UPD784938 Datasheet, PDF (463/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

(b) LSB-first
SCK0^Note
SI0 (input)
SO0 (output)
CHAPTER 19 3-WIRE SERIAL I/O MODE
Figure 19-4. 3-Wire Serial I/O Mode Timing (2/2)
1 2 34567 8
DI0 DI1 DI2 DI3 DI4 DI5 DI6 DI7
DO0 DO1 DO2 DO3 DO4 DO5 DO6 DO7
INTCSI
Transfer end
interrupt generation
Start of transfer synchronized with fall of SCK0
Execution of instruction that writes to SIO, etc.
Note Master CPU: ^Output
Slave CPU: ^Input
In the 3-wire serial I/O mode, the SO0 pin functions as a CMOS push-pull output.
Preliminary User’s Manual U13987EJ1V0UM00
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