CN8478 Datasheet, PDF (175/221 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
Octet Alignment (ALIGN)
Error
Abort Termination (ABT)
In the case of an Octet Alignment (ALIGN) error, the HDLC message size after
0-bit extraction is not a multiple of 8 bits.
Reasons:
• Bit errors during transmission.
• Incorrect transmission of HDLC messages from the distant end.
Effects:
• The Interrupt Descriptor in Interrupt Queue with ERROR = ALIGN,
DIR = 0 (if MSKMSG = 0 in Receive Channel Configuration Descriptor).
• The entire HDLC message is transferred to shared memory.
• DMAC accesses the Next Message Pointer from the current Message
Descriptor.
• Returns ownership of the current Message Descriptor to the host by
writing the Receive Buffer Status Descriptor with ONR = HOST,
ERROR = ALIGN (if INHRBSD = 0 in Receive Channel Configuration
Descriptor).
• The BLP scans for the opening flag of the next HDLC message.
• Simultaneously, DMAC checks for Message Descriptor ownership before
transferring received data to shared memory.
Channel Level Recovery Actions:
• None required.
In the case of an Abort Termination (ABT) error, the receiver detects an abort
sequence from the distant end. An abort sequence is defined as 0 followed by 7
consecutive 1s.
Reason:
• The distant end can not complete transmission of HDLC message.
Effects:
• The Interrupt Descriptor in Interrupt Queue with ERROR = ABT, DIR = 0
(if MSKMSG = 0 in Receive Channel Configuration Descriptor).
• Partial HDLC message is transferred to shared memory.
• DMAC accesses the Next Message Pointer from the current Message
Descriptor.
• Returns ownership of the current Message Descriptor to the host by
writing the Receive Buffer Status Descriptor with ONR = HOST,
ERROR = ABT (if INHRBSD = 0 in Receive Channel Configuration
Descriptor).
• The BLP scans for the opening flag of the next HDLC message.
• Simultaneously, DMAC checks for Message Descriptor ownership before
transferring received data to shared memory.
Channel Level Recovery Actions:
• None required.
100660E
Conexant
6-41