XRT79L71_1 Datasheet, PDF (68/434 Pages) Exar Corporation – 1-CHANNEL DS3/E3 ATM UNI/PPP/CLEAR-CHANNEL FRAMER IC -

XRT79L71
1-CHANNEL DS3/E3 ATM UNI/PPP/CLEAR-CHANNEL FRAMER IC - REGISTER/MAP DESCRIPTION
REV. 1.0.0
BIT NUMBER
NAME
7
Unused
6-4
Chunk_Size[2:0]/
TxFIFOPacket Fill
Level[2:0]
TYPE
R/O
R/W
DESCRIPTION
Chunk_Size[2:0]/TxFIFO Packet Fill Level[2:0]:
The exact function of these three READ/WRITE bit-fields
depends upon whether the Transmit POS-PHY Interface block
has been configured to operate in the Packet or Chunk Mode, as
described below.
If the Transmit POS-PHY Interface block is operating in the
Chunk Mode
If the user has configured the Transmit POS-PHY Interface block
to operate in the Chunk Mode, then these three bit-fields permit
the user to define the size of the fixed-size Chunks that the
Transmit POS-PHY Interface block will handle as it accepts PPP
packet data from the Link Layer Processor. The following table
presents the relationship between the contents of these three bit-
fields and the corresponding size of the fixed-size chunks that
the Transmit POS-PHY Interface block will accept from the Link
Layer Processor.
Chunk_Size[2:0]
000
001
010
011
100
101
11X
Number of Bytes/Chunk
4 Bytes
8 Bytes
16 Bytes
32 Bytes
64 Bytes
128 Bytes
Not Valid
59