touchwheel0 - capacitive touch wheel

What is it?

Similar to an iPod's wheel, touchwheel0 is a 30 mm (0.6") diameter rotary capactive touch slider that can be used with most any microcontroller. It uses three digital GPIO pins and requires no extra components. The included examples in CircuitPython and Arduino show how to turn the raw capacitive touch readings of the three pins into a linear 0-360º angle measurement.

Why did you make it?

I've become pretty good with capacitive touch sensors and I wanted to experiment with these "analog" sliders that can be made with only three touch pads and some math.

What makes it special?

Making a rotary control using just some copper traces is pretty amazing to me. I've not seen many hobbyist projects using that and I wanted to explore (and help others explore) how these controls may fit into our projects.

Demos:

There are several examples on how to use the touchwheel:

1. demo0 - CircuitPython example showing basic concept on touchwheel0
2. touchwheel_badgedemo - CircuitPython example for the Hackaday SuperCon 2023 badge (where touchwheel0 PCBs were given away)
3. demo_dual - CircuitPython example show two touchwheel0s in use
4. more demos in the github repo

What's in touchwheel0 kit:

The touchwheel0 kit comes with:

1. touchwheel0 black PCB
2. 4 x 1M 0805 SMD resistors (only three needed, one is a spare)
3. 1 x 4-pin pin header