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Rev. 1.00, 05/04, page 261 of 544
12.5.2 Multiprocessor Serial Data Reception
Figure 12.13 shows a sample flowchart for multiprocessor serial data reception. If the MPIE bit
in SCR is set to 1, data is skipped until data with a 1 multiprocessor bit is sent. On receiving data
with a 1 multiprocessor bit, the receive data is transferred to RDR. An RXI interrupt request is
generated at this time. All other SCI operations are the same as in asynchronous mode. Figure
12.12 shows an example of SCI operation for multiprocessor format reception.
MPIE
RDR
value
0 D0 D1 D7 1 1 0 D0 D1
D7
01
1
1
Data (ID1)Start
bit MPB
Stop
bit
Start
bit
Data (Data 1)
MPB
Stop
bit
Data (ID2)Start
bit
Stop
bit
Start
bit
Data (Data 2)
Stop
bit
RXI interrupt
request
(multiprocessor
interrupt)
generated
Idle state
(mark state)
RDRF
RDR data read
and RDRF flag
cleared to 0 in
RXI interrupt
handling routine
If not this station’s ID,
MPIE bit is set to 1
again
RXI interrupt request is
not generated, and RDR
retains its state
ID1
(a) Data does not match station’s ID
MPIE
RDR
value
0 D0 D1 D7 1 1 0 D0 D1
D7
01
1
1
MPB
MPB
RXI interrupt
request
(multiprocessor
interrupt)
generated
Idle state
(mark state)
RDRF
RDR data read and
RDRF flag cleared
to 0 in RXI interrupt
handling routine
Matches this station’s ID,
so reception continues, and
data is received in RXI
interrupt service routine
MPIE bit set to 1
again
ID2
(b) Data matches station’s ID
Data 2ID1
MPIE = 0
MPIE = 0
Figure 12.12 Example of SCI Receive Operation (Example with 8-Bit Data, Multiprocessor
Bit, One Stop Bit)