RX610 Group
20. Serial Communications Interface (SCI)
R01UH0032EJ0120 Rev.1.20
Page 648 of 1006
Feb 20, 2013
20.3.6
Serial Data Reception (Asynchronous Mode)
Figure 20.10 shows an example of the operation for serial data reception in asynchronous mode.
In serial data reception, the SCI operates as described below.
1. When the SCI monitors the communications line and detects a start bit, it performs internal synchronization, stores
receive data in RSR, and checks the parity bit and stop bit.
2. If an overrun error occurs, the ORER flag in SSR is set to 1. If the RIE bit in SCR is set to 1 at this time, an ERI
interrupt request is generated. Receive data is not transferred to RDR.
3. If a parity error is detected, the PER bit in SSR is set to 1 and receive data is transferred to RDR. If the RIE bit in
SCR is set to 1 at this time, an ERI interrupt request is generated.
4. If a framing error (when the stop bit is 0) is detected, the FER bit in SSR is set to 1 and receive data is transferred to
RDR. If the RIE bit in SCR is set to 1 at this time, an ERI interrupt request is generated.
5. When reception finishes successfully, receive data is transferred to RDR. If the RIE bit in SCR is set to 1 at this
time, an RXI interrupt request is generated. Continuous reception is enabled by reading the receive data transferred
to RDR in this RXI interrupt processing routine before reception of the next receive data is completed.
RXI interrupt signal
SSR.FER flag
0
1 frame
D0
D1
D7
0/1
1
0
D0
D1
D7
0/1
0
1
1
Data
Data
Parity
bit
Stop
bit
Start
bit
Parity
bit
Stop
bit
Start
bit
Idle state
(mark state)
ERI interrupt request
generated by framing error
RDR data read in RXI
interrupt processing routine
RXI interrupt
request
generated
Note:
*
For the corresponding interrupt vector number, see section 10, Interrupt Control Unit (ICU).
Figure 20.10 Example of SCI Operation for Serial Reception in Asynchronous Mode
(Example with 8-Bit Data, Parity, One Stop Bit)
Summary of Contents for RX600 Series
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