Android + ESP32 通过蓝牙 (BLE) 发送数据

如何解决Android + ESP32 通过蓝牙 (BLE) 发送数据

我正在尝试通过蓝牙 (BLE) 将数据从我的 android 应用程序发送到 esp32，但我找不到正确的方法。我现在能做的就是扫描并找到 ble 设备。我的 arduino 代码按我的意愿工作（它正确接收数据），因为我使用了另一个应用程序，它让我可以将数据发送到 ble 设备，所以我知道 arduino 代码没问题。

我在这里搜索了好几天并用谷歌搜索如何实现它，但我仍然坚持使用它。这是我现在的代码：

扫描仪：

class BluetoothFragment : Fragment() {
    private lateinit var binding: FragmentBluetoothBinding
    private var list : MutableList<BluetoothDevice> = ArrayList()
    private lateinit var  bluetoothAdapter : BluetoothAdapter

    override fun onCreateView(
        inflater: LayoutInflater,container: ViewGroup?,savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        Log.d("DeviceListActivity","onCreate()")
        return inflater.inflate(R.layout.fragment_bluetooth,container,false)
    }

    // Todo: 19/05/2021 implementar listener en el recycler view para crear la conexión con el ble

    override fun onViewCreated(view: View,savedInstanceState: Bundle?) {
        super.onViewCreated(view,savedInstanceState)
        binding = FragmentBluetoothBinding.bind(view)
        if (ContextCompat.checkSelfPermission(
                requireContext(),Manifest.permission.ACCESS_COARSE_LOCATION
            ) != PackageManager.PERMISSION_GRANTED
        ) {
            val permissions = arrayOf(
                android.Manifest.permission.ACCESS_COARSE_LOCATION,)
            ActivityCompat.requestPermissions(requireActivity(),permissions,0)
        }

        setRecyclerView(list)
    }

    private val bleScanner = object :ScanCallback() {
        override fun onScanResult(callbackType: Int,result: ScanResult?) {
            super.onScanResult(callbackType,result)
            Log.d("pepe","onScanResult: ${result?.device?.address} - ${result?.device?.name}")
            if(result?.device?.name?.isNotEmpty() == true){
                var bluetoothDevice = result?.device?.name?.let { BluetoothDevice(it) }
                if (bluetoothDevice != null) {
                    list.add(bluetoothDevice)
                    bluetoothAdapter.notifyDataSetChanged()
                }
            }
        }

        override fun onBatchScanResults(results: MutableList<ScanResult>?) {
            super.onBatchScanResults(results)
            Log.d("DeviceListActivity","onBatchScanResults:${results.toString()}")
        }

        override fun onScanFailed(errorCode: Int) {
            super.onScanFailed(errorCode)
            Log.d("DeviceListActivity","onScanFailed: $errorCode")
        }

    }

    private val bluetoothLeScanner: BluetoothLeScanner
        get() {
            val bluetoothManager = requireActivity().getSystemService(Context.BLUetoOTH_SERVICE) as BluetoothManager
            val bluetoothAdapter = bluetoothManager.adapter
            return bluetoothAdapter.bluetoothLeScanner
        }

    class ListDevicesAdapter(context: Context?,resource: Int) : ArrayAdapter<String>(context!!,resource)


    override fun onStart() {
        Log.d("DeviceListActivity","onStart()")
        super.onStart()
        bluetoothLeScanner.startScan(bleScanner)
    }

    override fun onStop() {
        bluetoothLeScanner.stopScan(bleScanner)
        super.onStop()
    }

    private fun setRecyclerView(allCategories: List<BluetoothDevice>) {
        val layoutManager: RecyclerView.LayoutManager = linearlayoutmanager(context)
        binding.rvBluetooth.layoutManager = layoutManager
        bluetoothAdapter = BluetoothAdapter(allCategories)
        binding.rvBluetooth.adapter = bluetoothAdapter
    }
}

Arduino 代码（我正在用它控制一辆小汽车，这就是为什么我有 5 个不同的值）：

#include <BLEDevice.h>
#include <bleutils.h>
#include <BLEServer.h>

#define SERVICE_UUID        "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHaraCTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"

// Motor 1
int motor1Pin1 = 23;
int motor1Pin2 = 22;
int enable1Pin = 21;

// Motor 2
int motor2Pin1 = 18;
int motor2Pin2 = 19;
int enable2Pin = 5;

const int freq = 30000;
const int pwmChannel = 0;
const int resolution = 8;
int dutyCycle = 200;

class MyCallbacks: public BLECharacteristicCallbacks {
    void onWrite(BLECharacteristic *pCharacteristic) {
      std::string value = pCharacteristic->getValue();

      if (value.length() > 0) {
        if (value[0] == '1') {
          dutyCycle = 200;
          Serial.println("Moving Forward");
          digitalWrite(motor1Pin1,LOW);
          digitalWrite(motor1Pin2,HIGH);
          digitalWrite(motor2Pin1,LOW);
          digitalWrite(motor2Pin2,HIGH);
          while (dutyCycle <= 255) {
            ledcWrite(pwmChannel,dutyCycle);
            dutyCycle = dutyCycle + 5;
            delay(500);
          }

        }
        if (value[0] == '4') {
          dutyCycle = 200;
          Serial.println("Moving Backwards");
          digitalWrite(motor1Pin1,HIGH);
          digitalWrite(motor1Pin2,LOW);
          digitalWrite(motor2Pin1,HIGH);
          digitalWrite(motor2Pin2,LOW);
          while (dutyCycle <= 255) {
            ledcWrite(pwmChannel,dutyCycle);
            dutyCycle = dutyCycle + 5;
            delay(500);
          }
        }
        if (value[0] == '2') {
          dutyCycle = 100;
          Serial.println("Motor right");
          digitalWrite(motor1Pin1,LOW);
        }
        if (value[0] == '3') {
          dutyCycle = 100;
          Serial.println("Motor left");
          digitalWrite(motor1Pin1,HIGH);
        }
        if (value[0] == '0') {
          Serial.println("Motor stopped");
          digitalWrite(motor1Pin1,LOW);
        }
      }
    }
};


void setup() {
  Serial.begin(115200);
  BLEDevice::init("Andruino");
  BLEServer *pServer = BLEDevice::createServer();

  BLEService *pService = pServer->createService(SERVICE_UUID);

  BLECharacteristic *pCharacteristic = pService->createCharacteristic(
                                         CHaraCTERISTIC_UUID,BLECharacteristic::PROPERTY_WRITE
                                       );

  pCharacteristic->setCallbacks(new MyCallbacks());
  pService->start();

  BLEAdvertising *pAdvertising = pServer->getAdvertising();
  pAdvertising->start();

  pinMode(motor1Pin1,OUTPUT);
  pinMode(motor1Pin2,OUTPUT);
  pinMode(enable1Pin,OUTPUT);

  pinMode(motor2Pin1,OUTPUT);
  pinMode(motor2Pin2,OUTPUT);
  pinMode(enable2Pin,OUTPUT);

  ledcSetup(pwmChannel,freq,resolution);

  ledcAttachPin(enable1Pin,pwmChannel);
  ledcAttachPin(enable2Pin,pwmChannel);
 
  ledcWrite(pwmChannel,dutyCycle);
}

void loop() {

}

如何通过蓝牙将数据从我的安卓应用发送到 esp32？

解决方法

为了让这个工作，如果我是你，我会做以下事情：-

A 部分：使用现有的 Android 应用程序（例如 nRF Connect - 也许您已经完成了这部分）

1. 从 Play 商店下载并安装 nRF Connect 应用。
2. 启动 nRF Connect 应用并扫描设备。
3. 连接到您的 ESP32（如果找到）。
4. 浏览 GATT 表，找到控制 ESP32 的特征的 UUID 和句柄。这很重要，因为它将在 B 部分中使用。
5. 找到后，尝试将值 0、1、2、3 和 4 写入此特征并确保一切正常。

如果上面的部分对您来说是新的，请查看下面的链接。如果您已成功完成上述所有操作，请转到 B 部分：-

• nRF Connect For Mobile - Get Started
• Bluetooth Low Energy Characteristics - A Beginner's Guide
• Introduction to BLE - GATT

B 部分：使用您的 Android 应用使其正常工作：-

1. 与 nRF Connect 应用程序类似，您的应用程序需要扫描并连接到 ESP32。您可以找到有关如何执行此操作的示例here。
2. 连接后，您需要浏览 GATT 表并找到正确的特征。您可以找到此 here 的示例。
3. 找到正确的特征及其句柄（这是您在上述第 4 步中记下的那个）后，继续向该特征写入值。您可以找到示例 here、here 和 here。

如果所有这些都已到位但仍然无法正常工作，请检查以下事项：-

• Are you waiting for the GATT write completion callback? 同时检查 this。
• Are you using the right Android write operation?
• Are you maybe using reliable writes instead of normal write?
• 您发送的是整数数据而不是字符串数据吗？该应用需要整数数据才能正常工作。

您可以在以下链接中找到有关上述步骤的示例和说明：-

• How to Send Data over a BLE Link
• Use BLE to connect to devices in an Android app
• The Ultimate Guide to Android BLE Development
• Getting Started with Bluetooth Low Energy on Android
• How to Use Android BLE to Communicate with Devices

,

我认为最好的方法是从这篇文章开始 - making-android-ble-work-part。

您的数据无法传递到设备的原因有很多：

1. 设备固件（使用 nRF Connect 应用程序检查）
2. Android 代码中的逻辑错误（查看文章以尝试修复它们）