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BO, and generates the transmit error (TXE) interrupt (if enabled). The
channel will resume transmission after the reception of the RESTART
TRANSMIT command.
NOTE
This error can occur only on synchronous links.
2. Clear to Send Lost (Collision) During Message Transmission. When this
error occurs and the channel is not programmed to control this line with
software, the channel terminates buffer transmission, closes the buffer,
sets the CTS lost (CT) bit in the BD, and generates the transmit error
(TXE) interrupt
Of
enabled). The channel resumes transmission after the
reception of the RESTART TRANSMIT command.
Reception Errors:
1. Carrier Detect Lost During Message Reception. When this error occurs
and the channel is not programmed to control this line with software,
the channel terminates message reception, closes the buffer, sets the
carrier detect lost (CD) bit in the BO, and generates the receive block
IRBK) interrupt (if enabled). This error has the highest priority. The rest
of the message is lost, and other errors in that message are not checked.
The channel will enter hunt mode immediately. It is possible that a
SYN1-SYN2-(SOH,DLE,ENQ) sequence in data will be incorrectly inter-
preted as the start of the next header, but this "header" will have a CRC
error.
2. Overrun Error. The DDCMP controller maintains an internal two-byte
FIFO for receiving data. The CP begins programming the SOMA channel
(if the data buffer is in external memory) and updating the CRC when
the first word is received into the FIFO. If the receive FIFO overrun error
occurs, the channel writes the received data byte to the internal FIFO
on top of the previously received byte. The previous data byte is lost.
Then the channel closes the buffer, sets the overrun (OV) bit in the BD,
and generates the receive block (RBK) interrupt (if enabled).
MOTOROLA
The channel will enter hunt mode immediately. It is possible that a
SYN1-SYN2-(SOH,DLE,ENQ) sequence in data will be incorrectly inter-
preted as the start of the next header, but this "header" will have a CRC
error.
MC68302 USER'S MANUAL
4-93
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