Datasheet

Section 12 Serial Communication Interface (SCI)
Rev.7.00 Feb. 14, 2007 page 481 of 1108
REJ09B0089-0700
12.3.4 Operation in Synchronous Mode
In synchronous mode, data is transmitted or received in synchronization with clock pulses, making
it suitable for high-speed serial communication.
Inside the SCI, the transmitter and receiver are independent units, enabling full-duplex
communication by use of a common clock. Both the transmitter and the receiver also have a
double-buffered structure, so that data can be read or written during transmission or reception,
enabling continuous data transfer.
Figure 12.14 shows the general format for synchronous serial communication.
Don't care Don't care
One unit of transfer data (character or frame)
Bit 0
Serial
data
Serial
clock
Bit 1
Bit 3 Bit 4 Bit 5
LSB MSB
B
it 2
Bit 6 Bit 7
*
Note: * High except in continuous transfer
*
Figure 12.14 Data Format in Synchronous Communication
In synchronous serial communication, data on the communication line is output from one falling
edge of the serial clock to the next. Data confirmation is guaranteed at the rising edge of the serial
clock.
In synchronous serial communication, one character consists of data output starting with the LSB
and ending with the MSB. After the MSB is output, the communication line holds the MSB state.
In synchronous mode, the SCI receives data in synchronization with the rising edge of the serial
clock.