252
Figure 10.11 shows a typical SCI3 data receive operation in asynchronous mode.
0
D0
D1
D7
0/1
1
D0
D1
D7
0/1
0
0
Start
bit
Parity
bit
Stop
bit
Parity
bit
Stop
bit
1
Start
bit
Mark
(idle state)
RDRF
FER
1 frame
Serial
data
RXI request
Detects stop bit = 0
ERI request due
to framing error
1 frame
1
SCI3 operation
Receive
data
Receive
data
Read RDR data
User processing
RDRF cleared
to 0
Framing error
handling
Figure 10.11 Typical Receive Operation in Asynchronous Mode
(8-Bit Data, Parity Bit Added, and 1 Stop Bit)
10.3.5
Operation in Synchronous Mode
In synchronous mode, data is sent or received in synchronization with clock pulses. This mode is
suited to high-speed serial communication.
SCI3 consists of independent transmit and receive modules, so full duplex communication is
possible, sharing the same clock between both modules. Both the transmit and receive modules
have a double-buffer configuration. This allows data to be written during a transmit operation so
that data can be transmitted continuously, and enables data to be read during a receive operation so
that data can be received continuously.