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XRT79L71
PRELIMINARY
521
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
Transitioning into the LOF State
However, if the Receive E3 Framer block resides in the OOF State for more than the User-Selectable number
of E3 frame periods without being able to locate the FA1 and FA2 bytes, then the Receive E3 Framer block will
automatically transition into the LOF State.
Selecting the number E3 Frame Periods, before transitioning into the LOF State
The user can configure the Receive E3 Framer block to reside in the OOF State and search the incoming E3
data-stream for either 1 or 3ms, prior to transitioning into the LOF State.
The user can accomplish this
configuration setting by writing the appropriate value into Bit 7 (Receive LOF Algo), within the Receive E3
Configuration and Status Register # 2 as depicted below.
Setting this bit-field to "0" configures the Receive E3 Framer block to reside within the OOF State for up to 3ms
(24 E3 frame periods) before transitioning into the LOF State. Conversely, setting this bit-field to "1" configures
the Receive E3 Framer block to reside within the OOF State for up to 1ms (8 E3 frame periods) before
transitioning into the LOF State.
The LOF (Loss of Frame) State
If the Receive E3 Framer block enters the LOF Condition state, then the following things will happen.
The Receive E3 Framer block will discard the most recent frame synchronization that it had, and
The Receive E3 Framer block will make an unconditional transition to the FA1, FA2 Octet Search State,
within the Receive E3 Framer Block's - Frame Acquisition/Maintenance Algorithm.
Additionally, the Receive E3 Framer block will notify the Microprocessor/Microcontroller of this transition into
the LOF State, by doing the following.
Declaring the LOF Defect Condition
The Receive E3 Framer block will indicate that it is declaring the LOF Defect Condition by setting bit 6 (LOF
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
Receive E3 Configuration and Status Register # 2 - G.832 (Direct Address = 0x1111)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Receive LOF
Algo
LOF Defect
Declared
OOF Defect
Declared
LOS Defect
Declared
AIS Defect
Declared
RxPLD
Unstab
RxTMark
FERF Defect
Declared
R/W
R/O
X
0