HD6473032F16 Datasheet, PDF (498/847 Pages) Renesas Technology Corp – Hardware Manual Renesas 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Series

Section 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.
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
All data
transmitted?
Yes
No
3
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 1 is output, then transmission
is possible.
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.
Read TEND flag in SSR
TEND = 1?
Yes
Output break
signal?
Yes
Clear DR bit to 0,
set DDR bit to 1
No
No
4
Clear TE bit to 0 in SCR
End
Figure 13.5 Sample Flowchart for Transmitting Serial Data
Rev. 3.00 Mar 21, 2006 page 468 of 814
REJ09B0302-0300