What is SPI?

SPI, or Serial Peripheral Interface, is a synchronous communication protocol that enables data exchange between a master device and one or more slave devices using separate lines for data send, data receive, a clock, and a chip select.

It might seem complicated explained like that, but let’s take an analogy. Imagine SPI like a well-organized conference call. One person (the master), say the host, can talk to several participants (the slaves), but addresses and listens to one participant at a time.

Back to the Raspberry Pi usage, you could have several sensors connected (think of a weather station, for example). If the Raspberry Pi wants to gather information from a temperature sensor, it selects that sensor and starts the data exchange, leaving other devices on hold.

Unlike I2C with its two-wire setup, SPI uses more wires but can often transfer data faster. This makes it a good choice when speed is a priority.

In the Raspberry Pi and Linux ecosystems, SPI is commonly used to connect a variety of components like LCD displays and SD card readers, facilitating quick data communication and allowing for more complex and responsive projects.