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PRELIMINARY
XRT79L71
208
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
a. Toggling the INT* output pin of the XRT79L71 "Low".
b. By asserting Bit 1 (Change of OOF Defect Condition Interrupt Status) within the Receive DS3 Interrupt
Status Register, as depicted below.
Forcing a Reframe via Software Command
The Receive DS3/E3 Framer block permits the user to command a reframe procedure with the Receive DS3
Framer block via software command. The user can accomplish this by inducing a "0" to "1" transition in Bit 0
(Reframe), within the I/O Control Register, as depicted below. Once the user executes this step then the
Receive DS3 Framer block will be forced into the Frame Acquisition Mode, or more specifically, in the F-Bit
Search State per Figure 93, and will begin its search for valid F-Bits. The XRT79L71 will also respond to this
command by setting the OOF Defect Declared bit-field to "1" and generating the Change in the OOF Defect
Condition interrupt.
NOTE: After the user has implemented the "0" to "1" transition within Bit 0 (Reframe), they should also go back and induce
a "1" to "0" transition within this bit-field.
4.3.2.3
DECLARING AND CLEARING THE LOS DEFECT CONDITION
The Receive DS3 Framer block has the responsibility for declaring and clearing the LOS (Loss of Signal)
defect condition within the incoming DS3 data-stream, as described below.
4.3.2.3.1
Declaring the LOS Defect Condition
The Receive DS3 Framer block will declare the Loss of Signal (LOS) defect condition when it detects at least
180 consecutive "0s" within the incoming DS3 data-stream or if the Receive DS3/E3 LIU Block declares the
LOS defect condition. The Receive DS3 Framer block will indicate that it is declaring the LOS defect condition
by:
Setting Bit 6 (LOS Defect Declared) within the Receive DS3 Configuration and Status Register to "1", as
depicted below.
Receive DS3 Interrupt Status Register (Address = 0x1113)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Detection of
CP Bit Error
Interrupt
Status
Change of
LOS Defect
Condition
Interrupt
Status
Change of
AIS Defect
Condition
Interrupt
Status
Change of
Idle
Condition
Interrupt
Status
Change of
FERF Defect
Condition
Interrupt
Status
Change of
AIC State
Interrupt
Status
Change of
OOF Defect
Condition
Interrupt
Status
Detection of
P-Bit Error
Interrupt
Status
RUR
0
1
0
I/O Control Register (Address = 0x1F01)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Disable
TxLOC
LOC
Disable
RxLOC
Unused
Reframe
R/W
R/O
R/W
R/O
R/W
1
0
1
0
1
0
0 -> 1