Manual

DS2154
031197 29/69
SEC IMR2.4 One Second Timer.
0=interrupt masked
1=interrupt enabled
TAF IMR2.3 Transmit Align Frame.
0=interrupt masked
1=interrupt enabled
LOTC IMR2.2 Loss Of Transmit Clock.
0=interrupt masked
1=interrupt enabled
RCMF IMR2.1 Receive CRC4 Multiframe.
0=interrupt masked
1=interrupt enabled
TSLIP IMR2.0 Transmit Side Elastic Store Slip Occurrence.
0=interrupt masked
1=interrupt enabled
5.0 ERROR COUNT REGISTERS
There are a set of four counters in the DS2154 that
record bipolar or code violations, errors in the CRC4
SMF code words, E bits as reported by the far end, and
word errors in the FAS. Each of these four counters are
automatically updated on either one second boundaries
(CCR2.7=0) or every 62.5 ms (CCR2.7=1) as deter-
mined by the timer in Status Register 2 (SR2.4). Hence,
these registers contain performance data from either
the previous second or the previous 62.5 ms. The user
can use the interrupt from the timer to determine when to
read these registers. The user has a full second (or
62.5 ms) to read the counters before the data is lost.
5.1 BPV or Code Violation Counter
Violation Count Register 1 (VCR1) is the most signifi-
cant word and VCR2 is the least significant word of a
16–bit counter that records either BiPolar Violations
(BPVs) or Code Violations (CVs). If CCR2.6=0, then the
VCR counts bipolar violations. Bipolar violations are
defined as consecutive marks of the same polarity. In
this mode, if the HDB3 mode is set for the receive side
via CCR1.2, then HDB3 code words are not counted as
BPVs. If CCR2.6=1, then the VCR counts code viola-
tions as defined in ITU O.161. Code violations are
defined as consecutive bipolar violations of the same
polarity. In most applications, the DS2154 should be
programmed to count BPVs when receiving AMI code
and to count CVs when receiving HDB3 code. This
counter increments at all times and is not disabled by
loss of sync conditions. The counter saturates at 65,535
and will not rollover. The bit error rate on a E1 line would
have to be greater than 10**
–2
before the VCR would
saturate.
VCR1: UPPER BIPOLAR VIOLATION COUNT REGISTER 1 (Address=00 Hex)
VCR2: LOWER BIPOLAR VIOLATION COUNT REGISTER 2 (Address=01 Hex)
(MSB) (LSB)
V15
V14 V13 V12 V11 V10 V9 V8
V7 V6 V5 V4 V3 V2 V1 V0
SYMBOL POSITION NAME AND DESCRIPTION
V15 VCR1.7 MSB of the 16–bit bipolar or code violation count .
V0 VCR2.0 LSB of the 16–bit bipolar or code violation count.
VCR1
VCR2