D12320VF25V Datasheet, PDF (522/1146 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 12 Serial Communication Interface (SCI)
In serial reception, the SCI operates as described below.
[1] The SCI performs internal initialization in synchronization with serial clock input or output.
[2] The received data is stored in RSR in LSB-to-MSB order.
After reception, the SCI checks whether the RDRF flag is 0 and the receive data can be
transferred from RSR to RDR.
If this check is passed, the RDRF flag is set to 1, and the receive data is stored in RDR. If a
receive error is detected in the error check, the operation is as shown in table 12.11.
Neither transmit nor receive operations can be performed subsequently when a receive error
has been found in the error check.
[3] If the RIE bit in SCR is set to 1 when the RDRF flag changes to 1, a receive-data-full interrupt
(RXI) request is generated.
Also, if the RIE bit in SCR is set to 1 when the ORER flag changes to 1, a receive-error
interrupt (ERI) request is generated.
Figure 12.19 shows an example of SCI operation in reception.
Serial
clock
Serial
data
RDRF
ORER
Bit 7 Bit 0
Bit 7 Bit 0 Bit 1
Bit 6 Bit 7
RXI interrupt request
generated
RDR data read and
RDRF flag cleared to 0
in RXI interrupt handling
routine
RXI interrupt request
generated
ERI interrupt request
generated by overrun
error
1 frame
Figure 12.19 Example of SCI Receive Operation
Simultaneous serial data transmission and reception (synchronous mode): Figure 12.20
shows a sample flowchart for simultaneous serial transmit and receive operations.
The following procedure should be used for simultaneous serial data transmit and receive
operations.
Rev.7.00 Feb. 14, 2007 page 488 of 1108
REJ09B0089-0700