Synchronizatrion And Re-Synchronization - Dallas Semiconductor DS21354L Manual

SYMBOL POSITION NAME AND DESCRIPTION
– RCR1.3
FRC RCR1.2
SYNCE RCR1.1
RESYNC RCR1.0
6.1.1 Synchronization and Re-synchronization
Once synchronization is accomplished there are certain criteria that can cause a re-synchronization.
These criteria are detailed in Table 6-2. Also see Figure 19-14 for a flow chart of the synchronization
process.
SYNC/RESYNC CRITERIA Table 6-2
FRAME OR
MULTIFRAME
LEVEL
FAS FAS present in frame N
and N + 2, and FAS not
present in frame N + 1
CRC4 Two valid MF alignment
words found within 8 ms
CAS Valid MF alignment word
found and previous
timeslot 16 contains code
other than all zeros
Not Assigned. Should be set to zero when written.
Frame Resync Criteria.
0 = resync if FAS received in error 3 consecutive times
1 = resync if FAS or bit 2 of non–FAS is received in error 3 consecutive
times
Sync Enable.
0 = auto resync enabled
1 = auto resync disabled
Resync. When toggled from low to high, a resync is initiated. Must be
cleared and set again for a subsequent resync.
SYNC CRITERIA RESYNC CRITERIA
Three consecutive incorrect FAS
received
Alternate (RCR1.2=1) the above
criteria is met or three
consecutive incorrect bit 2 of
non–FAS received
915 or more CRC4 code words
out of 1000 received in error
Two consecutive MF alignment
words received in error
31 of 117
DS21354 & DS21554
ITU SPEC.
G.706
4.1.1
4.1.2
G.706
4.2 and 4.3.2
G.732 5.2