This sounds really simplistic, and it actually is. A "0" and a "1" are all that are needed to make things happen. With the right code, the Arduino can tell a light to turn on, or tell a buzzer to sound, when a "1" is received on the board. It can do many other things as well, but this was a good starting point for me.
I didn't have the background knowledge to write the code from scratch, so I searched the web. At Makezine, a person had posted just such a project, PIR Sensor Arduino Alarm.
Using this tutorial, I gathered my parts, and assembled the project. Below are some pictures of the following materials:
- Arduino and breadboard
- PIR sensor
- Piezo buzzer
- Connecting wires
I assembled my materials according to the tutorial, and grabbed the code (sketch) from the website to upload to the Arduino IDE on my Mac. From there, I sent the code to the Arduino board and tested it out. Below is a short video clip of the results. As I move my hand in front of the PIR sensor, it reacts by sending a "1" to the board. Arduino then reacts by turning on the LED and sounding the buzzer.