Brume

A four-part multi-timbral synthesizer that runs on a Raspberry Pi Compute Module 5. Brume has four sound engines and six voices per part, a shared filter section feeding an effects chain, a sandboxed Lua scripting layer, and a 10.1-inch touchscreen UI. A single USB cable presents the device to a host computer as a class-compliant audio and MIDI interface.

What's in the box

• Engines: FM, Harmonic, Timbral, Granular
• Voices: 6 per part, 24 total
• Filter: One state-variable filter per voice
• Effects: Saturator, chorus, delay, dattorro plate reverb
• Modulation: 2 LFOs and 2 step sequencers per part, 24 named transition shapes
• Scripting: Sandboxed Lua 5.5; control scripts and FX scripts
• MIDI: 16 channels, over USB or a hardware MIDI input
• Audio: Stereo over USB; per-part stems also available
• Display: iced + wgpu touchscreen, 10.1 inch, 1920×1200

Hardware

Brume's reference platform is the Raspberry Pi Compute Module 5 on a carrier IO board, because Brume's audio and MIDI bridge to a host computer requires USB device-mode and the CM5 IO board exposes that mode through a USB OTG jumper. Whether the device-mode port on the carrier is Type-C or Type-A is incidental; what matters is that one of the carrier's USB ports is wired to the CM5's peripheral controller. The same combination pairs the CM5 with a 10.1-inch HDMI touchscreen; the reference unit's specific parts are documented in HARDWARE.md. The software is written against the stock Pi kernel and ALSA; notes from anyone who has gotten Brume running on different IO boards or displays are welcome in the same file.

Status

Brume is pre-1.0, hobby-grade, single-maintainer; the tracked surface is in CHANGELOG.md.

Documentation

• INSTALL.md: first-time CM5 bring-up.
• DEPLOY.md: iteration loop on a CM5.
• HARDWARE.md: IO board, screen, and audio notes.
• BOM.md: the exact parts we developed on, with links.
• CONTRIBUTING.md: house style, PR flow, and scope.
• AGENTS.md: entry point for AI coding agents.
• CHANGELOG.md: every user-observable change.

License

Copyright (C) 2026 Brandon Huey [email protected]

Brume is licensed under the GNU General Public License version 3.0 only (GPL-3.0-only). The full license text is in LICENSE. Contributions land under the same license without a CLA or copyright reassignment; see CONTRIBUTING.md for details.

The Brume wordmark and splash use Instrument Serif by Rodrigo Fuenzalida and the Instrument Serif Project Authors, distributed under the SIL Open Font License 1.1; the font and its license live under crates/ui-native/assets/.