If you’re building an omniscient home-automation system, it’s ability to make decisions is only as good as the input you give it. [Petewill]’s self-made panopticon now knows when someone is in bed. That way, the [petewill]’s automatic blinds won’t open when he’s sleeping late on weekends.
[Petewill] didn’t take the easy way out here. (In our mind, that would be a weight sensor under one of the bed’s feet.) Instead, his system more flexible and built on capacitive sensing. He’d tried force sensors and piezos under the mattress, but none of them were as reliable as capacitance. A network of copper tape under the mattress serves as the antenna.
The details are taken care of by an MPR121 from Microchip. An Arduino and an nRF24L01+ module round out the build. There’s some hints about using the capacitive-sensing chip for you in the video (below) and there’s Arduino code up on his website.
The advantage of capacitive sensing is that you can easily define the area you want to cover — simply lay the tape where you want it. That way you could build different rules depending which side of the bed is occupied.
So add capacitive sensors to your bed to push your ridiculously complicated home automation system over the edge into insanity!