XRT79L71_1 Datasheet, PDF (322/434 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
Receive PPP Packet Processor Block - Receive PPP Control Register (Address = 0x1703)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Unused
Receive
CRC-32/
CRC-16*
ABORT
Packet upon
RxFIFO
Overflow
Enable
Unused
De-Scram-
ble Enable
Delete FCS
from Incom-
ing Packet
Receive PPP
Packet
Processor
Block Enable
R/O
R/O
R/W
R/W
R/O
R/W
R/W
R/W
0
0
0
0
0
0
0
0
BIT NUMBER
NAME
7-6
Unused
5
Receive CRC-32/CRC-
16*
4
ABORT Packet upon
RxFIFO Overflow Enable
3
Unused
TYPE
R/O
R/W
R/W
R/O
DESCRIPTION
Receive CRC-32/CRC-16* Select:
This READ/WRITE bit-field permits the user to configure the
Receive PPP Packet Processor block to either compute and ver-
ify a CRC-32 or CRC-16 within the incoming PPP packet-
stream.
0 - Configures the Receive PPP Packet Processor block to com-
pute and verify a CRC-16 value within each incoming PPP
packet.
1 - Configures the Receive PPP Packet Processor block to com-
pute and verify a CRC-32 value within each incoming PPP
packet.
NOTE: This bit-field is only active if the XRT79L71 has been
configured to operate in the PPP Mode.
ABORT Packet upon RxFIFO Overflow Enable:
This READ/WRITE bit-field permits the user to configure the
Receive PPP Packet Processor block to automatically abort an
incoming PPP packet, anytime an RxFIFO Overflow event
occurs.
0 - Disables this Auto-Abort upon RxFIFO Overflow feature.
1 - Enables this Auto-Abort upon RxFIFO Overflow feature.
NOTE:
If the user invokes this feature, then the Receive PPP
Packet Processor and Receive POS-PHY Interface
blocks will automatically designate each incoming PPP
Packet as an erred packet (by pulsing the RxPERR
output pin "High" coincident to whenever the very last
byte or word of this packet is being placed on the
Receive POS-PHY Data Bus) for the duration that this
RxFIFO Overflow condition exists.
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