RX610 Group
20. Serial Communications Interface (SCI)
R01UH0032EJ0120 Rev.1.20
Page 647 of 1006
Feb 20, 2013
Initialization
Start data transmission
[ 1 ]
[ 1 ]
SCIn initialization:
The TxDn pin is automatically designated as the transmit
data output pin. After the TE bit in SCR is set to 1, a 1 is output
for a frame, and transmission is enabled.
[ 2 ]
Transmit data write to TDR upon accepting a TXI
interrupt request:
When transmit data is transferred from TDR to TSR, a transmit
data empty interrupt (TXI) request is generated. Write transmit
data to TDR once in the TXI interrupt processing routine.
[ 3 ]
Serial transmission continuation procedure:
To continue serial transmission, write transmit data to
TDR once upon accepting a TXI interrupt request.
Transmit data can also be written to TDR by initiating
the DMAC or DTC.
[ 4 ]
Break output at the end of serial transmission:
To output a break in serial transmission, set the Bi bit
in DDR of Pn for the port corresponding to the TxDn pin
to 1 (output port), clear the Bi bit in DR of Pn to 0
(low level output), then clear the TE bit in SCR to 0.
[ 2 ]
No
Yes
Write transmit data to TDR
No
Yes
No
Yes
Read TEND flag in SSR
No
Yes
Clear Bi bit in DR of Pn to 0 and
set Bi bit in DDR of Pn to 1
Clear bits TIE, TE, and TEIE
in SCR to 0
TXI interrupt
All data transmitted?
SSR.TEND = 1
Break output
[ 4 ]
[ 3 ]
Clear the TIE bit in SCR to 0
End
Figure 20.9 Example of Serial Transmission Flowchart in Asynchronous Mode