The Serial Peripheral Interface bus, known affectionately as spy, is a synchronous serial interface that was named by Motorola.39 The SPI protocol operates in full-duplex mode, allowing it to send and receive data simultaneously. Generally speaking, SPI has a speed advantage over the I2C protocol but requires more connections.
Devices on the SPI bus communicate on a master/slave basis. Multiple slaves coexist on a given SPI bus, with each slave being selected for communication by a slave select signal (also known as chip select). Figure 15-1 shows the Raspberry Pi as the master communicating with a slave. Additional ...