The serial peripheral interface (SPI) is a 4-wire, serial communication interface. SPI is an industry standard protocol that is widely used in embedded systems for interfacing microprocessors and various devices such as sensors, memory chips, shift registers, port expanders, display drivers, data converters, printers, data storage devices, sensors, and multimedia cards.

This interface standard has several advantages:

• Low pin count and simple wiring
• Full-duplex communication for higher throughput (allowing faster communication compared to other protocols such as I²C)
• No addressing; therefore, reduced overhead

Applications such as digital audio, digital signal processing, and telecommunication channels require high-speed data streams. The low-power, high-speed Altera^® MAX^® II, MAX V and MAX 10 devices are suitable for an SPI master, external to the host. This application note details the implementation of the SPI master in MAX II, MAX V and MAX 10 devices. A microprocessor is used to control the master, which you can use to select a slave device to read and write data to and from it.