MIDI Captain MAX Custom Firmware

Bidirectional, config-driven CircuitPython firmware for Paint Audio MIDI Captain foot controllers.

Includes a GUI Config Editor!

What It Does

This firmware transforms your MIDI Captain into a bidirectional MIDI controller where your host software (DAW, plugin host) can control the device's LEDs and display, not just receive button presses.

Momentary and toggle modes are currently supported. Many more issues are coming! See here for all open features and issues.

Key Features

• 🔄 Bidirectional MIDI — Host can update LEDs/display state
• ⚙️ Config-driven — Customize button labels, CC numbers, colors with the GUI Config Editor.
• 🎨 Visual feedback — LEDs and LCD reflect actual host state
• 🎛️ Full input support — Footswitches, rotary encoder, expression pedals
• 🎸 Stage-ready — No unexpected resets, no crashes, no surprises

Supported Devices

Device	Status
MIDI Captain STD10 (10-switch)	✅ Fully working
MIDI Captain Mini6 (6-switch)	✅ Fully working
4, 2, 1-button variations	❔ need hardware

Installation

1. Download the latest firmware.zip and appropriate GUI Config Editor
2. Connect your MIDI Captain via USB (hold Button 1 while powering on)
3. Copy all files and folders from the zip to the device drive (CIRCUITPY or MIDICAPTAIN)
4. On mini6, rename config-mini6.json to config.json, overwriting the existing one.
5. Power off/on or unplug and replug USB to restart

Configuration

Config Editor App (Recommended)

The MIDI Captain MAX Config Editor is a desktop app that makes configuration easy!

Download for your platform:

• macOS: MIDI-Captain-MAX-Config-Editor-[version].dmg
• Windows: MIDI-Captain-MAX-Config-Editor-[version].msi or MIDI-Captain-MAX-Config-Editor-[version]-setup.exe

Get the latest release from Releases

Installation

MacOS

1. Open the DMG and drag the app to your Applications folder

Windows

1. Run the MSI installer or setup.exe
2. At this time, Windows builds are unsigned. Users will see a Windows SmartScreen warning.
3. To continue installation, click "More Info" --> "Run Anyway".
   • Signing certificates will be obtained in the near future.

Usage

2. Launch the app and connect your MIDI Captain
3. Edit button labels, CC numbers, and colors using the visual editor
4. Save directly to the device.
5. Power cycle the device to load the new settings.

Features

• 🖱️ Visual editing — No JSON syntax to learn
• ✅ Real-time validation — Catch errors before saving
• 🎨 Color picker — Visual color selection
• 🔍 Device detection — Automatically detects connected MIDI Captain

Manual Configuration

You can also edit config.json directly on the device:

{
  "buttons": [
    {"label": "DELAY", "cc": 20, "color": [0, 0, 255]},
    {"label": "REVERB", "cc": 21, "color": [0, 255, 0]},
    {"label": "CHORUS", "cc": 22, "color": [255, 0, 255]},
    {"label": "DRIVE", "cc": 23, "color": [255, 128, 0]},
    {"label": "COMP", "cc": 24, "color": [0, 255, 255]},
    {"label": "MOD", "cc": 25, "color": [255, 255, 0]},
    {"label": "LOOP", "cc": 26, "color": [255, 0, 0]},
    {"label": "TUNER", "cc": 27, "color": [255, 255, 255]},
    {"label": "BANK-", "cc": 28, "color": [128, 128, 128]},
    {"label": "BANK+", "cc": 29, "color": [128, 128, 128]}
  ]
}

Field	Description	Default
label	Text shown on LCD (max ~6 chars)
cc	MIDI CC number sent on press (0-127)
color	RGB color for LED when ON [R, G, B]
off_mode	LED is off or dim when in OFF state	off

MIDI Protocol

Device → Host (button presses)

Input	MIDI Message
Encoder wheel	CC 11 (0-127 position)
Encoder push	CC 14 (127=press, 0=release)
Footswitch 1-10	CC 20-29 (127=ON, 0=OFF)
Expression 1	CC 12 (0-127)
Expression 2	CC 13 (0-127)

Host → Device (LED/state control)

Send CC to the switch on its CC Number with value 0 or 127 to set button state:

• CC 20, value 127 → Button 1 turns ON (LED lights up)
• CC 20, value 0 → Button 1 turns OFF (LED off/dim)

Use Cases

• Gig Performer / MainStage — Sync button states with plugin bypass
• Ableton Live — Control track mutes/solos with visual feedback
• Guitar Rig / Helix Native — Effect on/off with LED confirmation
• Any MIDI-capable host — Generic CC control with bidirectional sync

Repository Layout

Path	Purpose
firmware/dev/	Active firmware (copy to device)
config-editor/	Desktop config editor app (Tauri + Svelte)
firmware/original_helmut/	Helmut Keller's original code (reference)
docs/	Hardware specs, design docs
tools/	Helper scripts

License

Copyright © 2026 Maximilian Cascone. All rights reserved.

You may use this firmware freely for personal or commercial performances. Redistribution of modified versions requires permission. See LICENSE for details.

Attribution

This project builds on work by Helmut Keller (hfrk.de), whose original firmware demonstrated bidirectional MIDI on the MIDI Captain. His code is preserved in firmware/original_helmut/ as a reference.

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Questions, Comments, Suggestions are welcome

Open an issue or check AGENTS.md for developer documentation.