Licenses

The project’s own code, host software and firmware alike, is licensed under the MIT License, Copyright © 2018–2026 The Trustees of Indiana University. Some base-firmware files carry their own notice, “Copyright 2018 Geoffrey Brown, Licensed under the Apache License, Version 2.0”, and remain under that license.

Several of the programs built from that code link components that are available only under the GPL. Those programs, as distributed, are therefore covered by the GNU General Public License, version 3:

Distributed program	GPL component	Its license
Every tag and base-board firmware image	ChibiOS/RT kernel, OS library and Cortex‑M ports	GPL-3.0-only
sensorviz, btviz	QCustomPlot 2.1.1, statically linked	GPL-3.0-or-later
qtcalibrate	Qt Quick 3D and Qt Quick Timeline	GPL-3.0-only

MIT is compatible with GPL-3.0, so the MIT code can be combined into those programs. Each program as a whole is conveyed under GPL-3.0, while the MIT grant still applies to the project’s own code taken on its own. The remaining host programs and the external flash loaders contain no GPL code.

Third-party components

The software repository carries one index per side, listing every third-party component with its version, its license, and which programs it is used in. Each component has a notice file giving its copyright, where it is used and where its source is. These are the authoritative lists, kept beside the code they describe:

Host tools and their manual Firmware and flash loaders

The same files travel with the software itself rather than only living on GitHub: the host packages install them as tag_tools/licenses, builds that install firmware or loaders place them alongside as licenses/, and the firmware release archive carries them as firmware/licenses.

The inventory behind both indexes was taken on 6 October 2026. Each license was read from the component’s own license file or source header rather than from package metadata. The licensing overview describes how the notices are organized and kept current.

Getting the source

For the programs distributed under the GPL, the complete corresponding source is the software repository at the release tag the package was built from — vX.Y for the host tools and the flash loaders, fw-vX.Y for firmware images.

For the host tools that also means the third-party sources the repository names: the vcpkg ports at the baseline recorded in vcpkg-configuration.json, and Qt 6.8.2 from the Qt archive. For firmware it means the ChibiOS submodule at the commit that release tag records, which is also written into each image’s *-build-manifest.json.

Either offer is valid for at least three years from the release date, to anyone who receives the programs.

Hardware designs

The board and mechanical designs in the hardware repository are licensed under the CERN Open Hardware Licence Version 2 — Permissive (CERN-OHL-P-2.0), Copyright © 2018–2026 The Trustees of Indiana University.

You may use, study, modify, share and distribute the designs, and make and sell products from them, including in closed products, provided the notices travel with the source. The designs are distributed without warranty of any kind; the licence text gives the applicable conditions.

Of the three CERN licence variants this is the permissive one, matching the MIT terms the software carries rather than imposing reciprocal obligations the software side does not have. The STM32_open_pin_data submodule is ST’s and carries its own license.

Citing this work

We request that any use of this work, or of derivatives of this work, in scientific research appropriately cite our contributions in any publications.

Citation pending

The preferred citation has not been settled. Until it appears here, please get in touch and we will tell you what to cite.