XRT72L50 Datasheet, PDF (258/471 Pages) Exar Corporation – SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER WITH HDLC CONTROLLER
REV. 1.2.1
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TxE3 Configuration Register (Address = 0x30)
BIT 7
Tx
BIP-4
Enable
R/W
0
BIT 6
BIT 5
TxASourceSel[1:0]
R/W
R/W
X
X
BIT 4
BIT 3
TxNSourceSel[1:0]
R/W
R/W
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 Interface block to accept the A Bits from the Terminal
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 resides on the TxSer input pin, when the A bit is being processed by the
Transmit Section will be inserted into the A bit-field within the very next outbound E3 frame.
For completeness, the relationship between the contents 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 below.
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 Interface block to accept the N Bits from the Terminal Equipment,
then the user must write the value “11” into 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 contents 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 below.
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