HD6413007F20 Datasheet, PDF (491/798 Pages) Renesas Technology Corp – Hardware Manual Renesas 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Series

13. Serial Communication Interface
• Transmitting Serial Data (Asynchronous Mode): Figure 13.5 shows a sample flowchart for
transmitting serial data and indicates the procedure to follow.
Initialize
Start transmitting
Read TDRE flag in SSR
TDRE = 1
(1) ^{(1) SCI initialization:}
the transmit data output function of the TxD pin is
selected automatically.
After the TE bit is set to 1, one frame of 1s is output,
then transmission is possible.
(2)
No
(2) SCI status check and transmit data write:
read SSR and check that the TDRE flag is set to 1,
then write transmit data in TDR and clear the TDRE
flag to 0.
Yes
Write transmit data in TDR
and clear TDRE flag to 0 in SSR
All data transmitted?
Yes
Read TEND flag in SSR
No
(3)
No
TEND = 1
(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.
Yes
Output break signal?
No ₍₄₎
Yes
Clear DR bit to 0 and set
DDR bit to 1
Clear TE bit to 0 in SCR
<End>
Figure 13.5 Sample Flowchart for Transmitting Serial Data
Rev.5.00 Sep. 12, 2007 Page 461 of 764
REJ09B0396-0500