OpenPocket

!!! THIS PROJECT IS A PROOF OF CONCEPT, DONT EXPECT FULL FUNCTION AND SOUND QUALITY !!!

Install here: https://isod89.github.io/openpocket/ (Donner Pocket X; M-VAVE BlackBox: v31 has the fix for issue #1, being tested) NEW WEB EDITOR: https://isod89.github.io/openpocket/editor.html · What's new since v33: docs/WHATS-NEW-v34-v36.md

Open-source guitar multi-effects firmware for the Donner Pocket X and the M-VAVE BlackBox. Written from scratch for the pedal's own chip (JieLi AC791N, two cores), installable from the browser.

What it does

• 12-block chain, 77 models, in any order you like (double-click PUSH to move a block; the order is saved with the preset): GATE, COMP, PITCH, SPECIAL FX, SYNTH, DRIVE, AMP, CAB, EQ, MOD, DELAY, REVERB
• Synths, keyboards and other guitars from a normal guitar (no MIDI pickup): organ, church organ, string machine, choir, mono synth with pitch tracking and a resonant ladder filter, PWM synth, bass synth, 12-string, acoustic, sitar (bridge buzz + sympathetic strings), baritone
• 8 amps fitted to captures of the real ones (v34): Twin Reverb, AC15 Top Boost, JCM900, JCM2000, Mark IV, Dirty Shirley, Pro Mod, 5150. A computer sets the engine's numbers (tube stages oversampled ×4, tone stack, power amp, sag) so that it matches a Neural Amp Modeler capture of each amp on real guitar playing; same CPU cost as a voiced-by-ear amp. Method and results: docs/FITTED-MODELS.md
• 4 drives fitted the same way (TS9, Klon, MXR M77, HM-2) and 7 cabinets (the 4x12 V30 fitted to measurements; Greenback, T75, Alnico Blue, Jensen, Cream, DI) with a MIC position
• Pro levels (v36): every amp, block and preset at the same loudness (-23 LUFS, measured on real guitar); 24 factory presets round the fitted amps, 28 USER slots; a PRESET LVL per preset; soft output limiter
• What changed since v33: docs/WHATS-NEW-v34-v36.md
• New screen (v36): a PLAY page readable from a distance (preset number and name, amp, chain in colour) and an EDIT page with big values and bars
• 8 reverbs rebuilt in v35: an 8-line feedback delay network with early reflections and moving lines (no metallic tail), the decay time you set (low and high frequencies apart), and Dattorro's plate; delays up to 2 s
• 11 modulations, 8 delays, 8 reverbs, octaver / polyphonic octave / Whammy / harmonizer / detune, envelope filter, ring modulator, bitcrusher, slicer, square-wave synth, 4 compressors, 3 EQs
• 52 preset slots you can overwrite (hold PUSH = SAVE; power-cut safe, kept across updates), 52 factory presets (one per style), a flicker-free colour UI, a chromatic tuner
• Detailed cabinets (cone breakup, off-axis mic comb, open-back reflection) and tube stages with bias shift (the note compresses on a hard attack and blooms back)
• 24-bit audio in and out, guitar read from the left input channel only, like the official firmware (the right channel only carries noise: mixing it in was the constant hiss on high-gain amps)
• USB update: the pedal shows up as a USB-MIDI device and takes updates from the web installer

Full list of models, presets and controls: docs/SOUNDS-AND-CONTROLS.md. Development notes (how the audio path was found, what changed in each version): docs/AUDIO-SDK.md.

Install

Open the installer page (GitHub Pages of this repository) in Chrome or Edge on a computer, plug the pedal in over USB, press Connect, then Install. The page also takes the pedal back to the official firmware: pick the official .fwsc from the maker, it is checked in the browser.

On the Donner Pocket X the page works: updating OpenPocket → a newer OpenPocket is tested (2026-11-02, your saved presets are kept), and other Pocket X owners have installed it from the page. On the M-VAVE BlackBox, OpenPocket up to v30 restarted every ~4.3 s after the pedal was switched off and on (issue #1). M-VAVE's firmware turns the chip's long-press reset off as its very first step (P33 PINR_CON = 0); OpenPocket did not, and on the BlackBox a pin sits at its active level, so the chip reset itself 4 s after each start. Right after an install the setting was still the official firmware's (it survives a warm reset), so the pedal worked until the next power cycle. v31 turns it off at start (confirmed on the BlackBox). The boot screen shows RST <reset source> PINR <value found>. (v30 to v32 also set the power supplies the way the official firmware does; it was not needed, and on a Pocket X it made the DSP slower and crackle, so v33 leaves them as the boot loader does again.) Being tested on the BlackBox. For a pedal that restarts in a loop, the page has a rescue mode (step 2): tick it, press Connect, plug the pedal in; the install starts the moment the pedal answers and halts its DSP at once. A BlackBox can always go back to its official firmware from the page (step 3). It is the same JieLi update system as the M-VAVE FM-1, where this method is used by Felucca, CLIPPER and SLOOP. Keep the SD-card recovery at hand (flash/: fm1buddy on an ESP32-S3, makeimage.bat).

Without internet: double-click INSTALL-OFFLINE.bat (Windows; nothing to install: a small PowerShell server, tools/serve_offline.ps1) or run make serve (macOS, Linux; tools/serve.py, needs Python 3). It serves the installer and the packages from this folder on this computer only (http://localhost:8765) and opens them in Chrome or Edge. Same page, same steps; keep it running while you install. INSTALL-OFFLINE.bat editor opens the web editor the same way. It builds the packages first when docs\firmware has none (INSTALL-OFFLINE.bat build rebuilds them).

Preset editor

From OpenPocket v32, the Preset editor page (editor.html, linked from the installer) edits the pedal live over USB, in Chrome or Edge: the 52 presets (load, save, save as, move up / down, back to factory), the current sound (every block, type and setting, on / off, the block order by dragging the tiles, the name), and preset files (export one or all 52 as JSON, import one to try it or many back into their slots). What you change on the page plays at once, and what you change on the pedal shows on the page. The protocol: docs/EDITOR-PROTOCOL.md.

Build

The same on macOS, Linux and Windows, in one container (Docker and Node 18+): make package (Windows: build.bat), then make test. On Windows without Docker, build.bat builds in WSL instead, with the JieLi toolchain installed there once (wsl sh firmware/setup.sh). Details, pinned versions, the toolchain's licence and troubleshooting: docs/BUILDING.md. The build makes:

• firmware/openpocket.bin, the app;
• docs/firmware/PocketX_9NN.fwsc, BlackBox_9NN.fwsc, manifest.json, the installer's packages (tools/pxpkg.py, with the update loader built from loader/);
• fm1-300.bin with make appimage DUMP=fm1-1.bin (or makeimage.bat), from your factory backup (SD-card recovery image).

PUBLISH-GITHUB.bat does everything in one click: it runs build.bat, then publishes the source, a release with the packages, and the installer on GitHub Pages (with your own git / gh and GitHub login; never a forced push). GitHub's main becomes exactly this folder's files (v36): the version history from openpocket.bundle is merged in, edits made on the GitHub site stay underneath, and the tag vNN points at that commit. PUBLISH-SOURCE.bat publishes the source only, without building. Edit the README in this folder rather than on the site: the next publish replaces the files with this folder's.

Test (no pedal needed)

tests/run_tests.sh [PocketX_016.fwsc] checks, on the PC:

• the preset store on a simulated flash, with a power cut at every step of a save;
• the sound engine with the pedal's own math library: every block × model × extreme setting, no NaN, nothing runs away;
• the package builder: it rebuilds the official PocketX 016 app area byte for byte (with the official file);
• the installer against a simulated pedal that runs the pedal's real update code (ota.c, then the loader's ldr_core.c) on a simulated flash: update, install over the official firmware, wrong model refused, damaged package refused before anything is erased, way back to the official firmware (its loader staged and checked);
• the page itself in headless Chromium (Playwright), clicking Connect and Install.
• the preset editor against a simulated pedal that runs the pedal's real editor code (px_editor.h) and preset store on a simulated flash: every command, pushes both ways, a power cycle; then the editor page in Chromium (sliders, drag and drop, save, move, export / import).

Layout

engine/	the sound engine (px_dsp.c), portable C, float
firmware/	the pedal app: screen, controls, audio (I2S), USB, UI (ui.h), board support (bsp/, felucca-bsp)
loader/	the update loader (runs from RAM, writes the app area)
docs/	the web installer (GitHub Pages) and documentation
tools/	package builder, loader wrapper, font converter, flash image tools
tests/	host tests and the simulated pedal
flash/	SD-card recovery with fm1buddy (ESP32-S3)

Licence

GPL-3.0-only. Board support and loader: MPL-2.0 (felucca-bsp). JieLi SDK files: Apache-2.0. Inter: OFL 1.1. The fitted models were computed from the NAM captures of pelennor2170/NAM_models (GPL-3.0, thanks to their authors) and the DI recordings of Alec-Wright/Automated-GuitarAmpModelling (GPL-3.0); neither is shipped. Product names are trademarks of their owners, used only to describe the sound. See NOTICE.md. Not affiliated with Donner or M-VAVE. Install at your own risk.