UPD784938 Datasheet, PDF (428/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 18 ASYNCHRONOUS SERIAL INTERFACE/3-WIRE SERIAL I/O
18.1 Switching between Asynchronous Serial Interface Mode and 3-Wire Serial I/O Mode
The asynchronous serial interface mode and 3-wire serial I/O mode cannot be used simultaneously. Switching between
these modes is performed in accordance with the settings of the asynchronous serial interface mode register (ASIM/ASIM2)
and the clocked serial interface mode register (CSIM1/CSIM2) as shown in Figure 18-1.
Figure 18-1. Switching between Asynchronous Serial Interface Mode and 3-Wire Serial I/O Mode
7
6
5
4
3
ASIM TXE RXE PS1 PS0 CL
2
1
0 Address After reset R/W
SL ISRM SCK 0FF88H
00H
R/W
ASIM2 TXE2 RXE2 PS21 PS20 CL2 SL2 ISRM2 SCK2 0FF89H
00H
R/W
Asynchronous serial interface mode operation
specification (see Figure 18-3)
TXE RXE CTXE1 CRXE1 Operation Mode
TXE2 RXE2 CTXE2 CRXE2
0
0
0
0 Operation-stopped
mode
0
0
0
1 3-wire serial
0
0
1
0 ^{I/O mode}
0
0
1
1
0
1
0
0
1
0
0
0
1
1
0
0
Other than the above
Asynchronous
serial interface
mode
Setting prohibited
7
6
5
4
3
2
1
0 Address After reset R/W
CSIM1 CTXE1 CRXE1 0
0
0 DIR1 CSCK1 0 0FF84H
00H
R/W
CSIM2 CTXE2 CRXE2 0
0
0 DIR2 CSCK2 0 0FF85H
00H
R/W
3-wire serial I/O mode operation specification
(see Figure 18-11)
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Preliminary User’s Manual U13987EJ1V0UM00