This question already has an answer here:
I want to deploy sensors to the door to a private room in order to track people's presence in the room. These are the requirements:
- sensors must be outside of the door;
- it should detect both entrance and exit or whatever it takes to know there are someone in the room;
- due to the nature of the room, it can be assured that at most one person will be in the room at one time;
- the sensor should be able to communicate with a computer using either wifi or other wireless medium.
It has been pointed out by this post (What sensor to choose to track human presence indoors?) that PIR sensors can be the solution. However, I know very little of electrical engineering. I'd really appreciate it if you could explain this in details, e.g. what components to buy, where I can buy them, how do I collect the sensor data from a laptop using wireless media, etc.
I have a background in computer science, so the actual coding should be less of a problem.