DS2154
SSR: SYNCHRONIZER STATUS REGISTER (Address = 1E Hex)
(MSB)
(LSB)
CRC4SA
CSC5
CSC4
CSC3
CSC2
CSC0
FASSA
CASSA
SYMBOL
POSITION
NAME AND DESCRIPTION
CSC5
SSR.7
CRC4 Sync Counter Bit 5. MSB of the 6-bit counter.
CRC4 Sync Counter Bit 4.
CSC4
CSC3
CSC2
CSC0
SSR.6
SSR.5
SSR.4
SSR.3
CRC4 Sync Counter Bit 3.
CRC4 Sync Counter Bit 2.
CRC4 Sync Counter Bit 0. LSB of the 6-bit counter. The next
to LSB is not accessible.
FASSA
CASSA
CRC4SA
SSR.2
SSR.1
SSR.0
FAS Sync Active. Set while the synchronizer is searching for
alignment at the FAS level.
CAS MF Sync Active. Set while the synchronizer is searching
for the CAS MF alignment word.
CRC4 MF Sync Active. Set while the synchronizer is searching
for the CRC4 MF alignment word.
5.1 CRC4 Sync Counter
The CRC4 sync counter increments each time the 8ms CRC4 multiframe search times out. The counter is
cleared when the DS2154 has successfully obtained synchronization at the CRC4 level. The counter can
also be cleared by disabling the CRC4 mode (CCR1.0 = 0). This counter is useful for determining the
amount of time the DS2154 has been searching for synchronization at the CRC4 level. ITU G.706
suggests that if synchronization at the CRC4 level cannot be obtained within 400ms, then the search
should be abandoned and proper action taken. The CRC4 sync counter will rollover.
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ROCHESTER [ Rochester Electronics ]
