Chapter 1. Building Wireless XBee Motion Detectors

In this chapter, we are going to build a project around a very common home automation sensor: a motion sensor. Ever noticed those small modules in white plastic that are in the upper corners in some rooms of people's houses, modules that turn red when you walk in front of them? That's exactly the same thing we are going to do in this project.

However, instead of using proprietary technologies, which is usually the case for these modules, we are going to base our system on Arduino. And for the communication part, we are going to use XBee modules, which are low-power radio modules that are widely used with the Arduino platform. These modules are based on the ZigBee protocol, which is also used in many commercial home automation systems.

Here are the major takeaways that we will see in this chapter:

• First of all, we will list all the hardware and software components that we need for this project. With these components, we will build one motion sensor module composed of an Arduino board, a motion sensor, and one XBee module.
• Then, we will test this first module; the motion sensor will be tested on its own, and we will also test the communication part by sending commands via the serial monitor of the Arduino software.
• Finally, we are going to build a web-based graphical interface that centralizes all the data of our XBee sensors. With a simple interface built on web technologies, you'll be able to instantly see if some motion is detected in your home.