Bluetooth.Core & Bluetooth.Maui

A cross-platform .NET MAUI Bluetooth Low Energy (BLE) library providing a clean, unified API for Android, iOS/MacCatalyst, and Windows platforms.

Features

• 🔍 BLE Scanning - Discover nearby devices with customizable filtering
• 🔗 Connection Management - Robust connect/disconnect with auto-reconnect support
• 📡 GATT Operations - Full support for services, characteristics, and descriptors
• 📊 Read/Write/Notify - Read values, write data, and subscribe to notifications
• 🎯 Cross-Platform - Consistent API across all major platforms
• 🔄 Modern Async - Async/await throughout with cancellation token support
• 💉 DI-First - Built for MAUI dependency injection
• 🧩 Options Pattern - Flexible configuration via options objects
• 📝 Well-Documented - Comprehensive XML docs and examples

Platform Support

Platform	Scanning	Connection	GATT Operations	Broadcasting
Android	✅	✅	✅	✅
iOS	✅	✅	✅	❌
MacCatalyst	✅	✅	✅	❌
Windows	✅	✅	✅	❌

Note: Broadcasting (peripheral mode) is currently Android-only. iOS/MacCatalyst/Windows throw NotImplementedException.

Installation

dotnet add package Bluetooth.Maui

Or via NuGet Package Manager:

<PackageReference Include="Bluetooth.Maui" Version="1.0.0" />

Quick Start

1. Register Services in MauiProgram.cs

public static class MauiProgram
{
    public static MauiApp CreateMauiApp()
    {
        var builder = MauiApp.CreateBuilder();

        builder
            .UseMauiApp<App>()
            .UseMauiCommunityToolkit();

        // Register Bluetooth services
        builder.Services.AddBluetoothServices();

        return builder.Build();
    }
}

2. Inject and Use IBluetoothScanner

public class ScannerViewModel
{
    private readonly IBluetoothScanner _scanner;

    public ScannerViewModel(IBluetoothScanner scanner)
    {
        _scanner = scanner;

        // Subscribe to device discovery
        _scanner.DeviceListChanged += OnDeviceListChanged;
    }

    public async Task StartScanningAsync()
    {
        var options = new ScanningOptions
        {
            // Optional: Configure scanning behavior
        };

        await _scanner.StartScanningAsync(options);
    }

    private void OnDeviceListChanged(object? sender, DeviceListChangedEventArgs e)
    {
        foreach (var device in _scanner.Devices)
        {
            Console.WriteLine($"Found: {device.Name} ({device.Id})");
            Console.WriteLine($"  RSSI: {device.SignalStrengthDbm} dBm");
        }
    }
}

Usage Guide

Scanning for Devices

// Start scanning
await _scanner.StartScanningAsync();

// Access discovered devices
var devices = _scanner.Devices;

// Stop scanning when done
await _scanner.StopScanningAsync();

Connecting to a Device

// Get a device from the scanner
var device = _scanner.Devices.FirstOrDefault(d => d.Name == "MyDevice");

if (device != null)
{
    // Connect with options
    var connectionOptions = new ConnectionOptions
    {
        // Platform-specific connection parameters
    };

    await device.ConnectAsync(connectionOptions);

    // Check connection status
    Console.WriteLine($"Connected: {device.IsConnected}");
}

Service Discovery - Simplified API

The new exploration APIs use a single, flexible method with optional configuration:

// Simple exploration (defaults: services only, caching enabled)
await device.ExploreServicesAsync();

// Explore services AND characteristics
await device.ExploreServicesAsync(ServiceExplorationOptions.WithCharacteristics);

// Full exploration (services + characteristics + descriptors)
await device.ExploreServicesAsync(ServiceExplorationOptions.Full);

// Force re-exploration (ignore cache)
await device.ExploreServicesAsync(new ServiceExplorationOptions
{
    UseCache = false
});

// Filter by service UUID
await device.ExploreServicesAsync(new ServiceExplorationOptions
{
    ServiceUuidFilter = uuid => uuid == myServiceUuid
});

Getting Services and Characteristics

// Get a specific service by UUID
var service = device.GetService(serviceGuid);

// Or use a filter
var service = device.GetService(s => s.Id == serviceGuid);

// Explore characteristics (simple)
await service.ExploreCharacteristicsAsync();

// Explore characteristics AND descriptors
await service.ExploreCharacteristicsAsync(CharacteristicExplorationOptions.Full);

// Get a characteristic
var characteristic = service.GetCharacteristic(characteristicGuid);

Reading and Writing

// Read a characteristic value
var value = await characteristic.ReadValueAsync();
Console.WriteLine($"Value: {BitConverter.ToString(value.ToArray())}");

// Write a value
byte[] data = new byte[] { 0x01, 0x02, 0x03 };
await characteristic.WriteValueAsync(data);

// Check capabilities
if (characteristic.CanRead)
{
    // Safe to read
}

if (characteristic.CanWrite)
{
    // Safe to write
}

Subscribing to Notifications

// Subscribe to value changes
characteristic.ValueUpdated += (sender, args) =>
{
    Console.WriteLine($"New value: {BitConverter.ToString(args.NewValue.ToArray())}");
    Console.WriteLine($"Old value: {BitConverter.ToString(args.OldValue.ToArray())}");
};

// Start listening
await characteristic.StartListeningAsync();

// Check listening state
Console.WriteLine($"Listening: {characteristic.IsListening}");

// Stop listening when done
await characteristic.StopListeningAsync();

Working with Descriptors

// Explore descriptors
await characteristic.ExploreDescriptorsAsync();

// Get a specific descriptor
var descriptor = characteristic.GetDescriptor(descriptorGuid);

// Read descriptor value
var value = await descriptor.ReadValueAsync();

// Write descriptor value
await descriptor.WriteValueAsync(new byte[] { 0x01, 0x00 });

Advanced Features

Connection Priority (Android)

Optimize connection parameters for your use case:

// High priority: Fast data transfer, low latency (11.25-15ms)
await device.RequestConnectionPriorityAsync(BluetoothConnectionPriority.High);

// Balanced: Moderate performance and power (30-50ms)
await device.RequestConnectionPriorityAsync(BluetoothConnectionPriority.Balanced);

// Low power: Battery optimization, higher latency (100-125ms)
await device.RequestConnectionPriorityAsync(BluetoothConnectionPriority.LowPower);

Note: iOS, macOS, and Windows manage connection parameters automatically. This API is a no-op on those platforms.

Timeout and Cancellation

All async operations support timeouts and cancellation:

using var cts = new CancellationTokenSource();

try
{
    await device.ConnectAsync(
        connectionOptions: new ConnectionOptions(),
        timeout: TimeSpan.FromSeconds(10),
        cancellationToken: cts.Token
    );
}
catch (TimeoutException)
{
    Console.WriteLine("Connection timed out");
}
catch (OperationCanceledException)
{
    Console.WriteLine("Operation was cancelled");
}

Event-Driven Architecture

Subscribe to events for reactive programming:

// Scanner events
_scanner.RunningStateChanged += (s, e) => Console.WriteLine($"Scanning: {_scanner.IsRunning}");
_scanner.DeviceListChanged += OnDeviceListChanged;

// Device events
device.ConnectionStateChanged += (s, e) => Console.WriteLine($"State: {device.ConnectionState}");
device.Connected += (s, e) => Console.WriteLine("Connected");
device.Disconnected += (s, e) => Console.WriteLine("Disconnected");
device.UnexpectedDisconnection += (s, e) => Console.WriteLine($"Lost connection: {e.Exception}");

// Service events
service.CharacteristicListChanged += OnCharacteristicsChanged;

// Characteristic events
characteristic.ValueUpdated += OnValueUpdated;

Caching and Performance

The exploration APIs use intelligent caching by default:

// First call: Queries the device
await device.ExploreServicesAsync();  // UseCache = true (default)

// Subsequent calls: Returns cached results instantly
await device.ExploreServicesAsync();  // Cached, no device query

// Force refresh: Ignore cache
await device.ExploreServicesAsync(new ServiceExplorationOptions
{
    UseCache = false  // Forces device query
});

Cleanup and Disposal

Proper cleanup ensures resources are released:

// Clear services (stops notifications, clears cache)
await device.ClearServicesAsync();

// Clear specific service characteristics
await service.ClearCharacteristicsAsync();

// Clear characteristic descriptors
await characteristic.ClearDescriptorsAsync();

// Disconnect and dispose device
await device.DisconnectAsync();
await device.DisposeAsync();  // Implements IAsyncDisposable

Platform-Specific Setup

Android

Add Bluetooth permissions to AndroidManifest.xml:

<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.BLUETOOTH_SCAN"
                 android:usesPermissionFlags="neverForLocation" />
<uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

iOS / MacCatalyst

Add Bluetooth usage description to Info.plist:

<key>NSBluetoothAlwaysUsageDescription</key>
<string>This app needs Bluetooth to scan for BLE devices</string>
<key>NSBluetoothPeripheralUsageDescription</key>
<string>This app needs Bluetooth to scan for BLE devices</string>

Windows

Add Bluetooth capability to Package.appxmanifest:

<Capabilities>
  <DeviceCapability Name="bluetooth" />
</Capabilities>

Architecture

Plugin.Bluetooth/
├── Bluetooth.Abstractions/              # Core interfaces (platform-agnostic)
│   ├── Exceptions/
│   ├── Extensions/
│   └── Options/
├── Bluetooth.Abstractions.Scanning/     # Scanning-specific interfaces
│   ├── Events/
│   ├── Exceptions/
│   └── Options/
├── Bluetooth.Abstractions.Broadcasting/ # Broadcasting interfaces
│   ├── Events/
│   ├── Exceptions/
│   └── Options/
├── Bluetooth.Core/                      # Base implementations
│   ├── Base classes
│   └── Infrastructure
├── Bluetooth.Core.Scanning/             # Scanning base implementations
├── Bluetooth.Core.Broadcasting/         # Broadcasting base implementations
├── Bluetooth.Maui/                      # MAUI integration & DI
└── Platform Implementations/
    ├── Bluetooth.Maui.Platforms.Apple/     # iOS & MacCatalyst
    ├── Bluetooth.Maui.Platforms.Droid/     # Android
    ├── Bluetooth.Maui.Platforms.Windows/   # Windows
    └── Bluetooth.Maui.Platforms.DotNetCore # Fallback (throws NotImplementedException)

Core Interfaces

Scanning

• IBluetoothScanner - Device discovery and scanning control
• IBluetoothRemoteDevice - Remote device representation and connection
• IBluetoothRemoteService - GATT service on a remote device
• IBluetoothRemoteCharacteristic - GATT characteristic with read/write/notify
• IBluetoothRemoteDescriptor - GATT descriptor

Broadcasting (Android only)

• IBluetoothBroadcaster - Peripheral/advertising mode
• IBluetoothLocalService - Local GATT service
• IBluetoothLocalCharacteristic - Local characteristic for broadcasting
• IBluetoothConnectedDevice - Connected central device

Exception Handling

Comprehensive exception hierarchy for error handling:

try
{
    await device.ConnectAsync(connectionOptions);
}
catch (DeviceNotConnectedException ex)
{
    // Device is not connected when operation requires it
}
catch (ServiceNotFoundException ex)
{
    // Requested service not found on device
}
catch (CharacteristicNotFoundException ex)
{
    // Requested characteristic not found in service
}
catch (TimeoutException ex)
{
    // Operation timed out
}
catch (OperationCanceledException ex)
{
    // Operation was cancelled
}
catch (BluetoothException ex)
{
    // Base exception for all Bluetooth errors
}

API Design Principles

1. Async First - All I/O operations are async with cancellation support
2. Options Pattern - Flexible configuration via options objects
3. Caching - Intelligent caching enabled by default for performance
4. Events - Event-driven architecture for reactive patterns
5. IAsyncDisposable - Proper resource cleanup with async disposal
6. Immutability - ReadOnlyMemory for value types
7. Platform Parity - Consistent API across all platforms

Contributing

Contributions are welcome! Please:

1. Ensure all public APIs have XML documentation
2. Follow the existing code style and patterns
3. Add unit tests for new features
4. Update the README for API changes

Requirements

• .NET 10.0 or higher
• .NET MAUI application
• Platform-specific Bluetooth permissions (see setup section)

License

MIT License - Copyright (c) 2025 Laerdal Medical

See LICENSE.md for details.

Support

For issues, feature requests, or questions:

• 🐛 GitHub Issues
• 💬 Discussions

Changelog

Recent Changes

v1.0.0 (Current)

• ✅ Windows platform implementation complete
• ✅ Simplified exploration APIs (single method with options)
• ✅ Modern DI registration with AddBluetoothServices()
• ✅ Comprehensive XML documentation
• ✅ Options pattern for all configuration

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Built with ❤️ by Laerdal Medical