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Set bit MPIE to 1
1
in SCR3
Read bits OER
2
and FER in SSR
OER + FER = 1?
No
Read bit RDRF
3
in SSR
RDRF = 1?
Yes
Read receive
data in RDR
Own ID?
Yes
Read bits OER
and FER in SSR
OER + FER = 1?
No
Read bit RDRF
4
in SSR
RDRF = 1?
Yes
Read receive
4
data in RDR
Continue data
reception?
No
Clear bit RE to
0 in SCR3
End
Figure 14.19 Example of Multiprocessor Data Reception Flowchart
Yes
No
No
Yes
No
Receive error
5
processing
Yes
(A)
1.
Set bit MPIE to 1 in SCR3.
2.
Read bits OER and FER in the serial
status register (SSR) to determine if
there is an error. If a receive error has
occurred, execute receive error processing.
3.
Read SSR and check that bit RDRF is
set to 1. If it is, read the receive data in
RDR and compare it with this receiver's
own ID. If the ID is not this receiver's,
set bit MPIE to 1 again. When the RDR
data is read, bit RDRF is cleared to 0
automatically.
4.
Read SSR and check that bit RDRF is
set to 1, then read the data in RDR.
5.
If a receive error has occurred, read bits
OER and FER in SSR to identify the error,
and after carrying out the necessary error
processing, ensure that bits OER and FER
are both cleared to 0. Reception cannot be
resumed if either of these bits is set to 1.
In the case of a framing error, a break can
be detected by reading the value of the
RXD pin.
291
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