PM5347 datasheet(82/302 Pages) PMC

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PM5347 S/UNI-PLUS

DATA SHEET

PMC-941033

ISSUE 6

SATURN USER NETWORK INTERFACE PLUS

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

Idle/Unassigned Cell Generator

The Idle/Unassigned Cell Generator inserts idle or unassigned cells into the cell

stream when enabled. Registers are provided to program the GFC, PTI, and

CLP fields of the idle cell header and the idle cell payload. The idle cell HCS is

automatically calculated and inserted.

Scrambler

The Scrambler scrambles the 48 octet information field. Scrambling is performed

using a parallel implementation of the self synchronous scrambler described in

the references. The cell headers are transmitted unscrambled, and the

scrambler may optionally be disabled.

HCS Generator

The HCS Generator performs a CRC-8 calculation over the first four header

octets. A parallel implementation of the polynomial, x8+x2+x+1, is used. The

coset polynomial, x6+x4+x2+1, is added (modulo 2) to the residue. The HCS

Generator optionally inserts the result into the fifth octet of the header.

GFC Insertion Port

The GFC Insertion Port provides the ability to insert the GFC value downstream

of the FIFO. The four GFC bits are received on a serial stream that is

synchronized to the transmit cell by a framing pulse. The GFC enable register

bits control the insertion of each serial bit. If the enable is cleared, the default

GFC value is inserted. For idle/unassigned cells, the default is the contents of

the TACP Idle/Unassigned Cell Header Control register. For assigned cells, the

default is the value received from TDAT[15:0].

Transmit FIFO

The Transmit FIFO provides FIFO management and the synchronous interface

between the S/UNI-PLUS device and the external environment. The transmit

FIFO can accommodate four cells. It provides for the separation of the STS-3c/1

(STM-1) line or physical layer timing from the ATM layer timing.

The FIFO supports two data structures. The first data structure consists of

twenty-seven 16-bit words comprising the five octet cell header, a cell header

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