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CHAPTER 6 PHY FUNCTION
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(2) Reporting circuit quality deterioration (performance monitor)
When the
μ
PD98405 detects a cause of circuit quality deterioration while monitoring the circuit quality, it
sets a bit of an internal interrupt source register to issue a report to the host by means of an interrupt signal.
The host can identify the type of the cause of circuit quality deterioration by reading the interrupt source
register. Each source of the interrupt can either be masked or unmasked.
Table 6-8. Performance Cause Register (PCR Register)
B1 error detection
Detects a section layer BIP-8 error in the receive data. BIP-8 calculation is performed for all frame data (scrambled
data) except the first line of the previous frame’s SOH, and the result of this calculation is verified against the result
of the Section BIP-8 calculation executed at the transmission source (upstream) and stored into the B1 byte of the
current frame, to detect a B1 error.
B2 error detection
Detects a line layer BIP-24 error in the receive data. BIP-24 calculation is performed on all the frame data (data after
descrambling), except the first, second, and third lines of the previous frame’s SOH, and the result of this calculation
is verified against the result of the Line BIP-24 calculation executed at the transmission source (upstream) and
stored into the B2 byte of the current frame, to detect a B2 error.
B3 error detection
Detects a bus layer BIP-8 error in the receive data. BIP-8 calculation is performed for all the payload data (data after
descrambling) in the previous frame, and the result of this calculation is verified against the result of the Path BIP-8
calculation executed at the transmission source (upstream) and stored into the B3 byte of the current frame, to
detect a B3 error.
Line FEBE detection (Line Far End Block Error)
Line far end block error information. Detects whether a Line BIP-24 error has occurred in the unit at the transmission
destination (downstream).
Detection: Detects Line FEBE if the 4th through 8th bits of the receive Z2 (M1) byte are 01 to 18(H).
Clear:
Clears Line FEBE if the 4th through 8th bits of the receive Z2 (M1) byte are 00(H).
Path FEBE detection (Path Far End Block Error)
Path far end block error information. Detects whether a Path BIP-8 error has occurred in the unit at the transmission
destination (downstream).
Detection: Detects Path FEBE if the 1st to 4th bits of the receive G1 byte are 1 to 8(H).
Clear:
Clears Path FEBE if the 1st to 4th bits of the receive G1 byte are 0(H).
Frequency Justification occurrence
Detects the occurrence of Frequency Justification.
(3) Circuit quality monitor with count register
To monitor the circuit quality, the
μ
PD98405 counts the number of circuit quality deterioration causes, the
number of times receive Frequency Justification has been applied, and the number of cells dropped
because of the occurrence of an HEC error by using counters. The host can check the counts by reading
the registers.