![](http://datasheet.mmic.net.cn/Exar-Corporation/XRT79L71IB-F_datasheet_100145/XRT79L71IB-F_129.png)
PRELIMINARY
XRT79L71
114
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
NOTE: The six-bit code word must be written in Bits 1 through 6 within this register. Bits 0 and 7 are in-active bits and are
each forced to "0".
STEP 2- Enable the Transmit FEAC Controller Block
In order to enable the Transmit FEAC Controller Block the user must write a "1" into bit 2 (TxFEAC Enable)
within the Transmit DS3 FEAC Configuration and Status Register, as depicted below.
At this point, the Transmit FEAC Controller Block will be turned on and will begin to repeatedly transmit the Idle
FEAC pattern of [1, 1, 1, 1, 1, 1].
STEP 3 - Enable the Transmit FEAC Message Interrupt (Optional)
This step is optional. However, if this step is executed, then the XRT79L71 will generate an interrupt to the
Microprocessor, as soon as the Transmit FEAC Controller block has completed its 10th transmission of the
FEAC Message. The purpose of this interrupt is to alert the system Microprocessor that the Transmit FEAC
Controller block has completed its 10th transmission of the most recent outbound FEAC Message, and that it
is now available to transmit a different FEAC Message.
The procedure for enabling the Transmit FEAC Interrupt is actually a three-step process.
STEP 3a - Enable the DS3/E3 Framer block interrupt as the Operational Block Level
This step is accomplished by setting Bit 2 (DS3/E3 Framer Block Interrupt Enable) to "1" as illustrated below.
STEP 3b - Enable the Transmit DS3/E3 Framer Block Interrupts - at the Block Level
This step is accomplished by setting Bit 1 (Transmit DS3/E3 Framer Block Interrupt Enable), within the Block
Interrupt Enable Register to "1" as depicted below.
Transmit DS3 FEAC Register (Address = 0x1132)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Not Used
TxFEAC_Code_Word[5:0]
Not Used
R/O
R/W
R/O
0
d5
d4
d3
d2
d1
d0
0
Transmit DS3 FEAC Configuration and Status Register (Address = 0x1131)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Not Used
Tx FEAC
Interrupt
Enable
Tx FEAC
Interrupt
Status
Tx FEAC
Enable
Tx FEAC Go
Tx FEAC
Busy
R/O
R/W
R/O
R/W
R/O
0
X
1
0
Operation Block Interrupt Enable Register - Byte 1 (Address = 0x0116)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Unused
DS3/E3 LIU/JA
Block Interrupt
Enable
DS3/E3 Framer
Block Interrupt
Enable
Unused
R/W
R/O
R/W
R/O
0
1
0