PM7385 FREEDM-84A672
DATA SHEET
PMC-1990114
ISSUE 6
84 LINK, 672 CHANNEL FRAME ENGINE AND DATA LINK MANAGER
WITH ANY-PHY PACKET INTERFACE
following table and the HDLC processor is transmitting a packet and an end of
a packet is not stored in the channel FIFO, the partial packet buffer makes
expedited requests to the TAPI672 to retrieve XFER[3:0] + 1 blocks of data.
To prevent lockup, the channel transfer size (XFER[3:0]) can be configured to
be less than or equal to the start transmission level set by LEVEL[3:0] and
TRANS. Alternatively, the channel transfer size can be set, such that, the
total number of blocks in the logical channel FIFO minus the start
transmission level is an integer multiple of the channel transfer size. The
starving trigger level must always be set to a number of blocks greater than or
equal to the channel transfer size.
Table 22 – Level[3:0]/TRANS Settings
LEVEL[3:0]
Starving
Start
Start Transmission
Level (TRANS=1)
Trigger Level
Transmission
Level (TRANS=0)
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
2 Blocks
1 Block
1 Block
(32 bytes free)
(16 bytes free)
(16 bytes free)
3 Blocks
2 Blocks
1 Block
(48 bytes free)
(32 bytes free)
(16 bytes free)
4 Blocks
3 Blocks
2 Blocks
(64 bytes free)
(48 bytes free)
(32 bytes free)
6 Blocks
4 Blocks
3 Blocks
(96 bytes free)
(64 bytes free)
(48 bytes free)
8 Blocks
6 Blocks
4 Blocks
(128 bytes free)
(96 bytes free)
(64 bytes free)
12 Blocks
8 Blocks
6 Blocks
(192 bytes free)
(128 bytes free)
(96 bytes free)
16 Blocks
12 Blocks
8 Blocks
(256 bytes free)
(192 bytes free)
(128 bytes free)
24 Blocks
16 Blocks
12 Blocks
(384 bytes free)
(256 bytes free)
(192 bytes free)
32 Blocks
24 Blocks
16 Blocks
(512 bytes free)
(384 bytes free)
(256 bytes free)
48 Blocks
32 Blocks
24 Blocks
(768 bytes free)
(512 bytes free)
(384 bytes free)
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
133
PMC [ PMC-SIERRA, INC ]
