Build a musical Synth Guitar with Adafruit's RP2040 PropMaker Feather and CircuitPython!

This instrument uses CircuitPython SynthIO to generate musical notes that can be modulated using rotary encoders and the PropMaker Feather's on-board accelerometer.

Use NeoKey 'Cherry MX'-compatible key switches and a guitar-hero-like strum-bar to play notes.

The RP2040 PropMaker Feather features high-quality I2S audio output. You can switch between the on-board speaker or TRRS audio jack.

The NeoPixel change colors depending on the NeoKey that is pressed. 

The RP2040 PropMaker's built in speaker driver is not designed for use with headphones or line in.

Prerequisite Guides

For more information on the RP2040 PropMaker Feather and using the SynthIO module in CircuitPython, check out these guides.


Video of a white hand pressing a button to briefly turn an LED strip into white lights. Also wired up to the microcontroller are a servo motor and a speaker.
The Adafruit Feather series gives you lots of options for a small, portable, rechargeable microcontroller board. By picking a feather and stacking on a FeatherWing you can create...
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Angled shot of ten red Kailh key switches.
For crafting your very own custom keyboard, these Kailh Red Linear mechanical key switches are deeee-luxe! With smooth actuation and Cherry MX compatibility,...
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Group shot of Clear DSA Keycaps for MX Compatible Switches - 10 pack
Get ready to clacky to your heart's content. Here is a 10 pack of clear transparent DSA keycaps for your next mechanical keyboard or 
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Enclosed Speaker with wires
Listen up! This single  2.8" x 1.2" speaker is the perfect addition to any audio project where you need 4 ohm impedance and 3W or less of power. We...
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NeoPixel Stick with 8 x 5050 RGB LED
Make your own little LED strip arrangement with this stick of NeoPixel LEDs. We crammed 8 of the tiny 5050 (5mm x 5mm) smart RGB LEDs onto a PCB with mounting holes and a chainable...
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angled shot of TRRS jack breakout board.
Tip-Ring-Ring-Sleeve style audio cables are often used for situations where you want stereo audio and then an extra contact for a microphone input.
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2 x NeoKey 1x4 QT
Four Mechanical Key Switches with NeoPixels - STEMMA QT / Qwiic
3 x Rotary Encoder Stemma QT
Adafruit I2C Stemma QT Rotary Encoder Breakout with NeoPixel - STEMMA QT / Qwiic
1 x Mini Toggle Switch - SPDT
Mini Toggle Switch - SPDT
1 x Mini Toggle Switch - DPDT
Mini Toggle Switch - DPDT
1 x On/Off Switch
Rugged Metal On/Off Switch with Blue LED Ring - 16mm Blue On/Off
1 x AA Battery Holder
3 x AA Battery Holder with 2.1mm Plug
1 x Alkaline AA batteries
(LR6) - 3 pack

Cables and Such

1 x Long STEMMA QT Cable
JST SH 4-Pin Cable - 400mm long
1 x Medium STEMMA QT Cable
STEMMA QT / Qwiic JST SH 4-pin Cable - 100mm Long
4 x Short STEMMA QT Cable
STEMMA QT / Qwiic JST SH 4-Pin Cable - 50mm Long
1 x 10-wire Silicone Cover Ribbon Cable
10-wire Silicone Cover Ribbon Cable
1 x 1.25mm Pitch 2-pin Cable Matching Pair
40cm long - Molex PicoBlade Compatible
1 x JST PH 2-Pin Cable
Male Header 200mm
2 x JST PH 2-Pin Cable
Female Connector 100mm
1 x 1.25mm Pitch 3-pin Cable Matching Pair
40cm long Molex PicoBlade Compatible
1 x Clear Adhesive Squares
6 pack - UGlu Dashes


  • 4x M3 x 16mm button head screws
  • 30x M3 x 10mm button head screws
  • 2x M3 x 6mm button head screws
  • 2x M2.5 x 6mm button head screws
  • 8x M2.5 x 8mm button head screws
  • 4x M2 x 8mm button head screws
  • 30x M3 hex nuts

This guide was first published on Sep 20, 2023. It was last updated on Jul 15, 2024.

This page (Overview) was last updated on Mar 08, 2024.

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