Synchronous Operation - Hitachi H8/3006 Hardware Manual

Figure 13.13 shows an example of SCI receive operation using a multiprocessor format.
Start
1
bit
0
D0
MPIE
RDRF
RDR value
MPB detection
MPIE = 0
Start
1
bit
0 D0
MPIE
RDRF
RDR value
MPB detection
MPIE = 0
(8-Bit Data with Multiprocessor Bit and One Stop Bit)
13.3.4

Synchronous Operation

In synchronous mode, the SCI transmits and receives data in synchronization with clock pulses.
This mode is suitable for high-speed serial communication.
The SCI transmitter and receiver share the same clock but are otherwise independent, so full-
duplex communication is possible. The transmitter and the receiver are also double-buffered, so
continuous transmitting or receiving is possible by reading or writing data while transmitting or
receiving is in progress.
MPB
Data (ID1)
D1 D7
1
RXI interrupt RXI interrupt handler reads
request RDR data and clears
(multiprocessor RDRF flag to 0
interrupt)
a. Own ID does not match data
Data (ID2) MPB
D7
D1
1
ID1
RXI interrupt
request
(multiprocessor
interrupt)
b. Own ID matches data
Figure 13.13 Example of SCI Receive Operation
Stop Start
Data (data1)
bit bit
0 D0 D1
1
Stop Start
Data (data1)
bit bit
0
D0 D1
1
RXI interrupt handler Own ID, so receiving
reads RDR data and continues, with data
clears RDRF flag to 0 received by RXI
interrupt handler
Stop
MPB
bit
D7 1
0
Idle (mark)
state
ID1
Not own ID, so MPIE No RXI interrupt
bit is set to 1 again request, RDR not
updated
Stop
MPB
bit
D7 1
0
Idle (mark)
state
ID2
Data2
MPIE bit is set to
1 again
1
1
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