Serial Communication Controllers (SCCs)
MOTOROLA
MC68360 USER’S MANUAL
7-155
and the UART event register. The modem interface lines can be monitored by the port C
pins.
7.10.16.14.1 Transmission Error.
The following paragraph describes a UART transmis-
sion error.
CTS Lost During Character Transmission
.
When this error occurs, the channel stops trans-
mission after finishing transmission of the current character from the buffer. The channel
then sets the CT bit in the Tx BD and generates the TX interrupt if it is not masked. The chan-
nel will resume transmission after the RESTART TRANSMIT command is issued and the
CTS pin is asserted.
NOTE
The UART also offers an asynchronous flow control option using
CTS that does not generate an error. See the FLC bit in the
PSMR description.
7.10.16.14.2 Reception Errors.
The following paragraphs describe various types of UART
reception errors.
Overrun Error
.
Data is moved from the receive FIFO to the data buffer when the first byte is
received into the FIFO. If a receiver FIFO overrun occurs, the channel writes the received
character into the internal FIFO over the previous received character (previous character is
lost.) The channel writes the received character to the buffer, closes the buffer, sets the OV
bit in the Rx BD, and generates the RX interrupt if it is enabled. In automatic multidrop mode,
the receiver enters hunt mode immediately.
CD Lost During Character Reception
.
If this error occurs and the channel is using this pin to
automatically control reception, the channel terminates character reception, closes the
buffer, sets the CD bit in the Rx BD, and generates the RX interrupt (if enabled). This error
has the highest priority. The last character in the buffer is lost, and other errors are not
checked. In automatic multidrop mode, the receiver enters hunt mode immediately.
Parity Error
.
When a parity error occurs, the channel writes the received character to the
buffer, closes the buffer, sets the PR bit in the Rx BD, and generates the RX interrupt (if
enabled). The channel also increments the PAREC counter. In automatic multidrop mode,
the receiver enters hunt mode immediately.
Noise Error
.
Noise error is detected by the UART controller when the three samples taken
on every bit are not identical. When this error occurs, the channel writes the received char-
acter to the buffer and proceeds normally, but increments the NOSEC.
NOTE
In the synchronous mode of the UART controller, this error can-
not occur.
Idle Sequence Receive
.
An idle is detected when one character consisting of all ones is
received. When the UART is receiving data into a receive buffer, and an idle is received, the