Pétocontrôle: Beautiful Four-Knob MIDI Interface
This MIDI interface features four knobs, LED indicators, and a VFD for user feedback.
If you need a new idea for a knob-based MIDI controller, be sure to give svofski’s Pétocontrôle MIDI interface a look. The device's main board houses an STM32F103 microcontroller, several buttons, and a Futaba 8-MD-06INKM VFD for user output. On top of that, a plug-in mezzanine board houses four knobs that provide the setup’s main inputs.
What makes this build really interesting is how these knobs work. While they look like normal potentiometers from the top, each device's typical electromagnetic base has been heavily modified to rotate a magnet attached to the bottom.
Instead of direct electrical feedback, the magnet positions are read by AS5600 I2C position sensors on the main board. This allows the knobs to turn 360º as encoders, while still producing the same continuous mechanical resistance/feel that you’d expect when using potentiometers.
Each encoder-potentiometer amalgamation features a ring of 0402 LEDs around its circumference, creating a beautiful secondary output source. These rings can indicate volume on up to four channels, or they can be used as VU meters to indicate instantaneous output.
While the Pétocontrôle is designed to be used with svofski’s Le Pétomane synth, it could, in theory, be programmed to perform whatever other interfacing duties are needed. Or the project could provide great inspiration for your own custom control surface! Be sure to check it out in the video below; design files are available on GitHub.