Super minimalistic and compact native USB hid controller, recognized under all operating systems.
It is using super compact RP2040 (or 2350 but really no point) zero or pico board (~17.6mm x 23.6mm), and EC11 encoder.
Allows for volume up, down, mute/unmute (push button). Reset + boot buttons accessible on the bottom.
Example code assumes pin 0 routed to button leg, pins 1 and 2 to rotation encoder pins. Please install RP2040 support in Arduino IDE like in this guide, and install Adafruit_TinyUSB library, setup USB Stack to `Adafruit TinyUSB`, for device type select `Waveshare RP2040 zero`

Hardware used

• RP 2040 - this is more or less waveshare original (but there are absolutelly identical clones to be purchased at ⅔ of the waveshare price)

• EC11  + any potentiometer knobs, in this case 

   

Assembly

1. Solder all conections to RP, so that boot and reset buttons are on the bottom, and wires are extending in opposite direction. Keep connections as short as possible, because there is barelly any space left for that!
2. Cut unnecessary support legs of EC11, carefully flatten soldered legs, put some insulation table

3. Place EC11 (with insulation tape) DIRECTLY on top of RP cpu

   

4. Top/cover part inside grip material is cut out from one side, I recommend putting that on the side where ccw/gnd/cw legs are facing, in my case I could not squize everything without this removed material in this place. Use this code to install