PEB22554 SIEMENS [Siemens Semiconductor Group], PEB22554 Datasheet - Page 156

• Manufacturer Part Number: PEB22554
• Description: ICs for Communications
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

PEB 22554
Operational Description E1
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) will be set.
The specification of the loss of sync conditions is done via bits
RC1.SWD and RC1.ASY4. After loss of synchronization, the frame
aligner will resynchronize 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 pulse-frame
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 will be 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 will be generated.
RRA…
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 will be cleared when no alarm is detected. At the same
time a remote alarm recovery interrupt status ISR2.RAR will be
generated.
The bit RSW.RRA has the same function.
Both status and interrupt status bits will be set during alarm
simulation.
Semiconductor Group
156
09.98