XRT74L73 Datasheet, PDF (293/488 Pages) Exar Corporation – 3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER

PRELIMINARY
XRT74L73
3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER
REV. P1.0.1
TXE3 CONFIGURATION REGISTER (ADDRESS = 0X30)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
Tx
BIP-4
Enable
TxASourceSel[1:0]
TxNSourceSel[1:0]
R/W
R/W
R/W
R/W
R/W
0
X
X
X
X
BIT 2
Tx AIS
Enable
R/W
0
BIT 1
Tx LOS
Enable
R/W
0
BIT 0
Tx FAS
Source
Select
R/W
0
Configuring the Transmit Payload Data Input In-
terface block to accept the “A Bits” from the Ter-
minal Equipment
If the user wishes to configure the Transmit Payload
Data Input Interface block to accept the “A” bits from
the Terminal Equipment, then the user must write the
value “10” into the TxASourceSel[1:0] bit-fields.
Once the user does this, then any value, which re-
sides on the TxSer input pin, when the “A” bit is being
processed by the Transmit Section will be inserted in-
to the “A” bit-field within the very next outbound E3
frame.
For completeness, the relationship between the con-
tents of the TxASourceSel[1:0] bits and the resulting
source of the “A” bit is listed below.
Bit 6, 5, TxASourceSel[1:0]
These two Read/Write bit-fields combine to specify
the source of the A-bit, within each outbound E3
frame. The relationship between these two bit-fields
and the resulting source of the A Bit is tabulated be-
low.
TXASOURCESEL[1:0]
SOURCE OF A BIT
00
TxE3 Service Bits Register (Address = 0x35)
01
Transmit Overhead Data Input Interface
10
Transmit Payload Data Input Interface
11
Functions as a FEBE (Far-End-Block Error) bit-field.
This bit-field is set to "0", if the Near-End Receive Section (within this chip) detects no BIP-4
Errors within the incoming E3 frames.
This bit-field is set to "1", if the Near-End Receive Section (within this chip) detects a BIP-4
Error within the incoming E3 frame.
Configuring the Transmit Payload Data Input Inter-
face block to accept the “N” Bits from the Terminal
Equipment, then the user must write the value “11” in-
to the TxNSourceSel[1:0] bit-fields. Once the user
does this, then any value, which resides on the TxSer
input pin, when the “N” bit is being processed by the
Transmit Section will be inserted into the “N” bit-field
within the very next outbound E3 frame.
For completeness, the relationship between the con-
tents of the TxNSourceSel[1:0] bits and the resulting
source of the “N” bit is listed below.
Bits 4, 3, TxNSourceSel[1:0]
These two Read/Write bit-fields combine to specify
the source of the N-bit, within each outbound E3
frame. The relationship between these two bit-fields
and the resulting source of the N Bit is tabulated be-
low.
TXNSOURCESEL[1:0]
00
01
10
11
SOURCE OF N BIT
TxE3 Service Bits Register (Address = 0x35)
Transmit Overhead Data Input Interface
Transmit LAPD Controller
Transmit Payload Data Input Interface.
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