H83217 Datasheet, PDF (283/520 Pages) Renesas Technology Corp – Single-Chip Microcomputer

Transmitting Serial Data: Follow the procedure in figure 13-5 for transmitting serial data.
1
Initialize
Start transmitting
2
Read TDRE bit in SSR
No
TDRE = 1?
Yes
Write transmit data in TDR
If using multiprocessor format,
select MPBT value in SSR
Clear TDRE bit to 0
Serial transmission
End of
No
3
transmission?
Yes
Read TEND bit in SSR
No
TEND = 1?
Yes
4
Output break
No
signal?
Yes
Set DR = 0, DDR = 1
Clear TE bit in SCR to 0
1.
SCI initialization: the transmit data output function
of the TxD pin is selected automatically.
2.
SCI status check and transmit data write: read
the serial status register (SSR), check that the
TDRE bit is 1, then write transmit data in the
transmit data register (TDR) and clear TDRE to 0.
If a multiprocessor format is selected, after
writing the transmit data write 0 or 1 in the
multiprocessor bit transfer (MPBT) in SSR.
Transition of the TDRE bit from 0 to 1 can be
reported by an interrupt.
3. (a) To continue transmitting serial data: read the
TDRE bit to check whether it is safe to write; if
TDRE = 1, write data in TDR, then clear TDRE
to 0.
(b) To end serial transmission: end of transmission
can be confirmed by checking transition of the
TEND bit from 0 to 1. This can be reported by
a TEI interrupt.
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 TE to 0 in SCR.
End
Figure 13-5 Sample Flowchart for Transmitting Serial Data
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