CY7C955-NI [CYPRESS]
AX⑩ ATM-SONET/SDH Transceiver; AX ™ ATM- SONET / SDH收发器
| 型号： | CY7C955-NI |
| 厂家： | 
CYPRESS |
| 描述： | AX⑩ ATM-SONET/SDH Transceiver |
| 文件： | 总78页 (文件大小：464K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
PRELIMINARY
CY7C955
AX™ ATM-SONET/SDH Transceiver
— Line Far End Receive Failure
— Line Alarm Indication Signal
— B1 Parity Error
Features
WAN and LAN ATM physical layer device
•
•
Providescompletephysicallayer transportofATMcells
at:
— Loss Of Cell Alignment
— Loss Of Receive Data
— STS 3c/ STM 1 rate of 155.52 MHz
−
−
— STS 1 rate of 51.84 MHz
−
Controller interface for internal interrupt and
configuration registers including:
•
Compliant with ATM Forum User Network Interface 3.1
specification
UTOPIA ATM interface
ATM cell processing including:
— HEC generation/verification
•
— Error monitoring
— Status indication
— Device configuration
•
•
0.65 Low Power CMOS
•
µ
— Cell scrambling/descrambling
— Rate adaption/idle cell filtering
— Local Flow Control
• 128-pin PQFP
Functional Description
The Cypress Semiconductor CY7C955 is a Transceiver chip
designed to carry ATM cells across SONET/SDH systems.
— Cell alignment
SONET frame processing including:
•
On the transmit side, ATM cells coming from the Utopia inter-
face are being mapped into SONET/SDH frames and then se-
rialized for transmission over fiber or twisted pair (through an
optical module or an equalizer chip).
— Compliant with Bellcore GR 253, I.432,
−
T1.105, and G.709 for Jitter Tolerance and Jitter
Generation
— Frame generation/recovery
On the receive side, serial SONET/SDH datastreams coming
from an optical module or an equalizer chip are being recov-
ered by the intergrated clock and data recovery phase-locked
loop, framed, processed, and presented as parallel ATM cells
on the Receive Utopia Interface.
— SONET scrambling/descrambling
— Frequency justification/pointer processing
Complete line interface including:
— Clock and data recovery
•
•
The CY7C955 can be used in a Network Interface Card (NIC)
design to connect the segmentation and Reassembly (SAR)
chip to the optical modules or equalizer chip.
— Transmit timing derived from receiver or byte-rate
source
— SONET compliant PLL
— 100K PECL compatible I/O
Alarm indications including:
— Loss Of Signal
The CY7C955 can also be used in work group or enterprise
switches to connect the I/O FIFOs of the switch fabric to the
optical module or equalizer in the interface boards.
The applications of the CY7C955 include adapters, switches,
routers, hubs, and proprietary systems.
— Out Of Frame, Loss Of Frame
TABLE OF CONTENTS
Features
1
1
Functional Description
Pin Descriptions
2
Pin Configuration
7
Description
8
Transmit Section
8
Receive Section
10
12
16
17
18
60
61
61
61
Controller Interface (CI)
Loopback Operation
SONET Overhead Description
CY7C955 Register Map
Electrical Characteristics
Capacitance
AC Test Loads and Waveforms
Switching Characteristics
Cypress Semiconductor Corporation
•
3901 North First Street
•
San Jose
•
CA 95134
•
408-943-2600
November 29, 1999
PRELIMINARY
CY7C955
TABLE OF CONTENTS (continued)
Switching Waveforms
63
69
73
75
76
77
Functional Timing Diagram
Interface Termination and Biasing Schemes
Filter Pin Configuration
Ordering Information
Package Diagram
Transmit
Transmit
ATM Cell
Processor
Transmit
Path
Transmit
Line
Overhead
Processor
Transmit
Section
TXD±
Transmit
Clock
Multiplier &
Transmit
Buffer
UTOPIA I/F
TXC±
Transmit FIFO
4 Cell by 8 bit
Overhead
Processor
Overhead
Processor
TRCLK±
D[7:0]
A[7:0]
ALE
Configuration and Status
Register File
Controller
Interface
Rate
Selection
RDB
WRB
CSB
Error Monitoring
SONET/SDH
Clock
Recovery
INTB
RSTB
ALOS±
RRCLK±
RXD±
Receive
UTOPIA I/F
Receive FIFO
4 Cell by 8 bit
Receive
ATM Cell
Processor
Receive
Path
Overhead
Processor
Receive
Line
Overhead
Processor
Receive
Section
Overhead
Processor
RALM
RXDO±
7C955−1
Pin Descriptions
CY7C955 ATM-SONET/SDH Transceiver
Transmit Utopia Interface
Name
Pin
I/O
Description
TDAT[7:0] 87−94
Input
Transmit Utopia data: Byte-wide data driven from the ATM to PHY layer. TDAT[7] is the
MSB.
TPRTY
TSOC
95
96
Input
Input
Transmit Utopia Data Parity: Data parity calculated over TDAT[7:0]. Odd parity is as-
sumed unless the TXPTYP bit (Reg–63, bit 7) is set to even parity
Transmit Utopia Start of Cell: Assert TSOC HIGH when TDAT[7:0] contains the first
byte of an ATM cell. If TSOC is asserted sooner than 53 writes after the previous SOC,
an error condition will be generated. This input is optional after the first TSOC pulse.
TFCLK
84
Input
Input
Transmit Utopia Clock: Data transfer clock. Data is transferred to the AX on the rising
edge of TFCLK when TWRENB is asserted (LOW).
TWRENB 85
Transmit Utopia Data Enable: Enables the TFCLK input for data transfer to the AX. This
signal is active LOW.
2
PRELIMINARY
CY7C955
Transmit Utopia Interface (continued)
Name
Pin
I/O
Description
TCA
86
Output
Transmit Utopia Cell Available: An active state on this signal indicates that the Transmit
FIFO can accept at least N more cells (53 octets) of data where N and the active state
of the signal (HIGH or LOW) are programmable through the configuration registers
(Reg−63H and Reg−01H). In a special case, if Reg–63H bit2−3 is set to 00, Reg−01H,
bit 3 is set to 0, and TCALEVEL0 (Reg–63H, bit 1) set to 0. TCA will behave as an
active HIGH FULL indicator.
Transmit ATM Interface
Name
Pin
I/O
Description
XOFF
50
Input
Transmit Idle Cell: A HIGH state on this pin will force the ATM Cell Processor to send
an IDLE cell even if there are cells to send in the Transmit FIFO. XOFF is an asynchro-
nous input and has an integrated pull down resistor.
TGFC
TCP
52
51
Input
Transmit Generic Flow Control: This bit serial input provides the ability to overwrite the
four bits of the ATM cell header GFC field. These bits may be optionally written during
the four TCLK clock periods following the assertion of the TCP output.
Transmit Start Of GFC: This indicates that the first bit of the GFC for the next cell read
from the Transmit FIFO is expected on the TGFC pin during the next rising edge of
TCLK.
Output
Transmit Clock Generator
Name
Pin
I/O
Description
TRCLK±
9−10
Differential In
Transmit Input Clock: Accepts either a differential PECL, or a TTL or a CMOS byte rate
reference connected to TRCLK− with TRCLK+ grounded for the Transmit frequency
multiplier PLL. Optionally, this input can accept also the bit rate reference when TBYP
is true (held HIGH). In this mode the Transmit frequency multiplier is bypassed and the
bit rate clock is used directly for transmit side clocking.
TXC±
13−14
Differential Out Transmit Output Clock: Provides clock output for the transmit data. TXD± is updated
on the falling edge of this signal. In the default setting, TXC is disabled if RATE0 is
HIGH and a 51.84-MHz clock if RATE0 is LOW. XORTXC (Reg−04H, bit 6) can be used
to invert the default setting such that TXC is a 155.52-MHz clock if RATE0 is HIGH and
is disabled when RATE0 is LOW.
TXD±
15−16
Differential Out Transmit Data Output: Accepts NRZ encoded output data. This signal is updated on
the falling edge of TXC±.
TBYP
2
Input
Transmit Clock Bypass: When this input is held HIGH the transmit frequency multiplier
is disabled and TRCLK± input is used directly for transmit side clocking. When this input
is held LOW the transmit frequency multiplier multiplies the TRCLK± input by 8, 24, or
8/3 (depending on the TREFSEL (Reg−06H, bit 0) setting to provide the internal bit
rate clock.
RATE0
RATE1
97−98
Input
RATE: When the RATE0 input is HIGH the Transmit frequency generator and the Re-
ceive clock recovery are selected to operate at the STS−3c/STM−1 rate of 155.52 MHz.
When the RATE0 pin is LOW, the Transmit frequency generator and the Receive clock
recovery are selected to operate at the STS−1 rate of 51.84 MHz. RATE1 is for factory
testing use only and should be tied HIGH. Both RATE0 and RATE1 have integrated
pull-up resistors.
TCLK
TFPO
54
53
Output
Output
Transmit Byte Reference: Byte rate reference clock derived from the transmit line bit
rate.
Transmit Frame Reference. This signal is an 8-kHz frame rate reference that goes
HIGH during the transmission of the first A1 byte of the SONET/SDH frame. TFPO is
updated by the rising edge of TCLK.
Receive Clock Recovery
Name
Pin
I/O
Description
RXD±
25−26
Differential In
Receive Input Data: These line receiver inputs are connected to an internal Receive
PLL that recovers the embedded clock and data information. The incoming data rate
can be within one of two frequency ranges depending on the state of the RATE0 pin.
3
PRELIMINARY
CY7C955
Receive Clock Recovery (continued)
Name
Pin
I/O
Description
RXDO±
22−23
Differential Out Receive Output Data: These differential outputs represent the retimed version of the
input data stream (RXD±) in normal mode and the buffered version of the input datas-
tream (RXD±) in bypass mode. This output pair can be used as inputs to decision
feedback equalizers to correct for baseline wander. RXDO can be turned off to save
power by setting RXDOD (Reg−04H, bit 7) to 1.
RRCLK±
33−34
Differential In
Receive Clock: These inputs are used to clock in the differential data (RXD±) when the
Receive clock recovery block is bypassed (RBYP=HIGH). If RBYP is LOW, RRCLK is
multiplied by 8, 24, or 8/3 depending on the setting of RREFSEL (Reg−07H, bit 0) and
use as a reference for the Receiver PLL. Refer to the section on “Interface Termination
and Bias of Schemes” for connection examples to these pins.
RBYP
41
Input
Receive Clock Bypass: When this input is HIGH the Receiver clock recovery block is
bypassed. In this mode the device does not recover clock and data from the Receive
input data stream (RXD±) but instead uses the RRCLK± inputs to clock the differential
data into the device. When this input is LOW the Receiver clock recovery block recovers
the clock and data from the input data stream. In this mode a byte-rate clock is expected
on the RRCLK± inputs.
RCLK
RFP
57
58
Output
Output
Receive Byte Reference: Provides a byte-rate reference derived from the recovered
bit- rate Receive clock. RALM, RCP, and RGFC are aligned with this clock.
Receive Frame Reference: This output provides a frame-rate reference clock aligned
to the SONET/SDH frame alignment bytes. RFP will pulse HIGH for one RCLK cycle
every 125 seconds even at OOF and LOF situations.
LF+
42
Input
Input
NC. This pin is for factory testing only.
LF–, LFO
43, 44
These are the PLL filter pins. Connect a 0.47-µF capacitor across LF– and LFO.
Receive ATM Interface
Name
Pin
I/O
Description
RGFC
59
Output
Receive Generic Flow Control: This output provides the four bits of the current ATM
cell header GFC locations at each successive RCLK pulse. The RCP output indicates
the first GFC bit location. This output is forced LOW if the ATM Cell Processor has lost
cell delineation.
RALM
RCP
63
60
Output
Output
Receive Interrupt: This active HIGH signal is aligned with the RCLK byte-rate clock and
signals the presence of LAIS, PAIS, LOS, LOF, LOP, or LCD.
Receive Start Of GFC: This output indicates the first bit of the GFC presented on the
RGFC output. This output goes HIGH for 1 RCLK cycle 6 byte times after the corre-
sponding cell is written into the Receive FIFO.
Receive Utopia Interface
Name
Pin No I/O
Description
RDAT[7:0] 70−71
74−79
Output
Output
Output
Input
Receive Utopia Data: Byte-wide data driven from the PHY to ATM layer. RDAT[7] is the
MSB
RPRTY
RSOC
RFCLK
82
83
67
Receive Utopia Data Parity: Data parity calculated over RDAT[7:0]. Odd parity is as-
sumed unless the TXPRTY bit is set to even parity by Reg−50H, bit 6.
Receive Utopia Start of Cell: Asserted HIGH when RDAT[7:0] contains the first byte of
an ATM cell.
Receive Utopia Clock: Data transfer clock. Data is transferred from the AX on the rising
edge of RFCLK when RRDENB is asserted (LOW).
RRDENB
RCA
68
69
Input
Receive Utopia Enable: Enables the RFCLK input for data transfers from the AX.
Output
Receive Utopia Cell Available: An active signal indicates that the Receive FIFO con-
tains at least 1 or 4 more bytes of data. RCA is controlled by RCAINV (Reg−01H, bit
2) and RCALEVEL0 (Reg−59H, bit 2).
4
PRELIMINARY
CY7C955
Receive Utopia Interface (continued)
Name
Pin No I/O
66 Input
Description
TSEN
Receive Output Enable: This output operates in conjunction with the RRDENB output.
When TSEN is HIGH and RRDENB is HIGH the Receive UTOPIA data bus (RDAT[7:0],
RPRTY, and RSOC) is three-stated. When TSEN is HIGH and RRDENB is LOW the
data bus is driven with the requested data. When TSEN is LOW the data bus will not
three-state.
Controller Interface
Name
Pin No
I/O
Description
D[7:0]
110−112 I/O
115−118
Data[7:0]: Bidirectional data bus used to transfer data to and from the internal config-
uration, status, and error monitoring registers.
A[7:0]
ALE
119−126 Input
Address[7:0]: Address bus used to select the internal register for reading or writing.
127
Input
Address Latch Enable: When this input is LOW the address is latched from the A[7:0]
inputs. When this input is HIGH, the input is transparent. ALE has an integrated pull-
up resistor.
RDB
105
104
Input
Input
Read: This active LOW signal is used to read the internal register. The AX drives D[7:0]
when RDB and CSB are both LOW.
WRB
Write: This active LOW signal is used to write the internal registers. Data is latched
into the specified address register on the rising edge of WRB when CSB is LOW.
CSB
100
108
Input
Select: This active LOW device select has to be enabled during register accesses.
INTB
Output
Interrupt: This active LOW open drain output transitions LOW when an unmasked
interrupt source is active. This output transitions HIGH when the appropriate register
has been read. This interrupt signals the most critical error states of the device includ-
ing Loss of Pointer, Line Alarm Indication Signal (LAIS), Line Far End Receive Failure
(LFERF), Loss of Frame (LOF), Out of Frame (OOF), Loss of Signal (LOS), and many
others.
ALOS±
27−28
Differential In Carrier Detect: This differential input controls the recovery function of the Receive PLL
and can be driven by the carrier detect output from optical modules or from external
transition detection circuitry. When this input is at a Logic Low, the input data stream
(RXD±) is recovered normally by the Receive Clock Recovery PLL. When this input is
at a Logic High, the Receive PLL no longer aligns to RXD±, but instead aligns with the
RRCLK * 8 frequency and the LOS alarm register (RDOOLV) will be set. Besides
differential PECL, the ALOS− input can be set to accept single ended PECL input if
ALOS+ is tied to GND. ALOS− has to be decoupled.
RSTB
VCLK
101
99
Input
Reset: This active LOW signal provides a device reset. This line can be pulled LOW
to put the CY7C955 into the power-down mode. RSTB has an integrated pull-up resis-
tor.
Input
Factory test pin. Must be LOW for normal operation. VCLK has an integrated pull-down
resistor.
Transmit Power
Name
Pin No I/O
Description
TXVDD
12
Power
The Transmit Pad Power supplies the TXD± outputs. TXVDD is physically isolated from
the other device power pins and should be well regulated +5V DC and noise-free for good
performance when driving category 5 unshielded twist pair cabling.
TAVD1
TAVD2
4
6
Power
Power
The power pin for the transmit clock synthesizer reference circuitry. TAVD1 should be
connected to analog +5V.
The power pin for the transmit clock synthesizer oscillator. TAVD2 should be connected
to analog +5V.
TAVD3
8
Power
Power
The power pin for the transmit PECL inputs. TAVD3 should be connected to analog +5V.
TVDDO
18
Power for TXC± and RXDO±.
5
PRELIMINARY
CY7C955
Receive Power
Name
Pin No I/O
30 Power
Description
RAVD1
The power pin for receive clock and data recovery block reference circuitry. RAVD1 should
be connected to analog +5V.
RAVD2
RAVD3
RAVD4
36
24
32
Power
Power
Power
The power pin for receive clock and data recovery block active loop filter and oscillator.
RAVD2 should be connected to analog +5V.
The power pin for the RXD± and ALOS± PECL inputs. RAVD3 should be connected to
analog +5V.
The power pin for the RRCLK± PECL inputs. RAVD4 should be connected to analog +5V.
Core Power
Name
Pin No I/O
Description
V
20, 61, Power
107
The core power pins should be connected to a well decoupled +5V DC in common with
DDI
V
.
DDO
V
55, 73, Power
81, 114
The pad ring power pins should be connected to a well decoupled +5V DC in common
with V
DDO
.
DDI
Ground
Name
Pin No I/O
Description
TAVS1
5
Ground
The ground pin for the transmit clock synthesizer reference circuitry. TAVS1 should be
connected to analog GND.
TAVS2
7
Ground
The ground pin for the transmit clock synthesizer oscillator. TAVS2 should be connected
to analog GND.
TAVS3
11
17
Ground
Ground
The ground pin for the transmit PECL inputs. TAVS3 should be connected to analog GND.
TXV
The transmit pad ground is the return path for the TXC± and TXD± outputs. TXV is
SS
SS
physically isolated from the other device ground pins and should be noise-free for good
performance when driving category 5 unshielded twisted pair cabling.
RAVS1
RAVS2
31
37
Ground
Ground
The ground pin for receive clock and data recovery block reference circuitry. RAVS1 should
be connected to analog GND.
The ground pin for receive clock and data recovery block active loop filter and oscillator.
RAVS2 should be connected to analog GND.
RAVS3
RAVS4
29
35
Ground
Ground
The ground pin for the RRCLK± PECL inputs. RAVS3 should be connected to analog GND.
The ground pin for the RSD± and ALOS± PECL inputs. RAVS4 should be connected to
analog GND.
RVSSO
21
Ground
This pin is grounded for TXC± and RXDO±.
V
19, 62, Ground
106,48
The core ground (V ) pins should be connected to GND in common with V
.
SSO
SSI
SSI
V
56, 72, Ground
The pad ring ground (V
) pins should be connected to GND in common with V
.
SSI
SSO
SSO
80, 113,
49
V
1, 38,
39, 46,
47, 64,
65, 102,
103,
Ground
These pins must be connected to GND for correct operation.
SS
128
ATP1,
ATP2,
ATP3
40, 3,
46
I/O
These Analog Test Points (ATPx) are for factory testing use only. These pins have to be
tied to GND for correct chip operation.
6
PRELIMINARY
CY7C955
Pin Configuration
128-pin PQFP
Top View
102
101
VSS
1
VSS
TBYP
ATP2
TAVD1
RSTB
2
3
100
99
CSB
VSS
4
5
98
97
96
TAVS1
RATE[0]
RATE[1]
TSOC
TAVD2
TAVS2
6
7
8
9
95
94
TAVD3
TRCLK–
TRCLK+
TAVS3
TPRTY
TDAT[7]
TDAT[6]
93
92
91
90
10
11
TDAT[5]
TDAT[4]
TDAT[3]
TXV
12
13
14
DD
TXC+
TXC–
CY7C955
AX
89
88
TDAT[2]
TDAT[1]
TDAT[0]
TXD+
15
16
87
86
85
84
TXD–
TCA
TXV
17
18
19
20
SS
TWRENB
TVDDO
VSSI
ATM
SONET / SDH
TRANSCEIVER
TFCLK
RSOC
83
82
VDDI
RVSS
RPRTY
VDDO
VSSO
21
22
81
80
79
78
RXDO+
RXDO–
RAVD3
RXD–
23
24
25
26
RDAT[7]
RDAT[6]
RDAT[5]
77
76
RXD+
ALOS–
ALOS+
RAVS3
RAVD1
RAVS1
RDAT[4]
RDAT[3]
27
28
75
74
73
RDAT[2]
29
30
31
32
VDDO
VSSO
72
71
RAVD4
RRCLK–
RDAT[1]
RDAT[0]
RCA
RRDENB
RFCLK
TSEN
70
69
68
33
34
RRCLK+
35
36
37
38
RAVS4
RAVD2
RAVS2
VSS
67
66
65
VSS
7C955−2
7
PRELIMINARY
CY7C955
Transmit SONET Path Overhead Processor (TPOP)
Description
The SONET path overhead processor provides payload point-
er alignment (H1, H2), path overhead insertion, and insertion
of the Synchronous Payload Envelope (SPE). ATM cells (both
assigned and unassigned) are inserted into the SPE for trans-
mission in the SONET frame
Transmit Section
Transmit Utopia Interface (TUI)
The transmit interface provides a simple access from the ex-
ternal environment to the ATM Transceiver. The operation of
this interface is compliant with the Utopia interface specifica-
tion. The interface provides a 9-bit by 4-cell FIFO to decouple
the system interface from the ATM physical layer timing. 9-bit
words are clocked into the device through a clocked FIFO sys-
tem interface. These 9 bits include an 8-bit data word along
with a Start Of Cell (SOC) indication. The interface also pro-
vides full and almost full indications (TCA). Maximum clock
rate for this interface is 33 MHz.
SONET Overhead Insertion
The SONET/SDH STS−3c/STM−1 frame structure is shown in
Figure 1 and the SONET STS−1 frame structure is shown in
Figure 2. The SONET frame occurs once every 125 µs and is
transmitted beginning with the A1 bytes, followed by the A2
bytes, C1 bytes, 261 bytes (87 bytes for STS−1) of the Syn-
chronous Payload Envelope (SPE), B1 bytes, etc., until the
entire frame is transmitted.
The TPOP generates the H1 and H2 bytes that indicate the
beginning of the SPE and the H4 byte that indicates the ATM
cell offset within the SPE. The default initial value for H1 and
H2 pointer is 522, meaning that the first byte of the SPE (J1)
corresponding to a frame actually starts after the C1 byte of
the next frame.
Transmit ATM Cell Processor (TACP)
The ATM cell processor provides HEC generation, idle/unas-
signed cell header modification, payload scrambling, and GFC
insertion.
HEC Generator
In the default case described above, a 6h is present in the New
Data Flag (NDF) portion of the first H1 (bits 0−4), a 2h is
present in bits 5−7 and a 0Ah is present in the first H2 byte.
The remaining H1 bytes for STS−3c/STM−1 are set to 93h and
the remaining H2 bytes are set to FFh which is the concatena-
tion indication for the J1 pointer. The Pointer Action byte, H3,
is set to 00h. During Path AIS all of the H1 and H2 bits are set
to 1.
The Header Error Check (HEC) code is contained in the last
byte of the ATM cell header and is capable of single error cor-
rection and multiple error detection. When optionally generat-
ed, the Transmit ATM Cell Processor calculates a CRC−8 over
the first four bytes of the ATM cell header using the polynomial
x + x + x + 1. The coset x + x + x + 1 is added (modulo 2)
to the residue of this function. The HEC is calculated in accor-
dance with ANSI T1.624−1993 and CCITT Recommendation
I.432. This HEC sequence is placed in the 5th byte of the ATM
cell header.
8
2
6
4
2
The STS path trace J1 is set to all zeros. The path BIP−8 (B3)
byte provides path error monitoring. This function calculates
the bit-interleaved parity-8 code using even parity over the pre-
vious SPE before scrambling and is inserted into the current
B3 byte before scrambling. Bit-interleaved parity-8 forces the
number of 1s in the xth bit of every byte in the previous SPE
plus the xth bit of the B3 byte in the current SPE to be an even
number.
Idle/Unassigned Cell Header Modification
Idle (Unassigned) cells are sent by the ATM cell processor
whenever a complete cell is not contained within the Transmit
FIFO. This transforms the non-continuous cell input stream
into a continuous stream of assigned and unassigned cells.
The path signal level indicator, C2, defaults to 13h.
The ATM cell processor provides the ability to overwrite the
Generic Flow Control (GFC), the Payload Type Indication
(PTI), and the Cell Loss Priority (CLP) fields of Idle (Unas-
signed) cells with the values contained in the corresponding
configuration registers. VPI and VCI are set to zero in Idle (Un-
assigned) cells.
The path status, G1, has several functions. Bits 1 through 4
are used to indicate Far End Block Errors (FEBE) derived by
counting the number of BIP−8 errors occurred in the last frame
received. Valid codes are 0 through 8. If more than 8 errors
have accumulated since the last, frame the maximum value is
sent with the current frame, the FEBE counter is decremented
by 8, and the remaining errors are sent with the next frame.
FEBE may be inserted through register control for diagnostic
purposes. Bits 1 through 4 can also be used to transmit Far
End Receive Failures by setting these bits to 9 (1001). This
error indicates to the far end that cell delineation has been lost.
Bit 5 can be used to generate a yellow alarm condition. The
default value for this bit is 0 (no alarm).
Payload Scrambler
The 48 bytes of the ATM payload are scrambled using a par-
43
allel implementation of the polynomial x + 1 as described in
CCITT Recommendation I.432. The scrambler can be option-
ally deselected.
GFC Insertion
The transmitted GFC field of an ATM cell can be derived from
different sources. For assigned cells, the default is from pins
TDAT[7:0]. For Idle (Unassigned) cells, the default is from
GFC[3:0] (Reg−61H, bit 7−bit 4). However, if any bit of
TGFCE[3:0] (Reg−67H, bit 7−bit4) is set, the corresponding
transmitted GFC location will instead be taken from the serial
TGFC (pin 52) input following the functional timing specifica-
tions described in the section on Transmit GFC Serial Link
Interface.
The multi-frame indicator, H4, is used to indicate the first ATM
cell and may take on values of 00 to 34h.
The remaining bytes, F2, Z3, Z4, and Z5, are not used by the
SONET path processing and are set to 00h upon transmission.
When operating in STS−1 mode, SPE columns 30 and 59 can
be configured as fixed stuff columns.
8
PRELIMINARY
CY7C955
.
A1
A1 A1 A2 A2 A2 C1 C1 C1
B1
D1
E1
D2
F1
D3
J1
H1
H1 H1 H2 H2 H2 H3 H3 H3
K1
B3
C2
G1
F2
B2
D4
D7
B2 B2
K2
D6
D5
D8
Payload
D9
D10
D11
D12
Payload
HD1 HD2 HD3 HD4 HEC PAYLOAD
Z1 Z1 Z1 Z2 Z2 Z2 E2
H4
Z3
Z4
Z5
9 Bytes
261Bytes
7C955−3
Figure 1. STS−3c/STM−1 Framing Format
A1
A2 C1
B1 E1 F1
D1 D2 D3
J1
H1
B2
H2 H3
K1
K2
B3
D4 D5 D6
D7 D8 D9
C2
G1
F2
Payload
D10D11 D12
Z1 Z2 E2
Payload
HD1 HD2 HD3 HD4 HEC PAYLOAD
H4
Z3
Z4
Z5
87 Bytes
3 Bytes
7C955−4
Figure 2. STS−1 Framing Format
9
PRELIMINARY
CY7C955
Transmit SONET Line Overhead Processor (TLOP)
Parallel to Serial Converter (PSC)
The Transmit SONET line overhead processor (TLOP) pro-
vides BIP−8/24 generation and line level alarms.
The PSC converts the parallel data from the TSOP to serial
data. The bit rate clock is derived from the Transmit Clock Gen-
erator. The serialized data and aligned output clock are pre-
sented to the Transmit Output Multiplexer.
The BIP−8/24 code is calculated as if the STS−3c frame was
composed of three STS−1s. The first B2 byte is calculated over
the first STS−1 frame, the second B2 byte over the second
STS−1 frame and the third B2 byte over the third STS−1 frame.
Each B2 bit is calculated over the line and SPE portions of the
previous frame before scrambling using even parity and insert-
ed into the current frame before scrambling. For STS−1 RATE,
a BIP−8 is calculated over the entire SPE and line overhead
and placed in B2.
Transmit Output Multiplexer (TOM)
The TOM selects between the serialized output data stream
and associated clock provided by the PSC and the recovered
data and clock from the Receive Clock Recovery block for
transmission based on the state of the local loop back enable
(LLE) register (Reg−05H, bit 2). When LLE = 1 the recovered
data and recovered clock is selected for output on the transmit
data lines (TXD±) and the transmit clock lines (TXC±). The
output signal is 100K compatible differential Positive-refer-
enced ECL (PECL) signal capable of driving any copper or
fiber based media with impedances as LOW as 50Ω.
The Line Alarm Indication Signal (LAIS), is asserted by chang-
ing all bits of the SONET frame into 1 before scrambling. LAIS
generation is controlled by a register setting (Reg−14H, bit 0).
The Line Far End Receive Failure (LFERF), also called Line
RDI, is indicated by placing a 110 pattern in bits 6,7, and 8 of
the first K2 byte. LFERF can be asserted under register
(Reg−20H, bit 0) control.
Receive Section
Receive Clock Recovery (RCR)
The Line Far End Block Errors (LFEBE) are located in the third
Z2 byte and indicate the number of B2 errors in the previous
frame interval. Legal values for this byte are 00h through 18h.
The RCR provides clock and data recovery from an incoming
differential PECL data stream. Clock and data are recovered
from the incoming differential PECL data stream without the
need for external buffering and AC-coupling. The built-in line
receiver inputs have a wide common-mode range (2.5−5V)
and the ability to receive signals with as little as 200 mV differ-
ential voltage. They are compatible with all PECL signals. They
are compatible with all PECL signals driven by optical modules
or twisted-pair equalizers. The Receive PLL uses the RRCLK
as a byte-rate reference. This input is multiplied by 8 and is
used to improve PLL lock time and to provide a center frequen-
cy for operation in the absence of input data stream transitions.
The receiver can recover clock and data in two different fre-
quency ranges depending on the state of the RATE0 pin. To
insure accurate data and clock recovery, the received data
stream must be within 1000 ppm of RRCLK * 8 (The PLL will
declare Out Of Lock if the data rate is different from REFCLK
x 8 by more than 2000 ppm. The PLL will remain Out Of Lock
until the data rate pulls back to within 700 ppm of REFCLK x
8 frequency). The standards, however, specify that the
RRCLK*8 frequency accuracy be within 20−100 ppm. The wid-
er frequency tolerance range of the CY7C955 is an advantage
that allows for higher frequency tolerance in bench testing set-
ups.
All bytes of the line data communication channel (D4−D12)
and all other unused bytes are encoded to 00h.
Transmit SONET Section Overhead Processor (TSOP)
The Transmit SONET Line Overhead Processor (TSOP) pro-
vides A1,A2 framing pattern generation, section BIP−8 (B1)
insertion, section level alarm insertion, and frame scrambling.
The A1 and A2 bytes provide a framing pattern for frame align-
ment. All A1 bytes are coded to F6h and all A2 bytes are coded
to 28h. These bytes are not scrambled upon transmission.
The STS−1 identification bytes, C1, are used for framing and
de-interleaving purposes and are coded the order in their ap-
pearance in the STS−3c frame. The first C1 byte is coded to
01h, the second to 02h, and the third to 03h.
The section BIP−8 (B1) is the byte-interleaved parity-8 calcu-
lated over all bytes of the previous frame after scrambling and
inserted into the current frame before scrambling.
The bytes of the section data communication channel, D1−D3
and the remaining unused bytes are set to 00h.
The frame is scrambled prior to transmission with the generat-
A Loss of Signal (ROOLV = 1) is declared when no transitions
have been detected on the incoming data stream for more than
512 bit-times. LOS is cleared when two valid framing patterns
(A1, A2) have been found and the intervening data does not
contain a period that violates the minimum transitions limit.
7
6
ing polynomial x + x + 1. The A1, A2, and C1 bytes are not
scrambled. The scrambler runs continuously through the
frame and resets at the beginning of the next transmission
frame. The scrambler may be optionally disabled.
Transmit Clock Generator (TCG)
Serial to Parallel Conversion (SPC)
The TCG accepts a byte-rate transmit clock from TRCLK that
operates at either 19.44 MHz for STS−3c/STM−1 RATE or at
6.48 MHz for STS−1 RATE. The Transmit PLL multiplies this
byte-rate reference by eight to produce the bit-rate clock used
by the parallel-to-serial converter. Optionally a bit-rate source
can be taken from an external source (TBYP = 1) or from the
Receive Clock Recovery block when in loop-time mode
(LOOPT = 1). In loop-time mode the recovered clock is used
to provide timing to the transmitter.
The SPC converts bit serial data to byte serial data from either
the recovered received data or the transmit data from the PSC
depending on the state of the DLE register (Reg−05H, bit 1).
When DLE =1 transmit data is used for serial to parallel con-
version. The SPC also provides SONET framing by scanning
the incoming data for the SONET framing pattern A1, A2. For
STS−1 RATE the framer looks for the pattern F628h and for
STS−3 RATE the framer looks for the pattern
F6F6F6282828h. Out of Frame (OOF) is declared when four
consecutive frames contain a framing error. OOF clears when
two frames contain valid framing characters. Loss of Frame
10
PRELIMINARY
CY7C955
(LOF) is declared when the OOF condition fails to clear within
3 ms. LOF clears after 3 ms of frames with valid framing char-
acters.
is provided to the Receive ATM Cell Processor for cell extrac-
tion.
The BIP−8 value calculated over the previous SPE is com-
pared with the B3 byte of the current path overhead. Up to
65,535 errors can be detected per second. Errors are recorded
in a 16-bit saturating counter that can be read through the
controller interface.
Receive SONET Section Overhead Processor (RSOP)
The RSOP provides descrambling, SONET section alarm in-
dication, and error monitoring.
The data is descrambled using the generating polynomial 1 +
x + x . The A1, A2, and C1 bytes are not descrambled. The
scrambling process may be disabled under register control.
Path Far End Block Errors (PFEBE) are detected by examining
the value in bits 1 through 4 of G1. This value (0−8h) is added
to the count in a 16-bit saturating counter that can be read
through the controller interface.
6
7
The BIP−8 value calculated over the previous scrambled frame
is compared with the B1 byte of the current frame section over-
head after descrambling. If the two values do not match, the
B1PAR output is taken HIGH. Up to 64,000 errors can be de-
tected per second (8000 frames/second * 8 bit-errors
(max)/frame). Errors are recorded in a 16-bit saturating
counter that can be read through the controller interface.
Path Far End Receive Failures (PFERF) are detected by ex-
amining the value in bits 1 through 4 of G1. If this value is 9h
for two consecutive frames, PFERF is set. This register bit is
cleared when anything other than 9h appears for two consec-
utive frames.
Path Remote Defect Indication (Path RDI) is detected by ex-
amining bit 5 of G1. If this value is 1h for 5 consecutive frames,
PYEL is set. This register bit is cleared when a 0 appears in
bit 5 for 5 consecutive frames.
Receive SONET Line Overhead Processor (RLOP)
The RLOP provides SONET line alarm indications and error
monitoring.
Receive ATM Cell Processor (RACP)
A Line Alarm Indication Signal (LAIS) is asserted when a 111
pattern is detected for five consecutive frames in bits 6,7, and
8 of the first K2 byte of the Automatic Protection Switching
channel. LAIS is removed when anything other than a 111 pat-
tern is received for five consecutive frames.
The RACP block provides cell delineation, HEC checking and
correcting, cell filtering for idle/unassigned cells, cell payload
descrambling, status indications, and error monitoring.
Cell delineation is performed by comparing the HEC sequence
calculated over the first four bytes of the SPE to the fifth byte.
If these values match, cell boundary has been determined. If
not, the calculation advances one byte further into the payload
(bytes 2−5) and the check is performed again. The HEC se-
quence is a CRC−8 calculated over the first 4 octets of the ATM
A Line Far End Receive Failure (LFERF) or Line RDI is indi-
cated with a 110 pattern is detected for five consecutive frames
in bits 6,7, and 8 of the first K2 byte. LFERF is removed when
anything other than a 110 pattern is received for five consec-
utive frames.
8
2
6
cell header using the polynomial x + x + x + 1. The coset x
The BIP−24 (BIP−8 for STS−1 RATE) value calculated over the
previous line overhead and SPE is compared with the B2 bytes
of current frame. Up to 192,000 errors can be detected per
second (3 channels/frame * 8 errors (max)/channel * 8000
frames/second). Errors are recorded in a 20-bit saturating
counter that can be read through the controller interface.
4
2
+ x + x + 1 is added (modulo 2) to the residue before com-
parison with the received sequence. This is the HUNT state of
the cell delineation process. When a valid match has occurred
the process enters the PRESYNC state. When 7 consecutive
matches occur the process enters the SYNC state. If 6 con-
secutive incorrect HEC matches are detected the process
moves back to the HUNT state. The average time for cell de-
lineation is 93µs for STS−1 and 31µs for STS−3C.
Far End Block Errors (FEBE) are detected by examining the
value in the third Z2 byte. This value (0−18h) is added to the
count in an 18-bit saturating counter that can be read through
the controller interface.
The HEC sequence is used not only to check for cell align-
ment, but also to insure that integrity of the ATM header. The
HEC is used to correct single bit errors and to detect multiple
bit errors. This feature can be disabled. The register file con-
tains two saturating 8-bit counters for HEC errors; one for cells
with single bit errors and another for multiple-bit errors. Cells
with multiple bit errors are optionally discarded. Figure 3
shows the state diagram for HEC.
Receive SONET Path Overhead Processor (RPOP)
The RPOP provides pointer interpretation, SPE extraction,
SONET path alarm indications, and error monitoring.
The payload location is determined by examining the values in
the H1 and H2 bytes of the line overhead which indicate the J1
byte of the SPE. The RPOP can process a J1 byte located
anywhere in the SPE. Loss of Pointer (LOP) is set when a valid
pointer value has not been found within eight consecutive
frames. This register bit is cleared when a valid pointer is found
for three consecutive frames. Path Alarm Indication Signal
(PAIS) (Reg30H, bit 3) is set when the H1 and H2 bytes are
set to all ones for 3 consecutive frames. This register bit is
cleared when a valid pointer is found for three consecutive
frames. PAIS does not cause LOP to be set. The SPE location
The RACP optionally discards Idle/Unassigned cells. These
cells contain a VPI/VCI address of 0h. Also, a Header Mask
and Header Match register are provided to allow cells with a
particular header characteristic in GFC, PTI and CLP to be
filtered.
The payload of valid cells are descrambled using the polyno-
43
mial x +1. The cell headers are not descrambled since they
11
PRELIMINARY
CY7C955
were not scrambled upon transmission. The descrambling fea-
ture can be disabled.
ATM DELINEATION
SYNC STATE
ALPHA
Apparent Multi-Bit Error
(Drop Cell)
consecutive
HECs (From
HUNT state)
Errors
Detected
(Drop
No Errors
CORRECTION
DETECTION
MODE
Detected
MODE
Single Bit Error
(Correct Error
and Pass Cell)
Pass Cell
Cell)
No Errors Detected
(Pass Cell)
DELTA
consecutive HECs
7C955−5
(From PRESYNCstate)
Figure 3. HEC Verification State Diagram
Receive Utopia Interface (RUI)
Controller Interface (CI)
The RUI provides a simple access from the external environ-
ment to the ATM Transceiver. The operation of this interface is
compliant with the Utopia interface specification that is being
standardized by the ATM Forum. The interface provides a 10
bit by 4 cell FIFO to decouple the system interface from the
ATM physical layer timing. Ten bit words are clocked out from
the device through a clocked FIFO style interface. These 10
bits include an 8-bit data word along with an parity bit
(RXPRTY) and a Start Of Cell (SOC) indication. The interface
also provides a cell available (RCA) indication and a read en-
able (RRDENB) control. RCA allows the FIFO to indicate emp-
ty and almost empty conditions and RRDENB allows the
downstream circuit to pause the reading process in case the
downstream cannot accept anymore read. If the Receive FIFO
overflows, FIFO reset will occur and up to 4 cells may be lost
because of the operation.
The CI interface provides external access to the internal reg-
ister file, device resetting and external input for the carrier de-
tect signal. The ALOS input allows an external carrier detect
from an optical module to cause an interrupt to the controller.
The INTB and RALM pins can be configured to interrupt the
external controller whenever any of several different error con-
ditions occur. RALM signals the most important error condi-
tions such as LOS, LOF, line AIS, path AIS, LCD, and LOP.
INTB may indicate all possible errors depending on the state
of the mask registers. INTB provides notification of the individ-
ual processing block that generated the error condition. The
error register contained in each block will determine the exact
cause of the interrupt.
Controller
Interface
Byte Rate
Oscillator
Packet
Receive Parallel Data
Receive Serial Data
Carrier Detect
Fiber or Copper
Media Interface
Reassembly
Clock and Data
Recovery and
Receive
Receive Start of Cell
or
Receive Parity
ATM Switch
Core
Read Strobe
ATM Cell
Processing
Equalization
SONET/SDH
Overhead Processing
TransmitParallel Data
Buffered TransmitData
Packet
Segmentation
or
Fiber or Copper
Media Interface
Frequency
Multiplication &
Transmit
TransmitStart of Cell
TransmitParity
ATM Switch
Core
WriteStrobe
Buffering
7C955−6
CY7C955ATM−SONET/SDHTransceiver(AX)
Figure 4. SONET/SDH and ATM Interface
12
PRELIMINARY
CY7C955
F6
F6
F6
28
28
28
01
02
03
H
H
H
H
H
H
H
H
H
A1
NOTE
B1
A1
A1
A2
A2
A2
C1
C1
C1
1
00
00
00
00
00
00
00
00
H
H
H
H
H
H
H
H
E1
F1
00
00
00
00
H
00
00
00
00
00
H
H
H
H
H
H
H
H
D1
D2
D3
00
H3
00
H3
62
93
H1
93
0A
H2
FF
H2
FF
H
H2
00
H3
H
H
H
H
H
H
H
H
H1
[NOTE
B2
H1
[NOTE
B2
1]
[NOTE
1]
1]
00
00
K2
00
00
00
00
H
H
H
H
H
H
H
B2
K1
00
D4
00
00
00
H
00
D6
00
00
H
H
H
00
00
00
H
H
H
H
D5
00
D7
H
00
00
00
00
00
00
00
00
00
00
00
H
H
H
H
H
H
H
H
H
D9
D8
00
D10
00
D11
00
00
H
00
H
H
H
H
H
H
H
H
D12
[NOTE
1]
00
Z1
00
00
00
Z1
00
Z1
00
00
H
Z2
00
E2
H
H
H
H
H
H
Z2
Z2
7C955−7
Note:
1. B1, B2, Z2, G1, H4, and B3 are variables.
Figure 5. Default Values for the Transmitted Section and Line STS−3C/STM−1 Overhead
13
PRELIMINARY
CY7C955
00
C1
F6
A1
F6
H
A2
H
H
NOTE 1
00
00
H
H
E1
F1
B1
00
00
00
H
H
H
D1
D2
D3
62
0A
00
H
H
H
H1
H2
H3
NOTE
1
00
00
H
H
K2
B2
K1
00
00
00
H
H
H
D4
D5
D6
00
00
00
H
H
H
D7
D8
D9
00
D10
00
D11
00
D12
H
H
H
NOTE
1
00
Z1
00
E2
H
H
Z2
7C955−8
Figure 6. Default Values for the Transmitted Section and Line STS−1 Overhead
14
PRELIMINARY
CY7C955
00
H
J1
NOTE
1
B3
13
H
C2
NOTE
1
G1
00
H
F2
NOTE
1
H4
00
H
Z3
00
Z4
H
00
H
Z5
7C955−9
Figure 7. Default Values for the Transmitted Path Overhead
15
PRELIMINARY
CY7C955
Loopback Operation
Transmit
Transmit
ATM Cell
Processor
Transmit
Path
Transmit
Line
Overhead
Processor
Transmit
Section
TXD±
Transmit
Clock
Multiplier &
Transmit
Buffer
UTOPIA I/F
TXC±
Transmit FIFO
4 Cell by 8 bit
Overhead
Processor
Overhead
Processor
TRCLK±
D[7:0]
A[7:0]
Configuration and Status
Register File
ALE
Controller
Interface
Rate
Selection
RDB
WRB
CSB
Error Monitoring
SONET/SDH
Clock
Recovery
INTB
RSTB
ALOS±
RRCLK±
RXD±
Receive
UTOPIA I/F
Receive FIFO
4 Cell by 8 bit
Receive
ATM Cell
Processor
Receive
Path
Overhead
Processor
Receive
Line
Overhead
Processor
Receive
Section
Overhead
Processor
VCLK
RALM
RXDO±
High Speed Line Loopback
7C955−10
Transmit
Transmit
Transmit
Path
Transmit
Line
Overhead
Processor
Transmit
TXD±
Transmit
Clock
Multiplier &
Transmit
Buffer
UTOPIA I/F
ATM Cell
Section
Overhead
Processor
TXC±
Transmit FIFO
4 Cell by 8 bit
Processor
Overhead
Processor
TRCLK±
D[7:0]
Configuration and Status
Register File
A[7:0]
ALE
Controller
Interface
Rate
Selection
RDB
WRB
CSB
INTB
RSTB
VCLK
RALM
Error Monitoring
SONET/SDH
Clock
Recovery
ALOS±
RRCLK±
RXD±
Receive
UTOPIA I/F
Receive FIFO
4 Cell by 8 bit
Receive
ATM Cell
Processor
Receive
Path
Overhead
Processor
Receive
Line
Overhead
Processor
Receive
Section
Overhead
Processor
RXDO±
Diagnostic Loopback
7C955−11
16
PRELIMINARY
CY7C955
SONET Overhead Description
Signal Values
Description
The frame alignment bytes mark the beginning of a SONET frame. They are transmitted every 125
µs in both OC−1 and OC3c speeds. Transmit Side: In OC−1, A1(F6 ) and A2 (28 ) are inserted
A1, A2
H
H
into the transmitted stream at the beginning of every frame. These bytes are not scrambled by the
frame synchronous SONET scrambler. Receive Side: The receiver will search for and frame onto
the incoming A1, A2 bytes.
C1
This is the identification byte for the STS data stream. Transmit Side: In OC−1, C1 is transmitted as
OH. In OC−3c, the sequence C1, C1, C1 of every frame is transmitted as 01 , 02 , 03 . These
H
H
H
bytes are not scrambled by the frame-synchronous SONET scrambler. Receive side: The receiver
will ignore C1.
B1
This is the section bit interleave parity byte. Transmit Side: B1 is calculated using the BIP−8 algorithm
described in I.432. It is inserted into the SONET data stream before the frame synchronous SONET
scrambler. Receive Side: Received B1 error events are accumulated in the SBE [15:0] (Reg−12H
and Reg−13H).
H1, H2
These are the pointer value byte. These bytes are used to locate the beginning of the Synchronous
Payload Envelope (SPE) in the SONET/SDH frame. Transmit side: H1, H2 contains the normal new
data flag (0110) together with 522 (decimal) as the fixed pointer value field. The concatenation
indication byte is also inserted (H1* = 93, H2* = FF). Receive Side: H1 and H2 are used to locate
the beginning of the SPE. If a valid pointer cannot be found, CY7C955 will indicate a Loss of Pointer
State. Path AIS is detected by an all-ones pattern in H1 and H2 bytes.
H3
B2
K2
This is the pointer action byte. Transmit Side: H3 will be all zeroes. Receive Side: Synchronous
Payload Data will be stuffed in the H3 byte if a negative stuff event occurs. This byte is ignored
otherwise.
This is the line bit interleaved parity bytes, it is used to monitor line errors. Transmit Side: B2 is
calculated over all bits of the line overhead and the SPE capacity of the previous frame before the
frame is being scrambled. The B2 byte itself is then placed in the current frame before scramble.
This is the identity line layer maintenance signal. Transmit Side: Bits 6, 7, and 8 of this byte are ‘110’
before scrambling when Line Remote Defect Indication is true. The whole of K2 is an all-one pattern
before scrambling if Line AIS is inserted. Receive Side: Bits 6, 7, and 8 of the K2 byte are being
examined to determine the presence of AIS, and RDI signals. Access to APs registers will be
available in future revisions.
Z2
B3
C2
G1
H4
This is the growth byte. It is used to provide far end block error function useful for remote performance
monitoring. Transmit Side: The number of B2 errors detected in the last frame is inserted. Z2 is a
number from 0−24 indicating 0−24 errors. Receive Side: A legal (0−24) Z2 number will be added to
the line FEBE counter.
This is the interleaved parity byte. Transmit Side: B3 is calculated over all bits of the SPE of the
previous frame before scrambling and is placed in the current frame before scrambling. This provides
path error monitoring capability for the link. Receive Side: The value in B3 is accumulated in a
register.
This is the path signal label byte for indicating the contents of the SONET payload. Transmit Side:
It’s fixed value is 13H. This indicates the payload is ATM. Receive Side: The receive side expects
C2 to be 13H. If the data is not 13H for 3 consecutive frames, an interrupt (if enabled) will be
generated.
This is the path status byte. Transmit Side: Path remote defect Indication (Path RDI) together with
the number of B3 errors in the last frame are inserted into G1 before scrambling for transmission.
G1 is a number from 0−8, indicating 0−8 errors. Receive side: A legal G1 value (0−8) will be accu-
mulated in the FEBE counter. Path remote defect indication is also detected through this byte.
This is the cell offset byte. Transmit Side: This byte indicates the offset in bytes between the H4 byte
and the first cell byte after H4. Receive Side: H4 byte is ignored.
17
PRELIMINARY
CY7C955
CY7C955 Register Map
Address
Register
Reg−00H
Reg−01H
Reg−02H
Reg−04H
Reg−05H
Reg−06H
Reg−07H
Reg−10H
Reg−11H
Reg−12H
Reg−13H
Reg−14H
Reg−15H
Reg−18H
Reg−19H
Reg−1AH
Reg−1BH
Reg−1CH
Reg−1DH
Reg−1EH
Reg−1FH
Reg−20H
Reg−21H
Reg−30H
Reg−31H
Reg−33H
Reg−37H
Reg−38H
Reg−39H
Reg−3AH
Reg−3BH
Reg−3CH
Reg−40H
Reg−41H
Reg−45H
Reg−46H
Reg−48H
Reg−49H
Reg−50H
Reg−51H
Reg−52H
Reg−53H
Reg−54H
Master Reset/Type/Identify Register
Master Configuration Register
Master Interrupt Register
Master Clock Monitor Register
Master Control Register
Transmit Clock Synthesis Control Register
Receive Clock Synthesis Control Register
Receive Section Overhead Processor Control Register
Receive Section Overhead Processor Status Register
LSB of the Receive Section Overhead Processor Status BIP-8 Counter
MSB of the Receive Section Overhead Processor Status BIP-8 Counter
Transmit Section Overhead Processor Control Register
Transmit Section Overhead Processor Control Error Insertion Register
Receive Line Overhead Processor Control and Status Register
Receive Line Overhead Processor Interrupt Enable and Status Register
Line BIP−8/24 Register
Line BIP−8/24 Register
Line BIP−8/24 Register
Line Far-End Block Error Register
Line Far-End Block Error Register
Line Far-End Block Error Register
Transmit Line Overhead Processor Register
Transmit Line Overhead Processor Error Insertion Register
Receive Path Overhead Processor Interrupt Register
Receive Path Overhead Processor Register
Receive Path Overhead Processor Interrupt Enable Register
Receive Path Signal Label Register
Path BIP−8 (B3) Register
Path BIP−8 (B3) Register
Path Far-End Block Error Register
Path Far-End Block Error Register
Path Far-End Block Error Register
Transmit Path Overhead Processor Error Insertion Register
Transmit Path Overhead Processor Pointer Control Register
Transmit Path Overhead Processor Arbitrary Payload Pointer Register
Transmit Path Overhead Processor Arbitrary Payload Pointer Register
Transmit Path Overhead Processor Path Signal Label Register
Transmit Path Overhead Processor Arbitrary Path Status Register
Receive ATM Cell Processor Control and Status Register
Receive ATM Cell Processor Interrupt Register
Receive ATM Cell Processor Match Header Pattern Register
Receive ATM Cell Processor Match Header Mask Register
Receive ATM Cell Processor Correctable HCS Error Count Register
18
PRELIMINARY
CY7C955
CY7C955 Register Map (continued)
Address
Reg−55H
Register
Receive ATM Cell Processor Uncorrectable HCS Error Count Register
Receive ATM Cell Processor Receive Cell Counter Register
Receive ATM Cell Processor Receive Cell Counter Register
Receive ATM Cell Processor Receive Cell Counter Register
Receive ATM Cell Processor Receive Configuration Register
Transmit ATM Cell Processor Control and Status Register
Transmit ATM Cell Processor Unassigned Cell Header Register
Transmit ATM Cell Processor Unassigned Cell Payload Register
Transmit ATM Cell Processor FIFO Control Register
Reg−56H
Reg−57H
Reg−58H
Reg−59H
Reg−60H
Reg−61H
Reg−62H
Reg−63H
Reg−64H
Reg−65H
Reg−66H
Reg−67H
Reg−80H
Transmit ATM Cell Processor Transmit Cell Counter Register
Transmit ATM Cell Processor Transmit Cell Counter Register
Transmit ATM Cell Processor Transmit Cell Counter Register
Transmit ATM Cell Processor Transmit Configuration Register
CY7C955 Test Control Register
REG−00H
Master Reset / Type / Identity Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
RESET
TYPE[2]
TYPE[1]
TYPE[0]
ID[3]
R/W
R
0
0
1
1
1
1
1
1
R
R
R
ID[2]
R
ID[1]
R
ID[0]
R
RESET
This is the master reset bit. Toggling this register has the same effect as toggling the RSTB pin, except that RSTB will reset all
registers to their default values, while writing a 1 to this register will only reset all other registers (but not itself) to their default
values. Leaving a 1 in this register puts the AX in power-down mode.
0:
1:
Normal mode.
Reset / Power Down Mode.
TYPE[2:0]
These bits differentiate the AX with other Cypress products.
ID[3:0]
These bits show the revision number of the CY7C955.
19
PRELIMINARY
CY7C955
REG − 01H
Master Configuration Register
NAME
BIT POSITION
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
Unused
AUTOFEBE
AUTOLRDI
AUTOPRDI
TCAINV
R/W
R/W
R/W
R/W
R/W
R/W
1
1
1
0
0
0
RCAINV
RXDINV
Unused
AUTOFEBE
This bit controls whether Far End Block Error (FEBE) is transmitted when line or path BIP error is being detected on the receive
data stream.
0:
1:
Do not generate line or path FEBE error in response to incoming line or path BIP error.
Generate line or path FEBE error in response to incoming line or path BIP error.
AUTOLRDI
This bit controls whether Line Remote Defect Indication (LRDI) is transmitted when an incoming alarm is being detected.
0:
1:
Do not insert line RDI when line AIS, Loss of Frame (LOF) or Loss of Signal (LOS) is being detected.
Insert line RDI when line AIS, Loss of Frame (LOF) or Loss of Signal (LOS) is being detected.
AUTOPRDI
This bit controls whether STS Path Remote Defect Indication (PRDI) is transmitted when an incoming alarm is being detected.
0:
Do not insert STS path RDI when Loss of Signal (LOS), Loss of Pointer (LOP), STS path AIS, Loss of Frame (LOF), line
AIS, or Loss of Cell Delineation (LCD) is being detected.
1:
Insert STS path RDI when Loss of Signal (LOS), Loss of Pointer (LOP), STS path AIS, Loss of Frame (LOF), line AIS, or
Loss of Cell Delineation (LCD) is being detected.
TCAINV
This bit controls the polarity of TCA.
0:
1:
TCA is active HIGH.
TCA is active LOW.
RCAINV
This bit controls the polarity of RCA.
0:
1:
RCA is active HIGH.
RCA is active LOW.
RXDINV
This bit controls the interpretation of the differential pair RXD.
0:
1:
Logical 1 is represented by RXD+ HIGH and RXD− LOW.
Logical 0 is represented by RXD+ HIGH and RXD− LOW.
20
PRELIMINARY
CY7C955
REG − 02H
Master Interrupt Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
TROOLI
LCDI
R
R
R
R
R
R
R
R
RDOOLI
TACPI
RACPI
RPOPI
RLOPI
RSOPI
TROOLI
This is the Transmit Reference Out Of Lock Interrupt. This bit resets when Reg−02H is being read.
1:
TROOLV (Reg−06H, bit 3) has changed state since Reg−02H was last read.
TROOLV (Reg−06H, bit 3) has not changed state since Reg−02H was last read.
0:
LCDI
This is the Loss of Cell Delineation Interrupt. It has to be enabled by bit 7 of Reg−05H. This bit resets when Reg−02H is being
read.
1:
0:
Loss of cell delineation is entered or exited since Reg−02H was last read.
There is no change in the loss of cell delineation state.
RDOOLI
This is the Receive Data Out Of Lock Interrupt. This bit resets when Reg−02H is being read.
1:
RDOOLV (Reg−07H, bit 3) has changed state since Reg−02H was last read.
RDOOLV (Reg−07H, bit 3) has not changed state since Reg−02H was last read.
0:
TACPI
This is the Transmit ATM Cell Processor Interrupt. This bit resets when Reg−02H is being read. This register is a logical OR of
all the Transmit ATM Cell Processor (TACP) interrupts Reg−60H and 63H.
1:
0:
FOVRI, TSOCI, or TXPRTYI is HIGH.
FOVRI, TSOCI, and TXPRTYI are all LOW.
RACPI
This is the Receive ATM Cell Processor Interrupt. This bit resets when Reg−02H is being read. This register is a logical OR of
all the Receive ATM Cell Processor (RACP) interrupts of Reg−51H.
1:
0:
OOCDI, CHCSI, or UHCSI is HIGH.
OOCDI, CHCSI, and UHCSI are all LOW.
RPOPI
This is the Receive Path Overhead Processor Interrupt. This bit resets when Reg−02H is being read. This register is a logical
OR of all the Receive Path Overhead Processor (RPOP) interrupts of Reg−31H.
1:
0:
PSLI, LOPI, PAISI, PRDII, BIPEI, or FEBEI is HIGH.
PSLI, LOPI, PAISI, PRDII, BIPEI, and FEBEI are all LOW.
RLOPI
This is the Receive Line Overhead Processor Interrupt. This bit resets when Reg−02H is being read. This register is a logical
OR of all the Receive Line Overhead Processor (RLOP) interrupts of Reg−19H.
1:
0:
FEBEI, BIPEI, LAISI, or RDII is HIGH.
FEBEI, BIPEI, LAISI, and RDII are all LOW.
RSOPI
This is the Receive Section Overhead Processor Interrupt. This bit resets when Reg−02H is being read. This register is a logical
OR or all the Receive Section Overhead Processor (RSOP) interrupts or Reg−11H.
1:
0:
BIPEI, LOSI, LOFI, or OOFI is HIGH.
BIPEI, LOSI, LOFI, and OOFI are all LOW.
21
PRELIMINARY
CY7C955
REG − 04H
Master Clock Monitor Register
NAME
BIT POSITION
READ/WRITE
R/W
DEFAULT
7
RXDOD
XORTXC
Unused
Unused
RRCLKA
TRCLKA
RCLKA
TCLKA
0
0
6
R/W
5
4
3
R
R
R
R
2
1
0
RXDOD
This bit is used to turn off the RXDO output in case it is not needed. This helps save power and reduce power supply noise.
1:
0:
RXDO output is disabled.
RXDO is the retimed buffered output of RXDXORTXC.
XORTXC is used to invert the default-on status of the TXC output.
1:
0:
TXC is disabled if RATE0 is LOW, and TXC is a 155.52-MHz clock if RATE0 is HIGH.
TXC is a 51.84-MHz clock if RATE0 is LOW, and TXC is disabled if RATE0 is HIGH.
RRCLKA
This bit can be read to check for RRCLK transitions; when HIGH, this bit stays HIGH until Reg−04H is being read.
1:
0:
RRCLK+ has a LOW to HIGH transition since this register was last read.
RRCLK+ has no LOW to HIGH transitions since this register was last read.
TRCLKA
This bit can be read to check for TRCLK transitions; when HIGH, this bit stays HIGH until Reg−04H is being read.
1:
0:
TRCLK+ has a LOW to HIGH transition since this register was last read.
TRCLK+ has no LOW to HIGH transitions since this register was last read.
RCLKA
This bit can be read to check for RCLK transitions; when HIGH, this bit stays HIGH until Reg−04H is being read.
1:
0:
RCLK has a LOW to HIGH transition since this register was last read.
RCLK has no LOW to HIGH transitions since this register was last read.
TCLKA
This bit can be read to check for TCLK transitions; when HIGH, this bit stays HIGH until Reg−04H is being read.
1:
0:
TRCLK+ has a LOW to HIGH transition since this register was last read.
TRCLK+ has no LOW to HIGH transitions since this register was last read.
22
PRELIMINARY
CY7C955
REG − 05H
Master Control Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
LCDE
LCDV
FIXPTR
Unused
Unused
LLE
R/W
R
0
1
R/W
R/W
R/W
R/W
0
0
0
DLE
LOOPT
LCDE
This bit enables a change in the Loss of Cell Delineation state to generate an interrupt on pin INTB.
0:
INTB will not be affected by a transition in LCDV (Reg−05H, bit 6).
INTB will go LOW when there is a transition in LCDV (Reg−05H, bit 6).
1:
LCDV
This bit shows the present loss of cell delineation state of the Receive ATM Cell overhead Processor (RACP).
0:
1:
RACP is in SYNC state for longer than 4 ms.
RACP is out of cell delineation for more than 4 ms and there are no detected LOS, LOP, Path AIS, and Line AIS.
FIXPTR
This bit controls the operation of the transmit payload pointer adjustment function.
0:
The setting in Reg−41H can control the payload pointer adjustment operations.
1:
The transmit payload pointer is fixed at 522.
LLE
This bit controls the line loop-back path of the CY7C955; DLE and LLE cannot be both set to 1.
0:
Normal operation.
1:
RXD+ and RXD− are connected to TXD+ and TXD− internally.
DLE
This bit controls the diagnostic loop-back path of the CY7C955; DLE and LLE cannot be both set to 1.
0:
1:
Normal operation.
The transmitted data steam is being looped back to the received data stream.
LOOPT
This bit enables loop timing.
0:
The transmitted data stream derives its clock from TRCLK. The clock to use depends on the setting of TREFSEL
(Reg−06H, bit 0) and on the level of pins TBYP and RATE0.
1:
The transmitted data stream derives its clock from RRCLK if the clock and data recovery function of the receiver is not
active and from RXD if the clock and data recovery function is active. Again, the clock to use in RRCLK depends on
the setting of RREFSEL (Reg−07H), RBYP, and RATE0.
23
PRELIMINARY
CY7C955
REG − 06H
Transmit Clock Synthesis Control Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
Unused
Unused
Unused
Unused
TROOLV
Unused
TROOLE
TREFSEL
R
R/W
R/W
0
0
TROOLV
This bit is the Transmit Reference Out Of Lock Status register.
0:
1:
The divided-down synthesized transmit clock is within 2930 ppm of TRCLK or RRCLK (in loop timing mode).
The divided-down synthesized transmit clock is not within 2930 ppm of TRCLK or RRCLK (in loop timing mode).
TROOLE
This bit is the Transmit Reference Out Of Lock Interrupt Enable register.
0:
1:
INTB, the interrupt pin, will not be affected by transmit out of lock.
INTB, the interrupt pin, will pull LOW when there is a state change of TROOLV.
TREFSEL
This bit is the Transmit Reference Select. This bit is ignored in transmit bypass mode (TBYP = 1).
0:
TRCLK expects a 19.44-MHz reference clock. If RATE0 is HIGH (155.52 Mbps, STS−3c/STM−1), the transmit PLL will
multiply the TRCLK frequency by 8 times. If RATE0 is LOW (51.84 Mbps, STS−1), the transmit PLL will multiply the
TRCLK frequency by 8/3 times to clock the transmitter.
1:
TRCLK expects a 6.48-MHz reference clock. If RATE0 is HIGH (155.52 Mbps, STS−3c/STM−1), the transmit PLL will
multiply the TRCLK frequency by 24 times. If RATE0 is LOW (51.84 Mbps, STS−1), the transmit PLL will multiply the
TRCLK frequency by 8 times to clock the transmitter.
24
PRELIMINARY
CY7C955
REG − 07H
Receive Clock Synthesis Control Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
Unused
Unused
Unused
Unused
RROOLV
Unused
RROOLE
RREFSEL
R
R/W
R/W
0
0
RROOLV
This bit is the Receive Reference Out Of Lock Status register.
0:
The divided-down recovered clock is within 2930 ppm of RRCLK, and there is at least one transition on RXD during
the last 80 bit-periods.
1:
The divided-down recovered clock is not within 2930 ppm of RRCLK, or there are no transitions on RXD within the last
80 bit-periods.
RROOLE
This bit is the Receive Reference Out Of Lock Interrupt Enable register.
0:
1:
INTB, the interrupt pin, will not be affected by receiver out of lock.
INTB, the interrupt pin, will go LOW when there is a state change of RROOLV.
RREFSEL
This bit is the Receiver Reference Select. This bit is ignored in receiver bypass mode (RBYP = 1).
0:
RRCLK expects a 19.44-MHz reference clock. If RATE0 is HIGH (155.52 Mbps, STS−3c/STM−1), the recovered clock
is divided down 8 times before comparing with RRCLK. If RATE0 is LOW (51.84 Mbps, STS−1), the recovered clock is
divided down 3/8 times before comparing with RRCLK.
1:
RRCLK expects a 6.480-MHz reference clock. If RATE0 is HIGH (155.52 Mbps, STS−3c/STM−1), the recovered clock
is divided down 24 times before comparing with RRCLK. If RATE0 is LOW (51.84 Mbps, STS−1), the recovered clock is
divided down 8 times before comparing with RRCLK.
25
PRELIMINARY
CY7C955
REG − 10H
Receive Section Overhead Processor Control Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
Unused
DDS
R/W
W
0
0
FOOF
Unused
BIPEE
LOSE
LOFE
OOFE
R/W
R/W
R/W
R/W
0
0
0
0
DDS
This bit controls whether SONET descrambling is done on the receive data stream.
0:
Descrambling is performed.
1:
Descrambling is not performed.
FOOF
This bit can be used to manually put the Receive Section Overhead Processor out of frame.
0:
No action.
The Receive Section Overhead Processor will detect an out of frame alarm at the next frame boundary.
1:
BIPEE
This bit controls whether a section BIP−8 error (B1) generates an interrupt.
0:
The interrupt pin, INTB, is not affected by section BIP−8 errors.
1:
The interrupt pin, INTB, will go LOW upon receiving a section BIP−8 error.
LOSE
This bit controls whether a Loss of Signal alarm generates an interrupt.
0:
The interrupt pin, INTB, is not affected by the loss of signal alarm.
1:
The interrupt pin, INTB, will go LOW upon receiving a loss of signal alarm.
LOFE
This bit controls whether a Loss of Frame alarm generates an interrupt.
0:
The interrupt pin, INTB, is not affected by the loss of frame alarm.
1:
The interrupt pin, INTB, will go LOW upon receiving a loss of frame alarm.
OOFE
This bit controls whether an Out of Frame alarm generates an interrupt.
0:
1:
The interrupt pin, INTB, is not affected by the out of frame alarm.
The interrupt pin, INTB, will go LOW upon receiving an out of frame alarm.
26
PRELIMINARY
CY7C955
REG − 11H
Receive Section Overhead Processor Status Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
Unused
BIPEI
LOSI
R
R
R
R
R
R
R
LOFI
OOFI
LOSV
LOFV
OOFV
BIPEI
This is the section BIP−8 interrupt bit. This bit resets when Reg−11H is being read.
0:
No section BIP−8 error is detected since Reg−11H was last read.
Section BIP−8 error is detected since Reg−11H was last read.
1:
LOSI
This is the Loss of Signal (LOS) interrupt bit. This bit resets when Reg−11H is being read.
0:
No change in the LOS status.
1:
There is a change in the LOS status since Reg−11H was last read.
LOFI
This is the Loss of Frame (LOF) interrupt bit. This bit resets when Reg−11H is being read.
0:
No change in the LOF status.
1:
There is a change in the LOF status since Reg−11H was last read.
OOFI
This is the Out of Frame (OOF) interrupt bit. This bit resets when Reg−11H is being read.
0:
No change in the OOF status.
1:
There is a change in the OOF status since Reg−11H was last read.
LOSV
This bit shows the Loss of Signal (LOS) status of the CY7C955.
0:
The Receive Section Overhead Processor is not in a loss of signal state.
The Receive Section Overhead Processor is in a loss of signal state.
1:
LOFV
This bit shows the Loss of Frame (LOF) status of the CY7C955.
0:
1:
The Receive Section Overhead Processor is not in a Loss of Frame state.
The Receive Section Overhead Processor is in a Loss of Frame state. LOF is declared when OOF has lasted for more
than 3 ms. LOFV stays HIGH until the Receive Section Overhead Processor is in frame for more than 3 ms.
OOFV
This bit shows the Out of Frame (OOF) status of the CY7C955.
0:
1:
The Receive Section Overhead Processor is in frame.
The Receive Section Overhead Processor is in an out of frame state.
27
PRELIMINARY
CY7C955
REG − 12H
LSB of the Receive Section Overhead Processor Status BIP−8 counter
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
SBE[7]
SBE[6]
SBE[5]
SBE[4]
SBE[3]
SBE[2]
SBE[1]
SBE[0]
R
R
R
R
R
R
R
R
0
0
0
0
0
0
0
0
SBE[15:0]
Reg−12H and Reg−13H will load the number of BIP−8 errors from an internal counter approximately 1 µs after a write operation
is done to Reg−12H, Reg−13H, or Reg−00H. At that time (1 µs after the write operation), these two registers are updated and
the internal BIP−8 error counter is reset to zero to begin another round of error accumulation. Reading Reg−12H and Reg−13H
after the write yields the number of BIP−8 (B1) errors accumulated since the counter was last written to, if overflow has not
occurred.
REG − 13H
MSB of the Receive Section Overhead Processor Status BIP−8 counter
NAME READ/WRITE
BIT POSITION
DEFAULT
7
6
5
4
3
2
1
0
SBE[15]
SBE[14]
SBE[13]
SBE[12]
SBE[11]
SBE[10]
SBE[9]
R
R
R
R
R
R
R
R
0
0
0
0
0
0
0
0
SBE[8]
SBE[15:0]
Reg−12H and Reg−13H will load the number of BIP−8 errors from an internal counter approximately 1 µs after a write operation
is done to Reg−12H, Reg−13H, or Reg−00H. At that time (1 µs after the write operation), these two registers are updated and
the internal BIP−8 error counter is reset to zero to begin another round of error accumulation. Reading Reg−12H and Reg−13H
after the write yields the number of BIP−8 (B1) errors accumulated since the counter was last written to if overflow has not
occurred.
28
PRELIMINARY
CY7C955
REG − 14H
Transmit Section Overhead Processor Control Register
BIT POSITION
NAME
READ/WRITE
R/W
DEFAULT
7
6
5
4
3
2
1
0
Unused
DS
0
0
Unused
Unused
Unused
Unused
Unused
LAIS
R/W
DS
This bit controls whether SONET scrambling is done to the transmit data stream.
0:
Scrambling is performed.
1:
Scrambling is not performed.
LAIS
This bit controls whether line Alarm Indication Signal (AIS) is being inserted into the transmit data stream.
1:
All bits in the SONET frame (excluding the section overhead) are converted to a 1 prior to SONET scrambling. This
operation begins immediately at the next frame boundary.
0:
No line AIS is transmitted.
REG − 15H
Transmit Section Overhead Processor Error Insertion Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
Unused
Unused
Unused
Unused
Unused
DLOS
R/W
R/W
R/W
0
0
0
DBIP8
DFP
DLOS
This bit generates a continuous loss of signal error in the transmit data stream.
0:
Normal operation.
1:
TXD transmits all zeros.
DBIP8
This bit generates a continuous section BIP−8 (B1) error in the transmit data stream.
0:
Normal operation.
B1 byte is inverted.
1:
DFP
This bit generates a framing byte error in the transmit data stream.
0:
1:
Normal operation.
The most significant bit of the section overhead framing byte is converted from 1 to 0. In other words, F6H becomes H
in the first A1 byte of the section overhead.
29
PRELIMINARY
CY7C955
REG − 18H
Receive LIne Overhead Processor Control and Status Register
BIT POSITION
NAME
READ/WRITE
R/W
DEFAULT
7
6
5
4
3
2
1
0
BIPWORD
Unused
Unused
Unused
Unused
Unused
LAISV
0
R
R
0
0
RDIV
BIPWORD
This bit controls how many times a B2 error is recorded.
0:
1:
The B2 error counter increments only once per frame on receiving B2 bit-errors.
The B2 error counter increments once for every bit error represented in the B2 word. Note that in STS−3c, there could
be at most 24 B2 bit-errors per frame, and in STS−1, there could be, at most, 8 B2 bit-errors per frame.
LAISV
This bit is the Line Alarm Indication Signal (LAIS) status register.
0:
No Line AIS detected.
1:
Line AIS has been detected. Line AIS is triggered by LOS or LOF.
RDIV
This bit is the Remote Defect Indication status register.
0:
1:
No remote defect indication (RDI) detected.
Remote defect indication (RDI) has been detected.
30
PRELIMINARY
CY7C955
REG − 19H
Receive Line Overhead Processor Interrupt Enable and Status Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
FEBEE
BIPEE
LAISE
RDIE
R/W
R/W
R/W
R/W
R
0
0
0
0
FEBEI
BIPEI
LAISI
RDII
R
R
R
FEBEE
This bit controls whether line far end block error generates an interrupt by asserting INTB LOW.
0:
Line far-end block error will not generate an interrupt.
Line far-end block error will generate an interrupt.
1:
BIPEE
This bit controls whether BIP−24 (B2) error generates an interrupt by asserting INTB LOW.
0:
BIP−24 error will not generate an interrupt.
BIP−24 error will generate an interrupt.
1:
LAISE
This bit controls whether line alarm indication signal (LAIS) error generates an interrupt by asserting INTB LOW.
0:
LAIS error will not generate an interrupt.
LAIS error will generate an interrupt.
1:
RDIE
This bit controls whether a remote defect indication alarm detection generates an interrupt by asserting INTB LOW.
0:
A change in the RDIV state (Reg−18H, bit 0) will not generate an interrupt.
A change in the RDIV state (Reg−18H, bit 0) will generate an interrupt.
1:
FEBEI
This is the line far-end block error interrupt bit. This bit resets when Reg−19H is being read.
0:
No line far-end block error has been detected since Reg−19H was last read.
Line far-end block error has been detected since Reg−19H was last read.
1:
BIPEI
This is the section BIP−24 (B2) interrupt bit. This bit resets when Reg−19H is being read.
0:
No line BIP−24 (B2) error has been detected since Reg−19H was last read.
Line BIP−24 (B2) error has been detected since Reg−19H was last read.
1:
LAISI
This is the Line Alarm Indication Signal (LAIS) interrupt bit. This bit resets when Reg−19H is being read.
0:
No LAIS has been detected since Reg−19H was last read.
LAIS has been detected since Reg−19H was last read.
1:
RDII
This is the Remote Defect Indication (RDI) interrupt bit. This bit resets when Reg−19H is being read.
0:
1:
No line remote defect indication has been detected since Reg−19H was last read.
Line remote defect indication has been detected since Reg−19H was last read.
31
PRELIMINARY
CY7C955
REG − 1AH
Line BIP−8/24 Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
LBE[7]
LBE[6]
LBE[5]
LBE[4]
LBE[3]
LBE[2]
LBE[1]
LBE[0]
R
0
0
0
0
0
0
0
0
R
R
R
R
R
R
R
LBE[19:0]
Reg−1AH to Reg−1CH will be loaded with the number of BIP−8/24 (B2) errors from an internal counter approximately 1 µs after
a write operation is done to Reg−1AH, Reg−1BH, Reg−1CH, Reg−1DH, Reg−1EH, Reg−1FH, or Reg−00H. At that time (1 µs
after the write operation), these three registers are updated and the internal BIP−8/24 error counter reset to zero to begin
another round of error accumulation. Reading Reg−1AH, Reg−1BH, and Reg−1CH after the write yields the number of BIP−8/24
(B2) errors accumulated since the counter was last reset, if overflow has not occurred.
REG − 1BH
Line BIP−8/24 Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
LBE[15]
LBE[14]
LBE[13]
LBE[12]
LBE[11]
LBE[10]
LBE[9]
R
0
0
0
0
0
0
0
0
R
R
R
R
R
R
R
LBE[8]
LBE[19:0]
Reg−1AH to Reg−1CH will be loaded with the number of BIP−8/24 (B2) errors from an internal counter approximately 1 µs after
a write operation is done to Reg−1AH, Reg−1BH, Reg−1CH, Reg−1DH, Reg−1EH, Reg−1FH, or Reg−00H. At that time (1 µs
after the write operation), these three registers are updated and the internal BIP−8/24 error counter is reset to zero to begin
another round of error accumulation. Reading Reg−1AH, Reg−1BH, and Reg−1CH after the write yields the number of BIP−8/24
(B2) errors accumulated since the counter was last reset, if overflow has not occurred.
32
PRELIMINARY
CY7C955
REG − 1CH
Line BIP−8/24 Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
Unused
Unused
Unused
Unused
LBE[19]
LBE[18]
LBE[17]
LBE[16]
R
0
0
0
0
R
R
R
LBE[19:0]
Reg−1AH to Reg−1CH will be loaded with the number of BIP−8/24 (B2) errors from an internal counter approximately 1 µs after
a write operation is done to Reg−1AH, Reg−1BH, Reg−1CH, Reg−1DH, Reg−1EH, Reg−1FH, or Reg−00H. At that time (1 µs
after the write operation), these three registers are updated and the internal BIP−8/24 error counter is reset to zero to begin
another round of error accumulation. Reading Reg−1AH, Reg−1BH, and Reg−1CH after the write yields the number of BIP−8/24
(B2) errors accumulated since the counter was last reset, if overflow has not occurred.
REG − 1DH
Line Far End Block Error Register
NAME
BIT POSITION
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
LFE[7]
LFE[6]
LFE[5]
LFE[4]
LFE[3]
LFE[2]
LFE[1]
LFE[0]
R
0
0
0
0
0
0
0
0
R
R
R
R
R
R
R
LFE[19:0]
Reg−1DH, Reg−1EH, and Reg−1FH will be loaded with the number of line FEBE (Z2) errors from an internal counter approx-
imately 1 µs after a write operation is done to Reg−1AH, Reg−1BH, Reg−1CH, Reg−1DH, Reg−1EH, Reg−1FH, or Reg−00H.
At that time (1 µs after the write operation), these three registers are updated and the internal line FEBE error counter is reset
to zero to begin another round of error accumulation. Reading Reg−1DH, Reg−1EH, and Reg−1FH after the write yields the
number of line FEBE (Z2) errors accumulated since the counter was last reset, if overflow has not occurred.
33
PRELIMINARY
CY7C955
REG − 1EH
Line Far End Block Error Register
NAME
BIT POSITION
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
LFE[15]
LFE[14]
LFE[13]
LFE[12]
LFE[11]
LFE[10]
LFE[9]
R
0
0
0
0
0
0
0
0
R
R
R
R
R
R
R
LFE[8]
LFE[19:0]
Reg−1DH, Reg−1EH, and Reg−1FH will be loaded with the number of line FEBE (Z2) errors from an internal counter approx-
imately 1 µs after a write operation is done to Reg−1AH, Reg−1BH, Reg−1CH, Reg−1DH, Reg−1EH, Reg−1FH, or Reg−00H.
At that time (1 µs after the write operation), these three registers are updated and the internal line FEBE error counter are reset
to zero to begin another round of error accumulation. Reading Reg−1DH, Reg−1EH, and Reg−1FH after the write yields the
number of line FEBE (Z2) errors accumulated since the counter was last reset, if overflow has not occurred.
REG − 1FH
Line Far End Block Error Register
NAME
BIT POSITION
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
Unused
Unused
Unused
Unused
LFE[19]
LFE[18]
LFE[17]
LFE[16]
R
0
0
0
0
0
0
0
0
R
R
R
R
R
R
R
LFE[19:0]
Reg−1DH, Reg−1EH, and Reg−1FH will be loaded with the number of line FEBE (Z2) errors from an internal counter approx-
imately 1 µs after a write operation is done to Reg−1AH, Reg−1BH, Reg−1CH, Reg−1DH, Reg−1EH, Reg−1FH, or Reg−00H.
At that time (1 µs after the write operation), these three registers are updated and the internal line FEBE error counter are reset
to zero to begin another round of error accumulation. Reading Reg−1DH, Reg−1EH, and Reg−1FH after the write yields the
number of line FEBE (Z2) errors accumulated since the counter was last reset, if overflow has not occurred.
34
PRELIMINARY
CY7C955
REG − 20H
Transmit Line Overhead Processor Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
Unused
Unused
Unused
Unused
Unused
Unused
Unused
RDI
R/W
0
RDI
This bit controls whether line far end receive failure (RDI) is being inserted into the transmit data stream.
0:
1:
Transmit 000 in bits 6, 7, and 8 of K2.
Transmit 110 in bits 6, 7, and 8 of K2.
REG − 21H
Transmit Line Overhead Processor Error Insertion Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
Unused
Unused
Unused
Unused
Unused
Unused
Unused
DBIP
R/W
0
DBIP
This bit generates a continuous line BIP−8/24 (B2) error in the transmit data stream.
0:
1:
Normal operation.
Insert BIP8/24 (B2) error by inverting the B2 byte.
35
PRELIMINARY
CY7C955
REG − 30H
Receive Path Overhead Processor Interrupt Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
Unused
Unused
LOP
R
Unused
PAIS
R
R
PRDI
Unused
Unused
LOP
This bit is the Loss of Pointer (LOP) alarm register.
0:
No loss of pointer alarm detected.
Loss of pointer alarm detected.
1:
PAIS
This bit is the path Alarm Indication Signal (AIS) register.
0:
No path alarm indication signal detected.
Path alarm indication signal detected.
1:
PRDI
This bit is the path Far-End Receive Failure (RDI) alarm register.
0:
1:
No path far-end receive failure (RDI) alarm detected.
Path far-end receive failure (RDI) alarm detected.
36
PRELIMINARY
CY7C955
REG − 31H
Receive Path Overhead Processor Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
PSLI
R
Unused
LOPI
R
Unused
PAISI
R
R
R
R
PRDII
BIPEI
FEBEI
PSLI
This is the Path Signal Label (PSL) register interrupt bit. This bit resets when Reg−31H is being read.
0:
No change in the path signal label since Reg−31H was last read.
1:
There is a change in the path signal label since Reg−31H was last read.
LOPI
This is the Loss of Pointer (LOP) interrupt bit. This bit resets when Reg−31H is being read.
0:
No change in the loss of pointer state since Reg−31H was last read.
1:
There is a change in the loss of pointer state since Reg−31H was last read.
PAISI
This is the path Alarm Indication Signal (AIS) interrupt bit. This bit resets when Reg−31H is being read.
0:
No change in the path alarm indication signal since Reg−31H was last read.
There is a change in the path alarm indication signal since Reg−31H was last read.
1:
PRDII
This is the path Far-End Receive Failure (RDI) alarm interrupt bit. This bit resets when Reg−31H is being read.
0:
No change in the path far-end receive failure alarm since Reg−31H was last read.
There is a change in the path far-end receive failure alarm since Reg−31H was last read.
1:
BIPEI
This is the BIP−8 (B3) error interrupt bit. This bit resets when Reg−31H is being read.
0:
No BIP−8 (B3) error detected since Reg−31H was last read.
1:
BIP−8 (B3) error has been detected since Reg−31H was last read.
FEBEI
This is the path Far-End Block Error (FEBE) interrupt bit. This bit resets when Reg−31H is being read.
0:
1:
No path far-end block error detected since Reg−31H was last read.
Path far-end block error has been detected since Reg−31H was last read.
37
PRELIMINARY
CY7C955
REG − 33H
Receive Path Overhead Processor Interrupt Enable Register
BIT POSITION
NAME
READ/WRITE
R/W
DEFAULT
7
6
5
4
3
2
1
0
PSLE
0
0
Unused
LOPE
R/W
Unused
PAISE
PRDIE
BIPEE
FEBEE
R/W
R/W
R/W
R/W
0
0
0
0
PSLE
This bit controls whether a change in the Path Signal Label (PSL) generates an interrupt by asserting INTB LOW.
0:
A change in the path signal label (PSL) will not generate an interrupt.
1:
An interrupt will be generated if more than two consecutive non-13H C3 bytes are being detected in the path overhead.
LOPE
This bit controls whether a loss of pointer generates an interrupt by asserting INTB LOW.
0:
A change in the loss of pointer state will not generate an interrupt.
A change in the loss of pointer state will generate an interrupt.
1:
PAISE
This bit controls whether Path Alarm Indication Signal (PAIS) error generates an interrupt by asserting INTB LOW.
0:
1:
PAIS error will not generate an interrupt.
PAIS error will generate an interrupt.
PRDIE
This bit controls whether a path Remote Defect Indication (RDI) generates an interrupt by asserting INTB LOW.
0:
A change in the path remote defect indication state will not generate an interrupt.
A change in the path remote defect indication state will generate an interrupt.
1:
BIPEE
This bit controls whether BIP−8 (B3) error generates an interrupt by asserting INTB LOW.
0:
1:
BIP−8 (B3) error will not generate an interrupt.
BIP−8 (B3) error will generate an interrupt.
FEBEE
This bit controls whether line far end block error generates an interrupt by asserting INTB LOW.
0:
1:
Line far-end block error will not generate an interrupt.
Line far-end block error will generate an interrupt.
38
PRELIMINARY
CY7C955
REG − 37H
Receive Path Signal Label Register
NAME
BIT POSITION
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
PSL[7]
PSL[6]
PSL[5]
PSL[4]
PSL[3]
PSL[2]
PSL[1]
PSL[0]
R
R
R
R
R
R
R
R
PSL[7:0]
This is the path signal label (C2) register byte. This register is either 13H or the first non-13H value detected in the received
SONET data stream.
REG − 38H
Path BIP−8 (B3) Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
PBE[7]
PBE[6]
PBE[5]
PBE[4]
PBE[3]
PBE[2]
PBE[1]
PBE[0]
R
0
0
0
0
0
0
0
0
R
R
R
R
R
R
R
PBE[15:0]
Reg−38H and Reg−39H will be loaded with the number of path BIP−8 (B3) errors from an internal counter approximately 1 µs
after a write operation is done to Reg−38H, Reg−39H, Reg−3AH, Reg−3BH, or Reg−00H. At that time (1 µs after the write
operation), these three registers are updated and the internal BIP−8 (B3) error counter is reset to zero to begin another round
of error accumulation. Reading Reg−38H and Reg−39H after the write yields the number of BIP−8 (B3) errors accumulated
since the counter was last reset, if overflow has not occurred.
39
PRELIMINARY
CY7C955
REG − 39H
Path BIP−8 (B3) Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
PBE[15]
PBE[14]
PBE[13]
PBE[12]
PBE[11]
PBE[10]
PBE[9]
R
0
0
0
0
0
0
0
0
R
R
R
R
R
R
R
PBE[8]
PBE[15:0]
Reg−38H and Reg−39H will be loaded with the number of path BIP−8 (B3) errors from an internal counter approximately 1 µs
after a write operation is done to Reg−38H, Reg−39H, Reg−3AH, Reg−3BH, or Reg−00H. At that time (1 µs after the write
operation), these three registers are updated and the internal BIP−8 (B3) error counter is reset to zero to begin another round
of error accumulation. Reading Reg−38H and Reg−39H after the write yields the number of BIP−8 (B3) errors accumulated
since the counter was last reset, if overflow has not occurred.
REG − 3AH
Path Far-End Block Error Register
NAME
BIT POSITION
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
PFE[7]
PFE[6]
PFE[5]
PFE[4]
PFE[3]
PFE[2]
PFE[1]
PFE[0]
R
0
0
0
0
0
0
0
0
R
R
R
R
R
R
R
PFE[15:0]
Reg−3AH and Reg−3BH will be loaded with the number of path FEBE (G1) errors from an internal counter approximately 1 µs
after a write operation is done to Reg−38H, Reg−39H, Reg−3AH, Reg−3BH, or Reg−00H. At that time (1 µs after the write
operation), these three registers are updated and the internal path FEBE error counter is reset to zero to begin another round
of error accumulation. Reading Reg−3AH and Reg−3BH after the write yields the number of path FEBE (G1) errors accumulated
since the counter was last reset, if overflow has not occurred.
40
PRELIMINARY
CY7C955
REG − 3BH
Path Far End Block Error Register
NAME
BIT POSITION
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
PFE[15]
PFE[14]
PFE[13]
PFE[12]
PFE[11]
PFE[10]
PFE[9]
R
0
0
0
0
0
0
0
0
R
R
R
R
R
R
R
PFE[8]
PFE[15:0]
Reg−3AH and Reg−3BH will be loaded with the number of path FEBE (G1) errors from an internal counter approximately 1 µs
after a write operation is done to Reg−38H, Reg−39H, Reg−3AH, Reg−3BH, or Reg−00H. At that time (1 µs after the write
operation), these three registers are update and the internal path FEBE error counter is reset to zero to begin another round
of error accumulation. Reading Reg−3AH and Reg−3BH after the write yields the number of path FEBE (G1) errors accumulated
since the counter was last reset, if overflow has not occurred.
REG − 3DH
Path Far-End Block Error Register
NAME
BIT POSITION
READ/WRITE
R/W
DEFAULT
7
6
5
4
3
2
1
0
Unused
Unused
BLKBIP
Unused
Unused
Unused
Unused
Unused
0
BLKBIP
This bit controls how path BIP−8 (B3) errors are accumulated.
0:
1:
BIP−8 (B3) errors are accumulated and reported in a bit basis.
BIP−8 (B3) errors are accumulated and reported in a block basis. Only one BIP−8 error is reported to the upstream path
even if more than one path BIP−8 (B3) errors are detected.
41
PRELIMINARY
CY7C955
REG − 40H
Transmit Path Overhead Processor Error Insertion Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
Unused
Unused
Unused
Unused
Unused
Unused
DB3
R/W
R/W
0
0
PAIS
DB3
This bit generates a path BIP−8 error in the transmit data stream.
0:
Normal operation.
The path BIP−8 (B3) byte is inverted, eight BIP−8 (B3) errors are thus generated per frame PAIS.
1:
PAIS
This bit generates a path Alarm Indication Signal (AIS) in the transmit data stream.
0:
1:
Normal operation.
The whole synchronous payload envelope (SPE) together with the H1, H2, and H3 bytes are converted to 1 before
scrambling.
42
PRELIMINARY
CY7C955
REG − 41H
Transmit Path Overhead Processor Pointer Control Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
Unused
FTPTR
SOS
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
PLD
NDF
NSE
PSE
Unused
FTPTR
This bit enables the insertion of the arbitrary payload pointer value into the last 10 bits of H1, H2. The NDF flag is not automat-
ically changed by this operation.
0:
1:
Normal operation.
The bits contained in Arbitrary Pointer Register (APTR[9:0]) are inserted into H1 and H2 of the transmitted data stream.
This bit is provided for creating pointer byte errors to diagnose the downstream system.
SOS
This is the stuff opportunity spacing bit which controls how often stuff events can occur.
0:
Stuff event can occur in every other frame. Insertion of positive pointer movement or negative pointer movement can be
done through writing to NSE and PSE (bit 2 and 1 of Reg−41H)
1:
Stuff event can occur only once in every four frames. Insertion of positive pointer movement or negative pointer movement
can be done through writing to NSE and PSE (bit 2 and 1 of Reg−41H)
PLD
This bit enables the insertion of the arbitrary payload pointer value into the last 10 bits of H1 and H2 bytes. The value in NDF[3:0]
(Reg−46H, bit 7 − bit 4) will also be loaded into the new data flag (NDF) position of the H1 byte. PLD should be used instead
of FTPTR for non-diagnostic payload pointer adjustments.
0:
1:
Normal operation.
The bits contained in Arbitrary Pointer Register (APTR[9:0]) are inserted into H1 and H2 of the transmit data stream.
This operation will not affect the interpretation of the pointer in the received data stream, and will only be performed if
the value stored in APTR[9:0] is >0 and < 782.
NDF
This is the new data flag (NDF) insertion control bit. This bit is ignored if PLD is set to 1.
0:
The normal NDF pattern (0110) is being transmitted in the first four bytes of H1.
1:
The value stored in NDF[3:0] (Reg−46H, bit 7−bit 4) are inserted into the first four bytes of H1.
NSE
This bit can be used to generate a negative pointer movement. This bit has to be first enabled by setting FIXPTR (Reg−05H,
bit 5) to 1. This bit resets to zero automatically after every write to it.
0:
1:
Default state.
A single negative pointer adjustment will be made on the outgoing data stream. This bit will be cleared to zero
immediately
PSE
This bit can be used to generate a positive pointer movement. This bit has to be first enabled by setting FIXPTR (Reg−05H, bit
5) to 1. This bit resets to zero automatically after every write to it.
0:
1:
Default state.
A single positive pointer adjustment will be made on the outgoing data stream. This bit will be cleared to zero immediately.
43
PRELIMINARY
CY7C955
REG − 45H
Transmit Path Overhead Processor Arbitrary Payload Pointer Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
APTR[7]
APTR[6]
APTR[5]
APTR[4]
APTR[3]
APTR[2]
APTR[1]
APTR[0]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
APTR[9:0]
Reg−45H and Reg−46H are the arbitrary payload pointer registers. This two registers are used to store the new payload pointer
value to be loaded into H1and H2 of the transmitted data stream. The value loaded into these 10 bits has to be greater than or
equal to zero and smaller than 782. A legal value stored in APTR[9:0] is not loaded into the data stream until PLD or FTPTR
is toggled HIGH.
REG − 46H
Transmit Path Overhead Processor Arbitrary Payload Pointer Register
NAME READ/WRITE
BIT POSITION
DEFAULT
7
6
5
4
3
2
1
0
NDF[3]
NDF[2]
NDF[1]
NDF[0]
S[1]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
1
0
0
1
0
0
0
0
S[2]
APTR[9]
APTR[8]
NDF[3:0]
These bits are used to store the arbitrary new data flag to be loaded into the transmit data stream. These bits are loaded when
NDF is toggled HIGH or when PLD is toggled HIGH.
S[1:0]
These 2 bits are inserted into the 2 unused bits of H1 whenever PLD, NDF, or FTPTR are toggled HIGH.
APTR[9:0]
Reg−45H and Reg−46H are the arbitrary payload pointer registers. This two registers are used to store the new payload pointer
value to be loaded into H1 and H2 of the transmitted data stream. The value loaded into these 10 bits has to be greater than
or equal to zero and smaller than 782. A legal value stored in APTR[9:0] is not loaded into the data stream until PLD or FTPTR
is toggled HIGH.
44
PRELIMINARY
CY7C955
REG − 48H
Transmit Path Overhead Processor Signal Label Register
BIT POSITION
NAME
READ/WRITE
R/W
DEFAULT
7
6
5
4
3
2
1
0
C2[7]
C2[6]
C2[5]
C2[4]
C2[3]
C2[2]
C2[1]
C2[0]
0
0
0
1
0
0
1
1
R/W
R/W
R/W
R/W
R/W
R/W
R/W
C2[7:0]
These bits are inserted in the C2 byte position in the transmit stream.
REG − 49H
Transmit Path Overhead Processor Path Status Register
BIT POSITION
NAME
READ/WRITE
R/W
DEFAULT
7
6
5
4
3
2
1
0
FEBE[3]
FEBE[2]
FEBE[1]
FEBE[0]
PRDI
0
0
0
0
0
0
0
0
R/W
R/W
R/W
R/W
G1[2]
R/W
G1[1]
R/W
G1[0]
R/W
FEBE[3:0]
These bits are used to hold the FEBE value to be inserted into the transmitted data stream. After insertion of these bits into
the FEBE location of the next possible frame, FEBE[3:0] will be reset. If the value written to these register bits can still be read
back, it just mean that the insertion has not taken place yet.
PRDI
This bit is used to insert remote defect indication (RDI) into the transmitted data stream.
0:
Normal operation. With the PRDI bit of G1 only affected by the setting of AUTOPRDI (Reg−01H, Bit 4) and the alarm
conditions.
1:
The PRDI bit of G1 is set to 1.
G1[2:0]
These bits are inserted into the unused bit positions of G1 of every frame.
45
PRELIMINARY
CY7C955
REG − 50H
Receive ATM Cell Processor Control and Status Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
OOCDV
RXPTYP
PASS
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
1
0
0
DISCOR
HCSPASS
HCSADD
DDSCR
FIFORST
OOCDV
This bit is the cell delineation status register.
0:
This indicates that the cell delineation state machine is in the ‘SYNC’ state and ATM cells are passing though to the
receive FIFO.
1:
This indicates that the cell delineation state machine is in the ‘PRESYNC’ or ‘HUNT’ state.
RXPTYP
This bit controls whether odd or even parity is used for RXPRTY.
0:
Odd parity is generated for RDAT[7:0].
Even parity is generated for RDAT[7:0].
1:
PASS
This bit controls whether cells with VPI = 0 and VCI = 0 are dropped.
0:
1:
All cells with VPI = 0, VCI = 0 and header matching all the unmasked bits of Reg−52H are dropped.
No cell filtering is performed.
DISCOR
This bit controls whether header error (HCS) correction is performed.
0:
1:
Header error correction is performed. Single bit-errors detected in the header are corrected automatically.
Header error correction is not performed. Any HCS error detected is considered uncorrectable.
HCSPASS
This bit controls whether cells with HCS error are dropped.
0:
1:
All cells with an uncorrectable HCS error are dropped.
No cells are dropped if the cell delineation state machine is in SYNC state.
HCSADD
This bit controls whether the coset polynomial x +x +x +1 is added to the HCS byte before HCS comparison is performed.
6
4
2
0:
1:
No coset polynomial is added.
6
4
2
The coset polynomial x +x +x +1 is added to the HCS byte.
DDSCR
This bit controls whether cell payload descrambling is performed.
0:
1:
Cell payload descrambling is performed.
Cell payload descrambling is not performed.
FIFORST
This bit is the receive FIFO reset bit.
0:
1:
Normal receive FIFO operation.
All receive FIFO locations are reset and the receive FIFO will ignore all writes.
46
PRELIMINARY
CY7C955
REG − 51H
Receive ATM Cell Processor Interrupt Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
OOCDE
HCSE
R/W
R/W
R/W
R
0
0
0
FIFOE
OOCDI
CHCSI
UHCSI
FOVRI
Unused
R
R
R
OOCDE
This bit controls whether a change in cell delineation state generates an interrupt by asserting INTB LOW.
0:
A change in the cell delineation state will not generate an interrupt.
A change in the cell delineation state will generate an interrupt.
1:
HCSE
This bit controls whether an HCS error generates an interrupt by asserting INTB LOW.
0:
HCS errors will not generate an interrupt.
1:
A correctable or uncorrectable HCS error will both generate an interrupt.
FIFOE
This bit controls whether receive FIFO overflow will generate an interrupt by asserting INTB LOW.
0:
1:
Receive FIFO overflow will not generate an interrupt.
Receive FIFO overflow will generate an interrupt.
OOCDI
This is the change of cell delineation interrupt bit. This bit resets as Reg−51H is being read.
0:
1:
There is no change in the loss of cell delineation state.
There is a change from the PRESYNC state to SYNC state or from the SYNC state to the HUNT state.
CHCSI
This is the correctable HCS error detection bit. This bit resets as Reg−51H is being read.
0:
1:
No correctable HCS error has been detected since Reg−51H was last read.
One or more than one correctable HCS errors have been detected since Reg−51H was last read.
UHCSI
This is the uncorrectable HCS error detection bit. This bit resets as Reg−51H is being read.
0:
No uncorrectable HCS error has been detected since Reg−51H was last read.
1:
One or more than one uncorrectable HCS errors have been detected since Reg−51H was last read.
FOVRI
This is the receive FIFO overflow interrupt bit. This bit resets as Reg−51H is being read.
0:
1:
No receive FIFO overflow has occurred since Reg−51H was last read.
Receive FIFO overflow has occurred since Reg−51H was last read.
47
PRELIMINARY
CY7C955
REG − 52H
Receive ATM Cell Processor Match Header Pattern Register
BIT POSITION
NAME
READ/WRITE
R/W
DEFAULT
7
6
5
4
3
2
1
0
GFC[3]
GFC[2]
GFC[1]
GFC[0]
PTI[2]
PTI[1]
PTI[0]
CLP
0
0
0
0
0
0
0
0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
GFC[3:0]
These are the Generic Flow Control (GFC) register bits. If the PASS bit (Reg−50H, bit 5) is LOW, ATM cells with VPI = 0, VCI
= 0, and with other parts of their header matching all the unmasked bits of this register will be dropped. Each bit of this register
can be masked by its corresponding bit in Reg−53H. Masked bits are not compared.
PTI[2:0]
These are the Payload Type Indicator (PTI) register bits. If the PASS bit (Reg−50H, bit 5) is LOW, ATM cells with VPI = 0, VCI
= 0, and with other parts of their header matching all the unmasked bits of this register will be dropped. Each bit of this register
can be masked by its corresponding bit in Reg−53H. Masked bits are not compared.
CLP
This is the Cell Loss Priority (CLP) register bit. If the PASS bit (Reg−50H, bit 5) is LOW, ATM cells with VPI = 0, VCI = 0,and
with other parts of their header matching all the unmasked bits of this register will be dropped. Each bit of this register can be
masked bits corresponding bit in Reg−53H. Masked bits are not compared.
48
PRELIMINARY
CY7C955
REG − 53H
Receive ATM Cell Processor Match Header Mask Register
BIT POSITION
NAME
READ/WRITE
R/W
DEFAULT
7
6
5
4
3
2
1
0
MGFC[3]
MGFC[2]
MGFC[1]
MGFC[0]
MPTI[2]
MPTI[1]
MPTI[0]
MCLP
0
0
0
0
0
0
0
0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
MGFC[3:0]
This is the mask for the Generic Flow Control register. A HIGH in any bit of this register unmasks the corresponding bit of
Reg−52H and allows it to be compared with the current ATM cell. If PASS (Reg−50H, bit 5) is LOW, ATM cells with VPI = 0, VCI
= 0, and other parts of their header matching all the unmasked bits of Reg−52H are dropped.
MPTI[2:0]
This is the mask for the Payload Type Indicator register. A HIGH in any bit of this register unmasks the corresponding bit of
Reg−52H and allows it to be compared with the current ATM cell. If PASS (Reg−50H, bit 5) is LOW, ATM cells with VPI = 0,
VCI = 0, and other parts of their header matching all the unmasked bits of Reg−52H are dropped.
MCLP
This is the mask for the Cell Loss Priority (CLP) register. A HIGH in any bit of this register unmasks the corresponding bit of
Reg−52H and allows it to be compared with the current ATM cell. If PASS (Reg−50H, bit 5) is LOW, ATM cells with VPI = 0, VCI
= 0, and other parts of their header matching all the unmasked bits of Reg−52H are dropped.
REG − 54H
Receive ATM Cell Processor Correctable HCS Error Count Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
CHCS[7]
CHCS[6]
CHCS[5]
CHCS[4]
CHCS[3]
CHCS[2]
CHCS[1]
CHCS[0]
R
R
R
R
R
R
R
R
CHCS[7:0]
Reg−54H and Reg−55H will load the number of correctable HCS errors from an internal counter approximately 200 ns after a
write operation is done to Reg−54H, Reg−55H, or Reg−00H. At that time (200 ns after the write operation), this register is
updated and the internal correctable HCS error counter is reset to zero to begin another round of error accumulation. Reading
Reg−54H and Reg–55H after the write yields the number of correctable HCS errors accumulated since the counter was last
reset, if overflow has not occurred.
49
PRELIMINARY
CY7C955
REG − 55H
Receive ATM Cell Processor Uncorrectable HCS Error Count Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
UHCS[7]
UHCS[6]
UHCS[5]
UHCS[4]
UHCS[3]
UHCS[2]
UHCS[1]
UHCS[0]
R
R
R
R
R
R
R
R
UHCS[7:0]
Reg−54H and Reg−55H will load the number of uncorrectable HCS errors from an internal counter approximately 200 ns after
a write operation is done to Reg−54H, Reg−55H, or Reg−00H. At that time (200 ns after the write operation), this register is
updated and the internal uncorrectable HCS error counter is reset to zero to begin another round of error accumulation. Reading
Reg−54H and Reg.–55H after the write yields the number of uncorrectable HCS errors accumulated since the counter was last
reset, if overflow has not occurred.
REG − 56H
Receive ATM Cell Processor Receive Cell Counter Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
RCELL[7]
RCELL[6]
RCELL[5]
RCELL[4]
RCELL[3]
RCELL[2]
RCELL[1]
RCELL[0]
R
R
R
R
R
R
R
R
RCELL[18:0]
Reg−56H, Reg−57H, and Reg−58H will load the number of cells received from an internal counter approximately 200ns after
a write operation is done to Reg−54H, Reg−55H, Reg−56H, Reg−57H, Reg−58H, or Reg−00H. At that time (200ns after the
write operation), this register is updated and the internal receive cell counter is reset to zero to begin another round of accu-
mulation. Reading Reg−56H, Reg−57H, and Reg−58H after the write yields the number of cells received since the counter was
last reset, if overflow has not occurred.
50
PRELIMINARY
CY7C955
REG − 57H
Receive ATM Cell Processor Receive Cell Counter Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
RCELL[15]
R
RCELL[14]
R
R
R
R
R
R
R
RCELL[13]
RCELL[12]
RCELL[11]
RCELL[10]
RCELL[9]
RCELL[8]
RCELL[18:0]
Reg−56H, Reg−57H, and Reg−58H will load the number of cells received from an internal counter approximately 200 ns after
a write operation is done to Reg−54H, Reg−55H, Reg−56H, Reg−57H, Reg−58H, or Reg−00H. At that time (200 ns after the
write operation), this register is updated and the internal receive cell counter is reset to zero to begin another round of accu-
mulation. Reading Reg−56H, Reg−57H, and Reg−58H after the write yields the number of cells received since the counter was
last reset, if overflow has not occurred.
REG − 58H
Receive ATM Cell Processor Receive Cell Counter Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
Unused
Unused
Unused
Unused
Unused
RCELL[18]
RCELL[17]
RCELL[16]
R
R
R
RCELL[18:0]
Reg−56H, Reg−57H, and Reg−58H will load the number of cells received from an internal counter approximately 200 ns after
a write operation is done to Reg−54H, Reg−55H, Reg−56H, Reg−57H, Reg−58H, or Reg−00H. At that time (200 ns after the
write operation), this register is updated and the internal receive cell counter is reset to zero to begin another round of accu-
mulation. Reading Reg−56H, Reg−57H, and Reg−58H after the write yields the number of cells received since the counter was
last reset, if overflow has not occurred.
51
PRELIMINARY
CY7C955
REG − 59H
Receive ATM Cell Processor Receive Configuration Register
BIT POSITION
NAME
READ/WRITE
R/W
DEFAULT
7
6
5
4
3
2
1
0
RGFCE[3]
RGFCE[2]
RGFCE[1]
RGFCE[0]
FSEN
1
1
1
1
1
1
0
0
R/W
R/W
R/W
R/W
RCALEVEL0
HCSFTR[1]
HCSFTR[0]
R/W
R/W
R/W
RGFCE[3:0]
This is the Receive Generic Flow Control Enable register. Each bit is logical ANDed with its corresponding bit in the ATM cell
header. RGFCE[3] corresponds to the most significant bit of the GFC header. If RGFC[x] is set LOW, then bit x of the serial
RGFC output (pin 59) will appear LOW.
FSEN
This is the fix stuff expectation bit. This command only affects STS−1 frames.
0:
1:
No fix stuff bytes are expected in the STS−1 payload.
Fix stuff bytes are expected in Column 30 and 59 of the received STS−1 frame.
RCALEVEL0
This is the receive cell available (RCA) pin empty definition control register.
0:
1:
RCA is an active LOW indication for the receive FIFO being 4 bytes from empty.
RCA is an active LOW indication for the receive FIFO being empty.
HCSFTR[1:0]
This is the HCS cell acceptance threshold register. These bits control how many consecutive error-free cells are needed for the
Receive ATM cell processor to convert from detection mode to correction mode.
11:
10:
01:
00:
7 cells with no HCS error is needed before the 8th cell is accepted. Correction mode is entered immediately after that.
3 cells with no HCS error is needed before the 4th cell is accepted. Correction mode is entered immediately after that.
1 cell with no HCS error is needed before the 2nd cell is accepted. Correction mode is entered immediately after that.
All cell with no HCS error is accepted. Correction mode is entered immediately after that.
52
PRELIMINARY
CY7C955
REG − 60H
Transmit ATM Cell Processor Control and Status Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
FIFOE
R/W
R
0
0
TSOCI
FOVRI
R
DHCS
R/W
Unused
HCSADD
DDSCR
FIFORST
R/W
R/W
R/W
1
0
0
FIFOE
This bit controls whether transmit FIFO overflow or misplaced transmit start of cell (TSOC) will generate an interrupt.
0:
1:
Transmit FIFO overflow and misplaced TSOC will not generate an interrupt.
Transmit FIFO overflow or misplaced TSOC (TSOC appearing not with the first byte of an ATM cell) will generate an
interrupt.
TSOCI
This is the transmit start of cell interrupt bit. This bit resets as Reg−60H is being read.
0:
1:
No TSOC error has occurred since Reg−60H was last read.
TSOC has occurred at times other than at the beginning of an ATM cell. The internal 53-byte cell length counter is reset
to zero immediately if such an error occurs and the incomplete ATM cell is discarded.
FOVRI
This is the transmit FIFO overflow interrupt bit. This bit resets as Reg−60H is being read.
0:
1:
No transmit FIFO overflow has occurred since Reg−60H was last read.
Transmit FIFO overflow has occurred since Reg−60H was last read.
HCSADD
6
4
2
This bit controls whether the coset polynomial x +x +x +1 is added to the HCS byte before the ATM cell is inserted into the
Synchronous Payload Envelope (before SONET scrambling if enabled).
0:
1:
No coset polynomial is added.
6
4
2
The coset polynomial x +x +x +1 is added to the HCS byte. This is equivalent to substituting the HCS byte with (HCS
byte XOR 01010101).
DDSCR
This bit controls whether cell payload scrambling is performed.
0:
1:
Cell payload scrambling is performed.
Cell payload scrambling is not performed.
FIFORST
This bit is the transmit FIFO reset bit.
0:
1:
Normal transmit FIFO operation.
All transmit FIFO locations are reset and the transmit FIFO will ignore all writes.
53
PRELIMINARY
CY7C955
REG − 61H
Transmit ATM Cell Processor Unassigned Cell Header Register
BIT POSITION
NAME
READ/WRITE
R/W
DEFAULT
7
6
5
4
3
2
1
0
GFC[3]
GFC[2]
GFC[1]
GFC[0]
PTI[2]
PTI[1]
PTI[0]
CLP
0
0
0
0
0
0
0
0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
GFC[3:0]
These are the transmit Generic Flow Control (GFC) register bits. The bits in this register are appended to VPI = 0, and VCI =
0 before adding to the transmit data stream as idle cells. Idle cells are transmitted whenever there are no complete ATM cells
in the transmit FIFO.
PTI[2:0]
These are the transmit Payload Type Indicator (PTI) register bits. The bits in this register are appended to VPI = 0, and VCI =
0 before adding to the transmit data stream as idle cells. Idle cells are transmitted whenever there are no complete ATM cells
in the transmit FIFO.
CLP
This is the transmit Cell Loss Priority (CLP) register bit. The bits in this register are appended to VPI = 0, and VCI = 0 before
adding to the transmit data stream as idle cells. Idle cells are transmitted whenever there are no complete ATM cells in the
transmit FIFO.
REG − 62H
Transmit ATM Cell Processor Unassigned Cell Payload Register
BIT POSITION
NAME
READ/WRITE
R/W
DEFAULT
7
6
5
4
3
2
1
0
ICP[7]
ICP[6]
ICP[5]
ICP[4]
ICP[3]
ICP[2]
ICP[1]
ICP[0]
0
1
1
0
1
0
1
0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
ICP[7:0]
This register contains the octet to be placed in each byte of the transmitted idle cells. When there are no user ATM cells available
for transmission, the Transmit ATM Cell Processor generates its own idle cells based on setting in Reg−61H and 62H. Idle cells
allow CY7C955 to perform cell rate decoupling.
54
PRELIMINARY
CY7C955
REG − 63H
Transmit ATM Cell Processor FIFO Control Register
BIT POSITION
NAME
READ/WRITE
R/W
DEFAULT
7
6
5
4
3
2
1
0
TXPTYP
0
0
TXPRTYE
Unused
R/W
TXPRTYI
FIFODP[1]
FIFODP[0]
TCALEVEL0
Unused
R
R/W
R/W
R/W
0
0
0
0
TXPTYP
This is the polarity control bit for the interpretation of TXPRTY.
0:
1:
TXPRTY is the odd parity input for TDAT[7:0].
TXPRTY is the even parity input for TDAT[7:0].
TXPRTYE
This is the transmit parity error interrupt enable register.
0:
1:
Transmit parity error will not pull INTB (pin 108) LOW but will still be indicated on TXPRTYI.
Transmit parity error will pull INTB (pin 108) LOW as well as setting TXPRTYI.
TXPRTYI
This is the transmit parity error interrupt register. This bit resets when Reg−63H is being read.
0:
1:
No transmit parity error has been detected since Reg−63H was last read.
Transmit parity error has been detected since Reg−63H was last read.
FIFODP[1:0]
This bit controls the transmit cell available (TCA) pin definition. Note that this register only determines when TCA (pin 86) is to
be deasserted. The transmit FIFO is always 4 cells deep regardless of the setting of this register. This means that interrupt for
FIFO overflow, if enabled by FIFOE (Reg−60H, bit 7), will only occur if a write is attempted on a FIFO that is already filled up
with all 4 cells.
11:
10:
01:
00:
TCA will go LOW when transmit FIFO is 1 cell full (if TCALEVEL = 1) or 4 bytes away from 1 cell full (if TCALEVEL = 0).
TCA will go LOW when transmit FIFO is 2 cells full (if TCALEVEL = 1) or 4 bytes away from 2 cells full (if TCALEVEL = 0).
TCA will go LOW when transmit FIFO is 3 cells full (if TCALEVEL = 1) or 4 bytes away from 3 cells full (if TCALEVEL = 0).
TCA will go LOW when transmit FIFO is 4 cells full (if TCALEVEL = 1) or 4 bytes away from 4 cells full (if TCALEVEL = 0).
TCALEVEL0
This is the transmit cell available (TCA) pin transition definition control register.
0:
1:
TCA will go LOW when transmit FIFO is N cells full. N is determined by value in FIFODP[1:0] (Reg−63H, bit 2−3).
TCA will stay LOW when transmit FIFO is within 4 bytes from N cells full. N is determined by value in FIFODP[1:0]
(Reg−63H, bit 2−3).
55
PRELIMINARY
CY7C955
REG − 64H
Transmit ATM Cell Processor Transmit Cell Counter Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
TCELL[7]
TCELL[6]
TCELL[5]
TCELL[4]
TCELL[3]
TCELL[2]
TCELL[1]
TCELL[0]
R
0
0
0
0
0
0
0
0
R
R
R
R
R
R
R
TCELL[18:0]
Reg−64H, Reg−65H, and Reg−66H will load the number of cells transmitted from an internal counter approximately 200 ns
after a write operation is done to Reg−64H, Reg−65H, Reg−66H, or Reg−00H. At that time (200 ns after the write operation),
this register is updated and the internal transmit cell counter is reset to zero or one (depending on whether a cell transmission
has occurred while the write occurs) to begin another round of accumulation. Reading Reg−64H, Reg−65H, and Reg−66H after
the write yields the number of cell transmitted since the counter was last reset, if overflow has not occurred. TCELL[18:0] should
be polled once a second to prevent the register from being saturated.
REG − 65H
Transmit ATM Cell Processor Transmit Cell Counter Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
TCELL[15]
R
0
0
0
0
0
0
0
0
TCELL[14]
R
R
R
R
R
R
R
TCELL[13]
TCELL[12]
TCELL[11]
TCELL[10]
TCELL[9]
TCELL[8]
TCELL[18:0]
Reg−64H, Reg−65H, and Reg−66H will load the number of cells transmitted from an internal counter approximately 200 ns
after a write operation is done to Reg−64H, Reg−65H, Reg−66H, or Reg−00H. At that time (200 ns after the write operation),
this register is updated and the internal transmit cell counter is reset to zero or one (depending on whether a cell transmission
has occurred while the write occurs) to begin another round of accumulation. Reading Reg−64H, Reg−65H, and Reg−66H after
the write yields the number of cell transmitted since the counter was last reset, if overflow has not occurred. TCELL[18:0] should
be polled once a second to prevent the register from being saturated.
56
PRELIMINARY
CY7C955
REG − 66H
Transmit ATM Cell Processor Transmit Cell Counter Register
BIT POSITION
NAME
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
Unused
Unused
Unused
Unused
Unused
TCELL[18]
TCELL[17]
TCELL[16]
R
0
0
0
R
R
TCELL[18:0]
Reg−64H, Reg−65H, and Reg−66H will load the number of cells transmitted from an internal counter approximately 200 ns
after a write operation is done to Reg−64H, Reg−65H, Reg−66H, or Reg−00H. At that time (200 ns after the write operation),
this register is updated and the internal transmit cell counter is reset to zero or one (depending on whether a cell transmission
has occurred while the write occurs) to begin another round of accumulation. Reading Reg−64H, Reg−65H, and Reg−66H after
the write yields the number of cells transmitted since the counter was last reset, if overflow has not occurred. TCELL[18:0]
should be polled once a second to prevent the register from being saturated.
57
PRELIMINARY
CY7C955
REG − 67H
Transmit ATM Cell Processor Transmit Configuration Register
BIT POSITION
NAME
READ/WRITE
R/W
DEFAULT
7
6
5
4
3
2
1
0
TGFCE[3]
TGFCE[2]
TGFCE[1]
TGFCE[0]
FSEN
0
0
0
0
1
0
0
0
R/W
R/W
R/W
R/W
H4INSB
R/W
FIXBYTE[1]
FIXBYTE[0]
R/W
R/W
TGFCE[3:0]
This is the Transmit Generic Flow Control Enable register. Each bit of this register corresponds to a bit in the GFC field of the
transmitted ATM cell headers. If TGFCE[x] is set HIGH, bit x of the GFC field in the transmitted ATM cell headers will be using
the bit value collected from the TGFC (pin 52) pin (see description of Drop Side Transmit Interface). If TGFCE[x] is LOW, bit x
will be derived from either TDAT (if transmit FIFO has at least one cell available) or from the Idle/Unassigned header register
(if transmit FIFO has less than 1 cell available).
FSEN
This is the fix stuff enable bit. This bit will only affect the STS−1 frame.
0:
1:
No stuffing is performed.
Column 30 and 59 of the STS−1 frame contains fix stuff bytes. The contents for the fix stuff byte is controlled by
FIXBYTE[1:0] (Reg−67H, bit 0 −1).
H4INSB
This bit controls the contents of H4 byte.
0:
1:
H4 byte represents the cell indicator offset value.
H4 byte is set to 00H.
FIXBYTE[1:0]
This register holds the number to be used in the fixed byte columns.
11:
10:
01:
00:
FFH is inserted into the fixed byte columns.
AAH is inserted into the fixed byte columns.
55H is inserted into the fixed byte columns.
00H is inserted into the fixed byte columns.
58
PRELIMINARY
CY7C955
REG − 80H
CY7C955 Test Control Register
NAME
BIT POSITION
READ/WRITE
DEFAULT
7
6
5
4
3
2
1
0
Unused
Unused
Unused
Unused
Unused
Unused
HIZDATA
HIZIO
W
R/W
0
HIZDATA
This is the data bus three-state control bit.
0:
1:
Normal operation.
This data bus is held at HIGH impedance. Register reading is disabled but writing is still possible.
HIZIO
This is the input output three-state control bit.
0:
1:
Normal operation.
All I/Os except the data bus are being held at the HIGH impedance state. The CY7C955 read/write is still possible.
Latch-Up Current............................................................±100 mA
Maximum Ratings
Lead Temperature ........................................................300°C
Maximum Junction Temperature ..................................155°C
Maximum Power Dissipation ........................................ 1.5 W
(Above which the useful life may be impaired. For user guide-
lines, not tested.)
Storage Temperature ..................................–40°C to +125°C
Ambient Temperature under Bias ................ −40°C to +85°C
Supply Voltage to Ground Potential ............... –0.5V to +6.0V
DC Input Voltage............................................ –0.5V to +7.0V
DC Input Current ..............................................................±20 mA
Operating Range
Ambient
Range
Commercial
Industrial
Temperature
0°C to +70°C
–40°C to +85°C
V
CC
5V ± 10%
5V ± 10%
Static Discharge Voltage................................................± 2000V
(per MIL-STD-883, Method 3015)
59
PRELIMINARY
CY7C955
Electrical Characteristics Over the Operating Range
Parameter Description
Test Conditions
Min. Max.
Unit
PECL compatible Input Pins (RXD±, RRCLK±, ALOS± TRCLK±)
[1]
V
V
V
Input HIGH Voltage
V
V
V
IHP
CC
Input LOW Voltage
2.5
ILP
Input Differential Voltage
PECL Input HIGH Current
200
2500
500
mV
µA
µA
IDIFF
[3]
[3]
[2]
I
I
V
V
= V
CC
IHP
ILP
IN
IN
PECL Input LOW Current
= 2.5
–200
PECL compatible Output Pins (RXDO±, TXD±, TXC±)
[2]
[2]
[2]
V
Output HIGH Voltage
Output LOW Voltage
Output Differential Voltage
Terminated by 50Ω to V
–1.33V
V
V
V
V
V
OHP
CC
CC
CC
–1.03
–0.7
[2]
[2]
V
V
V
CC
OLP
CC
–1.92 –1.62
[6]
V
0.75V
0.6
ODIFF
AVG
PECL compatible Input Pin (ALOS–) When ALOS+ is grounded
[2]
V
Input HIGH Voltage
V
V
V
SIHP
CC
–1.03
[2]
V
Input LOW Voltage
V
CC
AILP
–1.62
TTL compatible Input Pins
V
Input HIGH Voltage
2.0
V
V
IHT
DD
+0.3
0.8
10
V
Input LOW Voltage
–0.3
–10
V
ILT
I
I
Input HIGH Current for Internal Pull-Up Pins
Input LOW Current for Internal Pull-Up
V
V
= V
DD
µA
µA
IHPU
ILPU
IH
IL
= 0V
−200
−20
[3]
Pins
I
I
I
I
Input HIGH Current for Internal Pull-Down
Pins
V
V
V
V
= V
20
200
10
µA
µA
µA
µA
IHPD
ILPD
IH
IH
IL
DD
[3]
Input LOW Current for Internal Pull-Down
= 0V
= V
–10
–10
–10
[3]
Pins
Input HIGH Current for Pins Without Pull-Up
10
IH
IL
DD
[3]
or Pull-Down Resistors
Input LOW Current for Pins Without Pull-Up
= 0V
10
IL
[3]
or Pull-Down Resistors
TTL compatible Output Pins
V
Output LOW Voltage
Output HIGH Voltage
Three-state Leakage
V
= 4.75V, I = 12 mA for INTB and
0.4
V
V
OLT
DD
OL
TCLK and 8 mA for all others
[4]
V
V
= 4.75V, I = 12 mA for TCLK and 8
2.4
OHT
DD
OH
mA for all others
I
I
DATA[0:7]
–10
–15
10
µA
OZ
[4]
[5]
Output Short Circuit Current
V
=0V
–90
mA
OST
OUT
Operating Current
[7]
I
Operational Current
Rate 0 = 0 (51.84 Mbps, STS–1)
Rate 0 = 1 (155.52 Mbps, STS–3c/ STM–1)
210
mA
mA
DD
I
Standby Current
RSTB = 0, or RESET (Reg–00H, bit 7) = 1
75
DDS
Notes:
2. RXVDD for RXD±, RRCLK±, and ALOS±, RXDO±; TXVDD for TRCLK±, TXD± and TXC±.
3. Current flowing out of the chip has a positive value, current flowing into the chip has a negative value.
4. Maximum leakage current of INTB output at VOHT = 900 µA.
5. Tested one output at a time, output shorted for less than one second, less than 10% duty cycle.
6. Typical is 0.75VAVG
.
7. Conditions: Outputs unloaded; VDD = 5.5V; TXD ± = RXD ± = OPEN.
60
PRELIMINARY
CY7C955
Capacitance
Parameter
Description
Max.
Unit
pF
C
C
C
Input pin capacitance
7
7
7
IN
Output pin capacitance
Input / Output pin capacitance
pF
OUT
IO
pF
AC Test Loads and Waveforms
5V
R1
R2
OUTPUT
V
CC
– 1.33
R1=910
R2=510
C < 30 pF
L
R =50
Ω
L
Ω
Ω
C
L
R
L
C
C < 5 pF
L
L
(Includes fixture and
probe capacitance)
(Includes fixture and
probe capacitance)
7C955-12
Load
(b) PECL AC Test
(a) TTL AC Test Load
3.0V
V
IHE
V
V
3.0V
IHE
2.0V
2.0V
1.0V
80%
80%
1.0V
20%
1 ns
20%
1 ns
GND
ILE
V
ILE
1 ns
1 ns
≤
≤
≤
≤
7C955-14
7C955-13
(c) TTL Input Test Waveform
(d) PECL Input Test Waveform
Switching Characteristics Over the Operating Range
Parameter
Description
Min.
Max.
Unit
Microprocessor Interface Read Cycle
t
t
t
t
t
t
t
t
t
t
Valid Address to Read Set-Up
Read to Address Invalid Hold
25
5
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
SAR
HRA
SAL
HLA
PL
Valid Address to Address Latch Enable Set-Up
Address Latch Enable to Address Invalid Hold
Address Latch Enable Pulse Width
Address Latch Enable to Read Set-Up
Read to Address Latch Enable Hold
Read to Valid Data Set-Up
20
10
20
0
SLR
HRL
SRD
HRD
SRI
5
80
20
50
Read to Data Invalid Hold
Read to Interrupt Inactive
Microprocessor Interface Write Cycle
t
t
t
t
t
t
Valid Address to Write Set-Up
25
20
20
10
20
0
ns
ns
ns
ns
ns
ns
SAW
SDW
SAL
HLA
PL
Valid Data to Write Set-Up
Valid Address to Address Latch Enable Set-Up
Address Latch Enable to Address Invalid Hold
Address Latch Enable Pulse Width
Address Latch Enable to Write Set-Up
SLW
61
PRELIMINARY
CY7C955
Switching Characteristics Over the Operating Range (continued)
Parameter
Description
Write to Address Latch Enable Hold
Min.
5
Max.
Unit
ns
t
t
t
t
HWL
Write to Data Invalid Hold
Write to Address Invalid Hold
Write Pulse Width
5
ns
HWD
HWA
PW
5
ns
40
ns
Line Interface (Receive Side) Timing
t
RRCLK± Duty Cycle
19.44 MHz or 6.48 MHz
(RBYP = 0)
30
70
%
R
[8, 9]
f
t
t
RRCLK± Frequency Tolerance
−250
250
ppm
ns
R
RXD± Stable to RRCLK± Rising Edge Setup Time. R
= 1
BYP
2
1
SDC
HCD
RRCLK± State Change to RXD Unstable Hold Time. R
= 1
ns
BYP
Receive Side Alarm Timing
t
RCLK HIGH to RALM or RFP Valid Delay
2
20
70
ns
%
DCR
Line Interface (Transmit Side) Timing
t
TRCLK± Duty Cycle
19.44 MHz or 6.48 MHz
(TBYP = 0)
30
T
f
t
t
TRCLK± Frequency Tolerance
TCLK HIGH to TFPO Valid Delay
TXC± LOW to TXD± Valid Delay
–250
3
250
20
2
ppm
ns
T
DTO
DTD
–2
ns
UTOPIA Interface (Receive Side) Timing [TSEN = 0]
f
t
t
t
t
RFCLK Frequency
33
60
MHz
%
RF
RFCLK Duty Cycle
40
10
1
RF
RRDENB Stable to RFCLK HIGH Set-Up
RFCLK HIGH to RRDENB Unstable Hold
RFCLK HIGH to RSOC / RCA / RXPRTY / RDAT [7:0] Valid Delay
ns
SRC
HCR
DCD
ns
2
20
ns
UTOPIA Interface (Receive Side) Timing [TSEN = 1]
f
t
t
t
t
t
t
RFCLK Frequency
33
60
MHz
%
RF
RFCLK Duty Cycle
40
10
1
RF
RRDENB Stable to RFCLK HIGH Set-Up
RFCLK HIGH to RRDENB Unstable Hold
RFCLK HIGH to RCA Valid Delay
ns
SRC
HCR
DCA
DCD
DCT
ns
2
20
20
20
ns
RFCLK HIGH to RSOC / RXPRTY / RDAT [7:0] Valid Delay
RFCLK HIGH to RSOC / RXPRTY / RDAT [7:0] Three-state Delay
2
ns
2
ns
GFC (RECEIVE SIDE) TIMING
t
RCLK HIGH to RGFC / RCP Valid Delay
−1
10
ns
DCG
UTOPIA INTERFACE (TRANSMIT SIDE) TIMING
f
t
t
TFCLK Frequency
33
60
MHz
%
TF
TFCLK Duty Cycle
40
10
TF
TWRENB / TDAT[7:0] / TXPRTY / TSOC Stable to TFCLK HIGH Set-Up
ns
STC
Notes:
8. Not Tested.
9. See description on Receive Clock Recovery (RCR) page 10
62
PRELIMINARY
CY7C955
Switching Characteristics Over the Operating Range (continued)
Parameter
Description
Min.
Max.
Unit
ns
t
t
TFCLK HIGH to TWRENB / TDAT[7:0] / TXPRTY / TSOC Unstable Hold
TFCLK HIGH to TCA Valid Delay
1
2
HCT
DTT
20
ns
GFC (Transmit Side) Timing
t
TGFC Stable to TCLK High Set-Up
10
1
ns
ns
ns
SGT
HTG
DTP
t
t
TCLK High to TGFC Unstable Hold
TCLK High to TCP Valid Delay
–1
10
Switching Waveforms
Microprocessor Interface Read Cycle
VALID ADDRESS
A[7:0]
t
SAL
t
HRA
t
HLA
t
PL
ALE
t
HRL
t
SLR
t
SAR
(RDB + CSB)
t
HRD
t
SRD
VALID DATA
D[7:0]
t
SRI
INTB
7C955–15
63
PRELIMINARY
CY7C955
Switching Waveforms (continued)
Microprocessor Interface Write Cycle
VALID ADDRESS
A[7:0]
t
SAL
t
HWA
t
HLA
t
PL
ALE
t
HWL
t
SLW
t
PW
t
SAW
(WRB + CSB)
t
HWD
t
SDW
VALID DATA
D[7:0]
7C955–16
Receive Side Line Interface Timing
RXD±
t
SDC
t
HCD
RRCLK±
7C955–17
64
PRELIMINARY
CY7C955
Switching Waveforms (continued)
Receiver Alarm Interface Timing
RCLK
t
DCR
RALM / RFP
7C955–18
Transmit Side Line Interface Timing
TCLK
t
DCT
TFPO
TXC±
TXD±
t
DCD
7C955–19
65
PRELIMINARY
CY7C955
Switching Waveforms (continued)
Utopia Interface (Receive Side) Timing [TSEN = 0]
RFCLK
t
SRC
t
HCR
RRDENB
t
DCD
RDAT[7:0] / RCA /
RSOC/ RXPRTY
7C955–20
66
PRELIMINARY
CY7C955
Switching Waveforms (continued)
Utopia Interface (Receive Side) Timing [TSEN=1]
RFCLK
t
SRC
t
HCR
RRDENB
t
DCA
RCA
t
DCT
t
DCD
RDAT[7:0] /
RSOC / RXPRTY
VALID RDAT[7:0] / RSOC / RXPRTY
7C955–21
GFC Interface (Receive Side) Timing
RCLK
t
DCG
RGFC / RCP
7C955–22
67
PRELIMINARY
CY7C955
Switching Waveforms (continued)
Utopia Interface (Transmit Side) Timing
RCLK
t
t
STC
HCT
RRDENB
t
DTT
RCA
7C955–23
GFC Interface (TransmitSide)Timing
TCLK
TGFC
t
t
SGT
HTG
t
DTP
TCP
7C955–24
68
PRELIMINARY
CY7C955
Functional Timing Diagram
Utopia Interface (Transmit Side) Functional Timing
Figure 8 shows, in a nutshell, all the functional timing require-
ments of the Transmit Side Utopia Interface. The Transmit Side
Utopia Interface consists of TDAT[7:0], TXPRTY, TSOC,
TWRENB, TCA, and TFCLK.
TSOCI (Reg−60H, bit 6) to go HIGH, and causes an interrupt
also if FIFOE (Reg−60H, bit 7) is enabled.
TWRENB
This transmit FIFO write enable bit (TWRENB) should be
pulled LOW whenever there is an ATM byte to send. It can be
deactivated at any time to pause the writing process—not nec-
essarily at cell boundaries.
TDAT[7:0]
ATM cells are expected to be clocked into the Utopia FIFO
interface through TDAT[7:0] with the 1st header byte first fol-
lowed by the remaining 52 bytes of headers and payload. The
fifth header byte (HEC) is required but is being ignored and
replaced by the HCS octet generated by the Transmit ATM Cell
Processor.
TCA
The transmit cell available (TCA) is affected by TCAINV
(Reg−01H, bit 3) and TCALEVEL0 (Reg−63H, bit 94). TCAINV
determines the active polarity of the TCA signal, and
TCALEVEL0 controls the meaning of TCA going active. If
TCALEVEL0 = 0, TCA will be deasserted when the transmit
FIFO is 4 writes from full. If TCALEVEL0 = 1, TCA will be
deasserted when the FIFO is full and can accept no more
writes.
TXPRTY
The TXPTYP (Reg−63, bit 7) and TXPRTYE (Reg−63H, bit 6)
can be set to make the Transmit Side Utopia Interface accept
odd, even, or no parity TXPRTY inputs.
TSOC
TFCLK
A HIGH TSOC input is expected along with the first header
byte of an ATM cell. If TSOC is absent, the Transmit ATM Cell
Processor will automatically generate a TSOC based on pre-
vious TSOC positions, no interrupt will be sent. However, if
TSOC is misplaced, the previously stored incomplete ATM cell
will be discarded and the transmit FIFO pointer will be set back
to the beginning of the same cell. A misplaced event will cause
TFCLK has to be a clock of 33 MHz or less. Although it can be
stopped if necessary, it is not recommended because some
registers and pins synchronized by this clock will not be updat-
ed. If this clock is stopped, the line side interface will still be
able to transmit the cells already stored into the FIFO. After
that, idle cells will be transmitted.
TFCLK
TDAT[7:0]
X
P46
X
H1
H2
H3
P44
P45
P47
P48
H1
TSOC
X
X
TXPRTY
TCA LEVEL 0 =1
TCA
TWNRENB
Figure 8. Transmit FIFO
69
PRELIMINARY
CY7C955
RDAT[7:0]
Functional Timing Diagram (continued)
ATM cells are clocked out of the Utopia FIFO interface through
RDAT[7:0] with the 1st header byte first followed by the remain-
ing 52 bytes of headers and payload. The cell stream can be
stopped at anytime by pulling RRDENB HIGH.
Utopia Interface (Receive Side) Functional Timing
Figure 9 shows, in a nutshell, all the functional timing require-
ments of the Receive Side Utopia Interface. The Receive Side
Utopia Interface consists of TSEN, RDAT[7:0], RXPRTY,
RSOC, RRDENB, RCA, and RFCLK.
RXPRTY
The RXPTYP (Reg–50, bit 6) can be set to make the receive
side Utopia interface produce odd or even parity RXPRTY out-
puts.
TSEN
This three-state enable pin can be used to implement shared
Utopia bus architecture for Multi-PHY operation. If TSEN is
tied HIGH, RDAT[7:0], RXPRTY, and RSOC will be three-stat-
ed if RRDENB is HIGH. If TSEN is pulled LOW, RDAT[7:0],
RXPRTY, and RSOC will always assume a logic 1 or logic 0.
TSEN has an integrated pull down resistor.
RSOC
RSOC will go HIGH when RDAT[7:0] contains the first header
byte of an ATM cell.
RFCLK
RDAT[7:0]
H1
H1
H2
P43
P44
P45
P46
P47
P48
RSOC
RRDENB
READ IGNORED
RCALEVEL0= 1
RCA
RXPRTY
Figure 9. Receive FIFO
70
PRELIMINARY
CY7C955
corresponding GFC bit of the next transmitted assigned ATM
cell. Unassigned/ Idle cells will maintain its default content and
will not be affected by the TGFC input.
(continued)
Functional Timing Diagram
GFC Interface (Transmit Side) Functional Timing
Figure 10 shows the functional timing for the TGFC input with
respect to TCLK and TCP.
GFC Interface (Receive Side) Functional Timing
Figure 11 shows the functional timing for the RGFC input with
TCP
respect to RCLK and RCP.
Transmit Cell Pulse toggles HIGH for one clock cycle 6 TCLK
periods before the first octet of the next ATM cell is read from
the transmit FIFO.
RCP
Receive Cell Pulse toggles HIGH whenever the most signifi-
cant GFC bit (GFC[3]) of an assigned ATM cell header is pre-
sented on the RGFC pin. GFC[3] can be present for as long
as 1 to 14 RCLK cycles on the RGFC pin, and so RCP can
also be HIGH for anywhere between 1 to 14 RCLK cycles.
TGFC
If enabled by TGFCE (Reg-67, bit 4−7), a stable TGFC[3] is
expected on the next rising edge of the TCLK after TCP goes
HIGH (see Figure 10). All enabled TGFC bits will replace the
TCLK
TCP
GFC[3]
GFC[2]
GFC[1]
GFC[0]
X
X
TGFC
Figure 10. Transmit GFC Serial Link
RCLK
RGFCE[3:0]=1111B
RCP
GFC[3]
CELL N
GFC[2] GFC[1] GFC[0]
CELL N CELL N CELL N
RGFC
RGFCE[3:0]=1001B
RCP
GFC[3]
CELL N
GFC[0]
CELL N
RGFC
Figure 11. Receive GFC Serial Link
71
PRELIMINARY
CY7C955
Functional Timing Diagram (continued)
Timing Modes
If the application is a LAN termination equipment, the config-
uration described in Figure 13 should be used. LOOPT
(Reg–5H, bit 0) is HIGH to enable loop timing mode. In loop
timing mode, The clock recovered from the received data
stream is being used to synchronize the transmit datastream.
If that clock is lost, RRCLK x 8 will be used as the clock refer-
ence. The clocking architecture of the CY7C955 is shown in
Figure 14.
Figure 12, 13, and 14 shows how to connect the clock refer-
ence for different applications.
In the presence of a 155.52 MHz/51.84 MHz primary reference
source (PRS). The configuration described in Figure 12 should
be used. TBYP is HIGH and RBYP is LOW. The primary
reference clock source provides the accurate bit synchroniza-
tion needed for the transmit data stream.
Stratum or free-run
reference
19.44 MHz
Stratum or free-run
reference
19.44 MHz
TRCLK±
TRCLK±
CY7C955
Input Data
CY7C955
RXD±
TCLK
Input Data
RXD±
TCLK
RRCLK±
RRCLK±
Figure 12. Clock Synthesis
Figure 13. Loop Timing
TRCLK±
Internal
Tx Clock
Source
A
B
Clock Synthesizer
/8
TCLK
Internal
Rx Clock
Source
RXD±
Clock Recovery
RRCLK±
Figure 14. Conceptual Clocking Structure
72
PRELIMINARY
CY7C955
Interface Termination and Biasing Schemes
PECL Input Termination and Biasing Recommendations
Figure 16 shows another possible type of a differential PECL
connection. Although this connection is allowed, the method
suggested in Figure 15 will give better switching characteris-
tics.
Figures 15−19 show how to connect different output types to
the CY7C955 PECL inputs. Differential termination and bias-
ing (Figure 15) is required for RXD, and is highly recommend-
ed for RRCLK, and TRCLK. Nevertheless it is also possible for
the input to accept single-ended signals. If the positive end of
a PECL input pair is tied to GND (with or without a pull-down
resistor), the negative input will become a single-ended input.
Figure 17 shows a CMOS connection; no termination is need-
ed if the trace is kept short. If the trace is long, follow common
transmission line termination practices.
Figure 18 shows a TTL connection. The 0.01µF AC-coupling
capacitor allows the CY7C955 inputs to self-bias itself to
This input is self-biased to its threshold at V /2. Notice that
CC
because the negative input is used, the signal entering the chip
through the input are inverted.
V
/2. This connection scheme is not suitable for the ALOS
CC
input because the signal is close to static.
Figure 15 shows a differential PECL connection. Whenever
possible, this differential PECL connection scheme should be
used. Differential signals are less susceptible to com-
mon-mode noise.
Figure 19 shows how to connect a single-ended PECL con-
nection to the ALOS− input. ALOS is almost a static signal, so
the connection must be DC-coupled. A 330Ω resistor to GND
is needed, as a current sink is needed for the PECL output to
operate correctly.
V
CC
80Ω
+ve–
PECL
Output
TRCLK+ /
RRCLK+ / RXD+
130Ω
CY7C955
Vcc
80Ω
–ve –
TRCLK– /
PECL
Output
RRCLK– / RXD–
130Ω
Figure 15. Differential PECL Termination (High Performance)
73
PRELIMINARY
CY7C955
+ve–
PECL
Output
ALOS+ / TRCLK+ /
RRCLK+ / RXD+
330Ω
CY7C955
100Ω
–ve –
PECL
Output
ALOS– / TRCLK– /
RRCLK– / RXD–
330Ω
Figure 16. Differential PECL Termination (Low Power)
ALOS+ / TRCLK+ /
RRCLK+ / RXD+
CY7C955
ALOS– / TRCLK– /
RRCLK– / RXD–
CMOS
Output
Figure 17. CMOS Connection
74
PRELIMINARY
CY7C955
TRCLK+ / RRCLK+
CY7C955
.01µF
TRCLK– / RRCLK–
TTL
Output
Figure 18. TTL Connection
ALOS+
CY7C955
Single-
ended–
PECL
ALOS–
330Ω
Output
Figure 19. Single-ended PECL Connection for ALOS
Filter Pin Configuration
The CY7C955 Phase-locked Loop is designed to meet the
Bellcore specifications on jitter generation, jitter transfer, and
jitter tolerance. The highly integrated charge pump design
drastically reduces the complexity of external filter compo-
nents. Only a single 0.47-µF non-polar capacitor is needed to
provide the damping factor needed to meet the jitter ceiling de-
fined in GR-253. Figure 14 describes how to connect the ca-
pacitor across the LF− and LFO pins of the CY7C955. The
LF+ pin is to be left unconnected.
The 1.0-µF capacitor should have the following characteristics:
Breakdown Voltage:
Tolerance:
Dielectric:
Polarity:
16V or higher
±10% or better
X7R or better
Non-polar or Bipolar
Size:
1206 or 1210 (0805 is not available commercially yet)
Example Part Number:
Size: 1206
Part Number: 1206YC474JAT1A
AVX Corporation
Breakdown: 16V
Capacitance: 0.47µF
Tel: 360 699 8746
75
PRELIMINARY
CY7C955
The 1.0-µF capacitor should have the following characteristics:
Breakdown Voltage:
Tolerance:
16V or higher
±10% or better
X7R or better
Dielectric:
Polarity:
Non-polar or Bipolar
Size:
1206 or 1210 (0805 is not available commercially yet)
Dielectric: X7R
Tolerance: ± 5%
Size: 1206
Part Number: EMK316BJ474K
Anderson Electronics Component Distribution
Tel: 408 577 1323
Breakdown: 16V
Capacitance: 0.47µF
Dielectric: X7R
Tolerance: ±10%
Data
FLIP
FLOP
CORE
LOGIC
Phase
Detector
Charge
Pump
Clock
VCO
LFO
LF-
0.47 uF
Figure 20. Phase-Locked Loop Capacitor Placement
Ordering Information
Package
Operating
Range
Ordering Code
CY7C955-NC
Name
N128
N128
Package Type
128-Lead Plastic Quad Flat Package
128-Lead Plastic Quad Flat Package
Commercial
Industrial
CY7C955-NI
Document #: 38-00417-D
76
PRELIMINARY
CY7C955
Package Diagram
128-Lead Plastic Quad Flatpack
77
PRELIMINARY
CY7C955
54-Byte Cell on RxUTOPIA Bus
ADDENDUM - Design Considerations for the
CY7C955
Received ATM cells in the RXFIFO can be read out from the
RxUTOPIA bus at various throughput. The throughput can be
throttled by two ways; one way is by changing the RFCLK fre-
quency; another way is using the RRDENB input and a fixed
RFCLK (for more information on the Rx UTOPIA bus opera-
tion, refer to the pin description, “Receive UTOPIA Interface”
section of the data sheet and the UTOPIA spec Level 1). When
the throughput writing into the RxFIFO is greater than the
throughput reading out, then, intermittently, the CY7C955 out-
puts a cell with 54bytes
This memo outlines current design considerations for the
CY7C955 - ATM PHY in reference to the ATM Forum UTOPIA
Level 1 specification.
Receive FIFO Reset
The Receive four-cell FIFO is reset by programming register
0x50(RACP)[0] to a logic '1'.
Under this condition the CY7C955 RCA output is not deassert-
ed immediately and the RDATA[7:0] output is not 0x00. The
CY7C955 RCA output is held asserted until the end of the
current transmission of the cell on the RxUTOPIA bus. The
RDATA is hold immediately after the RxFIFO Reset is recog-
nized, while the RCA output is still asserted (indicating a valid
cell).
FIFO RST
RCA
RDATA
Figure 21. CY7C955 Receive FIFO Reset Behavior
© Cypress Semiconductor Corporation, 1999. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility for the use
of any circuitry other than circuitry embodied in a Cypress Semiconductor product. Nor does it convey or imply any license under patent or other rights. Cypress Semiconductor does not authorize
its products for use as critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress
Semiconductor products in life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress Semiconductor against all charges.
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