SH7101 Datasheet, PDF (347/486 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

10. Serial Communication Interface (SCI)
10.6 Operation in Clocked Synchronous Mode
Figure 10.14 shows the general format for clocked synchronous communication. In clocked
synchronous mode, data is transmitted or received in synchronization with clock pulses. Data is
transferred in 8-bit units. In clocked synchronous serial communication, data on the transmission
line is output from one falling edge of the serial clock to the next. In clocked synchronous mode,
the SCI receives data in synchronization with the rising edge of the serial 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 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.
*
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 10.14 Data Format in Clocked Synchronous Communication (For LSB-First)
10.6.1 Clock
Either an internal clock generated by the on-chip baud rate generator or an external
synchronization clock input at the SCK pin can be selected, according to the setting of CKE1 and
CKE0 bits in SCR. When the SCI is operated on an internal clock, the serial clock is output from
the SCK pin. Eight serial clock pulses are output in the transfer of one character, and when no
transfer is performed, the clock is fixed high.
Rev.2.00 Sep. 27, 2007 Page 313 of 448
REJ09B0394-0200