Datasheet

DS2155
60 of 238
10.3 E1 Information Registers
Register Name:
INFO3
Register Description:
Information Register 3
Register Address:
12h
Bit # 7 6 5 4 3 2 1 0
Name — — — — — CRCRC FASRC CASRC
Default 0 0 0 0 0 0 0 0
Bit 0/CAS Resync Criteria Met Event (CASRC). Set when two consecutive CAS MF alignment words are
received in error.
Bit 1/FAS Resync Criteria Met Event (FASRC). Set when three consecutive FAS words are received in error.
Note: During a CRC resync the FAS synchronizer is brought online to verify the FAS alignment. If during this
process an FAS emulator exists, the FAS synchronizer may temporarily align to the emulator. The FASRC will go
active indicating a search for a valid FAS has been activated.
Bit 2/CRC Resync Criteria Met Event (CRCRC). Set when 915/1000 codewords are received in error.
Register Name:
INFO7
Register Description:
Information Register 7 (Real-Time, Non-Latched Register)
Register Address:
30h
Bit # 7 6 5 4 3 2 1 0
Name CSC5 CSC4 CSC3 CSC2 CSC0 FASSA CASSA CRC4SA
Default 0 0 0 0 0 0 0 0
Bit 0/CRC4 MF Sync Active (CRC4SA). Set while the synchronizer is searching for the CRC4 MF alignment
word. This is a read-only, non-latched, real-time bit. It is not necessary to precede the read of this bit with a write.
Bit 1/CAS MF Sync Active (CASSA). Set while the synchronizer is searching for the CAS MF alignment word.
This is a read-only, non-latched, real-time bit. It is not necessary to precede the read of this bit with a write.
Bit 2/FAS Sync Active (FASSA). Set while the synchronizer is searching for alignment at the FAS level. This is a
read-only, non-latched, real-time bit. It is not necessary to precede the read of this bit with a write.
Bits 3 to 7/CRC4 Sync Counter Bits (CSC0, CSC2 to CSC4). The CRC4 sync counter increments each time the
8ms CRC4 multiframe search times out. The counter is cleared when the framer has successfully obtained
synchronization at the CRC4 level. The counter can also be cleared by disabling the CRC4 mode (E1RCR1.3 = 0).
This counter is useful for determining the amount of time the framer 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 rolls over. CSC0 is the LSB of
the 6-bit counter. (Note: The bit next to LSB is not accessible. CSC1 is omitted to allow resolution to >400ms
using 5 bits.) These are read-only, non-latched, real-time bits. It is not necessary to precede the read of these bits
with a write.