Universal BLE

A cross-platform (Android/iOS/macOS/Windows/Linux/Web) Bluetooth Low Energy (BLE) plugin for Flutter.

Try it online, provided your browser supports Web Bluetooth.

Features

• Scanning
• Connecting
• Discovering Services
• Reading & Writing data
• Pairing
• Bluetooth Availability
• Command Queue
• Timeout

API Support Matrix

Getting Started

Add universal_ble in your pubspec.yaml:

dependencies:
  universal_ble:

and import it wherever you want to use it:

import 'package:universal_ble/universal_ble.dart';

Scanning

// Set a scan result handler
UniversalBle.onScanResult = (scanResult) {
  // e.g. Use scan result to connect
}

// Perform a scan
UniversalBle.startScan();

// Or optionally add a scan filter
UniversalBle.startScan(
  scanFilter: ScanFilter(
    withServices: ["SERVICE_UUID"],
    withManufacturerData: ["MANUFACTURER_DATA"]
  )
);

// Stop scanning
UniversalBle.stopScan();

Before initiating a scan, ensure that Bluetooth is available:

AvailabilityState state = await UniversalBle.getBluetoothAvailabilityState()
// Start scan only if Bluetooth is powered on
if (state == AvailabilityState.poweredOn) {
  UniversalBle.startScan();
}

// Or listen to bluetooth availability changes
UniversalBle.onAvailabilityChange = (state) {
  if (state == AvailabilityState.poweredOn) {
    UniversalBle.startScan();
  }
};

See the Bluetooth Availability section for more.

Connected Devices

Already connected devices, either through previous sessions or connected through system settings, won't show up as scan results. You can list those devices using getConnectedDevices(). You still need to explicitly connect before using them.

// You can set `withServices` to narrow down the results
await UniversalBle.getConnectedDevices(withServices: []);

Scan Filter

You can optionally set filters when scanning.

With Services

When setting this parameter, the scan results will only include devices that advertize any of the specified services. This is the primary filter. All devices are first filtered by services, then further filtered by other criteria. This parameter is mandatory on web if you want to access those services.

List<String> withServices;

With ManufacturerData

Use the withManufacturerData parameter to filter devices by manufacturer data. When you pass a list of ManufacturerDataFilter objects to this parameter, the scan results will only include devices that contain any of the specified manufacturer data.

List<ManufacturerDataFilter> withManufacturerData;

Connecting

// Connect to a device using the `deviceId` of the scanResult received from `UniversalBle.onScanResult`
String deviceId = scanResult.deviceId;
UniversalBle.connect(deviceId);

// Disconnect from a device
UniversalBle.disconnect(deviceId);

// Get notified for connection state changes
UniversalBle.onConnectionChanged = (String deviceId, BleConnectionState state) {
  print('OnConnectionChanged $deviceId, $state');
}

Discovering Services

After establishing a connection, you need to discover services. This method will discover all services and their characteristics.

// Discover services of a specific device
UniversalBle.discoverServices(deviceId);

Reading & Writing data

You need to first discover services before you are able to read and write to characteristics.

// Read data from a characteristic
UniversalBle.readValue(deviceId, serviceId, characteristicId);

// Write data to a characteristic
UniversalBle.writeValue(deviceId, serviceId, characteristicId, value);

// Subscribe to a characteristic
UniversalBle.setNotifiable(deviceId, serviceId, characteristicId, BleInputProperty.notification);

// Get characteristic updates in `onValueChanged`
UniversalBle.onValueChanged = (String deviceId, String characteristicId, Uint8List value) {
  print('onValueChanged $deviceId, $characteristicId, ${hex.encode(value)}');
}

// Unsubscribe from a characteristic
UniversalBle.setNotifiable(deviceId, serviceId, characteristicId, BleInputProperty.disabled);

Pairing

// Pair
UniversalBle.pair(deviceId);

// Get the pairing result
UniversalBle.onPairingStateChange = (String deviceId, bool isPaired, String? error) {
  // Handle Pairing state change
}

// Unpair
UniversalBle.unPair(deviceId);

// Check current pairing state
bool isPaired = UniversalBle.isPaired(deviceId);

Bluetooth Availability

// Get current Bluetooth availability state
AvailabilityState availabilityState = UniversalBle.getBluetoothAvailabilityState(); // e.g. poweredOff or poweredOn,

// Receive Bluetooth availability changes
UniversalBle.onAvailabilityChange = (state) {
  // Handle the new Bluetooth availability state
};

// Enable Bluetooth programmatically
UniversalBle.enableBluetooth();

Command Queue

By default, all commands are executed in a queue, with each command waiting for the previous one to finish. This is because some platforms (e.g. Android) may fail to send consecutive commands without a delay between them. Therefore, it is a good idea to leave the queue enabled.

// Disable queue
UniversalBle.queuesCommands = false;

Timeout

By default, all commands have a timeout of 10 seconds.

// Change timeout
UniversalBle.timeout = const Duration(seconds: 10);

// Disable timeout
UniversalBle.timeout = null;

Platform-Specific Setup

Android

Add the following permissions to your AndroidManifest.xml file:

<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" android:maxSdkVersion="30" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" android:maxSdkVersion="30" />

If you use BLUETOOTH_SCAN to determine location, modify your AndroidManifest.xml file to include the following entry:

 <uses-permission android:name="android.permission.BLUETOOTH_SCAN" tools:remove="android:usesPermissionFlags" tools:targetApi="s" />

If your app uses location services, remove android:maxSdkVersion="30" from the location permission tags.

iOS / macOS

Add NSBluetoothPeripheralUsageDescription and NSBluetoothAlwaysUsageDescription to Info.plist of your iOS and macOS app.

Add the Bluetooth capability to the macOS app from Xcode.

Windows / Linux

Your Bluetooth adapter needs to support at least Bluetooth 4.0. If you have more than 1 adapters, the first one returned from the system will be picked.

When publishing on Windows you need to declare the following capabilities: bluetooth, radios.

Web

On web, the withServices parameter in the ScanFilter is used as optional_services as well as a services filter. On web you have to set this parameter to ensure that you can access the specified services after connecting to the device. You can leave it empty for the rest of the platforms if your device does not advertize services.

ScanFilter(
      withServices: kIsWeb ?  ["SERVICE_UUID"] : [],
)

Customizing Platform Implementation of UniversalBle

// Create a class that extends UniversalBlePlatform
class UniversalBleMock extends UniversalBlePlatform {
  // Implement all commands
}

UniversalBle.setInstance(UniversalBleMock());