HD6432670 Hitachi, HD6432670 Datasheet - Page 714

• Manufacturer Part Number: HD6432670
• Description: (HD64F267x Series) 16-Bit Microcomputer
• Manufacturer: Hitachi

15.4.6
Figure 15.8 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
2. If an overrun error (when reception of the next data is completed while the RDRF flag is still
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 (when the stop bit is 0) is detected, the FER bit in SSR is set to 1 and receive
5. If reception finishes successfully, the RDRF bit in SSR is set to 1, and receive data is
Table 15.11 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
Rev. 2.0, 04/02, page 668 of 906
RDRF
FER
synchronization, receives receive data in RSR, and checks the parity bit and stop bit.
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.
RDR. If the RIE bit in SCR is set to 1 at this time, an ERI interrupt request is generated.
data is transferred to RDR. If the RIE bit in SCR is set to 1 at this time, an ERI interrupt
request is generated.
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 routine reads the receive data transferred to RDR before
reception of the next receive data has finished, continuous reception can be enabled.
1
Serial Data Reception (Asynchronous Mode)
Start
bit
0
D0
Figure 15.8 Example of SCI Operation in Reception
(Example with 8-Bit Data, Parity, One Stop Bit)
D1
1 frame
Data
D7
RXI interrupt
request
generated
Parity
bit
0/1
Stop
bit
1
Start
bit
0
RDR data read and RDRF
flag cleared to 0 in RXI
interrupt handling routine
D0
D1
Data
D7
Parity
bit
ERI interrupt request
generated by framing
error
0/1
Stop
bit
0
Idle state
(mark state)
1