3069RF-ZTAT Datasheet, PDF (512/1003 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER

• Receiving Serial Data (Asynchronous Mode): Figure 13.7 shows a sample flowchart for
receiving serial data and indicates the procedure to follow.
Initialize
Start receiving
(1) (1) SCI initialization:
the receive data input function of the RxD
pin is selected automatically.
Read ORER, PER, and FER
flags in SSR
(2)(3)
(2)
PER∨FER∨OPER = 1
Yes
(3)
No
Error handling
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.
(continued on next page)
Read RDRF flag in SSR
(4)
No
RDRF = 1
Yes
Read receive data from RDR, and
clear RDRF flag to 0 in SSR
No
All data received?
(5)
Yes
(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. When the DMAC
is activated by a receive-data-full interrupt
request (RXI) to read RDR, the RDRF flag
is cleared automatically.
Clear RE bit to 0 in SCR
<End>
Figure 13.7 Sample Flowchart for Receiving Serial Data (1)
Rev. 5.0, 09/04, page 490 of 978