Figure 12.9 Sample Serial Reception Flowchart (1) - Renesas H8SX/1520 Series Hardware Manual

Section 12 Serial Communication Interface (SCI)
No
No
Rev. 3.00 Mar. 14, 2006 Page 414 of 804
REJ09B0104-0300
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Initialization
Start reception
Read ORER, PER, and
FER flags in SSR
PER ∨ FER ∨ ORER = 1
No
Error processing
(Continued on next page)
Read RDRF flag in SSR
RDRF = 1
Yes
Read receive data in RDR, and
clear RDRF flag in SSR to 0
All data received?
Yes
Clear RE bit in SCR to 0
<End>

Figure 12.9 Sample Serial Reception Flowchart (1)

[1] SCI initialization:
[1]
The RxD pin is automatically
designated as the receive data input
pin.
[2] [3] Receive error processing and break
detection:
[2]
If a receive error occurs, read the
ORER, PER, and FER flags in SSR to
identify the error. After performing the
appropriate error processing, ensure
Yes
that the ORER, PER, and FER flags are
[3]
all cleared to 0. Reception cannot be
resumed if any of these flags are set to
1. In the case of a framing error, a
break can be detected by reading the
value of the input port corresponding to
[4]
the RxD pin.
[4] SCI state check and receive data read:
Read SSR and check that RDRF = 1,
then read the receive data in RDR and
clear the RDRF flag to 0. Transition of
the RDRF flag from 0 to 1 can also be
identified by an RXI interrupt.
[5] Serial reception continuation procedure:
To continue serial reception, before the
stop bit for the current frame is
received, read the RDRF flag and RDR,
[5]
and clear the RDRF flag to 0.
However, the RDRF flag is cleared
automatically when the DMAC is
initiated by an RXI interrupt and reads
data from RDR.