Rainbow Electronics DS2143Q - Manual (Page 8)

DS2143/DS2143Q
031397 8/40
RCR1: RECEIVE CONTROL REGISTER 1 (Address=10 Hex)
(MSB) (LSB)
RSMF RSM RSIO – – FRC SYNCE RESYNC
SYMBOL POSITION NAME AND DESCRIPTION
RSMF RCR1.7 RSYNC Multiframe Function. Only used if the RSYNC pin is pro-
grammed in the multiframe mode (RCR1.6=1).
0 = RSYNC outputs CAS multiframe boundaries
1 = RSYNC outputs CRC4 multiframe boundaries
RSM RCR1.6 RSYNC Mode Select.
0 = frame mode (see the timing in Section 13)
1 = multiframe mode (see the timing in Section 13)
RSIO RCR1.5 RSYNC I/O Select.
0 = RSYNC is an output (depends on RCR1.6)
1 = RSYNC is an input (only valid if elastic store enabled) (note: this bit must
be set to zero when RCR2.1=0)
– RCR1.4 Not Assigned. Should be set to zero when written to.
– RCR1.3 Not Assigned. Should be set to zero when written to.
FRC RCR1.2 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
SYNCE RCR1.1 Sync Enable.
0 = auto resync enabled
1 = auto resync disabled
RESYNC RCR1.0 Resync. When toggled from low to high, a resync is initiated. Must be
cleared and set again for a subsequent resync.
SYNC/RESYNC CRITERIA Table 2
FRAME OR
MULTIFRAME
LEVEL
SYNC CRITERIA RESYNC CRITERIA ITU SPEC.
FAS FAS present in frames N and N +
2, and FAS not present in frame
N + 1. Three consecutive incorrect FAS
received.
Alternate (RCR1.2=1) the above
criteria is met or three consecu-
tive incorrect bit 2 of non–FAS
received.
G.706
4.1.1
4.1.2
CRC4 Two valid MF alignment words
found within 8 ms. 915 or more CRC4 code words
out of 1000 received in error. G.706
4.2
4.3.2
CAS Valid MF alignment word found
and previous time slot 16 con-
tains code other than all zeros. Two consecutive MF alignment
words received in error. G.732
5.2