Are you working with MPR121? Does it at times start being screwy, having one channel get jammed, or another become unresponsive? Congrats, you’ve stumbled onto this IC being too smart for its own good according to Arya’s Bread Crumbs blog.

MPR121 is a wonderful capacitive touch sensing IC. It can do so much for you – all of that automatically, too. One of the things it does, is ongoing baseline calibration. It can adjust to electrode capacity changing over time, so that even if you go into different environment, your touches still get registered. Well, this is the norm for any self-respecting IC, but I digress. Also, this means it can adjust to you hotplugging electrodes!

What if you have a stable electrode configuration (say, all of your bananas and apples are already connected with jumper wires) and it glitches in some way, as it seems to often happen with mine?

What can you do? Well, you can have the IC calibrate for a certain baseline, and then lock that baseline in – disabling baseline tracking.

The blog shows MicroPython code to disable the baseline. Read more in the post here.