PM7345 datasheet(69/306 Pages) PMC

69 / 306 page

PM7345 S/UNI-PDH

DATA SHEET

PMC-931011

ISSUE 6

SATURN USER-NETWORK INTERFACE

PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE

9.13 XBOC Bit Oriented Code Generator

The Bit Oriented Code Generator (XBOC) Block transmits 63 of the possible 64 bit

oriented codes (BOC) in the C-bit parity Far End Alarm and Control (FEAC) channel.

A BOC is 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

code to be transmitted is programmed by writing the XBOC Code Register. The

64th code (111111) is similar to the HDLC idle sequence and is used to disable the

transmission of any bit oriented codes. When transmission is disabled, the FEAC

channel is set to all ones.

9.14 XFDL Facility Data Link Transmitter

The Facility Data Link Transmitter (XFDL) provides a serial data link for the C-bit

parity path maintenance data link in DS3, the serial Network Operator byte or the

General Purpose datalink in G.832 E3, or the National Use bit datalink in G.751

E3. The XFDL is used under microprocessor control to transmit HDLC data

frames. It performs all of the data serialization, CRC generation, zero-bit stuffing,

as well as flag, and abort sequence insertion. Upon completion of the message,

a CRC-CCITT frame check sequence (FCS) is appended, followed by flags. If

the XFDL Transmit Data register underflows, an abort sequence is automatically

transmitted.

When enabled, the XFDL continuously transmits flags (01111110). Data bytes to

be transmitted are written into the XFDL Transmit Data Register. After the

parallel-to-serial conversion of each data byte, an interrupt is generated to signal

the microprocessor to write the next byte. After the last data frame byte, the FCS

(if CRC insertion has been enabled), or a flag (if CRC insertion has not been

enabled) is transmitted. The XFDL then returns to the transmission of flag

sequences.

If there are more than five consecutive ones in the raw transmit data or in the

CRC data, a zero is stuffed into the serial data output. This prevents the

unintentional transmission of flag or abort sequences.

Abort characters can be continuously transmitted at any time by setting a control

bit. During transmission, an underrun situation can occur if data is not written to

the XFDL Transmit Data register before the previous byte has been depleted. In

this case, an abort sequence is transmitted, and the controlling processor is

notified via the UDR signal.

When the XFDL is disabled, a logical 1 is inserted in the path maintenance data

link.

PM7345 Datasheet(PDF) 69 Page - PMC-Sierra, Inc

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