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XRT79L71
PRELIMINARY
525
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
Configuration Options for the LOS Declaration/Clearance Criteria
The Receive DS3/E3 Framer block within the XRT79L71 permits the user to change the LOS Declaration
criteria such that the LOS defect condition is declared only if the Receive DS3/E3 LIU Block Interface declares
the LOS defect condition. If this configuration selection is implemented, then the internally-generated LOS
criteria of 32 consecutive 0s will be disabled. This configuration selection can be accomplished by writing a "0"
to bit 3 (Internal LOS Enable) within the Operating Mode Register as depicted below.
6.3.2.3.3
The Relationship between the LOS Defect Condition being declared or cleared in the Receive
DS3/E3 LIU Block and in the Receive DS3/E3 Framer Block
6.3.2.4
DECLARING AND CLEARING THE AIS DEFECT CONDITION
The Receive DS3/E3 Framer block has the responsibility for declaring and clearing the AIS (Alarm Indication
Signal) defect, as described below.
If the XRT79L71 has been configured to operate in the E3, ITU-T G.832 Framing format, then the Receive E3
Framer block will declare the AIS defect condition anytime it receives an E3 data-stream that contains 7 of less
"0s" within two consecutive E3 frame periods.
If the Receive E3 Framer block declares the AIS defect condition, then it will do all of the following.
It will set Bit 3 (AIS Defect Declared) within the Receive E3 Configuration and Status Register # 2 to "1", as
depicted below.
Receive E3 Interrupt Status Register # 1 - G.832 (Direct Address = 0x1114)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Unused
Change in
SSM MSG
Interrupt
Status
Change in
SSM OOS
Interrupt
Status
COFA
Interrupt
Status
Change in
OOF Defect
Condition
Interrupt
Status
Change in
LOF Defect
Condition
Interrupt
Status
Change in
LOS Defect
Condition
Interrupt
Status
Change in
AIS Defect
Condition
Interrupt
Status
R/O
RUR
0
1
0
Framer Operating Mode Register (Address = 0x1100)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Local Loop
Back
IsDS3
Internal LOS
Enable
RESET
Direct
Mapped
ATM
Frame For-
mat
TimRefSel[1:0]
R/W
0
1
0
1