Datasheet

Section 15 Serial Communication Interface (SCI)
Rev. 2.00 Sep. 28, 2009 Page 430 of 994
REJ09B0452-0200
No
[1]
Yes
Initialization
Start transmission
Read TDRE flag in SSR
[2]
Write transmit data to TDR
and clear TDRE flag in SSR to 0
No
Yes
No
Yes
Read TEND flag in SSR
[3]
No
Yes
[4]
[5]
Clear DR to 0 and
set DDR to 1
Clear TE bit in SCR to 0
TDRE = 1
All data transmitted?
TEND = 1
Break output?
[1] SCI initialization:
The TxD pin is automatically
designated as the transmit data
output pin.
After the TE bit is set to 1, a frame
of 1s is output, and transmission is
enabled.
[2] SCI status check and transmit
data write:
Read SSR and check that the
TDRE flag is set to 1, then write
transmit data to TDR and clear the
TDRE flag to 0.
[3] Serial transmission continuation
procedure:
To continue serial transmission,
read 1 from the TDRE flag to
confirm that writing is possible,
then write data to TDR, and clear
the TDRE flag to 0.
[4] Break output at the end of serial
transmission:
To output a break in serial
transmission, set DDR for the port
corresponding to the TxD pin to 1,
clear DR to 0, then clear the TE bit
in SCR to 0.
Note: Do not write to SMR, SCR,
BRR, and SDCR from the
start to the end of
transmission except the
process of [5].
End transmission
Figure 15.7 Sample Serial Transmission Flowchart