Fujitsu MB90390 Series Hardware Manual page 477

Figure 22.4-1 Extended I/O Serial Interface Operation Transitions
End of transfer
STRT=0, BUSY=0
MODE=0
MODE=0
STOP=0 &
& STOP=0
STRT=1 &
END
Transfer
STRT=1, BUSY=1
Figure 22.4-2 Serial Data Register Read/Write
SOT4
Data bus
SOT3
SIN4
Read
SIN3
Write
Interrupt output
Extended I/O
serial interface
1. If "1" is written to MODE, transfer ends according to the shift clock counter. The read/write standby
state starts when "1" is written to SIR. If "1" is written to the SIE bit, an interrupt signal is generated. No
interrupt signal is generated when SIE is inactive or transfer has been terminated by writing "1" to
STOP.
2. Reading or writing to the serial data register clears the interrupt request and starts serial transfer.
STOP=0 & STRT=0
STOP=1
STOP=1
STRT=1
MODE=1 & END & STOP=0
SDR R/W & MODE=1
Data bus
Read
Write
➀
➁
Interrupt input
Data bus
CHAPTER 22 SERIAL I/O
Reset
STOP
STRT=0, BUSY=0
STOP=0
&
Serial data register Read/Write standby
STRT=1, BUSY=0
MODE=1
CPU
Interrupt controller
STOP=1
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