HD64F2149YV datasheet(503/1075 Pages) RENESAS

503 / 1075 page

Section 15 Serial Communication Interface (SCI, IrDA)

Rev. 3.00 Jan 18, 2006 page 475 of 1044

REJ09B0280-0300

15.3.4

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 15.14 shows the general format for synchronous serial communication.

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

Bit 2

Bit 6

Bit 7

Note: * High except in continuous transfer

Figure 15.14 Data Format in Synchronous Communication

In synchronous serial communication, data on the transmission line is output from one falling edge

of the serial clock to the next. Data is guaranteed valid 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 transmission line holds the MSB state.

In synchronous mode, the SCI receives data in synchronization with the rising edge of the serial

clock.

Data Transfer Format

A fixed 8-bit data format is used.

No parity or multiprocessor bits are added.

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