uPD789871 Subseries 8-Bit Single-Chip Microcontrollers PUM
uPD789871 Subseries 8-Bit Single-Chip Microcontrollers PUM
uPD789871 Subseries 8-Bit Single-Chip Microcontrollers PUM
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102<br />
CHAPTER 10 SERIAL INTERFACE 10<br />
10.4.2 3-wire serial I/O mode<br />
The 3-wire serial I/O mode is useful for connection of peripheral I/Os and display controllers, etc., which incorporate<br />
a conventional clocked serial interface, such as the 75XL Series, 78K Series, 17K Series, etc.<br />
Communication is performed using three lines: the serial clock (SCK10), serial output (SO10), and serial input<br />
(SI10).<br />
(1) Register setting<br />
3-wire serial I/O mode settings are performed using serial operation mode register 10 (CSIM10).<br />
(a) Serial operation mode register 10 (CSIM10)<br />
CSIM10 is set with a 1-bit or 8-bit memory manipulation instruction.<br />
RESET input clears CSIM10 to 00H.<br />
Symbol 6 5 4 3 2 1 0 Address After reset R/W<br />
CSIM10<br />
CSIE10 0 TPS101TPS100 0 DIR10 CSCK10 0<br />
CSIE10<br />
0<br />
1<br />
TPS101 TPS100<br />
0<br />
0<br />
1<br />
1<br />
DIR10<br />
0<br />
1<br />
CSCK10<br />
0<br />
1<br />
Operation stopped<br />
Operation enabled<br />
0<br />
1<br />
0<br />
1<br />
MSB<br />
LSB<br />
fX/2 2 (1.25 MHz)<br />
fX/2 3 (625 kHz)<br />
fX/2 4 (313 kHz)<br />
fX/2 5 (157 kHz)<br />
Caution <strong>Bit</strong>s 0, 3, and 6 must be set to 0.<br />
Operation control in 3-wire serial I/O mode<br />
Remarks 1. fX: Main system clock oscillation frequency<br />
2. The parenthesized values apply to operation at fX = 5.0 MHz.<br />
Preliminary User’s Manual U14938EJ1V0UM<br />
FF72H 00H R/W<br />
Count clock selection during operation enabled in 3-wire serial I/O mode<br />
Input clock to SCK10 pin from external<br />
Count clock selected by TPS100, TPS101<br />
Start bit specification<br />
Clock selection in 3-wire serial I/O mode