NEC PD75402A User Manual page 103

(b) To transmit/receive MSB-first data using an external clock (slave operation).
<Sample program>
Main routine
MOV XA, #80H
MOV CSIM, XA
MOV XA, TDATA
MOV SIO, XA
EI IECSI
EI
Interrupt routine
MOV XA, TDATA
XCH XA, SIO
MOV RDATA, XA
RETI
92
CHAPTER 5. PERIPHERAL HARDWARE FUNCTIONS
PD75402A
P01/SCK
SI
SO/SB0
; Serial operation stopped, external clock specification
; Transfer data setting & start of transfer
; Receive data send data & start of transfer
; Receive data save
Other Microcomputer
SCK
SO
SI