Electronics America Single-Chip Microcontrollers User's Manual

CHAPTER 12 SERIAL INTERFACE 1A0
224 User’s Manual U15331EJ4V1UD
12.4 Serial Interface 1A0 Operation
Serial interface 1A0 provides the following three modes.
• Operation stop mode
• 3-wire serial I/O mode
• 3-wire serial I/O mode with automatic transmit/receive function
12.4.1 Operation stop mode
In operation stop mode, serial transfer is not executed, thereby reducing the power consumption. The P23/SCK10,
P24/SO10, and P25/SI10 pins can be used as normal I/O ports.
(1) Register setting
Operation stop mode is set by serial operation mode register 1A0 (CSIM1A0).
(a) Serial operation mode register 1A0 (CSIM1A0)
CSIM1A0 is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input clears CSIM1A0 to 00H.
Symbol <7> 6 <5> <4> 3 2 1 0 Address After reset R/W
CSIM1A0 CSIE10 DIR10 ATE0 LSCK10 0 0 SCL101 SCL100 FF78H 00H R/W
Specification of operation enable/disable
CSIE10
Shift register operation Serial counter Port
Note
0 Operation stopped Cleared Port function
1 Operation enabled Count operation enabled Serial function + port function
Note When CSIE10 = 0 (SIO1A0 operation stop status), the SCK10/P23, SO10/P24, and SI10/P25 pins can
freely be used as port pins.