HD6413002 Datasheet, PDF (466/700 Pages) Renesas Technology Corp – High-performance single-chip microcontroller

Transmitting Serial Data (Asynchronous Mode): Figure 13-5 shows a sample flowchart for
transmitting serial data and indicates the procedure to follow.
1
Initialize
Start transmitting
Read TDRE flag in SSR
2
No
TDRE = 1?
Yes
Write transmit data
in TDR and clear TDRE
flag to 0 in SSR
1. SCI initialization: the transmit data output function
of the TxD pin is selected automatically.
2. SCI status check and transmit data write: read SSR,
check that the TDRE flag is 1, then write transmit data
in TDR and clear the TDRE flag to 0.
3. To continue transmitting serial data: after checking
that the TDRE flag is 1, indicating that data can be
written, write data in TDR, then clear the TDRE
flag to 0. When the DMAC is activated by a transmit-
-data-empty interrupt request (TXI) to write data in TDR,
the TDRE flag is checked and cleared automatically.
4. To output a break signal at the end of serial transmission:
set the DDR bit to 1 and clear the DR bit to 0
(DDR and DR are I/O port registers), then clear the
TE bit to 0 in SCR.
All data
transmitted?
Yes
No 3
Read TEND flag in SSR
TEND = 1?
Yes
Output break
signal?
Yes
No
No
4
Clear DR bit to 0,
set DDR bit to 1
Clear TE bit to 0 in SCR
End
Figure 13-5 Sample Flowchart for Transmitting Serial Data
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