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Introduction

The OpenStompTM Coyote-1 is an open source audio effects processor built for guitar players. With the Coyote-1 you can develop custom audio effects in software (like distortion, echo, chorus etc.), mix multiple effects to build “patches”, and exchange those effects and patches with the OpenStomp community.

A companion Windows application (OpenStomp WorkbenchTM) allows you to combine effects into patches graphically, and to move patches and effects between the Coyote-1 device and your PC.

The Coyote-1 O/S is open source so you can tweak it to behave any way you like, and the hardware is fully documented so that you can take control of the whole pedal, dedicating all available system resources toward the implementation of unique custom solutions.

Inspiration Strikes!

For years I’d wanted a guitar pedal I could program myself. I wanted to write weird effects that nobody else in the industry was making. I wanted it to be rugged enough to throw in a gig bag and knock around on stage. I dreamed that a community of effect artists might one day spring up and be able to share their work with each other.

On the night of June 22nd 2007 I climbed into my car with a huge cup of coffee and set out for a three hour drive to go camping in Santa Barbara. By the time I stood on the starlit beach at 1AM jazzed on caffeine, the Coyote-1 was in my head and I knew I had to build it.

Propeller Powered

At the heart of the Coyote-1 is one the coolest, most innovative, and just plain knock-your-socks-off fun microprocessors to come along in a decade; the Propeller from Parallax. The Propeller contains 8 independent processor cores running simultaneously at 80MHz with a unique architecture supporting a high-level byte coded language called “Spin”, and a low-level assembly language with an amazingly versatile instruction set.

The Propeller development tools are all free, and the Propeller architecture allows users to develop firmware with nothing more than a simple USB cable.

Its revolutionary architecture allows the Propeller to generate video in software by adding just three external resistors, so the Coyote-1 includes a video out port which can be used by developers for debugging or adapted to implement things like graphical tuners, spectrum analyzers, oscilloscopes, or light shows.

An Audio Sandbox

The Coyote-1 is designed to be an “Audio Sandbox” where you can try out effect ideas, share them with others, and take them gigging. Its third bi-directional quarter-inch audio in/out can be configured either as an output for stereo effects, or as an input for modulation effects (like vocoders, where one audio input is used to modulate a second).

OpenStomp Workbench

The Coyote-1 ships with Open Stomp Workbench; a Windows application which allows you to create patches by graphically “wiring” effects to each other and to pedal resources such as knobs, buttons, LEDs, inputs, and outputs.

Modules and patches are saved from / loaded into OpenStomp Workbench as stand-alone files. To share content with someone, just give them your Coyote-1 patch file (*.c1p) or module file (*.c1m). To publish the source code for a self-authored or modified module, just provide that module’s single Propeller Spin file (*.spin).

Patches and modules can be exchanged on the OpenStomp forum here.

About Me

I’m Eric Moyer and I’ve spent the last 20 years designing hardware and software for networking systems, in-flight-entertainment, 3D scanning, and medical devices.

The Open Stomp project is my one-man “jedi” side-project to create a full device design single-handedly (hardware, firmware, applications software, artwork, PCB layout, 3D CAD, manuals, test software, and manufacturing specs).