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(3)
Asynchronous serial interface status register 20 (ASIS20)
ASIS20 indicates the type of a reception error, if it occurs while asynchronous serial interface mode is set.
ASIS20 is set with a 1-bit or 8-bit memory manipulation instruction.
The contents of ASIS20 are undefined in 3-wire serial I/O mode.
RESET input sets ASIS20 to 00H.
Figure 11-5. Format of Asynchronous Serial Interface Status Register 20
Symbol
7
6
ASIS20
0
0
PE20
0
No parity error occurred.
1
A parity error occurred (when the transmit parity and receive parity did not match).
FE20
0
No framing error occurred.
1
A framing error occurred (when stop bit was not detected).
OVE20
0
No overrun error occurred.
1
An overrun error occurred
(when the next receive operation was completed before the data was read from receive buffer register 20).
Notes 1. Even when the stop bit length is set to 2 bits by setting bit 2 (SL20) of asynchronous serial
interface mode register 20 (ASIM20), the stop bit detection at reception is performed with 1 bit.
2. Be sure to read receive buffer register 20 (RXB20) when an overrun error occurs. If not, an
overrun error will occur every time data is received.
CHAPTER 11 SERIAL INTERFACE 20
5
4
3
<2>
<1>
0
0
0
PE20 FE20 OVE20
Note 2
User's Manual U15331EJ4V1UD
<0>
Address
After reset
FF71H
00H
Parity error flag
Framing error flag
Note 1
Overrun error flag
R/W
R
193
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