STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
When the elastic store is being used, if the average frequency of the backplane
data is greater than the average frequency of the line clock, the buffer will fill.
Under this condition a controlled slip will occur upon the next frame boundary.
The following frame of PCM data will be deleted.
If the average frequency of the backplane data is less than the average
frequency of the line clock, the buffer empty. Under this condition a controlled
slip will occur upon the next frame boundary. The latest frame will be repeated.
A slip operation is always performed on a frame boundary. The TX-ELST is
upstream of the frame overhead insertion; therefore, frame slips do not corrupt
the frame alignment signal.
When the line timing is derived from BTCLK or BTCLK is an output, the elastic
store is bypassed to eliminate the two frame delay.
9.19 Transmit Per-Channel Serial Controller (TPSC)
The Transmit Per-channel Serial Controller allows data and signaling trunk
conditioning or idle code to be applied on the transmit DS-1 stream on a per-
channel basis. It also allows per-channel control of zero code suppression, data
inversion, and application of digital milliwatt.
The Transmit Per-channel Serial Controller function is provided by a Per-
Channel Serial Controller (PCSC) block. The PCSC is a general purpose triple
serializer. Data is sourced from three banks of thirty-two 8-bit registers, with
each bank supporting a single serial output.
The TPSC interfaces directly to the E1-TRAN and T1-XBAS blocks to provide
serial streams for signaling control, idle code data and PCM data control.
The registers are accessible from the µP interface in an indirect address mode.
The BUSY indication signal can be polled from an internal status register to
check for completion of the current operation.
9.20 T1 Inband Loopback Code Generator (XIBC)
The T1 Inband Loopback Code Generator (XIBC) block generates a stream of
inband loopback codes (IBC) to be inserted into a T1 data stream. The IBC
stream consists of continuous repetitions of a specific code and can be either
framed or unframed. When the XIBC is enabled to generate framed IBC, the
framing bit overwrites the inband code pattern. The contents of the code and its
length are programmable from 3 to 8 bits. The XIBC interfaces directly to the
XBAS Basic Transmitter block.
PROPRIETARY AND CONFIDENTIAL
54
PMC [ PMC-SIERRA, INC ]
