UPD75238GJ NEC [NEC], UPD75238GJ Datasheet - Page 108

• Manufacturer Part Number: UPD75238GJ
• Description: 4 BIT SINGLE-CHIP MICROCOMPUTER
• Manufacturer: NEC [NEC]

108
(8) Serial interface (channel 1) functions
(9) Serial interface (channel 1) configuration
The serial interface (channel 1) of the PD75238 has following two modes.
The functions of the two modes are outlined below.
• Operation halt mode
• Three-wire serial I/O mode
Fig. 4-59 shows the block diagram of the serial interface (channel 1).
This mode is used when serial transfer is not performed. This mode reduces power consumption.
8-bit data transfer is performed using three lines: Serial clock (SCK1), serial output (SO1), and serial
input (SI1).
The three-wire serial I/O mode allows full-duplex transmission, so data transfer can be performed at
higher speed.
Eight-bit data transfer always starts the MSB.
The three-wire serial I/O mode enables connections to be made with the 75X series, 78K series, and many
other types of peripheral I/O devices.
PD75238