UPD784938 Datasheet, PDF (440/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 18 ASYNCHRONOUS SERIAL INTERFACE/3-WIRE SERIAL I/O
18.3 3-Wire Serial I/O Mode
The 3-wire serial I/O mode is used to communicate with devices that incorporate a conventional clocked serial interface.
Basically, communication is performed using three lines: the serial clock (SCK), serial data output (SO), and serial data
input (SI). Generally, a handshake line is necessary for checking the communication status.
Figure 18-9. Example of 3-Wire Serial I/O System Configuration
3-wire serial I/O ↔ 3-wire serial I/O
Master CPU
Slave CPU
SCK
SO
SI
Port (interrupt)
Port
SCK
SI
SO
Note
Port
Interrupt (port)
Note Handshake lines
18.3.1 Configuration in 3-wire serial I/O mode
The block diagram in the 3-wire serial I/O mode is shown in Figure 18-10.
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Preliminary User’s Manual U13987EJ1V0UM00