#include "spibus.h"
WireSPI SPI;
...
SPI.begin();
...
SPI.beginTransaction( 1000000, -1, 0); // Start transaction at 1MHz in SPI mode 0, CS is not specified (-1)
SPI.transfer(data, len); // Transfer buffer data of length len bytes
SPI.endTransaction(); // End transaction
...
SPI.end();
...