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Data Sheet
197
Rev. 1.2, 2006-01-26
QuadFALC
TM
PEF 22554 E
Functional Description T1/J1
If the register bit CCR2.RBFE is set, BOM messages are accepted if at least seven consecutive and identical BOM
messages were received.
Dependent on the BOM mode (configured by register bits CCR1.BRM and CCR2.RBFE) the content of register
RSIS will be written as last byte into the receive FIFO.
Automatic loop switching by BOM messages is logically ored with the appropriate loop switching by register bits.
If ALS.SOLS (ALS_T) is set, the payload loop is activated after the “payload loopback activate“ code was detected
from the line side or the system side and if the local loop is not activated by LIM0.LL = 1
B. The payload loop is
deactivated after an appropriate deactivation Out-Band loop code was detected from the line side or the system
side. (But if the payload loop is additionally activated by FMR2.PLB = 1
B the payload loop is still active, because
automatic loop switching is logically ored with the appropriate loop switching by register bits.)
If ALS.LOLS is set, the remote loop is activated after the “l(fā)ine loopback activate” code was detected from the line
side or the system side and if the local loop is not activated by LIM0.LL = 1
B. The remote loop is deactivated after
the “l(fā)ine loopback deactivate” code was detected from the line side or the system side. (But if the remote loop is
additionally activated by LIM0.RL = 1
B the remote loop is still active, because automatic loop switching is logically
ored with the appropriate loop switching by register bits.)
If the remote loop is activated by an automatic loop switching the register bit LIM0.JATT controls also if the jitter
attenuator is active or not.
ALS.SOLS and ALS.LOLS both can be set to 1
B simultaneous.
Because BOM messages coming from the system side are not included in the E1/T1/J1 standards, receive of
these BOM messages and the possibility of automatic loop switching (ALS.SOLS) are features of the
QuadFALC
TM. It has to be handle carefully to avoid deadlocks.
If ALS.SOLS or ALS.LOLS are set after an Out-Band loop code was detected, no automatic loop switching is
performed.
If ALS.LOLS is cleared, an automatic activated remote loop is deactivated.
If ALS.SOLS is cleared, an automatic activated payload loop is deactivated.
The kind of performed automatic loop switching caused by the appropriate detected Out-band message is shown
in the register bits ISR6.(7:4). Masking of ISR6.(7:4) for controlling of the interrupt can be done by register bits
IMR6.(7:4). If an Out-band message were detected, the appropriate register bits ISR6.(7:4) will be set to 1
B,
independent if automatic loop switching has been enabled. (Because the micro controller knows if automatic loop
switching is enabled, it knows if a loop is activated or not.)
A detection of an Out-band loop message (BOM) “universal loopback deactivate” sets both bits ISR6.SOLSD and
ISR6.LOLSD, independent if a loop is active (switched) or not. Dependent on ALS.LOLS or ALS.SOLS the remote
or the payload loopback is switched off respectively.
A received BOM message causes setting of the interrupt bit ISR0.RME and is stored in the receive FIFO, marked
with a BOM frame.
Note that detection of Out-band Loop messages (BOM codes) is only possible either on the line side or the system
side, dependent on the configuration of the HDLC controller (see Chapter 5.3.1): If the HDLC/BOM controller 1 is
attached to the line side (MODE.HDLCI = 0
B) only BOM messages coming from the line side can be detected. If
the HDLC/BOM controller is attached to the system side (MODE.HDLCI = 1
B), so called “inverse configuration”)
only BOM messages coming from the system side can be detected. BOM messages coming from the system side
are not included in (ANSI-)standards, but can be handled by the QuadFALC
TM.
5.5.9
Transparent Mode (T1/J1)
The transparent modes are useful for loop-backs or for routing data unchanged through the QuadFALC
TM.
In receive direction, transparency for ternary or dual-/single-rail unipolar data is always achieved if the receiver is
in the synchronous state. All bits in F-bit position of the incoming multiframe are forwarded to RDO and inserted
in the FS/DL time slot or in the F-bit position. In asynchronous state the received data is switched through
transparently if bit FMR2.DAIS (FMR2_T) is set. Setting of bit LOOP.RTM (LOOP_T) disconnects control of the
elastic buffer from the receiver. The elastic buffer is now in a “free running” mode without any possibility to update
the time slot assignment to a new frame position in case of resynchronization of the receiver. Together with
FMR2.DAIS this function is used to realize undisturbed transparent reception.