3069RF-ZTAT Datasheet, PDF (521/1003 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER

Figure 13.13 shows an example of SCI receive operation using a multiprocessor format.
1
MPIE
Start
bit
Data (ID1)
0 D0 D1
Stop
MPB _bit
D7 1 1
Start
bit ^{Data (data1)}
0 D0 D1
Stop
MPB _bit
1
D7 0 1 _{Idle (mark)}
state
RDRF
RDR value
ID1
MPB detection
MPIE = 0
RXI interrupt
request
(multiprocessor
interrupt)
RXI interrupt handler reads
RDR data and clears
RDRF flag to 0
Not own ID, so MPIE
bit is set to 1 again
No RXI interrupt
request, RDR not
updated
a. Own ID does not match data
1
MPIE
Start
bit
Data (ID2)
0 D0 D1
Stop Start
MPB bit bit Data (data1)
D7 1 1 0 D0 D1
Stop
MPB _bit
1
D7 0 1
Idle (mark)
state
RDRF
RDR value
ID1
ID2
Data2
MPB detection
MPIE = 0
RXI interrupt
request
(multiprocessor
interrupt)
RXI interrupt handler
reads RDR data and
clears RDRF flag to 0
Own ID, so receiving
continues, with data
received by RXI
interrupt handler
MPIE bit is set to
1 again
b. Own ID matches data
Figure 13.13 Example of SCI Receive Operation
(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.
Rev. 5.0, 09/04, page 499 of 978