The HC-SR501 is a Passive Infrared (PIR) motion sensor that is extremely useful. It can be used all by itself or combined with an Arduino or Raspberry Pi
In this article you’ll learn how a PIR sensor works and you’ll build some cool projects using the HC-SR501. You can even make a motion activated camera that will tell you who is stealing your Jelly Beans!
I’m sure you have seen those inexpensive robot car chassis kits, the ones that come with two 6-volt motors. They are great fun and very useful and they even come with a couple of speed encoder disks (those little black circles full of holes). Problem is, no one tells you how to use them!
Let’s resolve that and build a robot car with speed sensors. Along the way we’ll learn how to use Interrupts, a valuable programming technique.