Meshtastic-Android/core/ble/README.md

:core:ble

Module dependency graph

graph TB
  :core:ble[ble]:::kmp-library

classDef android-application fill:#CAFFBF,stroke:#000,stroke-width:2px,color:#000;
classDef android-application-compose fill:#CAFFBF,stroke:#000,stroke-width:2px,color:#000;
classDef compose-desktop-application fill:#CAFFBF,stroke:#000,stroke-width:2px,color:#000;
classDef android-feature fill:#FFD6A5,stroke:#000,stroke-width:2px,color:#000;
classDef android-library fill:#9BF6FF,stroke:#000,stroke-width:2px,color:#000;
classDef android-library-compose fill:#9BF6FF,stroke:#000,stroke-width:2px,color:#000;
classDef android-test fill:#A0C4FF,stroke:#000,stroke-width:2px,color:#000;
classDef jvm-library fill:#BDB2FF,stroke:#000,stroke-width:2px,color:#000;
classDef kmp-feature fill:#FFD6A5,stroke:#000,stroke-width:2px,color:#000;
classDef kmp-library fill:#FFC1CC,stroke:#000,stroke-width:2px,color:#000;
classDef unknown fill:#FFADAD,stroke:#000,stroke-width:2px,color:#000;

Overview

The :core:ble module contains the foundation for Bluetooth Low Energy (BLE) communication in the Meshtastic Android app. It uses the Kable multiplatform BLE library to provide a unified, Coroutine-based architecture across all supported targets (Android, Desktop, and future iOS).

This module abstracts platform-specific BLE operations behind common Kotlin interfaces (BleDevice, BleScanner, BleConnection, BleConnectionFactory), ensuring that business logic in commonMain remains platform-agnostic and testable.

Key Components

1. BleConnection

A robust wrapper around Kable's Peripheral that simplifies the connection lifecycle and service discovery using modern Coroutine APIs.

• Features:
  • Connection & Await: Provides suspend functions to connect and wait for a terminal state (Connected or Disconnected).
  • Unified Profile Helper: A profile function that manages service discovery, characteristic setup, and lifecycle in a single block, with automatic timeout and error handling.
  • Observability: Exposes connectionState as a Flow for reactive UI and service updates.
  • Platform Setup: Seamlessly handles platform-specific configuration (like MTU negotiation on Android or direct connections on Desktop) via platformConfig() extensions.

2. BluetoothRepository

A Singleton repository responsible for the global state of Bluetooth on the device.

• Features:
  • State Management: Exposes a StateFlow<BluetoothState> reflecting whether Bluetooth is enabled, permissions are granted, and which devices are bonded.
  • Permission Handling: Centralizes logic for checking Bluetooth and Location permissions across different platforms.
  • Bonding: Simplifies the process of creating and validating bonds with peripherals.

3. BleScanner

A wrapper around Kable's Scanner to provide a consistent and easy-to-use API for BLE scanning with built-in peripheral mapping.

4. BleRetry

A utility for executing BLE operations with retry logic, essential for handling the inherent unreliability of wireless communication.

Integration in app

The :core:ble module is used by BleRadioInterface in the main application module to implement the RadioTransport interface for Bluetooth devices.

Usage

Dependencies are managed via the version catalog (libs.versions.toml).

[versions]
kable = "0.42.0"

[libraries]
kable-core = { module = "com.juul.kable:kable-core", version.ref = "kable" }

Architecture

The module follows a clean multiplatform architecture approach:

• Repository Pattern: BluetoothRepository mediates data access.
• Coroutines & Flow: All asynchronous operations use Kotlin Coroutines and Flows.
• Dependency Injection: Koin is used for dependency injection.

Testing

The module includes unit tests for key components, utilizing Kable's architecture and standard coroutine testing tools to ensure logic correctness.