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Data Sheet
371
Rev. 1.2, 2006-01-26
QuadFALCTM
PEF 22554 E
E1 Registers
LFA
5
r
Loss of Frame Alignment
This bit is set after detecting 3 or 4 consecutive incorrect FAS words or 3
or 4 consecutive incorrect service words (can be disabled). With the rising
edge of this bit an interrupt status bit (ISR2.LFA) is set. The specification
of the loss of synchronization conditions is done by bits RC0.SWD and
RC0.ASY4. After loss of synchronization, the frame aligner
resynchronizes automatically.
The following conditions have to be detected to regain synchronous state:
The presence of the correct FAS word in frame n.
The presence of the correct service word (bit 2 = 1) in frame n+1.
For a second time the presence of a correct FAS word in frame n+2.
The bit is cleared when synchronization has been regained (directly after
the second correct FAS word of the procedure described above has been
received).If the CRC-multiframe structure is enabled by setting bit
FMR2.RFS1, multiframe alignment is assumed to be lost if pulseframe
synchronization has been lost. The resynchronization procedure for
multiframe alignment starts after the bit FRS0.LFA has been
cleared.Multiframe alignment has been regained if two consecutive CRC-
multiframes have been received without a framing error (refer to
FRS0.LMFA).The bit is set during alarm simulation and reset if
FMR0.SIM is cleared and no alarm condition exists.If bit FRS0.LFA is
cleared a loss of frame alignment recovery interrupt status ISR2.FAR is
generated.
RRA
4
r
Receive Remote Alarm
Set if bit 3 of the received service word is set. An alarm interrupt status
ISR2.RA can be generated if the alarm condition is detected.
FRS0.RRA is cleared if no alarm is detected. At the same time a remote
alarm recovery interrupt status ISR2.RAR is generated. The bit
RSW.RRA has the same function.Both status and interrupt status bits are
set during alarm simulation.
NMF
2
r
No Multiframe Alignment Found
This bit is only valid if the CRC4 interworking is selected (FMR2.RFS(1:0)
= 11B). Set if the multiframe pattern is not detected in a time interval of
400 ms after the framer has reached the doubleframe synchronous state.
The receiver is then automatically switched to doubleframe format.This
bit is reset if the basic framing has been lost.
LMFA
1
r
Loss of Multiframe Alignment
Not used in doubleframe format (FMR2.RFS1 = 0B). In this case LMFA is
set.In CRC-multiframe mode (FMR2.RFS1 = 1B), this bit is set
If force resynchronization is initiated by setting bit FMR0.FRS, or
If multiframe force resynchronization is initiated by setting bit
FMR1.MFCS, or
If pulseframe alignment has been lost (FRS0.LFA).
It is reset if two CRC-multiframes have been received at an interval of
n x 2 ms (n = 1, 2, 3 and so forth) without a framing error. If bit
FRS0.LMFA is cleared a loss of multiframe alignment recovery interrupt
status ISR2.MFAR is generated.
Field
Bits
Type
Description