PM7311 pmc-sierra, PM7311 Datasheet - Page 93

• Manufacturer Part Number: PM7311
• Description: Freedm 84a1024l Assp Telecom Standard Datasheet
• Manufacturer: pmc-sierra

Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC-2021832, Issue 2
10.9.15
Table 12 SBI-SPE Tributary to TCAS Link Mapping
As shown in the table above, TCAS links 0, 4 and 8 are mapped to tributary 1 of SPE 1, 2 and 3
respectively. These links may be configured to operate at DS3 rate. (They may also be
configured to output data to the TD[0,4,8] outputs at rates up to 52 Mbps.) For each of these
high-speed links, the TCAS-12 provides a 4 byte FIFO. For the remaining links (TCAS links 12
to 332 mapped to tributaries 2 to 28 of each SPE), the TCAS-12 provides a single byte holding
register. In the event where multiple links are in need of data, TCAS-12 requests data from
upstream blocks on a fixed priority basis with link 0 having the highest priority and link 332 the
lowest.
It should be noted that for every SBI/SPE used as a serial link, the SBI/SPE must be disabled on
the SBI Bus interface and visa versa.
Links containing a T1/J1 or an E1 stream may be channelized. Data at each time-slot can be
independently assigned to be sourced from a different HDLC channel. The position of T1/J1 and
E1 framing bits/bytes is identified by frame pulse. With knowledge of the transmit link and time-
slot identity, the TCAS-12 performs a table look-up to identify the HDLC channel from which a
data byte is to be sourced.
Links containing a DS3 stream are unchannelized; in which case, all data bytes on the link belong
to one HDLC channel. The TCAS-12 performs a table look-up to identify the HDLC channel to
which a data byte belongs using only the outgoing link identity, as no time-slots are associated
with unchannelized links. Links may additionally be configured to operate in an unframed “clear
channel” mode, in which case the FREEDM 84A1024L will output HDLC data in all bit
positions, including those normally reserved for framing information. Links so configured
operate as unchannelized regardless of link rate and the TCAS-12 performs a table lookup using
only the link number to determine the associated HDLC channel.
SBI Inserter
The SBI transmit circuitry processes data for the three Synchronous Payload Envelopes (SPEs)
conveyed on the SBI ADD BUS. It receives data bytes from the transmit channel assignor and
inserts it into the SBI ADD BUS. The SBI Insert block may be configured to enable or disable
transmission of individual tributaries on to the SBI ADD bus. Individual tributaries may also be
configured to operate in framed or unframed mode.
SPE
No.
l
l
l
1
1
1
1
Trib.
SBI
No.
28
1
2
3
TCAS
Link
No.
324
12
24
0
FREEDM 84A1024L ASSP Telecom Standard Product Data Sheet
SPE
No.
2
2
2
2
Trib.
SBI
No.
28
1
2
3
TCAS
Link
No.
328
16
28
4
SPE
No.
3
3
3
3
Trib.
SBI
No.
28
1
2
3
Released
TCAS
Link
No.
332
20
32
l
l
l
8
93