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User’s Manual U12697EJ3V0UM
CHAPTER 17 3-WIRE SERIAL I/O MODE
17.4
Operation
3-wire serial I/O has the following two operation modes.
• Operation stop mode
• 3-wire serial I/O mode
(1) Operation stop mode
Since serial transfers are not performed in the operation stopped mode, power consumption can be decreased.
In the operation stop mode, the pin can be used as an ordinary I/O port.
(a) Register settings
The operation stop mode is set in serial operation mode register 0 (CSIM0).
CSIM0 is set by a 1-bit or 8-bit memory manipulation instruction.
RESET input sets CSIM0 to 00H.
Figure 17-3. Format of Serial Operation Mode Register 0 (CSIM0)
Address: 0FF90H After reset: 00H R/W
Symbol
7
6
5
4
3
2
1
0
CSIM0
CSIE0
0
0
0
0
MODE0
SCL01
SCL00
CSIE0
SIO0 operating enable/disable setting
Shift register operation
Serial counter
Port
0
Operation disabled
Clear
Port function
Note
1
Operation enabled
Operation count enabled
Serial fu port function
Note
If CSIE0 = 0 (SIO0 operation stopped state), the pins connected to SI0, SO0 and SCK0 can function
as ports.
Содержание mPD784225 Series
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