STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
Pin Name
Type
Pin No.
Function
-RI
49
-NI
BRFP
I/O
F6
Backplane Receive Frame Pulse (BRFP). When BRFP is configured as an
output, it indicates the frame alignment of BRPCM and BRSIG. BRFP is
generated on the active edge of BRCLK.
T1 mode:
If basic frame alignment is desired, BRFP pulses high for one BRCLK cycle
during bit 1 of each 193-bit frame. Optionally, BRFP may pulse high every
second frame to ease the identification of data link bits. If superframe
alignment is desired, BRFP pulses high for one BRCLK cycle during bit 1 of
frame 1 of every 12-frame or 24-frame superframe. Optionally, BRFP may
pulse high every second superframe to ease the conversion between SF and
ESF.
E1 mode:
If basic frame alignment is desired, BRFP pulses high for one BRCLK cycle
during bit 1 of each 256-bit frame. Optionally, BRFP may pulse high every
second frame to ease the identification of NFAS frames. If multiframe
alignment is desired, BRFP transitions high to mark bit 1 of frame 1 of every
16-frame signaling multiframe and transitions low following bit 1 of frame 1 of
every 16-frame CRC multiframe. Note that if the signaling and CRC
multiframe alignments are coincident, BRFP pulses high for one BRCLK cycle
every 16 frames.
When BRFP is configured as an input, it is used to frame align the receive data
to the backplane frame alignment. When frame alignment is required, a pulse
at least one BRCLK cycle wide must be provided on BRFP a maximum of once
every frame (193 bit periods in T1 mode or 256 bit periods in E1 mode). BRFP
is sampled on the active edge of BRCLK.
After a reset, BRFP is configured as an input.
BRPCM
Output
with
51
E9
Backplane Receive PCM Data (BRPCM). BRPCM contains the recovered data
stream passed through the elastic store, signaling extractor and per-DS0 serial
controller. When the receive elastic store is not bypassed, the BRPCM stream
is aligned to the backplane input timing. When BRCLK is either 4.096 MHz,
8.192 MHz or 16.384 MHz, BRPCM can be tristated and is only active during
programmable timeslots. This allows byte interleaving of PCM data streams
from up to 4 COMET devices with no external logic.
Tristate
After a reset, BRPCM is high impedance.
BRPCM is updated on the active edge of BRCLK.
PROPRIETARY AND CONFIDENTIAL
22
PMC [ PMC-SIERRA, INC ]
