TMP89FH46 Datasheet, PDF (247/390 Pages) Toshiba Semiconductor – 8 Bit Microcontroller

TMP89FH46
17.5 Transfer Modes
17.5.1 8-bit transmit mode
The 8-bit transmit mode is selected by setting SIO0CR<SIOM> to "01".
17.5.1.1 Setting
Before starting the transmit operation, select the transfer edges at SIO0CR<SIOEDG>, a transfer format
at SIO0CR<SIODIR> and a serial clock at SIO0CR<SIOCKS>. To use the internal clock as the serial
clock, select an appropriate serial clock at SIO0CR<SIOCKS>. To use an external clock as the serial
clock, set SIO0CR<SIOCKS> to "111".
The 8-bit transmit mode is selected by setting SIO0CR<SIOM> to "01".
The transmit operation is started by writing the first byte of transmit data to SIO0BUF and then setting
SIO0CR<SIOS> to "1".
Writing data to SIO0CR<SIOEDG, SIOCKS and SIODIR> is invalid when the serial communication is
in progress, or when SIO0SR<SIOF> is "1". Make these settings while the serial communication is
stopped. While the serial communication is in progress (SIO0SR<SIOF>="1"), only writing "00" to
SIO0CR<SIOM> or writing "0" to SIO0CR<SIOS> is valid.
17.5.1.2 Starting the transmit operation
The transmit operation is started by writing data to SIO0BUF and then setting SIO0CR<SIOS> to "1".
The transmit data is transferred from SIO0BUF to the shift register, and then transmitted as the serial data
from the SO0 pin according to the settings of SIO0CR<SIOEDG, SIOCKS and SIODIR>. The serial data
becomes undefined if the transmit operation is started without writing any transmit data to SIO0BUF.
In the internal clock operation, the serial clock of the selected baud rate is output from the SCLK0 pin.
In the external clock operation, an external clock must be supplied to the SCLK0 pin.
By setting SIO0CR<SIOS> to "1", SIO0SR<SIOF and SEF> are automatically set to "1" and an
INTSIO0 interrupt request is generated.
SIO0SR<SEF> is cleared to "0" when the 8th bit of the serial data is output.
17.5.1.3 Transmit buffer and shift operation
If data is written to SIO0BUF when the serial communication is in progress and the shift register is
empty, the written data is transferred to the shift register immediately. At this time, SIO0SR<TBFL>
remains at "0".
If data is written to SIO0BUF when some data remains in the shift register, SIO0SR<TBFL> is set to
"1". If new data is written to SIO0BUF in this state, the contents of SIO0BUF are overwritten by the new
value. Make sure that SIO0SR<TBFL> is "0" before writing data to SIO0BUF.
17.5.1.4 Operation on completion of transmission
The operation on completion of the data transmission varies depending on the operating clock and the
state of SIO0SR<TBFL>.
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