DS21Q42 Datasheet, PDF (45/119 Pages) Dallas Semiconductor – Enhanced QUAD T1 FRAMER

DS21Q42
8. ERROR COUNT REGISTERS
There are a set of three counters in each framer that record bipolar violations, excessive zeros, errors in
the CRC6 code words, framing bit errors, and number of multiframes that the device is out of receive
synchronization. Each of these three counters are automatically updated on either one second boundaries
(CCR3.2=0) or every 42 ms (CCR3.2=1) as determined by the timer in Status Register 2 (SR2.5). Hence,
these registers contain performance data from either the previous second or the previous 42 ms. The user
can use the interrupt from the one second timer to determine when to read these registers. The user has a
full second (or 42 ms) to read the counters before the data is lost. All three counters will saturate at their
respective maximum counts and they will not rollover (note: only the Line Code Violation Count Register
has the potential to overflow but the bit error would have to exceed 10 -2 before this would occur).
Line Code Violation Count Register (LCVCR)
Line Code Violation Count Register 1 (LCVCR1) is the most significant word and LCVCR2 is the least
significant word of a 16–bit counter that records code violations (CVs). CVs are defined as Bipolar
Violations (BPVs) or excessive zeros. See Table 8-1 for details of exactly what the LCVCRs count. If the
B8ZS mode is set for the receive side via CCR2.2, then B8ZS code words are not counted. This counter is
always enabled; it is not disabled during receive loss of synchronization (RLOS=1) conditions.
LCVCR1: LINE CODE VIOLATION COUNT REGISTER 1 (Address = 23 Hex)
LCVCR2: LINE CODE VIOLATION COUNT REGISTER 2 (Address = 24 Hex)
(MSB)
LCV15
LCV7
LCV14
LCV6
LCV13
LCV5
LCV12
LCV4
LCV11
LCV3
LCV10
LCV2
LCV9
LCV1
(LSB)
LCV8
LCV0
LCVCR1
LCVCR2
SYMBOL
POSITION NAME AND DESCRIPTION
LCV15
LCV0
LCVCR1.7
LCVCR2.0
MSB of the 16–bit code violation count
LSB of the 16–bit code violation count
LINE CODE VIOLATION COUNTING ARRANGEMENTS Table 8-1
COUNT EXCESSIVE
ZEROS?
(RCR1.7)
no
yes
no
yes
B8ZS ENABLED?
(CCR2.2)
no
no
yes
yes
WHAT IS COUNTED
IN THE LCVCRs
BPVs
BPVs + 16 consecutive zeros
BPVs (B8ZS code words not
counted)
BPV’s + 8 consecutive zeros
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