The Serial Peripheral Interface Bus or SPI bus is a synchronous serial data link standard named by Motorola that operates in full duplex mode. Devices communicate in a master/slave mode where the master device initiates the data frame. Multiple slave devices are allowed with individual slave select (chip select) lines using a pin for each device. The begin() method starts SPI communication.
SPI.begin(slaveSelectPin)(Arduino Due only)
slaveSelectPin: slave device SS pin (Arduino Due only)