Introduction: Arduino DUE Guitar Pedal - Open Hardware.

About: We are MAD about guitar pedals.

pedalSHIELD is an Open-Hardware / Open-Source Arduino guitar pedal shield. It is designed as a platform to learn about digital signal processing, guitar effects, and synthesizers — without needing an in-depth knowledge of electronics or programming.

It allows you to design your own effects in C/C++, or download them from the online library.

Some of the downloadable presets include an octave, reverb, delay and even distortion pedals!

The pedal features three programmable potentiometers, two switches, one programmable LED and the foot pedal switch. The shield is directly plugged into an Arduino DUE. All the schematics and part list are open-hardware. It is completely designed in KiCad (open source electronics CAD design suite).

Step 1: Get the Components.

The components to build this Arduino guitar pedal are all through hole and easy-to-find parts. You can download the Bill of Materials in .txt, .pdf, excel or Open Office format. There is also a topic in the forum where you can ask for advice or alternatives.

In the ElectroSmash store you can buy a DIY assembly kit or just the PCB. In the forum there are also the PCB transfers so you can do the board at home.

Step 2: Soldering the PCB

The document "How to Build pedalSHIELD in 5 Steps" explains how to mount the PCB step by step with photographs and detailed information. There is a topic in the forum for any additional question.
There is also a Flickr gallery with high-res photos of each step.

Step 3: Closer Look to the Schematic

The shield has three parts:

  1. The Input Stage or Preamp: Amplifies the guitar input signal and sends it to the Arduino microcontroller to be processed.
  2. Arduino Board: It does all the Digital Signal Processing (DSP) modifying the signal and adding the effect (delay, echo, distortion, volume...).
  3. The Output Stage: Once the waveform is processed, the signal is taken from the Arduino DACs and prepared to be sent to the Guitar Amplifier. This part also includes a Summing Amplifier which is very useful for delay effects like echo or chorus.

Step 4: Start Programming !

Check the forum topic "How to Start Programming pedalSHIELD". It is a short guide to start coding this arduino guitar pedal in 3 steps. The aim is to understand the basic ideas and then progress as fast as possible through a series of examples.

You are very welcome to upload your ideas and pedals to the forum!

Step 5: Create Your Own Guitar Sounds.

The easiest way to progress is to take the basic examples from the forum and try to modify them to fit your taste. Just changing some values or parameters can make a great difference.

You can also think about how to create your own new pedals (reverse delay? bit-crash distortion?) or mixing some of the examples (delay+distortion).

There are a lot of unexplored areas to be discovered!