PM7311 pmc-sierra, PM7311 Datasheet - Page 149

• 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
FLAG[2:0]
LEVEL[3:0]
The flag insertion control (FLAG[2:0]) configures the minimum number of flags or bytes of
idle bits the HDLC processor inserts between HDLC packets. The value of FLAG[2:0] to be
written to the channel provision RAM, in an indirect channel write operation, must be set up
in this register before triggering the write. The minimum number of flags or bytes of idle (8
bits of 1’s) inserted between HDLC packets is shown in the table below. FLAG[2:0] reflects
the value written until the completion of a subsequent indirect channel read operation.
Table 20 FLAG[2:0] Settings
The indirect channel FIFO trigger level (LEVEL[3:0]), in concert with the TRANS bit,
configure the various channel FIFO free space levels which trigger the HDLC processor to
start transmission of a HDLC packet as well as trigger the partial packet buffer to request data
from the upstream device as shown in the following table. The channel FIFO trigger level to
be written to the channel provision RAM, in an indirect write operation, must be set up in this
register before triggering the write. LEVEL[3:0] reflects the value written until the
completion of a subsequent indirect channel read operation.
The HDLC processor starts transmitting a packet when the channel FIFO free space is less
than or equal to the level specified in the appropriate Start Transmission Level column of the
following table or when an end of a packet is stored in the channel FIFO. When the channel
FIFO free space is greater than or equal to the level specified in the Starving Trigger Level
column of the 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 upstream device to retrieve XFER[3:0] + 1 blocks of data.
FLAG[2:0]
000
001
010
011
100
101
110
111
Minimum Number of Flag/Idle Bytes
1 flag / 0 Idle byte
2 flags / 0 idle byte
4 flags / 2 idle bytes
8 flags / 6 idle bytes
16 flags / 14 idle bytes
32 flags / 30 idle bytes
64 flags / 62 idle bytes
128 flags / 126 idle bytes
FREEDM 84A1024L ASSP Telecom Standard Product Data Sheet
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