Wire Serial I/O Mode Timing - NEC mPD780208 Subseries User Manual

CHAPTER 14 SERIAL INTERFACE CHANNEL 1
(2) Communication operation
The 3-wire serial I/O mode is used for data transmission/reception in 8-bit units. Data transmission/
reception is carried out bit by bit in synchronization with the serial clock.
Shift operations of serial I/O shift register 1 (SIO1) are carried out at the falling edge of the serial clock
(SCK1). The transmit data is held in the SO1 latch and is output from the SO1 pin. The receive data
input to the SI1 pin is latched into SIO1 at the rising edge of SCK1.
Upon termination of 8-bit transfer, the SIO1 operation stops automatically and the interrupt request flag
(CSIIF1) is set.
Figure 14-6. 3-Wire Serial I/O Mode Timing
SCK1 1 2 3 4 5 6 7 8
SI1 DI7 DI6 DI5 DI4 DI3 DI2 DI1 DI0
SO1 DO7 DO6 DO5 DO4 DO3 DO2 DO1 DO0
CSIIF1
End of transfer
Transfer start at the falling edge of SCK1
SIO1 write
Caution The SO1 pin becomes low level by SIO1 write.
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User's Manual U11302EJ4V0UM