Electronics America 4-Bit Single-Chip Microcomputer User's Manual

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CHAPTER 5. PERIPHERAL HARDWARE FUNCTIONS
(7) 3-wire serial I/O mode applications
(a) To transfer data MSB-first (master operation) using a 262 kHz transfer clock (when operating at 4.19 MHz).
<Sample program>
MOV XA, #10000010B
MOV CSIM, XA ; Transfer mode setting
MOV XA, TDATA ; TDATA is transfer data storage address
MOV SIO, XA ; Transfer data setting & start of transfer
Note From the second time onward, the transfer can be started by setting data in SIO (MOV SIO, XA or XCH XA,
SIO).
SCK
µ PD75402A
SO/SB0
SCK
SI
In this application the µ PD75402A SI pin can be used as an input port.
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