A Raspberry Pico* MIDI device that plays physical (toy) instruments via servos.

MidiBanger supports both percussive (mallet-type) and pressed (key-type) instruments.

• Pan-and-tilt mode using just two servos to play reachable notes
• Servo-per-note mode
• Solenoid-per-note mode (soon)

The current version supports up to 16 directly-connected servos, later versions may support I2C servo controllers allowing hundreds of servos to be used.

*Tested on Raspberry Pi Pico, Raspberry Pi Pico W, and Waveshare RP2040-Zero.

• Raspberry Pico or compatible such as RP2040-Zero
• Servo per note eg. SG90 9g Micro Servo, or a pair if using pan-and-tilt
• Optional - Micro speaker - handy for debugging and setup
• Optional - 5V PSU for servos, if you think you need it
• Some 3D-printed parts to hold servos etc.

Some sample 3D parts are included in the 3D directory, there are FreeCAD designs and .3mf files for slicing.

See the comments in src/config.h for details.

To avoid masses of commented-out congfiguration I have put the configuration that is specific to a particular physical instrument in a separate file which is then #included in the main config.h. Example configurations are chicco_toy_glock_config.h and janod_toy_glock_config.h.

For the servo-per-note mode, the critical configuration item is the NOTEPIN_INITIALISER. Leave its first line alone, then replace the contents with a maximum of sixteen [MIDI note number] = GPIO_PIN pairs.

For the two-servo pan-and-tilt mode it's the NOTE_PAN_INITIALISER that you will need to adjust to set the angles for each note. This will be a trial-and-error process, I suggest you start by installing the servos so that their centres of movement roughly point to the middle of the instrument and then do a first run WITHOUT the hammer attached.

If you are connecting up several MidiBangers I suggest you use a different string or number for each one at the end of the USB_PRODUCT string. It will make your life a lot simpler!

Don't forget to set PICO_BOARD to match your target microcontroller in CMakeLists.txt, then...

mkdir build
cd build
cmake ..
make

• Try a metal-geared servo for the panning action, these seem to have less play than the plastic-geared equivalent.
• For greater accuracy playing large intervals (leaps) you can try setting the angles for the lowest and highest notes just a little towards the centre, this will compensate for some overshoot.