How to Use Bluetooth in FlutterFlow for Device Connectivity

1<!-- AndroidManifest.xml additions -->
2<uses-permission android:name="android.permission.BLUETOOTH" android:maxSdkVersion="30" />
3<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" android:maxSdkVersion="30" />
4<uses-permission android:name="android.permission.BLUETOOTH_SCAN" />
5<uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
6<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

1import 'package:flutter_blue_plus/flutter_blue_plus.dart';
2
3Future<List<Map<String, dynamic>>> scanForDevices() async {
4  final devices = <String, Map<String, dynamic>>{};
5
6  // Check if Bluetooth is on
7  final adapterState = await FlutterBluePlus.adapterState.first;
8  if (adapterState != BluetoothAdapterState.on) {
9    throw Exception('Bluetooth is off. Please enable Bluetooth.');
10  }
11
12  // Start scan
13  await FlutterBluePlus.startScan(timeout: const Duration(seconds: 10));
14
15  // Collect scan results (deduplicated by device ID)
16  await for (final results in FlutterBluePlus.scanResults) {
17    for (final r in results) {
18      devices[r.device.remoteId.str] = {
19        'id': r.device.remoteId.str,
20        'name': r.device.platformName.isNotEmpty
21            ? r.device.platformName
22            : 'Unknown Device',
23        'rssi': r.rssi,
24        'connectable': r.advertisementData.connectable,
25      };
26    }
27    // Stop collecting after scan timeout
28    if (!FlutterBluePlus.isScanningNow) break;
29  }
30
31  await FlutterBluePlus.stopScan();
32  return devices.values.toList();
33}

1import 'package:flutter_blue_plus/flutter_blue_plus.dart';
2
3// Singleton to hold the connected device across page navigations
4class BLEConnection {
5  static BluetoothDevice? connectedDevice;
6  static List<BluetoothService> services = [];
7}
8
9Future<Map<String, dynamic>?> connectToDevice(String deviceId) async {
10  final device = BluetoothDevice.fromId(deviceId);
11
12  try {
13    await device.connect(timeout: const Duration(seconds: 10));
14    final services = await device.discoverServices();
15
16    BLEConnection.connectedDevice = device;
17    BLEConnection.services = services;
18
19    final serviceMap = services.map((s) => {
20      'serviceUuid': s.serviceUuid.str,
21      'characteristics': s.characteristics.map((c) => {
22        'uuid': c.characteristicUuid.str,
23        'canRead': c.properties.read,
24        'canWrite': c.properties.write,
25        'canNotify': c.properties.notify,
26      }).toList(),
27    }).toList();
28
29    return {'deviceId': deviceId, 'services': serviceMap};
30  } catch (e) {
31    return {'error': e.toString()};
32  }
33}

1import 'package:flutter_blue_plus/flutter_blue_plus.dart';
2
3// Read a characteristic value once
4Future<String> readCharacteristic(
5  String serviceUuid,
6  String characteristicUuid,
7) async {
8  final service = BLEConnection.services.firstWhere(
9    (s) => s.serviceUuid.str.toLowerCase() == serviceUuid.toLowerCase(),
10    orElse: () => throw Exception('Service not found: $serviceUuid'),
11  );
12
13  final characteristic = service.characteristics.firstWhere(
14    (c) => c.characteristicUuid.str.toLowerCase() == characteristicUuid.toLowerCase(),
15    orElse: () => throw Exception('Characteristic not found: $characteristicUuid'),
16  );
17
18  final value = await characteristic.read();
19  return String.fromCharCodes(value);
20}
21
22// Write a string value to a characteristic
23Future<void> writeCharacteristic(
24  String serviceUuid,
25  String characteristicUuid,
26  String value,
27) async {
28  final service = BLEConnection.services.firstWhere(
29    (s) => s.serviceUuid.str.toLowerCase() == serviceUuid.toLowerCase(),
30  );
31  final characteristic = service.characteristics.firstWhere(
32    (c) => c.characteristicUuid.str.toLowerCase() == characteristicUuid.toLowerCase(),
33  );
34  await characteristic.write(value.codeUnits);
35}
36
37// Subscribe to real-time notifications from a characteristic
38Future<void> subscribeToCharacteristic(
39  String serviceUuid,
40  String characteristicUuid,
41  Function(String value) onData,
42) async {
43  final service = BLEConnection.services.firstWhere(
44    (s) => s.serviceUuid.str.toLowerCase() == serviceUuid.toLowerCase(),
45  );
46  final characteristic = service.characteristics.firstWhere(
47    (c) => c.characteristicUuid.str.toLowerCase() == characteristicUuid.toLowerCase(),
48  );
49  await characteristic.setNotifyValue(true);
50  characteristic.onValueReceived.listen((value) {
51    onData(String.fromCharCodes(value));
52  });
53}