DS2155G datasheet(79/238 Pages) DALLAS

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DS2155

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14.3 Frames Out-of-Sync Count Register (FOSCR)

14.3.1 T1 Operation

The FOSCR is used to count the number of multiframes that the receive synchronizer is out of sync. This

number is useful in ESF applications needing to measure the parameters loss-of-frame count (LOFC) and

ESF error events as described in AT&T publication TR54016. When the FOSCR is operated in this

mode, it is not disabled during receive loss-of-synchronization (RLOS = 1) conditions. The FOSCR has

an alternate operating mode whereby it counts either errors in the Ft framing pattern (in the D4 mode) or

errors in the FPS framing pattern (in the ESF mode). When the FOSCR is operated in this mode, it is

disabled during receive loss-of-synchronization (RLOS = 1) conditions. Table 14-D shows what the

FOSCR is capable of counting.

Table 14-D. T1 Frames Out-of-Sync Counting Arrangements

FRAMING MODE

(T1RCR1.3)

COUNT MOS OR

F-BIT ERRORS

(ERCNT.1)

COUNTED IN THE FOSCRs

MOS

Number of multiframes out-of-sync

F-Bit

Errors in the Ft pattern

ESF

MOS

Number of multiframes out-of-sync

ESF

F-Bit

Errors in the FPS pattern

14.3.2 E1 Operation

The FOSCR counts word errors in the FAS in time slot 0. This counter is disabled when RLOS is high.

FAS errors are not counted when the framer is searching for FAS alignment and/or synchronization at

either the CAS or CRC4 multiframe level. Since the maximum FAS word error count in a one-second

period is 4000, this counter cannot saturate.

The frames out-of-sync count register 1 (FOSCR1) is the most significant word and FOSCR2 is the least

significant word of a 16-bit counter that records frames out-of-sync.

FOSCR1

Frames Out-of-Sync Count Register 1

46h

Bit #

Name

FOS15

FOS14

FOS13

FOS12

FOS11

FOS10

FOS9

FOS8

Default

Bits 0 to 7/Frames Out-of-Sync Counter Bits 8 to 15 (FOS8 to FOS15). FOS15 is the MSB of the 16-bit frames

out-of-sync count.

FOSCR2

Frames Out-of-Sync Count Register 2

47h

Bit #

Name

FOS7

FOS6

FOS5

FOS4

FOS3

FOS2

FOS1

FOS0

Default

Bits 0 to 7/Frames Out-of-Sync Counter Bits 0 to 7 (FOS0 to FOS7). FOS0 is the LSB of the 16-bit frames out-

of-sync count.

DS2155G Datasheet(PDF) 79 Page - Dallas Semiconductor

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