OpenMynd — Bluetooth controller for the MYND Open Hardware Project

An OSS Kotlin Multiplatform app for discovering, connecting, and controlling the MYND open-source hardware over Bluetooth LE using a modern Compose Multiplatform UI.

Features

• Scan for and connect to supported MYND devices
• Feature-driven controls, including:
  • Auto‑off timer
  • Battery and charging status
  • Battery‑friendly charging
  • Bluetooth and MCU firmware versions
  • Device color
  • ECO mode
  • EQ gain
  • LED brightness
  • Master volume and mute
  • Multipoint
  • PartyLink broadcast
  • Sound icons
  • Source selection

Architecture

Feature‑driven, testable KMP architecture with a clear separation of concerns.

graph TD
  UI[Compose UI] --> VM[ViewModels]
  VM --> Provider[DeviceFeatureProvider]
  Provider --> Features[Features]
  Features --> Connector[DeviceConnector]
  Connector --> BF[BlueFalcon]
  Connector --> KB[Kable]

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Key points:

• UI in composeApp/src/commonMain uses Compose Multiplatform with Voyager tabs/navigation.
• DI via Koin wires the DeviceConnector implementation and feature modules.
• DeviceConnector abstracts BLE and exposes state/operations used by features.
• Two BLE backends are available; BlueFalcon is default and optimized for Android+iOS here.
• The protocol layer implements MYND’s Actions protocol (command/response over a dedicated service/characteristics).
• You can find a full spec for this protocol and connection in specs/mynd.txt.

Bluetooth LE backends

• Default: BlueFalcon (BlueFalconDeviceConnector)
• Alternative: Kable (KableDeviceConnector)
• Switch at:
  • composeApp/src/commonMain/kotlin/de/teufel/openmynd/modules/core/di/DeviceConnectorModule.kt
  • Set selectedBackend to ConnectorBackend.KABLE (default is ConnectorBackend.BLUE_FALCON).
• Note: Seems with Kable we cannot raise MTU (e.g. to 512), which means we fail to communicate with MYND.

Permissions

• Android: Requests Bluetooth runtime permissions in app (scan/connect; location may be needed on older OS versions). Accept them on first launch via the permissions screen.
• iOS: Ensure Bluetooth usage descriptions are present in your app’s Info.plist when shipping to users.

Screenshots

Android (Dark)	iOS (Light)

Build and run

Prerequisites

• JDK 17+
• Android Studio (Giraffe/Koala+ recommended) with Kotlin Multiplatform support
• Xcode (for iOS simulator/device)
• Android SDK installed and local.properties pointing to it
• Optional: run KDoctor for environment checks

Android

• Assemble debug APK:
  • ./gradlew :composeApp:assembleDebug
  • Output: composeApp/build/outputs/apk/debug/composeApp-debug.apk
• Run from Android Studio using the composeApp configuration
• Gradle Android config:
  • compileSdk = 35, targetSdk = 34, minSdk = 24
  • App id: de.teufel.openmynd.androidApp

iOS

• Open iosApp/iosApp.xcodeproj and run the iosApp scheme (device or simulator)
• Or run from Android Studio’s iOS run configuration (KMP plugin)
• Simulator tests:
  • ./gradlew :composeApp:iosSimulatorArm64Test

Tech stack

• Compose Multiplatform UI (Material 3, resources)
• Koin dependency injection, Kotlinx Coroutines/Serialization
• Voyager navigation/tabs, Napier logging, Kermit
• BLE: BlueFalcon (default) and Kable (alternative)

Project layout

• composeApp/ — shared KMP module (Android + iOS)
  • .../modules/core — BLE, device models, features, protocol
  • .../modules/screens — screens and feature UIs
  • .../modules/navigation — tabs and root navigation
  • .../modules/ui — common UI components, theme
• iosApp/ — iOS host app (Xcode project)

Contributing

• For now, This repo is not actively maintained. Please fork it and feel free to make your own version. It is just provided as a reference.

License

MIT — see LICENSE.