spiLookup method
SPI lookup - mraa_spi_lookup
Get the SPI bus index by bus name, the board must be initialised. Returns the MRAA index for SPI bus or Mraa.generalError on error.
Implementation
int spiLookup(String spiName) =>
_impl.mraa_spi_lookup(spiName.toNativeUtf8().cast<Char>());