3-Wire Serial I/O Mode - NEC PD78081(A) User Manual

11.4.3 3-wire serial I/O mode

The 3-wire serial I/O mode is useful for connection of peripheral I/Os and display controllers, etc., which incorporate
a conventional synchronous clocked serial interface, such as the 75X/XL series, 78K series, 17K series, etc.
Communication is performed using three lines: the serial clock (SCK2), serial output (SO2), and serial input (SI2).
(1) Register setting
3-wire serial I/O mode settings are performed using serial operating mode register 2 (CSIM2), the asynchro-
nous serial interface mode register (ASIM), and the baud rate generator control register (BRGC).
(a) Serial operating mode register 2 (CSIM2)
CSIM2 is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets CSIM2 to 00H.
Symbol
7 6
CSIM2 CSIE2 0
Caution Set 0 to the bits 0 and 3 to 6.
CHAPTER 11 SERIAL INTERFACE CHANNEL 2
5 4 3 2
CSIM
0 0 0
CSCK
22
1 0 Address After Reset
FF72H
0
CSCK Clock Selection in 3-wire Serial I/O Mode
0 Input clock from off-chip to SCK2 pin
1 Dedicated baud rate generator output
First Bit Specification
CSIM22
0 MSB
1 LSB
CSIE2 Operation Control in 3-wire Serial I/O Mode
0 Operation stopped
1 Operation enabled
R/W
00H R/W
163