NEC PD78078 User Manual

SI2

SCK2

1

2

3

4

5

6

7

8

DI7

DI6

DI5

DI4

DI3

DI2

DI1

DI0

SO2

DO7

DO6

DO5

DO4

DO3

DO2

DO1

DO0

SRIF

Transfer Start at the Falling Edge of SCK2

End of Transfer

In the 3-wire serial I/O mode, data transmission/reception is performed in 8-bit units.  Data is transmitted/

received bit by bit in synchronization with the serial clock.

Transmit shift register (TXS/SIO2) and receive shift register (RXS) shift operations are performed in

synchronization with the fall of the serial clock (SCK2).  Then transmit data is held in the SO2 latch and output

from the SO2 pin.  Also, receive data input to the SI2 pin is latched in the receive buffer register (RXB/SIO2)

on the rise of SCK2.

At the end of an 8-bit transfer, the operation of TXS/SIO2 and RXS stops automatically, and the interrupt

request flag (SRIF) is set.