Multieff

RiffPi

RiffPi is the control daemon for Kleag's MFX, a DIY guitar multi-effect pedalboard built around a Raspberry Pi, a Pisound sound card, and Guitarix as the effects engine. It reads the pedalboard's foot switches, rotary encoders, keypad, joystick, and expression pedal, and turns them into MIDI sent to Guitarix.

Full documentation: https://kleag.github.io/riffpi/

Features

• 4 foot switches with LEDs toggle Guitarix effects, and stay in sync if Guitarix changes state on its own (e.g. loading a preset).
• 4 rotary encoders send relative MIDI CC changes; the last one's button cycles preset banks A-D.
• A 4x4 keypad selects presets directly and doubles as mouse left/right click.
• A joystick moves the mouse pointer, for fine-tuning Guitarix's on-screen knobs, and its push acts as a middle click.
• An expression pedal sends a smoothed, continuous MIDI CC.
• Hardware design (KiCad) for the controller PCB, in kicad_board/.

Quick start

pip install riffpi
riffpi install-service   # writes, enables, and starts a systemd --user service

See Installation for the full Raspberry Pi setup (I2C, uinput permissions, installing and autostarting Guitarix and its guitariqx GUI, headless/no-login boot, WiFi power management), and Usage for what each control does and the full MIDI CC mapping.

Hardware

Wiring, MCP23017/ADS1115 pin maps, a block diagram, and the schematic/PCB renders are in Architecture. Hardware design source (KiCad 9) is in kicad_board/.

Development

uv build                       # or: python -m build
uvx ruff check src/            # lint
uvx twine check dist/*         # validate package metadata
.venv/bin/mkdocs serve         # preview the docs site locally
uvx bumpver update --minor     # bump the version (patch/minor/major)

CI (.github/workflows/) lints and builds the package on every push/PR, deploys the docs site on changes to docs/, and publishes to PyPI on GitHub Release.

License

Copyright Gaël de Chalendar, 2025-2026.

This project describes Open Hardware and is licensed under the CERN-OHL-W v2. You may redistribute and modify it and make products using it under the terms of the CERN-OHL-W v2 — see LICENSE.md. It is distributed WITHOUT ANY EXPRESS OR IMPLIED WARRANTY, INCLUDING OF MERCHANTABILITY, SATISFACTORY QUALITY AND FITNESS FOR A PARTICULAR PURPOSE.

Source location: https://github.com/kleag/riffpi. As per CERN-OHL-W v2 section 4.1, should you produce hardware based on these sources, you must keep the source location visible on the external case of the pedal or other product you make using this documentation.