I'm trying to get capacitive touch on an Arduino with CapSense library to work on batteries. I want to detect touch to a large metal object, namely a metal door which is connected to the sense pin. The fact that it is a large metal object is what's giving me issues and is why I can't seem to find solutions online. When I hook the Arduino up to my (grounded) PC via USB, everything works fine. When I remove the grounding to the PC it doesn't work. When connecting Arduino ground to the mains ground via a wire it also works. The problem is that there is no elegant way to run a wire to mains ground and hence want to avoid this. When googling I read that I should create my own ground plane and not rely on the mains grounding pin as a reference. So I created the following box covered in aluminum foil and then wrapped in a plastic foil. The aluminum foil is connected to ground. However, it still doesn't detect anything. Is there another way I should go about getting this to work? Thanks!
Do you really need to detect contact with the door. Would contact with the handle suit your requirement?
The door is acting as a sort of ground-plane itself. Perhaps you could connect the door to the Arduino ground and connect the sense pin to the door handle? You would of course have to make sure that the door handle is isolated from the door.
Russell.
Hi Russel, thanks for the reply!
Well no I don't need contact with the door, actually the wire is connected to the lock (behind the box) and not the door. I'm detecting touch to the lock but the problem is that this (like the handle) is connected to the door which is a large metal object.