HD64336901G Renesas Technology, HD64336901G Datasheet - Page 234

• Manufacturer Part Number: HD64336901G
• Description: (HD64xxx Series) 16-BIT MICROCONTROLLER
• Manufacturer: Renesas Technology

14.4.4
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
2. If an overrun error occurs (when reception of the next data is completed while the RDRF flag
3. If a parity error is detected, the PER bit in SSR is set to 1 and receive data is transferred to
4. If a framing error is detected (when the stop bit is 0), the FER bit in SSR is set to 1 and receive
5. If reception is completed successfully, the RDRF bit in SSR is set to 1, and receive data is
Table 14.5 shows the states of the SSR status flags and receive data handling when a receive error
is detected. If a receive error is detected, the RDRF flag retains its state before receiving data.
Reception cannot be resumed while a receive error flag is set to 1. Accordingly, clear the OER,
FER, PER, and RDRF bits to 0 before resuming reception. Figure 14.9 shows a sample flow chart
for serial data reception.
Rev. 1.00, 11/03, page 206 of 376
Serial
data
RDRF
FER
LSI
operation
User
processing
synchronization, receives receive data in RSR, and checks the parity bit and stop bit.
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.
RDR. If the RIE bit in SCR3 is set to 1 at this time, an ERI interrupt request is generated.
data is transferred to RDR. If the RIE bit in SCR3 is set to 1 at this time, an ERI interrupt
request is generated.
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.
Serial Data Reception
1
Start
Figure 14.8 Example of SCI3 Reception in Asynchronous Mode
bit
0
D0
D1
Receive
1 frame
data
(8-Bit Data, Parity, One Stop Bit)
D7
Parity
0/1
bit
RXI request
Stop
bit
1
Start
bit
0
D0
RDRF
cleared to 0
RDR data read
1 frame
D1
Receive
data
D7
Parity
0/1
bit
Stop
bit
0
0 stop bit
detected
Mark state
(idle state)
1
ERI request in
response to
framing error
Framing error
processing