Two-Wire Serial I/O Mode; Example Of Two-Wire Serial I/O System Configuration - NEC PD750004 User Manual

µPD750008 USER'S MANUAL
<Sample program> (master side):
LOOP : SKTCLR

5.6.6 Two-Wire Serial I/O Mode

The two-wire serial I/O mode can be made compatible with any communication format by programming.
In this mode, communication is basically performed using two lines: Serial clock (SCK) and serial data input/
output (SB0 or SB1).
Figure 5-47. Example of Two-Wire Serial I/O System Configuration
Remark The µPD750008 can also be used as a slave CPU.
(1) Register setting
To set the two-wire serial I/O mode, manipulate the following two registers:
• Serial operation mode register (CSIM)
• Serial bus interface control register (SBIC)
144
CLR1 MBE
MOV XA,#10000011B
MOV CSIM,XA
MOV XA,TDATA
MOV SIO,XA
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IRQCSI
BR LOOP
MOV XA,SIO
2-wire serial I/O
Master CPU
(µPD750008)
SCK
SB0, SB1
; Set transfer mode
; Set transfer data, and start transfer
; Test IRQCSI
; Read in receive data
2-wire serial I/O
Slave CPU
SCK
V
DD
SB0, SB1