NEC PD78F9488 - Manual (Page 193)

CHAPTER 11 SERIAL INTERFACE 20
User’s Manual U15331EJ4V1UD
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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
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 occurred.
A parity error occurred (when the transmit parity and receive parity did not match).
FE20
0
1
Framing error flag
No framing error occurred.
A framing error occurred (when stop bit was not detected). Note 1
OVE20
0
1
Overrun error flag
No overrun error occurred.
An overrun error occurred Note 2
(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.