In this chapter, we introduced various ways to connect your Raspberry Pi to the outside world by looking at the various interfaces available on the GPIO. We've understood how to connect things to the digital pins on your Raspberry Pi's GPIO connector, and control and read them using simple Bash scripts. In particular, we've safely and properly connected a switch to a digital input pin, which will form the foundation for our home security detection circuits.
In the next chapter, we'll look at ways to expand the number of things we can connect to our Raspberry Pi, overcoming the limitation of having just the 8 digital pins available to us on the GPIO by tapping into other interfaces on the GPIO and building our own input/output expansion board.
