
MT9072
Advance Information
84
12.0 Performance Monitoring
12.1 T1 Error Counters
The MT9072 has nine error counters for each framer, which can be used for maintenance testing and ongoing
measurement of the quality of a DS1 link and to assist the designer in meeting specifications such as TR62411
and T1.403. All counters can be preset or cleared by writing to the appropriate counter registers.
Associated with each counter is a maskable event occurrence interrupt and a maskable counter overflow
interrupt. Overflow interrupts are useful when cumulative error counts are being recorded. For example, every
time the framing bit error counter overflow interrupt (FEO) occurs, 65536 frame errors have been received
since the last FEO interrupt. Also if a counter overflows, the overflow indicators are latched in the Overflow
reporting latch register(Y24).
All counters are cleared by a counter clear bit -CNTCLR - low to high transition (bit 2 of the IO Control Word,
YF1). An alternative approach to event reporting is to mask error events and to enable the 1 second sample bit
(SAMPLE - bit 1 of the Interrupt and IO Control Word). When this bit is set the latched version of the
counters(Y28 to Y2C) for change of frame alignment, loss of frame alignment, bpv errors, crc errors, errored
framing bits, and multiframes out of sync are updated on one second intervals coincident with the maskable
one second interrupt timer.
.
12.2 E1 Error Counters
The MT9072 has eight error counters, which can be used for maintenance testing, and ongoing measurement
of the quality of a PCM30 link and to assist the designer in meeting specifications such as ITU-T I.431 and
G.821. All counters can be preset or cleared by writing to the appropriate locations. In addition, four error count
latches are provided which latch the counter data coincident with the one second status bit. Counters can
automatically be cleared (ACCLR register address Y03) after their data is latched. Associated with each
Counter
Interrupt Status Bits
1 Second Latch
Description
Bits
Address Indication
Overflow
Description
Bit
Address
PRBS Error Counter
and CRC
Multiframe counter
for PRBS
PS7-0,
PSM7-0
Y15
PRBSI
PRBSOI
PRBSMFOI
NA
NA
NA
Multiframe Out of
Frame Counter
MFOOF
7-0
Y16
MFOOFI
MFOOFOI
Multiframe Out of
Frame Count Latch
MFOO
FL15-0
Y2C
Framing Bit Error
Counter
FC15-0
Y17
FBEI
FEOI
Framing Bit Error
Counter Latch
FCL15-
0
Y28
BPV Counter
BPV15-0
Y18
BPVI
BPVOI
Bipolar Violation
Count Latch
BPVL
15-0
Y29
CRC-6 Error counter
CC15-0
Y19
CRCI
CRCOI
CRC-6 Error Count
Latch
CRCL
15-0
Y2A
Out of frame counter,
change of frame
alignment counter
OOF7-0,
COFA7-0
Y1A
OOFOI
COFAI
OOFOI
COFOIL
Out of Frame, Change
of Frame Alignment
Count Latch
OOFL
7-0
COFAL
7-0
Y2B
Excessive Zero
counter
EXZ7-0,
Y1B
EXZI
EXZOL
NA
NA
NA
Table 41 - Error Counters Summary (T1)