115,
117
Capture P6.n input from pin
Update P6.n output to pin
118, 120, 122,
124, 126, 128,
130, 132
Capture P7.n output enable from MCU
Update P7.n output enable to pin
119, 121, 123,
125, 127, 129,
131, 133
Capture P7.n input from pin
Update P7.n output to pin
25.1.1. EXTEST Instruction
The EXTEST instruction is accessed via the IR. The Boundary DR provides control and observability of all
the device pins as well as the Weak Pullup feature. All inputs to on-chip logic are set to logic 1.
25.1.2. SAMPLE Instruction
The SAMPLE instruction is accessed via the IR. The Boundary DR provides observability and presetting of
the scan-path latches.
25.1.3. BYPASS Instruction
The BYPASS instruction is accessed via the IR. It provides access to the standard JTAG Bypass data reg-
ister.
25.1.4. IDCODE Instruction
The IDCODE instruction is accessed via the IR. It provides access to the 32-bit Device ID register.
JTAG Register Definition 25.2. DEVICEID: JTAG Device ID
Reset Value
Version
Part Number
Manufacturer ID
1
0xn0003243
Bit31
Bit28 Bit27
Bit12 Bit11
Bit1
Bit0
Version = 0000b
Part Number = 0000 0000 0000 0111b (C8051F120/1/2/3/4/5/6/7 or C8051F130/1/2/3)
Manufacturer ID = 0010 0100 001b (Silicon Labs)
Rev. 1.4
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25.2. Flash Programming Commands
The Flash memory can be programmed directly over the JTAG interface using the Flash Control, Flash
Data, Flash Address, and Flash Scale registers. These Indirect Data Registers are accessed via the JTAG
Instruction Register. Read and write operations on indirect data registers are performed by first setting the
appropriate DR address in the IR register. Each read or write is then initiated by writing the appropriate
Indirect Operation Code (IndOpCode) to the selected data register. Incoming commands to this register
have the following format:
19:18
17:0
IndOpCode
WriteData
IndOpCode: These bit set the operation to perform according to the following table:
IndOpCode
Operation
Poll
0x
10
11
Read
Write
The Poll operation is used to check the Busy bit as described below. Although a Capture-DR is performed,
no Update-DR is allowed for the Poll operation. Since updates are disabled, polling can be accomplished
by shifting in/out a single bit.
The Read operation initiates a read from the register addressed by the DRAddress. Reads can be initiated
by shifting only 2 bits into the indirect register. After the read operation is initiated, polling of the Busy bit
must be performed to determine when the operation is complete.
The write operation initiates a write of WriteData to the register addressed by DRAddress. Registers of any
width up to 18 bits can be written. If the register to be written contains fewer than 18 bits, the data in Write-
Data should be left-justified, i.e. its MSB should occupy bit 17 above. This allows shorter registers to be
written in fewer JTAG clock cycles. For example, an 8-bit register could be written by shifting only 10 bits.
After a Write is initiated, the Busy bit should be polled to determine when the next operation can be initi-
ated. The contents of the Instruction Register should not be altered while either a read or write operation is
busy.
Outgoing data from the indirect Data Register has the following format:
19
0
18:1
0
ReadData
Busy
The Busy bit indicates that the current operation is not complete. It goes high when an operation is initiated
and returns low when complete. Read and Write commands are ignored while Busy is high. In fact, if poll-
ing for Busy to be low will be followed by another read or write operation, JTAG writes of the next operation
can be made while checking for Busy to be low. They will be ignored until Busy is read low, at which time
the new operation will initiate. This bit is placed ate bit 0 to allow polling by single-bit shifts. When waiting
for a Read to complete and Busy is 0, the following 18 bits can be shifted out to obtain the resulting data.
ReadData is always right-justified. This allows registers shorter than 18 bits to be read using a reduced
number of shifts. For example, the results from a byte-read requires 9 bit shifts (Busy + 8 bits).
344
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JTAG Register Definition 25.3. FLASHCON: JTAG Flash Control
Reset Value
SFLE
WRMD2 WRMD1 WRMD0 RDMD3 RDMD2 RDMD1 RDMD0 00000000
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
This register determines how the Flash interface logic will respond to reads and writes to the FLASH-
DAT Register.
Bit7:
SFLE: Scratchpad Flash Memory Access Enable
When this bit is set, Flash reads and writes are directed to the two 128-byte Scratchpad
Flash sectors. When SFLE is set to logic 1, Flash accesses out of the address range 0x00-
0xFF should not be attempted (with the exception of address 0x400, which can be used to
simultaneously erase both Scratchpad areas). Reads/Writes out of this range will yield
undefined results.
0: Flash access directed to the Program/Data Flash sector.
1: Flash access directed to the two 128 byte Scratchpad sectors.
Bits6–4: WRMD2–0: Write Mode Select Bits.
The Write Mode Select Bits control how the interface logic responds to writes to the FLASH-
DAT Register per the following values:
000:
A FLASHDAT write replaces the data in the FLASHDAT register, but is otherwise
ignored.
001:
A FLASHDAT write initiates a write of FLASHDAT into the memory address by the
FLASHADR register. FLASHADR is incremented by one when complete.
A FLASHDAT write initiates an erasure (sets all bytes to 0xFF) of the Flash page
containing the address in FLASHADR. The data written must be 0xA5 for the erase
to occur. FLASHADR is not affected. If FLASHADR = 0x1FBFE – 0x1FBFF, the
entire user space will be erased (i.e. entire Flash memory except for Reserved area
0x1FC00 – 0x1FFFF).
010:
(All other values for WRMD2-0 are reserved.)
Bits3–0: RDMD3–0: Read Mode Select Bits.
The Read Mode Select Bits control how the interface logic responds to reads from the
FLASHDAT Register per the following values:
0000: A FLASHDAT read provides the data in the FLASHDAT register, but is otherwise
ignored.
0001: A FLASHDAT read initiates a read of the byte addressed by the FLASHADR register
if no operation is currently active. This mode is used for block reads.
0010: A FLASHDAT read initiates a read of the byte addressed by FLASHADR only if no
operation is active and any data from a previous read has already been read from
FLASHDAT. This mode allows single bytes to be read (or the last byte of a block)
without initiating an extra read.
(All other values for RDMD3–0 are reserved.)
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JTAG Register Definition 25.4. FLASHDAT: JTAG Flash Data
Reset Value
0000000000
Bit9
Bit0
This register is used to read or write data to the Flash memory across the JTAG interface.
Bits9–2: DATA7–0: Flash Data Byte.
Bit1:
FAIL: Flash Fail Bit.
0: Previous Flash memory operation was successful.
1: Previous Flash memory operation failed. Usually indicates the associated memory loca-
tion was locked.
Bit0:
BUSY: Flash Busy Bit.
0: Flash interface logic is not busy.
1: Flash interface logic is processing a request. Reads or writes while BUSY = 1 will not ini-
tiate another operation.
JTAG Register Definition 25.5. FLASHADR: JTAG Flash Address
Reset Value
0x00000
Bit16
Bit0
This register holds the address for all JTAG Flash read, write, and erase operations. This register
autoincrements after each read or write, regardless of whether the operation succeeded or failed.
Bits15–0: Flash Operation 17-bit Address.
346
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25.3. Debug Support
Each MCU has on-chip JTAG and debug logic that provides non-intrusive, full speed, in-circuit debug sup-
port using the production part installed in the end application, via the four pin JTAG I/F. Silicon Labs' debug
system supports inspection and modification of memory and registers, breakpoints, and single stepping.
No additional target RAM, program memory, or communications channels are required. All the digital and
analog peripherals are functional and work correctly (remain synchronized) while debugging. The Watch-
dog Timer (WDT) is disabled when the MCU is halted during single stepping or at a breakpoint.
The C8051F120DK is a development kit with all the hardware and software necessary to develop applica-
tion code and perform in-circuit debug with each MCU in the C8051F12x and C8051F13x device families.
Each kit includes development software for the PC, a Serial Adapter (for connection to JTAG) and a target
application board with a C8051F120 installed. Serial cables and wall-mount power supply are also
included.
Rev. 1.4
347
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NOTES:
348
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DOCUMENT CHANGE LIST
Revision 1.3 to Revision 1.4
•
•
•
•
Added new paragraph tags: SFR Definition and JTAG Register Definition.
Product Selection Guide Table 1.1: Added RoHS-compliant ordering information.
Overview Chapter, Figure 1.8, “On-Chip Memory Map”: Corrected on-chip XRAM size to “8192 Bytes”.
SAR8 Chapter: Table 7.1, “ADC2 Electrical Characteristics”: Track/Hold minimum spec corrected to
“300 ns”.
•
SAR8 Chapter: Table 7.1, “ADC2 Electrical Characteristics”: Total Harmonic Distortion typical spec
corrected to “-51 dB”.
•
•
Oscillators Chapter, Figure 14.1, “Oscillator Diagram”: Corrected location of IOSCEN arrow.
CIP51 Chapter, Section 11.3: Added note describing EA change behavior when followed by single-
cycle instruction.
•
CIP51 Chapter, Interrupt Summary Table: Added “SFRPAGE” column and SFRPAGE value for each
interrupt source.
•
•
•
CIP-51 Chapter, Figure 11.2, “Memory Map”: Corrected on-chip XRAM size to “8192 Bytes”.
Port I/O Chapter, Crossbar Priority Figures: Character formatting problem corrected.
Port I/O Chapter, P7MDOUT Register Description: Removed references to UART and SMBus periph-
erals.
•
•
•
Port I/O Chapter, P3MDOUT Register Description: Corrected text to read “P3MDOUT.[7:0]”.
Timers Chapter: References to “TnCON” corrected to read “TMRnCN”.
PCA0 Chapter, Section 24.1: Added note about PCA0CN Register and effects of read-modify-write
instructions on the CF bit.
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C8051F130/1/2/3
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