CHAPTER 16 ASYNCHRONOUS SERIAL INTERFACE/3-WIRE SERIAL I/O
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User’s Manual U12697EJ3V0UM
(e) Receive error
Errors that occur during reception are of three types: parity errors, framing errors, and overrun errors. As
the data reception result error flag is set inside asynchronous serial interface status register n (ASISn), the
receive error interrupt request (INTSERn) is generated. A receive error interruption is generated before a
receive end interrupt request (INTSRn). Receive error causes are shown in Table 16-4.
What type of error has occurred during reception can be detected by reading the contents of asynchronous
serial interface status register n (ASISn) during processing of the receive error interrupt (INTSERn) (rerer
to
Table 16-4
and
Figure 16-10
).
The contents of ASISn are reset to 0 either when receive buffer register n (RXBn) is read or when the next
data is received (If the next data has an error, this error flag is set).
Remark
n = 1, 2
Table 16-4. Receive Error Causes
Receive Error
Cause
ASISn
Parity error
Parity specified for transmission and parity of receive data don’t match
04H
Framing error
Stop bit was not detected
02H
Overrun error
Next data reception was completed before data was read from the receive buffer register
01H
Figure 16-10. Receive Error Timing
Note
INTSRn will not be triggered if an error occurs when the ISRMn bit has been set (1).
Cautions 1. The contents of ASISn are reset to 0 either when receive buffer register n (RXBn) is
read or when the next data is received. To find out the contents of the error, be sure
to read ASIS before reading RXBn.
2. Be sure to read receive buffer register n (RXBn) even when a receive error occurs.
If RXBn is not read, an overrun error will occur at reception of the next data, and the
receive error status will continue indefinitely.
Remark
n = 1, 2
D1
D2
D6
D7
Parity
D0
RxDn (input)
INTSRn
Note
STOP
START
INTSERn
(when framing/
overrun error
occurs)
INTSERn
(when parity
error occurs)
