Datasheet

RL78/L12 CHAPTER 12 SERIAL ARRAY UNIT
R01UH0330EJ0200 Rev.2.00 484
Dec 13, 2013
Figure 12-79. Flowchart of UART Transmission (in Single-Transmission Mode)
Starting UAR
T
communication
Write STmn bit to 1
Transmission completed?
No
Yes
End of communication
Writing transmit data to
TxDq (=SDRmn[7:0])
When Transfer end interrupt is generated, it
moves to interrupt processing routine
Setting transmit data
For the initial setting, refer to Figure 12-75.
(Select transfer end interrupt)
SAU default setting
Wait for transmit completes
Transfer end interrupt
Enables interrupt
Clear interrupt request flag (XXIF), reset interrupt mask (XXMK) and set
interrupt enable (EI).
Disable interrupt (MASK)
Set data for transmission and the number of data. Clear communication end flag
(Storage area, transmission data pointer, number of communication data and
communication end flag are optionally set on the internal RAM by the software)
Check completion of transmission by
verifying transmit end flag
Communication starts by writing
to SDRmn[7:0]
Read transmit data from storage area and write it
to TxDq. Update transmit data pointer.
Read transmit data, if any, from storage area and
write it to TxDq. Update transmit data pointer.
If not, set transmit end flag
Main routine Main routineInterrupt processing routine
Transmitting next data?
Writing transmit data to
TxDq (=SDRmn[7:0])
No
Sets communication
completion flag
RETI
Yes
<R>