PM6344 datasheet(45/256 Pages) PMC

45 / 256 page

STANDARD PRODUCT

PMC-Sierra, Inc.

PM6344 EQUAD

PMC-951013

ISSUE 5

QUADRUPLE E1 FRAMER

FRMR has found CRC multiframe alignment, the PCM data is continuously

monitored for CRC multiframe alignment pattern errors, and CRC-4 errors. The

FRMR also detects and indicates loss of frame, loss of CAS multiframe, and loss

of CRC multiframe, based on user-selectable criteria. The reframe operation can

be initiated by software (via the FRMR Frame Alignment Options Register), by

excessive CRC errors, or when CRC multiframe alignment is not found within 8

ms. The FRMR also identifies the position of the frame, the CAS multiframe, and

the CRC multiframe.

The FRMR extracts timeslot 16 for optional use as a data link and also extracts

the contents of the International bits (from both the FAS frames and the NFAS

frames), the National bits, and the Extra bits (from timeslot 16 of frame 0 of the

CAS multiframe), and stores them in the FRMR International/National Bits

The FRMR identifies the raw bit values for the remote (or distant frame) alarm

(bit 3 in timeslot 0 of NFAS frames) and the remote signaling multiframe (or

distant multiframe) alarm (bit 6 of timeslot 16 of frame 0 of the CAS multiframe)

via the FRMR International/National Bits Register, and the FRMR Extra Bits

and remote signaling multiframe alarm bits which are set when the

corresponding signals have been a logic 1 for 2 or 3 consecutive occurrences, as

per Recommendation O.162. Detection of AIS and timeslot 16 AIS are provided;

AIS is also integrated and an AIS Alarm is indicated if the AIS condition has

persisted for at least 100 ms. The out of frame (OOF=1) condition is also

integrated, indicating a red Alarm if the OOF condition has persisted for at least

100 ms.

An interrupt may be generated to signal a change in the state of any status bits

(OOF, OOSMF, OOCMF, AIS, or RED), and to signal when any event (RRA,

RRMA, AISD, T16AISD, COFA, FER, SMFER, CMFER, CRCE, or FEBE) has

occurred.

Frame Find

The Frame Find Block searches for frame alignment using one of two user-

selectable algorithms, as defined in Recommendation G.706. Optionally, a two

frame check sequence can be added to either algorithm to provide protection

against false frame alignment in the presence of random mimic patterns.

The first algorithm finds frame alignment by using the following sequence:

1. Search for the presence of the correct 7-bit FAS;

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