beginTransaction()
Initializes the SPI bus using the defined SPISettings. SPI.beginTransaction();SPI.beginTransaction(mySettings);
SPI.beginTransaction(*mySettings);
mySettings the chosen settings according SPISettings() None SPI.beginTransaction(clock, bitOrder, dataMode);
clock: the maximum speed of communication. bitOrder: MSBFIRST or LSBFIRST. dataMode: SPI_MODE0, SPI_MODE1, SPI_MODE2, or SPI_MODE3. None