CN8478 Datasheet, PDF (179/221 Pages) Conexant Systems, Inc – Multichannel Synchronous Communications Controller (MUSYCC)

CN8478/CN8474A/CN8472A/CN8471A
Multichannel Synchronous Communications Controller (MUSYCC™)
6.0 Basic Operation
6.4 Protocol Support
6.4.9.3 Transmit Errors
Underflow Due to Host
Ownership of Buffer (ONR)
Underflow Due to Internal
FIFO Buffer Under-Run
(BUFF)
Transmit Errors are service-affecting and require a corrective action by the host to
resume normal bit-level processing.
In the case of underflow due to host ownership of buffer (ONR), sufficient data
throughput from shared memory is not maintained to support the data rate of the
serial interface. That is, ownership of messages was not handed over to MUSYCC
in a timely manner.
Reason:
• Degradation of the host subsystem or application software performance.
Effects:
• The Interrupt Descriptor in Interrupt Queue with ERROR = ONR,
DIR = 1.
• Data from Data Buffer not being read.
• The Buffer Descriptor not overwriting the Buffer Status Descriptor.
• No additional activity on the PCI bus for this channel direction.
• Transmit channel activity is suspended.
Channel Level Recovery Actions:
• Provide sufficient amount of data for transmission using lists of Message
Descriptors with ownership given to MUSYCC.
• Reactivate transmit channel.
In the case of underflow due to internal FIFO buffer under-run (BUFF), the
internal FIFO buffer becomes empty when MUSYCC must output data bits (at
the serial interface clock rate) and MUSYCC has ownership of a message buffer
in shared memory.
Reasons:
• Degradation of the host subsystem or application software performance.
• Congestion of the PCI bus.
Effects:
• MUSYCC writes the Interrupt Descriptor in Interrupt Queue with
ERROR = BUFF, DIR = 1.
• Continuous idle code transmission.
• Data from data buffer not being read.
• The Buffer Descriptor not overwriting the Buffer Status Descriptor.
• No additional activity on the PCI bus for this channel direction.
• Transmit channel activity is suspended.
Channel Level Recovery Actions:
• Provide sufficient amount of data for transmission using lists of Message
Descriptors with ownership given to MUSYCC.
• Reactivate transmit channel.
100660E
Conexant
6-45