HD64F36024FX Datasheet, PDF (228/386 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 13 Serial Communication Interface 3 (SCI3)
13.5 Operation in Clocked Synchronous Mode
Figure 13.9 shows the general format for clocked synchronous communication. In clocked
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 clocked
synchronous serial communication, data on the transmission line is output from one falling edge of
the synchronization clock to the next. In clocked synchronous mode, the SCI3 receives data in
synchronous with the rising edge of the synchronization clock. After 8-bit data is output, the
transmission line holds the MSB state. In clocked synchronous mode, no parity or multiprocessor
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 13.9 Data Format in Clocked Synchronous Communication
13.5.1 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 SCR3. When the SCI3 is operated on an internal clock,
the synchronization clock is output from the SCK3 pin. Eight synchronization clock pulses are
output in the transfer of one character, and when no transfer is performed the clock is fixed high.
Rev. 4.00 Sep. 23, 2005 Page 200 of 354
REJ09B0025-0400