Figure 8.10-2 Bidirectional Serial I/O Operation - Fujitsu F2MC-8L Series Hardware Manual

CHAPTER 8 8-BIT SERIAL I/O
SIO-A
Start
Halt operation of SIO-A
(SST="0")
Set the SI pin as the serial data input
(input port).
•Set the SCK pin as the shift clock
output
•Set the SO pin as the serial data
output
•Select an internal shift clock
•Set the data transfer (shift)
Is serial
NO
transfer enabled
on SIO-B?
Set output data
Start serial transfer
(SST="1")
Serial data transfer in progress
NO
Have 8 bits been
transferred?
Read input data
YES
More data to send?
END
214

Figure 8.10-2 Bidirectional Serial I/O Operation

*1
YES
Transfer enabled state
*2
SIO-A
SIO-A outputs serial data
Simultaneously, SIO-B inputs data
*3
YES (SST="0")
SST: The SST bit is the serial I/O transfer start bit in the serial mode register (SMR).
*1 : If the SO, SI, and SCK pins only are connected, there is no direct method of confirming whether SIO-
B has enabled serial transfer. Therefore, SIO-A must use a software timer or similar to delay time for
a sufficient time for SIO-B to enable serial transfer.
NO
*2 : Data is not transferred correctly if SIO-A starts data transfer when SIO-B has not enabled serial
transfer.
*3 : An interrupt request is generated after 8-bit data has been transferred.
SIO-B
Start
Halt operation of SIO-B
(SST="0")
Set the SI pin as the serial data input
(input port).
•Set the SCK pin as the shift clock
input
•Set the SO pin as the serial data
output
•Select external shift clock
•Select the same data transfer
Set output data
Enable serial transfer
(SST="1")
SIO-B
Serial data transfer in progress
Have 8 bits been
transferred? *3
YES (SST="0")
Read input data
(Shift)
NO