The GPIO Port
Eben Upton, Gareth Halfacree · 2016
All modern Raspberry Pi's, bar the industrial-friendly Raspberry Pi Compute Module design, feature a standardised 40-pin general-purpose input-output (GPIO) header. Each pin of the GPIO port has its own purpose, with several pins working together to form particular interfaces. This chapter shows the layout of the GPIO port. This chapter discusses how to construct and program the simple electronic circuits that demonstrate how to use the GPIO port for input and output. The Raspberry Pi Zero is unique in the mainstream Pi family, and not just because of its small size: it is the only model to be sold with an unpopulated GPIO header, meaning that it does not have the pins found on most models. Using male pin headers makes the Pi Zero compatible with any HAT or other add-on board designed for the Raspberry Pi family.