SH7080 Datasheet, PDF (904/1644 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperH™ RISC engine Family

Section 16 Serial Communication Interface with FIFO (SCIF)
In transmitting serial data, the SCIF operates as follows:
1. When data is written into the transmit FIFO data register (SCFTDR), the SCIF transfers the
data from SCFTDR to the transmit shift register (SCTSR) and starts transmitting. Confirm that
the TDFE flag in the serial status register (SCFSR) is set to 1 before writing transmit data to
SCFTDR. The number of data bytes that can be written is (16 – transmit trigger setting).
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 below the transmit trigger number set in the
FIFO control register (SCFCR), the TDFE flag is set. If the TIE bit in the serial control register
(SCSR) is set to 1 at this time, a transmit-FIFO-data-empty interrupt (TXIF) request is
generated.
If clock output mode is selected, the SCIF outputs eight synchronous clock pulses. If an
external clock source is selected, the SCIF outputs data in synchronization with the input
clock. Data is output from the TXD pin in order from the LSB (bit 0) to the MSB (bit 7).
3. The SCIF checks the SCFTDR transmit data at the timing for sending the MSB (bit 7). If data
is present, the data is transferred from SCFTDR to SCTSR, the MSB (bit 7) is sent, and then
serial transmission of the next frame is started. If there is no transmit data, the TEND flag in
SCFSR is set to 1, the MSB (bit 7) is sent, and then the TXD pin holds the states.
4. After the end of serial transmission, the SCK pin is held in the high state.
Figure 16.14 shows an example of SCIF transmit operation.
Synchronization
clock
Serial data
LSB
Bit 0 Bit 1
MSB
Bit 7 Bit 0 Bit 1
Bit 6 Bit 7
TDFE
TEND
TXIF
interrupt
request
Data written to SCFTDR _TXIF
and TDFE flag cleared _interrupt
to 0 by TXIF interrupt _request
handler
One frame
Figure 16.14 Example of SCIF Transmit Operation
Rev. 3.00 May 17, 2007 Page 846 of 1582
REJ09B0181-0300