CHAPTER 12 SERIAL INTERFACE 20
User’s Manual U15075EJ1V0UM00
218
(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 12-5. Format of Asynchronous Serial Interface Status Register 20
PE20
0
1
Parity error flag
0
0
0
0
0
PE20 FE20 OVE20
ASIS20
Symbol
Address
After reset
R/W
FF71H
00H
R
7
6
5
4
3
<2>
<1>
<0>
No parity error has occurred.
A parity error has occurred (when the parity of transmit data does not match).
FE20
0
1
Flaming error flag
No framing error has occurred.
A framing error has occurred (when stop bit is not detected).
Note 1
OVE20
0
1
Overrun error flag
No overrun error has occurred.
An overrun error has occurred.
Note 2
(when the next receive operation is completed before the data is read from reception 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 reception buffer register 20 (RXB20) when an overrun error occurs. If not, every
time the data is received an overrun error will occur.
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