STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
When FPMODE is a logic 1, frame pulse slave mode is selected and BRFP is
an input. When configured as an input, BRFP only has effect when the
elastic store is in use (RXELSTBYP is logic 0); otherwise, it is ignored.
ALTFDL:
In T1 mode, the ALTFDL bit enables the framing bit position on the backplane
PCM output to contain a copy of the FDL bit. When ALTFDL is set to logic 1,
each M-bit value in the ESF-formatted stream is duplicated and replaces the
subsequent CRC bit or F-bit in the output signal stream on BRPCM. When
ALTFDL is set to logic 0, the output BRPCM stream contains the received M,
CRC, or F bits in the framing bit position. Note that this function is only valid
for ESF-formatted streams, ALTFDL should be set to logic 0 when other
framing formats are being received.
This bit is ignored in E1 mode.
ALTBRFP:
The ALTBRFP bit suppresses every second output pulse on the backplane
output BRFP. When ALTBRFP is set to logic 1 and BRXCMFP and BRXSMP
bits are both logic 0, the output signal on BRFP pulses every 386 bits or 512
bits, indicating the first bit of every second frame. Under this condition, BRFP
indicates the Signaling Alignment bits (S1-S6) for T1 SF, the data link bits for
T1 ESF and the NFAS frames for E1. If the BRXCMFP or BRXSMFP bit is
logic 1 when ALTBRFP is logic 1, the output signal on BRFP pulses every 24,
32 or 48 frames. In T1 mode, this latter setting (i.e. both ALTBRFP and
BRXSMFP set to logic 1) is useful for converting SF formatted data to ESF
formatted data between two COMET devices. When ALTBRFP is set to
logic 0, the output signal on BRFP pulses in accordance to the ROHM,
BRXCMFP and BRXSMP bit settings.
ALTBRFP has no effect if the FPMODE bit or the ROHM bit is a logic 1.
PROPRIETARY AND CONFIDENTIAL
141
PMC [ PMC-SIERRA, INC ]
