![](http://datasheet.mmic.net.cn/Exar-Corporation/XRT79L71IB-F_datasheet_100145/XRT79L71IB-F_155.png)
PRELIMINARY
XRT79L71
140
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
NOTE: This step configures the Transmit DS3/E3 Framer block to transmit a Framed, Repeating X, Y, Z, A, .. pattern,
whenever the user commands it to transmit the Idle Pattern.
STEP 2 - Command the Transmit DS3/E3 Framer block to generate and transmit the DS3 Idle Pattern
This is accomplished by setting Bit 5 (TxIdle) within the Transmit DS3 Configuration Register to "1" as depicted
below.
Once the user executes this step, then the Transmit DS3/E3 Framer block will begin to generate and transmit a
Framed, Repeating X, Y, Z, A…. pattern.
NOTE: This bit-field is ignored whenever either Bits 3 (TxLOS) or 4 (TxAIS) are set to "1".
4.2.5.4
TRANSMITTING THE FERF/RDI INDICATOR
The Transmit DS3 Framer block provides the user with two options associated with transmitting the FERF
(Far-End-Receive Failure) condition within the outbound DS3 data-stream.
Forced transmission of the FERF indicator (e.g., under Software control)
Automatic transmission of the FERF indicator.
Forced Transmission of the FERF/RDI Indicator
The XRT79L71 permits the user to force the Transmit DS3 Framer block to transmit the FERF indicator to the
remote terminal equipment. The user can accomplish this by setting Bit 7 (Tx FERF Indicator) within the
Transmit DS3 Configuration Register, to "1" as illustrated below.
To transmit the FERF Indicator then each of the X-bits, in the outbound DS3 frames will be set to '0'
NOTE: This bit-field is ignored when either the TxIDLE, TxAIS, or the TxLOS bit-fields are set to "1".
Transmit DS3 Pattern Register (Address = 0x114C)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
TxAIS -
Unframed All
Ones
DS3 AIS
Non-Stuck
Stuff
Unused
TxLOS
Pattern
Transmit_Idle_Pattern[3:0]
R/W
R/O
R/W
0
X
Y
Z
A
Transmit DS3 Configuration Register (Address = 0x1130)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Tx Yellow
Alarm
Tx X-Bits
TxIdle
TxAIS
TxLOS
TxFERF
upon LOS
TxFERF
upon OOF
TxFERF
upon AIS
R/W
0
1
0
1
Transmit DS3 Configuration Register (Address = 0x1130)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Tx FERF
Indicator
Tx X-Bits
TxIdle
TxAIS
TxLOS
TxFERF
upon LOS
TxFERF
upon OOF
TxFERF
upon AIS
R/W
1
0
1