In this chapter we covered the four most common sensors found in the average home or small business areas, and briefly discussed how they work. These sensors, with the exception of door contacts, come in all different shapes, sizes, and models.

For example, there are a number of different models of PIRs. Some are "pet tolerant", meaning that a dog or cat won't set them off in the middle of the night.

In the next chapter we will be learning the theory behind our first alarm system. We will also be writing some simple code to simulate a one-zone alarm system, using the built-in IDE of BeagleBone.