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CHAPTER 19 SERIAL INTERFACE CHANNEL 2
Notes 1. The receive buffer register (RXB) must be read when an overrun error is generated. Overrun errors
will continue to be generated until RXB is read.
2. Even if the stop bit length has been set as 2 bits by bit 2 (SL) of the asynchronous serial interface
mode register (ASIM), only single stop bit detection is performed during reception.
(3) Asynchronous serial interface status register (ASIS)
This is a register which displays the type of error when a reception error is generated in the asynchronous
serial interface mode.
ASIS is read with a 8-bit memory manipulation instruction.
In 3-wire serial I/O mode, the contents of the ASIS are undefined.
RESET input sets ASIS to 00H.
Figure 19-5. Asynchronous Serial Interface Status Register Format
PE
65432107
Symbol
ASIS 0 0 0 0 0 FE OVE
FF71H 00H R
Address After Reset R/W
OVE
0
1
Overrun Error Flag
Overrun error not generated
Overrun error generated
Note 1
(When next receive operation is completed before
data from receive buffer register is read)
FE
0
1
Framing Error Flag
Framing error not generated
Framing error generated
Note 2
(When stop bit is not detected)
PE
0
1
Parity Error Flag
Parity error not generated
Parity error generated (When transmit data parity
does not match)