CN8478 Datasheet, PDF (168/221 Pages) Conexant Systems, Inc – Multichannel Synchronous Communications Controller (MUSYCC)

6.0 Basic Operation
6.4 Protocol Support
CN8478/CN8474A/CN8472A/CN8471A
Multichannel Synchronous Communications Controller (MUSYCC™)
End of Message (EOM]
End of Padfill (EOP]
6.4.8.2 Receive Events
End of Buffer (EOB)
End of Message (EOM)
Reason:
• BLP has transmitted the last bit of a data buffer and the Transmit Buffer
Descriptor signified the end of a message by the bit field EOM in a
Transmit Buffer Descriptor. The last EOB and an EOM are coincident and
result in two separate events being generated.
Effects:
• Interrupt Descriptor in Interrupt Queue with EVENT = EOM, DIR = 1
(if MSKEOM = 0 in Transmit Channel Configuration Descriptor).
• BLP and DMAC continue with normal message processing. If the DMAC
does not receive more data from shared memory before the BLP must
output the next data bit, the BLP outputs another octet of idle code.
Reason:
• BLP has transmitted the specified number of pad fill octets.
Effects:
• Interrupt Descriptor in Interrupt Queue with EVENT = EOP, DIR = 1
(if EOPI = 1 in Transmit Channel Configuration Descriptor).
• BLP and DMAC continue with normal message processing. If the DMAC
does not receive more data from shared memory before the BLP must
output the next data bit, the BLP outputs another octet of idle code.
Receive events are informational in nature and do not require channel recovery
actions.
Reason:
• One message is stored across multiple message buffers. MUSYCC reached
the end of a buffer by servicing a number of octets equal to the bit field
BLEN in a Receive Buffer Descriptor.
Effects:
• The Interrupt Descriptor in the Interrupt Queue with EVENT = EOB,
DIR = 0
(if EOBI = 1 in Receive Buffer Descriptor).
• BLP and DMAC continue with normal message processing.
Reason:
• BLP detected the end of a message (closing flag or an error condition) in
the received data stream. Error conditions include ABT, LNG, ALIGN,
BUFF, and ONR errors.
Effects:
• Interrupt Descriptor in Interrupt Queue with EVENT = EOM, DIR = 0
(if MSKEOM = 0 in Receive Channel Configuration Descriptor).
• DMAC sets bit field EOM = 1 in Receive Buffer Status Descriptor
(if INHRBSD = 0 in Receive Channel Configuration Descriptor).
• BLP and DMAC continue with normal message processing.
6-34
Conexant
100660E