Starting setting
End of communication
Disable interrupt (MASK)
Setting storage data and number of data for transmission/reception data
(Storage area, Transmission data pointer, Reception data, Number of
communication data and Communication end flag are optionally set on
the internal RAM by the software)
Clear interrupt request flag (xxIF), reset interrupt mask (xxMK), and
set interrupt enable (EI)
Wait for transmission/reception
completes
Subtract –1 from number of
communication data
Reading reception data from SIOp
(= SDRmn [7:0])
Number of
communication data
= 0?
RETI
Number of
communication
data?
Buffer empty/transfer end interrupt
SAU initial setting
No
Set STmn bit to 1
Continuing Communication?
Set MDmn0 bit to 1
Yes
Yes
No
Main routine Interrupt processing routine Main routine
<1>
<3> <6>
<8>
BFFmn = 1?
Yes
≥ 2
<4>
<7>
Writing transmit data to SIOp
(= SDRmn [7:0])
Enables interrupt
Setting transmission/reception data
When buffer empty/transfer end interrupt is generated,
it moves to interrupt processing routine.
<2>
Clear MDmn0 bit to 0
Writing transmit data to SIOp
(= SDRmn [7:0])
<5>
= 1= 0
No
Read transmit data from storage area and write it to
SIOp. Update transmit data pointer.
Writing to SIOp makes SOp
and SCKp signals out
(communication starts)
Except for initial interrupt, read data received then write
them to storage area, and update receive data pointer
If transmit data is left (number of communication data is equal
or greater than 2), read them from storage area then write into
SIOp, and update transmit data pointer.
If it s waiting for the last data to receive (number of
communication data is equal to 1), change interrupt timing to
communication end
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