PM5342 Datasheet, PDF (420/558 Pages) PMC-Sierra, Inc – SONET/SDH Payload Extractor/Aligner

DATA SHEET
PMC-970133
ISSUE 4
PM5342 SPECTRA-155
SONET/SDH PAYLOAD EXTRACTOR/ALIGNER
DOPJ0- DOPJ1:
The diagnose pointer justification bits (DOPJ[1:0]) allow downstream pointer
processing elements to be diagnosed for correct reaction to pointer
justification events. Setting DOPJ[1] high and DOPJ[0] low, forces the TTAL
to generate positive stuff justification events in the transmit stream at the rate
of one every four frames regardless of the current depth of the internal FIFO.
Prolonged application may cause the FIFO to overflow. Setting DOPJ[1] low
and DOPJ[0] high, forces the TTAL to generate negative stuff justification
events at the rate of one every four frames, regardless of the current depth of
the internal FIFO. Prolonged application may cause the FIFO to underflow.
Setting both DOPJ[1] and DOPJ[0] high disables the TTAL from generating
pointer justification events. If the incoming and outgoing clocks have a
frequency offset, the internal FIFO may under/overflow depending on the
relative frequencies of the clocks. Pointer justification events are generated
based on the current depth of the internal FIFO when DOPJ[1] and DOPJ[0]
are both set low. When DOPJ[1:0] is set to values other than 'b00, the
detection of elastic store over/underflow is disabled.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE 398