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Figure 13.18 Sample Flowchart for Serial Receiving (2)
In receiving, the SCI operates as follows.
1. The SCI synchronizes with serial clock input or output and initializes internally.
2. Receive data is stored in RSR in order from LSB to MSB.
After receiving the data, the SCI checks that the RDRF flag is 0 so that receive data can be
transferred from RSR to RDR. If this check passes, the RDRF flag is set to 1 and the
received data is stored in RDR. If the check does not pass (receive error), the SCI operates
as indicated in table 13.11.
When a receive error has been identified in the error check, subsequent transmit and
receive operations are disabled.
3. After setting the RDRF flag to 1, if the RIE bit is set to 1 in SCR, the SCI requests a
receive-data-full interrupt (RXI). If the ORER flag is set to 1 and the RIE bit in SCR is also
set to 1, the SCI requests a receive-error interrupt (ERI).
Figure 13.19 shows an example of SCI receive operation.
Section 13 Serial Communication Interface
3
Error handling
Overrun error handling
Clear ORER flag to 0 in SSR
End
Rev. 3.00 Mar 21, 2006 page 485 of 814
REJ09B0302-0300
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