PM5345 datasheet(53/196 Pages) PMC

53 / 196 page

PM5345 S/UNI-155

DATA SHEET

PMC-930305

ISSUE 4

SATURN USER NETWORK INTERFACE

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

FUNCTIONAL DESCRIPTION

10.1

Serial to Parallel Converter

The Serial to Parallel Converter (SIPO) converts the received 155.52 Mbit/s

SONET stream to a 19.44 Mbyte/s stream. The SIPO searches for the

SONET/SDH framing pattern (A1, A2 ) in the incoming stream, and performs

serial to parallel conversion on octet boundaries.

10.2

Receive Section Overhead Processor

The Receive Section Overhead Processor (RSOP) provides frame

synchronization, descrambling, section level alarm and performance monitoring.

10.2.1 Framer

The Framer Block determines the in-frame/out-of-frame status of the STS-3c

data stream. Output OOF reflects this status, and is updated with timing aligned

to RCLK.

While in-frame, the framing bytes (A1, A2) in each frame are compared against

the expected pattern. Out-of-frame is declared when four consecutive frames

containing one or more framing pattern errors have been received.

While out-of-frame, upstream circuitry (the SIPO block or an external serial to

parallel converter depending on the interface selected using the RSER input)

monitors the bit serial STS-3c data stream for an occurrence of the framing

pattern. A high level on input FPIN (when the byte serial interface is selected)

reinitializes the channel counter to the new frame alignment. The Framer Block

verifies that an error free framing pattern is present in the next frame before

declaring in-frame.

10.2.2 Descramble

The Descramble Block utilizes a frame synchronous descrambler to process the

received byte serial stream. The generating polynomial is 1 + x6 + x7 and the

sequence length is 127. Details of the descrambling operation are provided in

the references. Note that the framing bytes (A1 and A2) and the identity bytes

(C1) are not descrambled. A register bit is provided to disable the descrambling

operation.

PM5345 Datasheet(PDF) 53 Page - PMC-Sierra, Inc