PM7344 datasheet(64/293 Pages) PMC

64 / 293 page

PM7344 S/UNI-MPH

DATA SHEET

PMC-950449

ISSUE 6

MULTI-PHY USER NETWORK INTERFACE

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

This block monitors the transmit AMI-coded T1 stream, detecting when the

stream is about to violate the ANSI T1.403 12.5% pulse density rule over a

moving 192-bit window. If a density violation is detected, the XPDE can be

enabled to insert a logic 1 into the digital stream to ensure the resultant output no

longer violates the pulse density requirement. When the XPDE is disabled from

inserting logic 1s, the transmit stream from the TRAN is passed through

unaltered.

9.12

T1 Bit Oriented Code Generator (XBOC)

The 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 link

channel in T1-ESF framing format, as defined in ANSI T1.403.

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

facility data link except for ESF yellow CFA. The code to be transmitted is

programmed by writing the code register.

9.13

T1 HDLC Transmitter (T1 XFDL)

The HDLC Transmitter function is provided by the XFDL block. This block

interfaces with the TRAN block. The XFDL is used under microprocessor or

DMA control to transmit HDLC data frames in the facility data link for the T1-ESF

frame format, or in timeslot 16 or the National bits of timeslot 0 for the E1 frame

format.

The XFDL 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 on an interrupt-driven basis by writing to a double-

buffered transmit data register. A CRC-CCITT frame check sequence is

appended to the data frame, followed by idle flag sequences. If the transmit data

When enabled for use, the XFDL continuously transmits the flag character

(01111110). Data bytes to be transmitted are written into the Transmit Data

generated to signal the controller to write the next byte into the Transmit Data

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 characters.

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