STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
9.21 T1 Bit Oriented Code Generator (XBOC)
The T1 Bit Oriented Code Generator function is provided by the XBOC block.
This block transmits 63 of the possible 64 bit oriented codes in the Facility Data
th
Link channel in ESF framing format, as defined in ANSI T1.403-1989. The 64
code (111111) is similar to the HDLC Flag sequence and is used in the XBOC to
disable transmission of any bit oriented codes.
Bit oriented codes are transmitted on the Facility Data Link channel as a 16-bit
sequence consisting of 8 ones, a zero, 6 code bits, and a trailing zero
(111111110xxxxxx0) which is repeated as long as the code is not 111111. The
transmitted bit oriented codes have priority over any data transmitted on the FDL
except for ESF Yellow Alarm. The code to be transmitted is programmed by
writing the code register.
9.22 HDLC Transmitters
The HDLC Transmit function is provided by the TDPR block. Three TDPR blocks
are provided for flexible insertion of standardized data links:
• T1 ESF facility data link
• T1DM data link
• ISDN D-channel
• E1 Common Channel Signaling data link
• V5.1/V5.2 D-channel and C-channels.
• E1 Sa-bit data link
The TDPR is a general purpose HDLC transmitter. The TDPR is used under
microprocessor control to transmit HDLC data frames. The TDPR performs all of
the data serialization, CRC generation, zero-bit stuffing, as well as flag, idle, and
abort sequence insertion. Data to be transmitted is provided by writing to a
transmit data register. Upon completion of the frames, a CRC-CCITT frame
check sequence is transmitted, followed by flag sequences. If the transmit data
register underflows, an abort sequence is automatically transmitted.
When enabled, the TDPR continuously transmits the flag sequence (01111110)
until data is ready to be transmitted. Data bytes to be transmitted are written into
the Transmit Data Register. The TDPR performs a parallel-to-serial conversion
of each data byte and transmits it using one of two procedures.
PROPRIETARY AND CONFIDENTIAL
55
PMC [ PMC-SIERRA, INC ]
