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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
Clear TE bit in SCR to 0
<End>
Figure 14.17 Sample Serial Transmission Flowchart
[1] SCI initialization:
[1]
The TxD pin is automatically
designated as the transmit data output
pin.
[2] SCI status check and transmit data
[2]
write:
Read SSR and check that the TDRE
flag is set to 1, then write transmit data
No
to TDR and clear the TDRE flag to 0.
[3] Serial transmission continuation
procedure:
To continue serial transmission, be
sure to read 1 from the TDRE flag to
confirm that writing is possible, then
write data to TDR, and then clear the
TDRE flag to 0.
No
Checking and clearing of the TDRE
[3]
flag is automatic when the DTC is
activated by a transmit data empty
interrupt (TXI) request and data is
written to TDR.
No
Rev. 1.0, 09/02, page 335 of 568
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