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STANDARD PRODUCT
PM8315 TEMUX
DATASHEET
PMC-1981125
ISSUE 7
HIGH DENSITY T1/E1 FRAMER WITH
INTEGRATED VT/TU MAPPER AND M13 MUX
PROPRIETARY AND CONFIDENTIAL
129
MVIP CAS signals CASID[1:7]. Note also that in this mode, a receive signaling
elastic store is used to adapt any timing differences between the data interface
and the CCS H-MVIP interface.
9.40 Extract Scaleable Bandwidth Interconnect (EXSBI)
The Extract Scaleable Bandwidth Interconnect block demaps up to 28 1.544Mb/s
links, 21 2.048Mb/s links or a single 44.736Mb/s link from the SBI shared bus.
The 1.544Mb/s links can be unframed when used in a straight multiplexer or
mapper application, or they can be T1 framed and channelized for insertion into
the DS3 multiplex or SONET/SDH mapping. The 2.048Mb/s links can be
unframed when used in a straight mapper application, or they can be E1 framed
and channelized for insertion into the SONET/SDH mapping. The 44.736Mb/s
link can also be unframed for mapping into SONET/SDH or it can be DS3
unchannelized when the TEMUX is used as a DS3 framer.
All egress links extracted from the SBI bus can be timed from the source or from
the TEMUX. When Timing is from the source the EXSBI commands the PISO to
generate 1.544Mb/s, 2.048Mb/s or 44.736Mb/s clocks slaved to the arrival rate
of the data or from timing link rate adjustments provided from the source and
carried with the links over the SBI bus. The 1.544Mb/s clock is synthesized from
the 19.44MHz reference clock, SREFCLK, by dividing the clock by either 12 or
13 in a fixed sequence that produces the nominal 1.544Mb/s rate. The
2.048Mb/s clock is synthesized from the 19.44MHz reference clock by dividing
the clock by either 9 or 10 in a fixed sequence that produces the nominal
2.048Mb/s rate. Timing adjustments are made over 500uS intervals and are
done by either advancing or retarding the phase or by adding or deleting a whole
1.544Mb/s or 2.048Mb/s clock cycle over the 500uS period.
The 44.736Mb/s clock is synthesized from the 51.84MHz or 44.928MHz
reference clock, CLK52M. Using either reference clock frequency, the
44.736Mb/s rate is generated by gapping the reference clock in a fixed way.
Timing adjustments are performed by adding or deleting four clocks over the
500uS period.
When the TEMUX is the SBI egress clock master for a link, clocks are sourced
within the TEMUX. Based on buffer fill levels, the EXSBI sends link rate
adjustment commands to the link source indicating that it should send one
additional or one fewer bytes of data during the next 500uS interval. Failure of
the source to respond to these commands will ultimately result in overflows or
underflows which can be configured to generate per link interrupts.
Channelized T1s extracted from the SBI bus optionally have the channel
associated signaling (CAS) bits explicitly defined and carried in parallel with the