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Chapter 15
Serial Interface Channel UART
User’s Manual U16504EE1V1UD00
(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 the data reception, an error flag is set to the asynchronous serial interface
status register (ASIS0), a receive error interrupt (INTSER0) will occur. Receive error interrupts are
generated before receive interrupts (INTSR0).
Table 15-5 lists the causes of receive errors.
As part of the receive error interrupt (INTSER0) servicing, the contents of ASIS0 can be read to
determine which type of error occurred during the receive operation (see Table 14-5 and Figure
15-13).
The content of ASIS0 is reset (to “0”) if the receive buffer register (RXB0) is read or when the next
data is received (if the next data contains an error, another error flag will be set).
Figure 15-13:
Receive Error Timing
Cautions: 1. The contents of ASIS0 are reset (to “0”) when the receive buffer register (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 (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.
Table 15-5:
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 receive buffer
register
01H
RXD0 (input)
D0
D1
D2
D6
D7
Parity
STOP
START
INTSR0
INTSER0
INTSER0
(When parity error occurs)