Guitar Pedal DSP

Bare DSP Hardware
Bare testing hardware

I've played guitar since highschool, and I've always been curious about electric guitar effects and signal processing. Fortunately PJRC has an audio board along with supporting software that makes exploring this domain very simple. I've used the Teensy hardware (ARM Cortex M0, M4, M7) extensively, so this was a drop in solution. The audio board provides a codec that gives CD quality audio, which is more than adequate for my needs pumping crunchy guitar through an amp.

Complimenting the board is an audio library that provides high level access to the underlying hardware and data. The library exposes an audio object that presents the current audio buffer that can be arbitrarily manipulated and sent back to the speakers, which is a convenient hook into exploring custom logic. I use this in addition to implementing the audio libraries interfaces for my own effects to test and learn about guitar effects.

I've implemented a simple command interface via the USB Serial connection that allows me to configure parameters without requiring hardware controls. I use this interface to build GUI applications that can be run on desktop or on my phone to control the pedal and conveniently toggle and configure effects.

Hardware and Software

  • Teensy 3.6
    • Any Teensy with floating point support will work (3.x and 4.x)
  • Audio Adapter
  • 2.5W Amplifier
    • Allows powering small speakers if not outputting to amp or headphones
  • Cabling
    • You'll want to adapt from 1/8" to 1/4" jacks to plug into guitars and amps
  • Firmware in C++