前言

官方套件使用範例

想帶大家認識 Flutter Blue 套件 怎麼使用。
了解裡面的參數。

藍牙中具體有些哪些：藍牙名字（name）藍芽裝置（device）藍牙信號強度（riss）藍牙服務(service) 藍牙服務下麵又有小服務。

藍芽物件介紹

BluetoothState 藍芽狀態

可以去監聽 Stream = FlutterBlue.instance.state
BluetoothState

• unknown, // 未知狀況，通常我設定這個為初始值
• unavailable, // 不存在藍芽
• unauthorized, // 未授權
• turningOn, // 正在開啟
• on, // 已經開啟
• turningOff, // 正在關閉
• off // 已經關閉

ScanResult 藍芽裝置資訊

可以去監聽 Stream = FlutterBlue.instance.scanResults

• rssi
• advertisementData
  發出廣播封包的裝置，其中廣播封包包含裝置的 MAC 位址也可以有其他額外的資料，像是 device name等...。
• device(BluetoothDevice)
  • name // 裝置名稱
  • id // 裝置 id
  • type(BluetoothDeviceType) // 裝置的狀態
  • services // 裝置服務
  • mtu // 監聽 MTU (byte 為單位)
  • state // 監聽裝置的狀態
  • isDiscoveringServices 監聽搜尋服務
  • discoverServices() // 從新搜尋服務
  • disconnect() // 取消連接服務
  • connect() 連接服務
  • requestMtu() // 請求改變 Mtu 大小， (IOS 不支援)

BluetoothService

當搜尋到 ScanResult 拿到裡面的 device 後。
stream: device.services,
BluetoothService

• uuid
• deviceId
• isPrimary
• characteristics
• includedServices

歡迎上官網了解GATT、參數

想要監聽已經連藍芽的狀態

可以每 2 秒監聽 Devices 這樣子。
Stream.periodic(Duration(seconds: 2)).asyncMap((_) => FlutterBlue.instance.connectedDevices),

用法

初始化藍芽

FlutterBlue flutterBlue = FlutterBlue.instance;

開始搜尋藍芽

// Start scanning
flutterBlue.startScan(timeout: Duration(seconds: 4));

// Listen to scan results
var subscription = flutterBlue.scanResults.listen((results) {
    // do something with scan results
    for (ScanResult r in results) {
        print('${r.device.name} found! rssi: ${r.rssi}');
    }
});

// Stop scanning
flutterBlue.stopScan();

連接、中斷 藍芽

// Connect to the device
await device.connect();

// Disconnect from device
device.disconnect();

啟用 BlueTooth Service

List<BluetoothService> services = await device.discoverServices();
services.forEach((service) {
    // do something with service
});

讀寫 characteristics

https://pub.dev/packages/flutter_blue#read-and-write-characteristics

var characteristics = service.characteristics;
for(BluetoothCharacteristic c in characteristics) {
    List<int> value = await c.read();
    print(value);
}

// Writes to a characteristic
await c.write([0x12, 0x34])

讀寫 descriptors

https://pub.dev/packages/flutter_blue#read-and-write-descriptors

// Reads all descriptors
var descriptors = characteristic.descriptors;
for(BluetoothDescriptor d in descriptors) {
    List<int> value = await d.read();
    print(value);
}

// Writes to a descriptor
await d.write([0x12, 0x34])

Set notifications and listen to changes

https://pub.dev/packages/flutter_blue#set-notifications-and-listen-to-changes

await characteristic.setNotifyValue(true);
characteristic.value.listen((value) {
    // do something with new value
});

讀取 MTU and 請求更改 Mtu size

https://pub.dev/packages/flutter_blue#read-the-mtu-and-request-larger-size

final mtu = await device.mtu.first;
await device.requestMtu(512);

Refrence

flutter_blue 套件
GATT
參數