Renesas RX100 Series User Manual page 646

RX13T Group
Initialization
Start data transmission
TXI interrupt
Write transmit data to TDR
All transmit data written?
Set the SCR.TIE bit to 0 and set the
SCR.TEIE bit to 1
TEI interrupt
Break output
Set the I/O port functions
Set bits SCR.TIE, TE, and TEIE to 0
End
Figure 23.12 Example of Serial Transmission Flowchart in Asynchronous Mode
R01UH0822EJ0100 Rev.1.00
Jul 31, 2019
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23. Serial Communications Interface (SCIg, SCIh)
[ 1 ] SCI initialization:
[ 1 ]
Set data transmission.
After the TE bit in SCR is set to 1, high is output for a frame,
and transmission is enabled.
[ 2 ] Transmit data write to TDR by a TXI interrupt request:
When transmit data is transferred from TDR to TSR, a transmit
data empty interrupt (TXI) request is generated.
[ 2 ]
Write transmit data to TDR once in the TXI interrupt handling
routine.
[ 3 ] Serial transmission continuation procedure:
To continue serial transmission, write transmit data to TDR
[ 3 ]
once using a TXI interrupt request.
Transmit data can also be written to TDR by activating the DTC.
When TEI interrupt requests are in use, set the SCR.TIE bit to 0
and the SCR.TEIE bit to 1 after the last of the data to be
transmitted are written to the TDR
[ 4 ] Break output at the end of serial transmission:
To output a break in serial transmission, set the I/O port
function corresponding to the TXDn pin (corresponding to
output of the low level), and after switching the TXDn pin to the
general I/O port function, set the TE bit in the SCR to 0.
[ 4 ]
Note: The TDR register becomes the TDRH and TDRL registers
when 9-bit data length is selected. Write data in the order from
TDRH to TDRL.
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