XRT79L71_1 Datasheet, PDF (71/434 Pages) Exar Corporation – 1-CHANNEL DS3/E3 ATM UNI/PPP/CLEAR-CHANNEL FRAMER IC -

REV. 1.0.0
XRT79L71
1-CHANNEL DS3/E3 ATM UNI/PPP/CLEAR-CHANNEL FRAMER IC - REGISTER/MAP DESCRIPTION
Transmit POS-PHY Interface - Transmit Control Register Byte - 0 (Address = 0x0582)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
Runt Packet Parity Check
ABORT
Enable
ODD Parity Transmit_PO
S_PHY_Add
r[4:0]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
X
X
X
X
X
X
X
BIT 0
R/W
X
BIT NUMBER
NAME
7
Runt Packet ABORT
6
Parity Check Enable
TYPE
R/W
R/W
DESCRIPTION
Runt Packet ABORT:
This READ/WRITE bit-field permits the user to either enable or
disable the RUNT Packet Abort feature.
If the user enables this feature, then anytime the Transmit POS-
PHY Interface block receives a RUNT packet from the Link
Layer Processor, this packet will be transmitted to the remote
terminal as an Aborted Packet.
NOTE:
An example of a RUNT packet being accepted by the
Transmit POS-PHY Interface block is whenever the Link
Layer Processor asserts the TxPSoP [Start of Packet)
indicator multiple times without asserting the TxPEOP
(End of Packet) indicator.
0 - Disables the RUNT Packet Abort feature.
1 - Enables the RUNT Packet Abort feature.
Parity Check Enable
This READ/WRITE bit-field permits the user to either enable or
disable parity checking of all data that is accepted by the Trans-
mit POS-PHY Interface.
If the user enables this feature, then the XRT79L71 will compute
either the EVEN or ODD parity value (depending upon the set-
ting of Bit 5, within this register) of each byte or word that is
accepted by the Transmit POS-PHY Interface - Data Bus. The
Transmit POS-PHY Interface block will then compare this locally
calculated parity value with the state of the TxPPrty input pin.
If these two values match, then the Transmit POS-PHY Interface
block will presume that it has accepted PPP data from the Link
Layer Processor in an un-erred manner. Conversely, if these
two values do not match, then the Transmit POS-PHY Interface
block will presume that it has accepted PPP data from the Link
Layer Processor in an erred manner and it will transmit this PPP
Packet as an Aborted Packet.
0 - Disables Parity Checking via the Transmit POS-PHY Inter-
face.
1 - Enables Parity Checking via the Transmit POS-PHY Inter-
face.
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