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• Transmitting
Figure 10.6 shows an example of a flowchart for data transmission. This procedure should be
followed for data transmission after initializing SCI3.
Sets bits SPC31 and
SPC32 to 1 in SPCR
Read bit TDRE
1
TDRE = 1?
Write transmit
data to TDR
Continue data
2
transmission?
Read bit TEND
TEND = 1?
3
Break output?
Set PDR = 0,
Clear bit TE to 0
Figure 10.6 Example of Data Transmission Flowchart (Asynchronous Mode)
Start
in SSR
No
Yes
Yes
No
in SSR
No
Yes
No
Yes
PCR = 1
in SCR3
End
1.
Read the serial status register (SSR)
and check that bit TDRE is set to 1,
then write transmit data to the transmit
data register (TDR). When data is
written to TDR, bit TDRE is cleared to 0
automatically.
(After the TE bit is set to 1, one frame of
1s is output, then transmission is possible.)
2.
When continuing data transmission,
be sure to read TDRE = 1 to confirm that
a write can be performed before writing
data to TDR. When data is written to
TDR, bit TDRE is cleared to 0
automatically.
3.
If a break is to be output when data
transmission ends, set the port PCR to 1
and clear the port PDR to 0, then clear bit
TE in SCR3 to 0.
279
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