CN8478/CN8474A/CN8472A/CN8471A
6.0 Basic Operation
Multichannel Synchronous Communications Controller (MUSYCC™)
6.4 Protocol Support
Change of Frame Alignment
(T1/E1 Modes) (COFA)
In the case of a Change of Frame Alignment while receiving an HDLC message
(T1/E1 modes), the RSYNC input signal transitions from low to high
unexpectedly by the “frame synchronization flywheel mechanism.” This error
applies only to ports configured for T1, E1, 2xE1, or 4xE1 signals. Frame
synchronization indicates the location of time slot 0 in the serial data stream.
Lacking frame synchronization, the received channelized data becomes unaligned
and unmappable. This error affects all active channels in the channel group.
Reason:
•
A signal failure detected by the physical interface providing the serial data,
clock frequency, and synchronization to the serial interface on MUSYCC.
Effects:
•
•
MUSYCC writes the Interrupt Descriptor in Interrupt Queue with
ERROR = COFA, DIR = 0.
If OOFABT bit field is set to 0 in the Group Configuration Descriptor,
then continue channel activity. That is, received data bits are sampled and
eventually copied into shared memory.
•
If bit field OOFABT is set to 1 in the Group Configuration Descriptor,
suspend channel activity. Received data bits are discarded and lost to the
host processor.
Channel Level Recovery Actions:
•
If OOFABT = 1, once the received signal has recovered, reactivate receive
channel with a Channel Activate or Channel Jump Service Request or with
a slave write into the Receive Channel Configuration Table.
Out of Frame (OOF)
Out-of-frame or loss-of-frame indicates the entire serial data stream is invalid,
and data cannot be recovered from such a signal.
Reasons:
•
A signal failure detected by the physical interface providing the serial data,
clock frequency, and synchronization to the serial interface on MUSYCC.
Effects:
•
•
•
MUSYCC writes the Interrupt Descriptor in Interrupt Queue with
ERROR = OOF, DIR = 0.
The received data in the internal FIFO buffer is discarded and lost to the
host.
If OOFABT bit field is set to 0 in the Group Configuration Descriptor,
continue channel activity but transfer all 1s data into shared memory for
the duration of the OOF. When the OOF condition clears, normal bit-level
processing resumes automatically without host intervention.
If OOFABT bit field is set to 1 in the Group Configuration Descriptor,
channel activity suspends without transferring any data to shared memory.
•
Channel Level Recovery Actions:
•
When OOFABT selects receive message processing disabled, the host must
reactivate the receive channel after the OOF condition has cleared.
Reactivation is not required if OOFABT allows receive message
processing to continue.
100660E
Conexant
6-47
CONEXANT [ CONEXANT SYSTEMS, INC ]
