Renesas H8 Series Hardware Manual page 406

Section 10 Serial Communication Interface
• Transmitting
Figure 10.6 shows an example of a flowchart for data transmission. This procedure should be
followed for data transmission after initializing SCI3.
Sets bit SPC32 to
Read bit TDRE
Write transmit
data to TDR
Continue data
transmission?
Read bit TEND
Break output?
Set PDR = 0,
Clear bit TE to 0
Figure 10.6 Example of Data Transmission Flowchart (Asynchronous Mode)
Rev. 7.00 Mar 10, 2005 page 364 of 652
REJ09B0042-0700
Start
1 in SPCR
[1]
in SSR
No
TDRE = 1?
Yes
[2]
Yes
No
in SSR
No
TEND = 1?
Yes
[3]
No
Yes
PCR = 1
in SCR3
End
[1] Read the serial status register (SSR)
and check that bit TDRE is set to 1,
then write transmit data to the transmit
data register (TDR). When data is
written to TDR, bit TDRE is cleared to 0
automatically.
(After the TE bit is set to 1, one frame of
1s is output, then transmission is possible.)
[2] When continuing data transmission,
be sure to read TDRE = 1 to confirm that
a write can be performed before writing
data to TDR. When data is written to
TDR, bit TDRE is cleared to 0
automatically.
[3] If a break is to be output when data
transmission ends, set the port PCR to 1
and clear the port PDR to 0, then clear bit
TE in SCR3 to 0.