DS2154 datasheet(40/87 Pages) DALLAS

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DS2154

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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 1-second boundaries (CCR2.7=0) or every 62.5 ms

(CCR2.7=1) as determined 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 significant 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 violations 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 an 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

VCR1

VCR2

SYMBOL

POSITION

NAME AND DESCRIPTION

V15

VCR1.7

MSB of the 16-bit bipolar or code violation count .

VCR2.0

LSB of the 16-bit bipolar or code violation count.

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