Serial Data Reception; Figure 14.8 Example Of Sci3 Reception In Asynchronous Mode (8-Bit Data, Parity, One Stop Bit) - Renesas H8 Series Hardware Manual
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Section 14 Serial Communication Interface 3 (SCI3)
14.4.4
Serial Data Reception
Figure 14.8 shows an example of operation for reception in asynchronous mode. In serial
reception, SCI3 operates as described below.
1. SCI3 monitors the communication line. If a start bit is detected, SCI3 performs internal
synchronization, receives receive data in RSR, and checks the parity bit and stop bit.
2. If an overrun error occurs (when reception of the next data is completed while the RDRF flag
is still set to 1), the OER bit in SSR is set to 1. If the RIE bit in SCR3 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 SCR3 is set to 1 at this time, an ERI interrupt request is generated.
4. If a framing error is detected (when the stop bit is 0), the FER bit in SSR is set to 1 and receive
data is transferred to RDR. If the RIE bit in SCR3 is set to 1 at this time, an ERI interrupt
request is generated.
5. If reception is completed successfully, the RDRF bit in SSR is set to 1, and receive data is
transferred to RDR. If the RIE bit in SCR3 is set to 1 at this time, an RXI interrupt request is
generated. Continuous reception is possible because the RXI interrupt routine reads the receive
data transferred to RDR before reception of the next receive data has been completed.
Start
bit
Serial
1
0
D0
data
RDRF
FER
LSI
operation
User
processing
Figure 14.8 Example of SCI3 Reception in Asynchronous Mode
Rev. 3.00 Sep. 14, 2006 Page 216 of 408
REJ09B0105-0300
Receive
Parity
Stop
data
bit
bit
D1
D7
0/1
1
1 frame
RXI request
(8-Bit Data, Parity, One Stop Bit)
Start
Receive
bit
data
0
D0
D1
D7
1 frame
RDRF
cleared to 0
RDR data read
Parity
Stop
Mark state
bit
bit
(idle state)
0/1
0
1
0 stop bit
ERI request in
detected
response to
framing error
Framing error
processing
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