Hitachi H8/3048 Hardware Manual page 492

Figure 13-13 shows an example of SCI receive operation using a multiprocessor format.
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Start
1
bit
MPIE
RDRF
RDR value
MPB detection
MPIE= 0
Start
1
bit
MPIE
RDRF
RDR value
MPB detection
MPIE= 0
Figure 13-13 Example of SCI Receive Operation (8-Bit Data with Multiprocessor Bit and
Data (ID1) MPB
0 D0 D1 D7 1
RXI request
(multiprocessor
interrupt)
a. Own ID does not match data
Data (ID2) MPB
0 D0 D1 D7 1
RXI request
(multiprocessor
interrupt)
b. Own ID matches data
One Stop Bit)
Stop Start
Data (data1)
bit bit
1 0 D0 D1 D7
ID1
RXI handler reads Not own ID, so
RDR data and clears MPIE bit is set
RDRF flag to 0 to 1 again
Stop Start
Data (data2)
bit bit
1 0 D0 D1 D7
ID2
RXI interrupt handler Own ID, so receiving
reads RDR data and continues, with data
clears RDRF flag to 0 received by RXI
interrupt handler
481
Stop
MPB
1
bit
0 1 Idle (mark)
state
No RXI request,
RDR not updated
Stop
MPB
1
bit
0 1 Idle (mark)
state
Data 2
MPIE bit is set
to 1 again