UPD784026 Renesas Electronics Corporation., UPD784026 Datasheet - Page 460

• Manufacturer Part Number: UPD784026
• Description: 16/8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

420
Remark If the PD784026 is connected to a 2-wire serial I/O device, a buffer should be connected to the SO1 pin as
(b) LSB-first
SO1 (Output)
shown in Figure 16-13. In the example shown in Figure 12-13, the output level is inverted by the buffer, and
therefore the inverse of the data to be output should be written to SIO1.
In addition, non-connection of the internal pull-up resistor should be specified for the P33/SO1 pin.
SI1 (Input)
INTCSI1
SCK1*
CHAPTER 16 ASYNCHRONOUS SERIAL INTERFACE/3-WIRE SERIAL I/O
Figure 16-13 Example of Connection to 2-Wire Serial I/O
PD784026
Figure 16-12 3-Wire Serial I/O Mode Timing (2/2)
1
DO0 DO1 DO2 DO3 DO4 DO5 DO6 DO7
DI0
SCK1
SO1
SI1
2
Execution of instruction that writes to SIO1, etc.
Start of transfer synchronized with fall of SCK1
DI1
3
DI2
4
DI3
5
DI4
6
DI5
7
DI6
8
SCK
SIO
2-Wire Serial I/O
Device
DI7
Transfer End
Interrupt Generation
* Master CPU: Output
Slave CPU : Input