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Synchronization
clock
Serial data
TDRE
TEND
TXI interrupt
request generated
Figure 13.16 Example of Operation for Transmission in Clocked Synchronous Mode
Initialization
Start transmission
Read TDRE flag in SSR
TDRE = 1
Write transmit data to TDR and
clear TDRE flag in SSR to 0
All data transmitted
Read TEND flag in SSR
TEND = 1
Clear TE bit in SCR to 0
<End>
Figure 13.17 Sample Serial Transmission Flowchart
Transfer direction
Bit 0
Bit 1
Data written to TDR
and TDRE flag cleared
to 0 in TXI interrupt
processing routine
1 frame
[1]
[2]
No
Yes
No
[3]
Yes
No
Yes
Section 13 Serial Communication Interface (SCI)
Bit 7
Bit 0
Bit 1
TXI interrupt
request generated
[1] SCI initialization:
The TxD pin is automatically
designated as the transmit data output
pin.
[2] SCI state 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, 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. However, the TDRE
flag is checked and cleared
automatically when the DTC is
initiated by a transmit data empty
interrupt (TXI) request and writes data
to TDR.
Rev.2.00 Jun. 28, 2007 Page 501 of 666
Bit 6
Bit 7
TEI interrupt request
generated
REJ09B0311-0200
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