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XRT79L71
PRELIMINARY
533
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
6.3.2.8
DETECTING FRAMING BYTE ERRORS
proper Frame Synchronization with the incoming E3 data-stream, it will continuously check and verify that the
FA1 and FA2 bytes (1) can be found in their proper locations, and (2) that they are of the correct value. This
Section went on to state that if the Receive E3 Framer block were to detect errors in the FA1 or FA2 bytes,
within four (4) consecutive E3 frames, then it (the Receive E3 Framer block) would transition over to 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 Framing (FA1 or FA2) Byte 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 FA1 and FA2 bytes. If the Receive E3 Framer block detects any errors in the FA1 or FA2 bytes, then it will
do the following.
It will generate the Detection of Framing Byte Error Interrupt request by asserting the Interrupt Output pin
(e.g., by pulling it "Low") and setting Bit 1 (Detection of Framing Byte Error Interrupt Status), within the
Receive E3 Interrupt Status Register # 2 as depicted below.
It will increment the PMON Framing Bit/Byte Error Count Registers, once for each E3 frame that is
determined to contain an erred FA1 or FA2 byte. The PMON Framing Bit/Byte Error Count Register is
located at Address = 0x1152/1153. The bit-format of these registers is presented below.
NOTES:
Receive E3 Interrupt Status Register # 2 - G.832 (Address = 0x1115)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Unused
Change in
RxTTB
Message
Interrupt
Status
Reserved
Detection of
FEBE Event
Interrupt
Status
Change in
FERF/RDI
Defect
Condition
Interrupt
Status
Detection of
BIP-8 Error
Interrupt
Status
Detection of
Framing
Byte Error
Interrupt
Status
RxPLD
Mismatch
Interrupt
Status
R/O
RUR
R/O
RUR
0
1
0
PMON Framing Bit/Byte Error Count Register - MSB (Address = 0x1152)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
PMON_Framing_Bit/Byte_Error_Count_Upper_Byte[7:0]
RUR
0
PMON Framing Bit/Byte Error Count Register - LSB (Address = 0x1153)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
PMON_Framing_Bit/Byte_Error_Count_Lower_Byte[7:0]
RUR
0