NEC uPD78054Y User Manual

The 3-wire serial I/O mode is used for data transmission/reception in 8-bit units.  Bit-wise data transmission/

reception is carried out in synchronization with the serial clock.

Shift operation of the serial I/O shift register 1 (SIO1) is 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.

SI1

SCK1

1

2

3

4

5

6

7

8

DI7

DI6

DI5

DI4

DI3

DI2

DI1

DI0

SO1

DO7

DO6

DO5

DO4

DO3

DO2

DO1

DO0

CSIIF1

Transfer Start at the Falling Edge of SCK1

End of Transfer

SIO1 Write