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XRT79L71
PRELIMINARY
391
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
NOTE: For instructions on how to read out these "Performance Monitor" Registers, please see Section 2.5. 5.3.2.8
DETECTING FAS PATTERN ERRORS
PAGE 379., we mentioned that in order to verify that the Receive E3 Framer block is maintaining proper Frame
Synchronization with the incoming E3 data-stream, it will continuously check and verify that the FAS pattern (1)
can be found in its proper location, and (2) that the FAS pattern is of the correct value. This Section went on to
state that if the Receive E3 Framer block were to detect errors in the FAS pattern, within four (4) consecutive
E3 frames, then it (the Receive E3 Framer block) would transition over into the "OOF State" and would declare
the "OOF Defect" Condition.
In addition to checking and determining whether or not to declare the "OOF" or "LOF" defect condition, the
Receive DS3/E3 Framer block will also flag and tally the occurrences of any FAS Pattern errors (that are
detected within the incoming E3 data-stream), as described below.
While the Receive E3 Framer block is operating in the "Frame Maintenance" Mode, it will continue to check for
valid FAS patterns. If the Receive E3 Framer block detects any errors in the FAS pattern, then it will do the
following.
It will generate the "Detection of FAS Pattern Error" Interrupt request by asserting the Interrupt Output pin
(e.g., by pulling it "LOW") and setting Bit 1 (Detection of FAS Bit Error Interrupt Status), within the "Receive
E3 Interrupt Status Register # 2" as depicted below.
PMON FEBE Event Count Register - MSB (Address = 0x1156)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
PMON_FEBE_Event_Count_Upper_Byte[7:0]
RUR
0
PMON FEBE Event Count Register - LSB (Address = 0x1157)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
PMON_FEBE_Event_Count_Lower_Byte[7:0]
RUR
0
Receive E3 Interrupt Status Register # 2 - G.751 (Address = 0x1115)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Unused
Change of
FERF/RDI
Defect
Condition
Interrupt
Status
Detection of
BIP-4
Error
Interrupt
Status
Detection of
FAS Bit
Error
Interrupt
Status
Reserved
R/O
RUR
R/O
0
1
0