STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
Register 00AH: Master Diagnostics
Bit
Type
Function
Default
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Unused
ID[5]
X
1
0
0
0
0
0
0
R
R/W
R/W
R/W
R/W
R/W
R/W
PAYLB
LINELB
RAIS
DDLB
TXMFP
TXLOS
ID[5]:
The ID[5] bit was added for COMET Rev G. In prior revisions, this bit was
unused and defaulted to X. Please see the Register 00DH: Revision/Chip
ID/Global PMON Update description for how to distinguish between COMET
Rev F and G in software.
PAYLB:
The PAYLB bit selects the payload loopback mode, where the received data
output from the RX-ELST is internally connected to the transmit data input of
the transmitter. The data read out of RX-ELST is timed to the transmitter
clock, and the transmit frame alignment is used to synchronize the output
frame alignment of RX-ELST. The transmit frame alignment is either arbitrary
(when the TX-ELST is used) or is specified by the BTFP input (when the TX-
ELST is bypassed). During payload loopback, the data on BRPCM is only
valid when the COMET is configured as a BRCLK master, BRFP master and
the RX-ELST is bypassed. When the RX-ELST is not bypassed, the BRPCM
output is forced to all-ones. When PAYLB is set to logic 1, the payload
loopback mode is enabled. When PAYLB is set to logic 0, the loopback
mode is disabled. In T1 mode, if the TDPR #1 is configured to send
performance reports from the T1-APRM, this bit requires two updating cycles
before being included in the performance report. Only one of PAYLB,
LINELB, and DDLB can be enabled at any one time.
LINELB:
The LINELB bit selects the line loopback mode, where the recovered data are
internally directed to the digital inputs of the transmit jitter attenuator. In
analog mode (RUNI is logic 0), the data sent to the TJAT is the recovered
PROPRIETARY AND CONFIDENTIAL
98
PMC [ PMC-SIERRA, INC ]
