PM7385 FREEDM-84A672
DATA SHEET
PMC-1990114
ISSUE 6
84 LINK, 672 CHANNEL FRAME ENGINE AND DATA LINK MANAGER
WITH ANY-PHY PACKET INTERFACE
The maximum amount of data transferred during one request is limited by a
software programmable limit (XFER[3:0]).
The roamer round-robins between all channel FIFOs and pushes the status to
the TAPI672 block. The status consists of two pieces of information: (1) is there
space in the channel FIFO for at least one XFER[3:0] of data, and (2) is this
channel FIFO at risk of underflowing. Where a channel FIFO is at risk of
underflowing, the THDL672 pushes a starving status for that channel FIFO to the
TAPI672 at the earliest possible opportunity.
The configuration of the HDLC processor is accessed using indirect channel read
and write operations as well as indirect block read and write operations. When
an indirect operation is performed, the information is accessed from RAM during
a null clock cycle identified by the TCAS672 block. Writing new provisioning data
to a channel resets the entire state vector.
8.9 Transmit Channel Assigner
The Transmit Channel Assigner block (TCAS672) processes up to 672 channels.
Data for all channels is sourced from a single byte-serial stream from the
Transmit HDLC Controller / Partial Packet Buffer block (THDL672). The
TCAS672 demultiplexes the data and assigns each byte to any one of 84 links.
When sending data to the SBI SIPO blocks, each link may be configured to
support channelised T1/J1/E1 traffic, unchannelised DS-3 traffic or unframed
traffic at T1/J1, E1 or DS-3 rates. When sending data to the TD outputs, links 0,
1 and 2 support unchannelised data at arbitary rates up to 51.84 Mbps. Each link
is independent and has its own associated clock.
The 84 TCAS links have a fixed relationship to the SPE and tributary numbers on
the SBI ADD BUS as shown in the following table.
Table 10 – SBI SPE/Tributary to TCAS Link Mapping
SBI
SBI
TCAS
Link
No.
SBI
SBI
TCAS
Link
No.
SBI
SBI
TCAS
Link
No.
SPE Trib.
SPE Trib.
SPE Trib.
No.
No.
No.
No.
No.
No.
1
1
0
2
1
1
3
1
2
1
1
1
1
2
3
4
5
3
6
9
12
2
2
2
2
2
3
4
5
4
7
10
13
3
3
3
3
2
3
4
5
5
8
11
14
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
55
PMC [ PMC-SIERRA, INC ]
