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Initialization
Start transmission
Read TDRE flag in SSR
TDRE = 1
Yes
Write transmit data to TDR
and clear TDRE flag in SSR to 0
All data transmitted?
Yes
Read TEND flag in SSR
TEND = 1
Yes
Break output
Yes
Clear DR to 0 and
set DDR to 1
Clear TE bit in SCR to 0
End transmission
Figure 14.7 Sample Serial Transmission Flowchart
Section 14 Serial Communication Interface (SCI)
[1] SCI initialization:
[1]
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
[2]
enabled.
[2] SCI status check and transmit
No
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:
No
To continue serial transmission,
read 1 from the TDRE flag to
confirm that writing is possible,
then write data to TDR, and clear
[3]
the TDRE flag to 0.
[4] Break output at the end of serial
transmission:
To output a break in serial
No
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.
No
[4]
Note:
Do not write to SMR, SCR,
BRR, and SDCR from the
start to the end of
transmission except the
process of [5].
[5]
Rev. 1.00 May 09, 2008 Page 389 of 954
REJ09B0462-0100
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