SH7760 Datasheet, PDF (633/1345 Pages) Renesas Technology Corp – SuperHTM RISC engine

2. When data is transferred from SCFTDR to SCTSR and transmission is started, consecutive
transmit operations are performed until there is no transmit data left in SCFTDR. When the
number of transmit data bytes in SCFTDR falls to or below the transmit trigger number set in
SCFCR, the TDFE flag is set. If the TIE bit in SCSCR is set to 1 at this time, a transmit-FIFO-
data-empty interrupt (TXI) request is generated.
The serial transmit data is sent from the SCIF_TXD pin in the following order.
A. Start bit: One 0-bit is output.
B. Transmit data: 8-bit or 7-bit data is output in LSB-first order.
C. Parity bit: One parity bit (even or odd parity) is output. A format in which a parity bit is
not output can also be selected.
D. Stop bit(s): One or two 1-bits (stop bits) are output.
E. Mark state: 1 is output continuously until the start bit that starts the next transmission is
sent.
3. The SCIF checks the SCFTDR transmit data at the timing for sending the stop bit. If data is
present, the data is transferred from SCFTDR to SCTSR, the stop bit is sent, and then serial
transmission of the next frame is started.
If there is no transmit data after the stop bit is sent, the TEND flag in SCFSR is set to 1, the
stop bit is sent, and then the line goes to the mark state in which 1 is output from the
SCIF_TXD pin.
Figure 17.10 shows an example of the operation for transmission in asynchronous mode.
1
Serial
data
Start
bit
Data
Parity Stop Start
bit bit bit
Data
Parity Stop
bit bit
0 D0 D1
D7 0/1 1 0 D0 D1
D7 0/1 1
1
Idle state
(mark state)
TDFE
TEND
TXI interrupt
request
Data written to SCFTDR
and TDFE flag read as 1
then cleared to 0 by TXI
interrupt handler
TXI interrupt
request
One frame
Figure 17.10 Sample SCIF Transmission Operation
(Example with 8-Bit Data, Parity, One Stop Bit)
Rev. 1.0, 02/03, page 583 of 1294