STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
Pin Name
Type
Pin No.
Function
-RI
-NI
BTFP
I/O
13
E4
Backplane Transmit Frame Pulse (BTFP). When BTFP is configured as an
input, it is used to frame align the transmitter to the system backplane.
T1 mode:
If only frame alignment is required, a pulse at least one BTCLK cycle wide
must be provided on BTFP at multiples of 193 bit periods. If superframe
alignment is required, transmit superframe alignment must be enabled, and
BTFP must be brought high for at least one BTCLK cycle to mark bit 1 of frame
1 of every 12-frame or 24-frame superframe.
E1 mode:
If basic frame alignment only is required, a pulse at least one BTCLK cycle
wide must be provided on BTFP at multiples of 256 bit periods. If multiframe
alignment is required, transmit multiframe alignment must be enabled, and
BTFP must be brought high to mark bit 1 of frame 1 of every 16-frame
signaling multiframe and brought low following bit 1 of frame 1 of every 16-
frame CRC multiframe. This mode allows both multiframe alignments to be
independently controlled using the single BTFP signal. Note that if the
signaling and CRC multiframe alignments are coincident, BTFP must pulse
high for one BTCLK cycle every 16 frames.
When BTFP is configured as an output (only valid when the transmit backplane
clock rate is no greater than 2.048 MHz), transmit frame alignment is derived
internally and BTFP is updated on the configured active edge of BTCLK.
BTFP pulses high for one cycle to indicate the first bit of each frame or
multiframe, as optioned.
After a reset, BTFP is configured as an input.
BTPCM
Input
11
E1
Backplane Transmit PCM Data (BTPCM). The non-return to zero, digital data
stream to be transmitted is input on this pin. BTPCM may present a
1.544 Mbit/s, 2.048 Mbit/s or sub-rate NxDS0 data stream or may present a
byte-interleaved 4.096 Mbit/s or 8.192 Mbit/s multiplexed data stream.
The bit alignment of BTPCM relative to BTFP is configurable. Two mappings
of a DS-1 into a 2.048 Mbit/s format are defined: every fourth timeslot unused
and 24 contiguous timeslots.
The BTPCM signal is sampled on the configured active edge of BTCLK.
BTSIG
Input
12
E3
Backplane Transmit Signaling (BTSIG). The BTSIG input signal contains the
signaling bits for each channel in the transmit data frame, repeated for the
entire superframe. Each channel's signaling bits are in bit locations 5, 6, 7 and
8 of the channel and are channel-aligned with the BTPCM data stream.
The BTSIG signal is sampled on the configured active edge of BTCLK.
PROPRIETARY AND CONFIDENTIAL
20
PMC [ PMC-SIERRA, INC ]
