Serial Data Reception (Asynchronous Mode); Figure 12.8 Example Of Sci Operation For Reception (Example With 8-Bit Data, Parity, One Stop Bit) - Renesas H8SX/1520 Series Hardware Manual

Section 12 Serial Communication Interface (SCI)
12.4.6

Serial Data Reception (Asynchronous Mode)

Figure 12.8 shows an example of the operation for reception in asynchronous mode. In serial
reception, the SCI operates as described below.
1. The SCI monitors the communication line, and if a start bit is detected, performs internal
synchronization, stores receive data in RSR, and checks the parity bit and stop bit.
2. If an overrun error (when reception of the next data is completed while the RDRF flag in SSR
is still set to 1) occurs, the ORER bit 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. The RDRF
flag remains to be set to 1.
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. If reception finishes successfully, the RDRF 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 RXI interrupt request is
generated. Because the RXI interrupt processing routine reads the receive data transferred to
RDR before reception of the next receive data has finished, continuous reception can be
enabled.
Start
1 bit
RDRF
FER
Rev. 3.00 Mar. 14, 2006 Page 412 of 804
REJ09B0104-0300
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Data
0 D0 D1 D7
1 frame
Figure 12.8 Example of SCI Operation for Reception
(Example with 8-Bit Data, Parity, One Stop Bit)
Parity Stop Start
bit bit bit
0/1 1 0 D0
RXI interrupt RDR data read and RDRF
request flag cleared to 0 in RXI
generated interrupt processing routine
Data Parity Stop
bit bit
D1 D7 0/1 0
ERI interrupt request
generated by framing
error
1
Idle state
(mark state)