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CHAPTER 13 SERIAL INTERFACE (UART0)
Preliminary User’s Manual U16035EJ1V0UM
(e) Receive errors
Three types of errors can occur during a receive operation: parity error, framing error, or overrun error. If,
as the result of data reception, an error flag is set to the asynchronous serial interface status register 0
(ASIS0), a receive error interrupt request (INTSER0) will occur. Receive error interrupt requests are
generated before receive completion interrupt request (INTSR0). Table 13-4 lists the causes behind receive
errors.
As part of receive error interrupt request (INTSER0) servicing, the contents of ASIS0 can be read to determine
which type of error occurred during the receive operation (see
Table 13-4
and
Figure 13-10
).
The contents of ASIS0 are reset (0) when the receive buffer register 0 (RXB0) is read or when the next data
is received (if the next data contains an error, its error flag will be set).
Table 13-4. Causes of Receive Errors
Receive Error
Cause
ASIS0 Value
Parity error
Parity specified during transmission does not match parity of receive data
04H
Framing error
Stop bit was not detected
02H
Overrun error
Reception of the next data was completed before data was read from the
01H
receive buffer register 0 (RXB0)
Figure 13-10. Receive Error Timing
RxD0 (input)
D0
D1
D2
D6
D7
Parity
STOP
START
INTSR0
Note
INTSER0
(When framing/overrun error occurs)
INTSER0
(When parity error occurs)
Note
If a receive error occurs when ISRM0 bit has been set (1), INTSR0 does not occur.
Cautions 1. The contents of asynchronous serial interface status register 0 (ASIS0) are reset (0)
when the receive buffer register 0 (RXB0) is read or when the next data is received. To
obtain information about the error, be sure to read the contents of ASIS0 before reading
RXB0.
2. Be sure to read the contents of the receive buffer register 0 (RXB0) even when a receive
error has occurred. Overrun errors will occur during the next data receive operations
and the receive error status will remain until the contents of RXB0 are read.
