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• Receiving Serial Data (Asynchronous Mode): Figure 12.7 shows a sample flowchart for
receiving serial data and indicates the procedure to follow.
Initialize
Start receiving
Read ORER, PER, and FER
flags in SSR
PER∨FER∨OPER= 1
Read RDRF flag in SSR
No
RDRF= 1
Read receive data from RDR, and
clear RDRF flag to 0 in SSR
No
All data received?
Clear RE bit to 0 in SCR
<End>
Figure 12.7 Sample Flowchart for Receiving Serial Data
(1)
(2)
Yes
(3)
Error handling
No
(continued on next page)
(4)
Yes
(5)
Yes
(1)
SCI initialization:
the receive data input function of the RxD
pin is selected automatically.
(2)(3)
Receive error handling and break detection:
if a receive error occurs, read the ORER,
PER, and FER flags in SSR to identify the
error. After executing the necessary error
handling, clear the ORER, PER, and FER
flags all to 0. Receiving cannot resume if
any of these flags remains set to 1. When a
framing error occurs, the RxD pin can be
read to detect the break state.
(4)
SCI status check and receive data read:
read SSR, check that the RDRF flag is set
to 1, then read receive data from RDR and
clear the RDRF flag to 0. Notification that
the RDRF flag has changed from 0 to 1 can
also be given by the RXI interrupt.
(5)
To continue receiving serial data:
check the RDRF flag, read RDR, and clear
the RDRF flag to 0 before the stop bit of the
current frame is received.
393
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