Renesas rl78 Manual Do Utilizador
RL78/G1A
CHAPTER 12 SERIAL ARRAY UNIT
R01UH0305EJ0200 Rev.2.00
514
Jul 04, 2013
Figure 12-82. Flowchart of UART Transmission (in Continuous Transmission Mode)
Setting transmit data
Write 1 to STmn bit
For the initial setting, see Figure 12-77.
(Select buffer empty interrupt)
(Select buffer empty interrupt)
SAU default setting
Yes
No
No
End of communication
Yes
No
Communication
continued?
Yes
Number of
communication data > 0?
<2>
<3>
<4>
<5>
<6>
<1>
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)
(Storage area, Transmission data pointer, Number of communication data and
Communication end flag are optionally set on the internal RAM by the software)
Clear MDmn0 bit to 0
Writing transmit data to the
SDRmn[7:0] bits (TXDq
register) (8 bits) or the
SDRmn[8:0] bits (9 bits)
Writing transmit data to the
SDRmn[7:0] bits
(TXDq register) (8 bits) or
the SDRmn[8:0] bits (9 bits)
SDRmn[7:0] bits
(TXDq register) (8 bits) or
the SDRmn[8:0] bits (9 bits)
If transmit data is left, read them from storage area then
write into TxDq, and update transmit data pointer and
number of transmit data.
If no more transmit data, clear MDmn bit if it s set. If not,
finish.
Subtract -1 from number of
transmit data
RETI
Transmission completed?
Starting UART
communication
When transfer end interrupt is generated, it moves to
interrupt processing routine.
Buffer empty/transfer end interrupt
Write 1 to MDmn0 bit
Yes
No
MDmn = 1?
Sets communication
completion interrupt flag
Wait for transmit completes
Clear interrupt request flag (XXIF), reset interrupt mask (XXMK) and set
interrupt enable (EI).
interrupt enable (EI).
Enables interrupt
Disable interrupt (MASK)
Check completion of transmission by
verifying transmit end flag
Transmission starts by writing
to the SDRmn[7:0] bits (TXDq
register) (8 bits) or the
SDRmn[8:0] bits (9 bits).
Read transmit data from storage area and write it
to TXDq. Update transmit data pointer.
to TXDq. Update transmit data pointer.
Main routine
Main routine
Interrupt processing routine
<2>
Remarks 1. <1> to <6> in the figure correspond to <1> to <6> in Figure 12-81 Timing Chart of UART
Transmission (in Continuous Transmission Mode).
2.
m: Unit number (m = 0, 1), n: Channel number (n = 0, 2), q: UART number (q = 0 to 2)
mn = 00, 02, 10
<R>
<R>
<R>
<R>