Modifications

     int wiringPiSPIDataRW(int channel, unsigned char *data, int len);

     int wiringPiSPIDataRW(int channel, unsigned char *data, int len);

This performs a simultaneous write/read transaction over the selected SPI bus. Data that was in your buffer is overwritten by data returned from the SPI bus.

Effectue simultanément une transaction d'écriture/lecture sur le bus SPI sélectionné. Les données qui étaient disponibles dans votre mémoire tampon (buffer) sont écrasées avec les données obtenues sur le bus SPI.

That’s all there is in the helper library. It is possible to do simple read and writes over the SPI bus using the standard read() and write() system calls though – write() may be better to use for sending data to chains of shift registers, or those LED strings where you send RGB triplets of data. Devices such as A/D and D/A converters usually need to perform a concurrent write/read transaction to work.

That’s all there is in the helper library. It is possible to do simple read and writes over the SPI bus using the standard read() and write() system calls though – write() may be better to use for sending data to chains of shift registers, or those LED strings where you send RGB triplets of data. Devices such as A/D and D/A converters usually need to perform a concurrent write/read transaction to work.