Receive Error Timing - NEC V850/SA1 mPD703015 Preliminary User's Manual

(v) Receive error
There are three types of error during the receive operation, pariy error, framing error, and overrun error.
When, as the result of data receive, an error flag is set in the asynchronous serial interface status register
(ASISn), the receive error interrupt request (INTSERn) is generated. The receive error interrupt request is
generated prior to the receive completion interrupt request (INTSRn). Table 10-9 shows receive error
causes.
By reading the contents of ASISn during receive error interrupt processing (INTSERn), it is possible to detect
which error has occurred at reception (see Table 10-9 and Figure 10-37).
The contents of ASISn are reset (0) by reading the receive buffer register (RXBn) or receiving subsequent
data (If there is an error in the subsequent data, the error flag is set).
Receive error
Parity error Parity specification at transmission and receive data parity do not match.
Framing error Stop bit is not detected.
Overrun error Reception of subsequent data was completed before data was read from the
receive buffer register.
RxDn(Input)
Note
INTSRn
INTSERn
INTSERn
(When parity error occurs)
Note Even if a receive error occurs when the ISRMn bit of ASIMn is set (1), INTSRn is not generated.
Cautions 1. The contents of the asynchronous serial interface status register (ASISn) are reset
(0) by reading the receive buffer register (RXBn) or receiving subsequent data. To
check the contents of error, always read ASISn before reading RXBn.
2. Be sure to read the receive buffer register (RXBn) even in receive error generation. If
RXBn is not read out, an overrun error will occur during subsequent data reception
and as a result receive errors will continue to occur.
Remark n = 0, 1
CHAPTER 10 SERIAL INTERFACE FUNCTION
Table 10-9. Receive Error Causes
Cause
Figure 10-37. Receive Error Timing
START D0 D1 D2
ASISn value
Parity
D6 D7
STOP
04H
02H
01H
299