In this chapter, we gained more experience with expanding the Pi's hardware capability by adding additional means of communication to it and adding hardware using a new protocol, that is, SPI.

Arduino also played a large part in this chapter and has helped to provide an example of a wide range of hardware that could possibly be used with the Pi. Even if a sensor, motor, or other device cannot be controlled directly from the Pi, it is almost guaranteed that there is an additional piece of hardware that can sit between the Pi and the device and allow control of the device from the Pi.

We also had a more in-depth look at the type of web applications that can be created using Python and Flask and introduced quite a few new features into the security web application over the application made in the previous chapter.

We will continue to explore the way web applications can be used as an input method for the Pi and control physical hardware in the later chapters in this book by using several...