PM4388 datasheet(40/284 Pages) PMC

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PM4388 TOCTL

DATA SHEET

PMC-960840

ISSUE 5

OCTAL T1 FRAMER

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

When the elastic store is being used, if the average frequency of the incoming

data is greater than the average frequency of the backplane clock, the write

pointer will catch up to the read pointer and the buffer will be filled. Under this

condition a controlled slip will occur when the read pointer crosses the next

frame boundary. The subsequent ingress frame is deleted.

If the average frequency of the incoming data is less than the average frequency

of the backplane clock, the read pointer will catch up to the write pointer and the

buffer will be empty. Under this condition a controlled slip will occur when the

read pointer crosses the next frame boundary. The previous ingress frame is

repeated.

A slip operation is always performed on a frame boundary.

For payload conditioning, the ELST inserts a programmable idle code into all

channels when the FRMR is out of frame synchronization. If the data is required

to pass through the TOCTL unchanged during an out-of-frame condition, then

the elastic store may be bypassed.

9.9

Signaling Extractor (SIGX)

The Signaling Extraction (SIGX) block provides signaling bit extraction from the

ingress stream for ESF, and SF framing formats. When the external signaling

interface is enabled, the SIGX serializes the bits into a serial stream aligned to

the synchronized outgoing data stream. The signaling data stream contains the

A,B,C,D bits in the lower 4 channel bit locations (bits 5,6,7,8) in ESF framing

format. In SF format, the A and B bits are repeated in locations C and D (i.e. the

signaling stream contains the bits ABAB for each channel). The SIGX also

provides user control over signaling freezing and provides control over signaling

bit fixing and signaling debounce on a per-DS0 basis. The block contains three

superframes worth of signal buffering to ensure that there is a greater than 95%

probability that the signaling bits are frozen in the correct state for a 50% ones

density out-of-frame condition, as specified in TR-TSY-000170 and BELL PUB

43801. With signaling debounce enabled, the per-DS0 signaling state must be in

the same state for 2 superframes before appearing on the serial output stream.

The SIGX indicates the occurrence of a change of signaling state for each DS0

via an interrupt and by a change of signaling state bit for each DS0.

9.10

Receive Per-DS0 Serial Controller (RPSC)

The RPSC allows data and signaling trunk conditioning to be applied on the

receive DS-1 stream on a per-DS0 basis. It also allows per-DS0 control of data

inversion, the extraction of clock and data on ICLK[x] and ID[x] (when the Clock

PM4388 Datasheet(PDF) 40 Page - PMC-Sierra, Inc

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