Fujitsu F2MC-8L F202RA Hardware Manual page 351

Figure 14.10-2 Bidirectional Serial I/O Operation
SIO-A
START
Stop SIO-A operation
(SST=0)
Set SI pin to serial data
input (input port)
-
Set SCK pin to shift clock
output
- Set SO pin to serial data
output
- Select internal shift clock
-
Set data transfer (shift
clock) direction
Is SIO-B in
NO
serial transfer allowance
(*1)
state?
YES
Set output data
(*2)
Start serial I/O transfer
(SST=1)
SIO-A
Serial data transfer
NO
End of 8-bit transfer?
(*3)
YES(SST=0)
Read input data
YES
Is next data available?
NO
END
*1
If only the SO, SI, and SCK pins are connected, there is no method for directly checking
whether SIO-B is in the serial transfer allowance state. For this reason, a timer, etc., must be
used to monitor the wait time period that lasts until SIO-B is allowed for transfer via software.
*2
If SIO-B is not allowed for serial I/O transfer, data cannot be transferred correctly even if
SIO-A starts serial I/O transfer.
*3
When 8-bit data transfer terminates, a interrupt request occurs.
Transfer allowance state
Serial data output via SIO-A
Simultaneous data input via SIO-B
SST: The SST bit is the serial I/O transfer start bit of the serial mode
register (SMR).
CHAPTER 14 8-BIT SERIAL I/O
SIO-B
START
Stop SIO-B operation
(SST=0)
Set SI pin to serial data
input (input port)
-
Set SCK pin to shift clock
input
-
Set SO pin to serial data
output
-
Select external shift clock
-
Select same data transfer
(shift) direction as SIO-A
Set output data
Allow serial data transfer
(SST=1)
SIO-B
Serial data transfer
End of 8-bit transfer?
(*3)
YES(SST=0)
Read input data
NO
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