# Melodee licensing Melodee is a modified version of Felucca by Leo Kuroshita (@kurogedelic), Hügelton Instruments (), and keeps Felucca's licensing. Melodee is free software, licensed under the GNU General Public License, version 3 only (`GPL-3.0-only`, full text in `LICENSE`). That covers the code and its own assets. A few bundled or ported parts keep their own licences; they are listed below, and their licence texts are in `LICENSES/`. Melodee code and modifications: Copyright (C) 2026 Kerem Kilic (Ellic Studio)\ Retained Felucca portions: Copyright (C) 2026 Leo Kuroshita (@kurogedelic), Hügelton Instruments\ Tessera code and modifications (melodee-tess): Copyright (C) 2026 Theo Dainis Copyright notices follow the code's actual origin. Independently written Melodee files credit Kerem Kilic; mixed files also identify the retained Felucca portions. Unchanged upstream files and third-party ports retain their original notices. Sharing Felucca's GPL licence does not make new Melodee code Hügelton Instruments' work. ## What is GPL-3.0-only Every file in this tree that carries an `SPDX-License-Identifier: GPL-3.0-only` header: - the firmware: `firmware/` (app, HAL, update loader) - the build script and tools: `build.sh`, `tools/` - the web pages (installer, editor) and their tests: `web/` (not the Fukiai font, below) - the host tests: `tests/` Two source files are ports and keep the licence of their originals: `firmware/src/phys_dsp.c` (DaisySP, MIT) and `firmware/src/phys_symp.c` (Rings, MIT). `firmware/src/fm6_core.c` and `firmware/src/eng_fm6.c` restate MSFA (Apache-2.0) and Dexed (GPL-3.0-or-later) in C with native fp32 signal arithmetic (below). The firmware built with them is GPL-3.0-only as a whole. You may use, study, change and share Melodee under the GPL. If you distribute Melodee, or firmware derived from it, you must also give your recipients its complete corresponding source under the same licence. That includes devices that ship with modified Melodee inside. ## Retained Hügelton Instruments material The following original material is by Hügelton Instruments (Leo Kuroshita). Melodee's additions and modifications are credited separately in the source files: | What | Licence | Where | | --- | --- | --- | | Original Felucca portions retained in the firmware, tools, web pages and tests | GPL-3.0-only | Source notices; `LICENSE` | | Felucca 1.6's fix for its issue #236 (rows dark while a storage erase stops the LED scan), ported by hand | GPL-3.0-only | `firmware/src/storage_hw.c` | | Felucca 1.6.1's safe CPU1 hold (`fm1_cpu1_halt`, release commit a53ecf4), as adapted in Melodee 1.4.3 (keremimo/melodee 6e6a580) | GPL-3.0-only | `firmware/hal/fm1_core1_stop.h` | | The PHASE engine's waveforms: a C port of the oscillator of CrispyZebra () | GPL-3.0 | `firmware/src/eng_phase.c` | | The panel picture | GPL-3.0-only | `docs/panel.jpg` | | Felucca 1.6.1's update package check (the update entry takes only a package whose flash.bin is an FM-1's size; another board's is refused before anything is erased), ported by hand | GPL-3.0-only | `firmware/src/ota.c`, `tests/ota_test.c`, `tests/ldr_test.c` | | The Fukiai icon font (): the web editor's icons (the firmware draws its own: `tools/gen_icons.py`, GPL-3.0-only; `tools/gen_aa_icons.py` still rasterises Fukiai for comparison) | MIT | `web/fukiai.ttf`, `LICENSES/MIT-Fukiai.txt`, `web/FUKIAI-LICENSE.txt` | ## Third-party material | What | Licence | Where | | --- | --- | --- | | ChoralRoot FM-1 contributors (, v0.16, commit `9c7445cdd7b767c779741d28654fb59cca3acd97`): boot stub, interrupted-update write ordering, commit-marker/CRC compensation, and recovery tests, adapted for Melodee. The shared `CRSTUB` / `CRBM` format is retained. | GPL-3.0-only | `firmware/stub/`, `firmware/loader/ldr_core.c`, `tools/build.py`, `tools/fm1pkg_make.py`, `tests/boot_stub*`, `tests/loader_powercut_test.c` | | Chakra Petch font by The Chakra Petch Project Authors (): the UI text and the keycap labels, rasterised into the firmware at build time (`tools/gen_aa_font.py`, `tools/gen_aa_keycaps.py`; the generated tables are not offered as a font, and the font declares no Reserved Font Name) | SIL OFL 1.1 | `assets/fonts/ChakraPetch-*.ttf`, `LICENSES/OFL-ChakraPetch.txt` | | Rubik font by The Rubik Project Authors (): Melodee's UI face, kept for the `rubik` preset of `tools/gen_aa_font.py` (not in the firmware since Tessera's look) (`tools/gen_aa_font.py`, `tools/gen_aa_keycaps.py`; the generated tables are not offered as a font, and the font declares no Reserved Font Name) | SIL OFL 1.1 | `assets/fonts/Rubik[wght].ttf`, `LICENSES/OFL-Rubik.txt` | | Inter Tight font by The Inter Project Authors: the panel diagram (`tools/gen_panel_diagram.py`, `docs/panel.jpg`) and the `inter-tight` preset of `tools/gen_aa_font.py` (the firmware's text was Inter Tight up to Melodee 0.13) | SIL OFL 1.1 | `assets/fonts/InterTight[wght].ttf`, `LICENSES/OFL-InterTight.txt` (also `assets/fonts/OFL.txt`) | | DaisySP by Electrosmith, Corp and Emilie Gillet (): the PHYS engine's modal and string models and the resonator, ported to fixed point | MIT | `firmware/src/phys_dsp.c`, `LICENSES/MIT-DaisySP.txt` | | Rings by Emilie Gillet (): the PHYS engine's sympathetic strings, ported to fixed point | MIT | `firmware/src/phys_symp.c`, `LICENSES/MIT-Rings.txt` | | Grids by Emilie Gillet (): the ATLAS generator's map of 25 drum patterns (`grids/resources.cc` node_0..node_24, unchanged) and its way of reading it (`grids/pattern_generator.cc` ReadDrumMap and EvaluateDrums: the blend, CHAOS, the accent), restated in C | GPL-3.0-or-later | `firmware/src/gen_grids.h`, `firmware/src/gen.c` | | Plaits and stmlib by Emilie Gillet ( `f4cfa76`, `d18def8`): the MACRO engine's synthesis (the lean set of Plaits' models), compiled as C++ with the few changes marked `melodee-tess` (see its README); built only with `MELODEE_PLAITS=1` | MIT | `firmware/third_party/mi/` (its `LICENSE`, `README.md`), `firmware/src/eng_macro.c`, `firmware/src/macro_glue.cc` | | EuroPi's Polyrhythmic Sequencer (Allen Synthesis EuroPi contrib, ; after the Moog Subharmonicon's rhythm generators): the POLY generator's idea, four clock dividers advancing a four-step pitch sequence, restated in C (no code copied) | CC0-1.0 | `firmware/src/gen.c` | | initenere, a norns script (): the QUAD generator's idea, a 4 x 4 note matrix whose rows are voices with their own direction and play probability, and one voice's tick moving another (time routing), restated in C (no code copied) | not applicable (idea only) | `firmware/src/gen.c`, `firmware/src/tessera.c` | | Fall, a norns script by ambalek (, MIT): the idea of BOUNCE's FALL, leaves falling at speeds of their own and playing where they land, then falling again, restated in C (no code copied) | not applicable (idea only) | `firmware/src/gen.c`, `firmware/src/ui_graph.c` | | Constellation, a norns script by timothy-taylor (, no licence given): the idea of CONSTELLATION, a sky of stars passing a ship whose crosshair catches them into a loop, restated in C (no code copied) | not applicable (idea only) | `firmware/src/gen.c`, `firmware/src/ui_graph.c` | | nørgård, a norns script (), and Per Nørgård's infinity series: the idea of SERIES, the series worked out from the bits of the step's number, restated in C (no code copied) | not applicable (idea only) | `firmware/src/gen.c` | | less concepts, a norns script by dan_derks (): the idea of CELLS, eight cells of an elementary automaton picking the notes, restated in C (no code copied) | not applicable (idea only) | `firmware/src/gen.c`, `firmware/src/ui_graph.c` | | FM-1 Studio Tess by Inputsignwave (, Performance 6, `tess_features.c` `features_duration_*`): the NOTE LENGTH page's held-note timing (FIXED, HIT, keys held at once), restated for melodee-tess's sequencer; its MIDI out and one-pass capture are not taken | GPL-3.0-only | `firmware/src/note_len.c` | | Triple Sloth by Nonlinear Circuits (Andrew Fitch, ), with J. C. Sprott's piecewise-linear jerk system (1997): the SLOTH mod sources' idea, three slow chaotic circuits (TORPOR, APATHY, INERTIA), restated in C (no code copied) | not applicable (idea only) | `firmware/src/organic.c` | | ochd by Instruō and DivKid (): the OCHD mod sources' idea, eight free-running LFOs, each faster than the one before and never in step, restated in C (no code copied) | not applicable (idea only) | `firmware/src/organic.c` | | MSFA (Music Synthesizer for Android, Copyright 2012 Google Inc.) and Dexed (Copyright 2013-2025 Pascal Gauthier, ; portamento rates by Jean Pierre Cimalando): the FM6 engine restates their synthesis in C with native fp32 signals and discrete DX7 envelopes/ROMs (MSFA's envelopes, pitch envelope, LFO, operator kernels and Dx7Note, Apache-2.0; Dexed's MARK I and OPL engines and its voice handling, GPL-3.0-or-later); their DX7 measurement tables and the tables Dexed computes at start (sine, 2^x, frequency, log-sine / exponent, OPL ROM, detune, LFO, portamento) are used as data. `tests/dexed_ref.cc` builds Dexed's own sources (from a checkout, not in this tree) to compare against. The FM6 factory patches are Felucca's own (F1..F8) and Melodee's own (F9..F24) | Apache-2.0, GPL-3.0-or-later | `firmware/src/fm6_core.c`, `firmware/src/eng_fm6.c`, `tools/gen_tables.py`, `tests/dexed_ref.cc`, `LICENSES/Apache-2.0-msfa.txt` | | ZEN-1 by aceyprime ( 1.1, `firmware/src/dsp/zen_patches.h`) and FuMi-1 by cartesive (, via ZEN-1's `fumi_patches.h`): their own FM6 patches, written as operator settings, as the FM6 presets after INIT VOICE (SOFT PAD .. FURIN from ZEN-1; HYOSHIGI, MOKUGYO, KOTO PLUCK, KOTO RING, KOTO WARM, KUGO HARP from FuMi-1), packed bytes unchanged but for the names; FuMi's patches taken from community banks are not included | GPL-3.0-only | `firmware/src/eng_fm6_zen.h` | | reSID by Dag Lem (): the SID engine restates in C, at the register level, its waveform generator (accumulator, noise register, ring modulation, hard sync), envelope generator (rate and exponential counters, the ADSR delay), its R-2R DAC model (reSID 1.0 `dac.cc`), the 6581 / 8580 filter's resonance laws and output sum and the C64 output stage; its measured 6581 and 8580 cutoff curves and its spline interpolation (reSID 0.16) make the cutoff tables at build time; its samples of a real 6581's and 8580's combined waveforms (`wave*.dat`, unchanged) are packed into the firmware as data. Used under GPL-3.0 | GPL-2.0-or-later | `firmware/src/eng_sid.c`, `firmware/src/drum_sid.c` (its 6581 DC offsets, reSID 0.16), `tools/gen_tables.py`, `assets/resid/` | | klattsch by Tony Gies (): design reference for the VOICE engine; no code copied. Formant data from Klatt (1980) / Hillenbrand et al. (1995) | MIT (klattsch) | credit only | | JieLi AC79 SDK by JieLi Technology: three external files go into every `.fwsc` package; the optional RAM recovery helper is in `assets/recovery/` | Apache-2.0 | `LICENSES/Apache-2.0.txt` | On the device, HOME held > ABOUT opens the information screen; turning PRESETS scrolls on into CREDITS, a short list of these authors, licences and source URLs. ## JieLi SDK files in the packages (Apache-2.0) A `.fwsc` package made by `tools/build.py` (with `tools/fm1pkg_make.py`; this is the package the web installer installs) holds three unmodified files from the JieLi AC79 SDK (, `cpu/wl82/tools/`). They are read from your SDK checkout at build time (see BUILDING.md); those three SDK files are not in this tree. | File in the package | What it is | | --- | --- | | `uboot.boot` | the first-stage boot loader (SPL) | | `cfg_tool.bin` | the chip configuration block | | `eq_cfg_hw.bin` | the default hardware EQ table | They are licensed under the Apache License, Version 2.0 (`LICENSES/Apache-2.0.txt`), not under the GPL, and their copyright stays with JieLi Technology. The SDK has no NOTICE file. Apache-2.0 files may be distributed together with GPL-3.0 code; Melodee itself stays GPL-3.0-only. Every distribution of a package carries the licence texts with it: the release folder (`tools/build.py --release`) and the site (`web/make_site.py`, next to the package in `firmware/` and linked from the installer page). ## Standalone ROM recovery tool The optional `fm1-recover` executables include `assets/recovery/wl82loader.bin`, an unmodified RAM recovery helper from JieLi's AC79 SDK under Apache-2.0. Its source version and checksum are recorded in `assets/recovery/README.md`; it is loaded into RAM, not installed in flash. Copyright remains with JieLi Technology. This SDK file is included in the source tree and the recovery distributions; the three SDK files in firmware packages are still read from an external checkout. Recovery archives carry Melodee's GPL-3.0-only licence, the SDK's Apache-2.0 licence, and the bundled Python/PyUSB/PyInstaller/libusb notices. libusb is dynamically loaded under LGPL-2.1-or-later; its corresponding source archive is included, and `--libusb PATH` allows using a replacement library. PyInstaller's bootloader exception permits distributing the generated executable under Melodee's licence. ## No vendor firmware material No M-VAVE material is part of Melodee. The firmware links no vendor code and contains no vendor data, and the packages hold only Melodee and the three SDK files above. The installer's "Return to official V15" holds only the official file's size and SHA-256: you select the official firmware file you downloaded yourself, and it is checked and installed in your browser, never uploaded or redistributed. ## Contributions Contributions are welcome under GPL-3.0-only. ## Trademarks "Felucca" and "Hügelton Instruments" are names of Hügelton Instruments. "M-VAVE" and "FM-1" are trademarks of their respective owners. Melodee is independent firmware that runs on FM-1 hardware. It is not affiliated with, endorsed by or supported by those owners, nor by Hügelton Instruments. ## Radio Melodee never enables the Bluetooth / Wi-Fi radio of the hardware.