HD64F38602R Datasheet, PDF (297/552 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer

Section 14 Serial Communication Interface 3 (SCI3, IrDA)
14.5 Operation in Clock Synchronous Mode
Figure 14.9 shows the general format for clock synchronous communication. In clock
synchronous mode, data is transmitted or received synchronous with clock pulses. A single
character in the transmit data consists of the 8-bit data starting from the LSB. In clock
synchronous serial communication, data on the transmission line is output from one falling edge of
the serial clock to the next. In clock synchronous mode, the SCI3 receives data in synchronous
with the rising edge of the serial clock. After 8-bit data is output, the transmission line holds the
MSB state. In clock synchronous mode, no parity bit is added. Inside the SCI3, the transmitter and
receiver are independent units, enabling full-duplex communication through the use of a common
clock. Both the transmitter and the receiver also have a double-buffered structure, so data can be
read or written during transmission or reception, enabling continuous data transfer.
8-bit
*
Synchronization
clock
Serial data
One unit of transfer data (character or frame)
*
LSB
MSB
Bit 0 Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7
Don’t care
Don’t care
Note: * High except in continuous transfer
Figure 14.9 Data Format in Clock Synchronous Communication
14.5.1 Clock
Either an internal clock generated by the on-chip baud rate generator or an external
synchronization clock input at the SCK3 pin can be selected, according to the setting of the COM
bit in SMR and CKE0 and CKE1 bits in SCR. When the SCI3 is operated on an internal clock, the
serial clock is output from the SCK3 pin. Eight serial clock pulses are output in the transfer of one
character, and when no transfer is performed the clock is fixed high.
14.5.2 SCI3 Initialization
Before transmitting and receiving data, the SCI3 should be initialized as described in a sample
flowchart in figure 14.4.
Rev. 3.00 May 15, 2007 Page 265 of 518
REJ09B0152-0300