Transmitting Serial Data (Synchronous Mode): Figure 13-16 shows a sample flowchart for
transmitting serial data and indicates the procedure to follow.
Figure 13-16 Sample Flowchart for Serial Transmitting
Start transmitting
Read TDRE flag in SSR
TDRE = 1?
Write transmit data in
TDR and clear TDRE flag
to 0 in SSR
End
1
2
3
No
Yes
No
Yes
SCI initialization: the transmit data output function
of the TxD pin is selected automatically. After setting
TE bit to 1, output 1 from frame one transmission is
possible.
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.
Read TEND flag in SSR
No
Yes
1.
2.
3.
Initialize
Clear TE bit to 0 in SCR
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.
All data
transmitted?
TEND = 1?
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