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Table 14.5 SSR Status Flags and Receive Data Handling
SSR Status Flag
RDRF*
OER
1
1
0
0
0
0
1
1
1
1
0
0
1
1
Note:
* The RDRF flag retains the state it had before data reception.
No
Yes
(A)
Figure 14.9 Sample Serial Reception Data Flowchart (Asynchronous Mode)
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FER
PER
0
0
1
0
0
1
1
0
0
1
1
1
1
1
Start reception
Read OER, PER, and
FER flags in SSR
OER+PER+FER = 1
No
Error processing
(Continued on next page)
Read RDRF flag in SSR
RDRF = 1
Yes
Read receive data in RDR
All data received?
No
Clear RE bit in SCR3 to 0
<End>
Receive Data
Lost
Transferred to RDR
Transferred to RDR
Lost
Lost
Transferred to RDR
Lost
[1] Read the OER, PER, and FER flags in
SSR to identify the error. If a receive
error occurs, performs the appropriate
error processing.
[1]
[2] Read SSR and check that RDRF = 1,
then read the receive data in RDR.
The RDRF flag is cleared automatically.
[3] To continue serial reception, before the
Yes
stop bit for the current frame is
[4]
received, read the RDRF flag and read
RDR.
The RDRF flag is cleared automatically.
[4] If a receive error occurs, read the OER,
PER, and FER flags in SSR to identify
[2]
the error. After performing the
appropriate error processing, ensure
that the OER, PER, and FER flags are
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
the RxD pin.
[3]
Receive Error Type
Overrun error
Framing error
Parity error
Overrun error + framing error
Overrun error + parity error
Framing error + parity error
Overrun error + framing error +
parity error
Rev. 1.00, 11/03, page 207 of 376
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