Android + ESP32 通过蓝牙 (BLE) 发送数据

Question

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 代码正在按我的意愿工作(它可以正确接收数据)，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 代码很好。
我已经在这里搜索了几天并用谷歌搜索了如何实现它，但我仍然坚持下去。这是我现在的代码:
扫描器:

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(我用它控制一辆小车，所以我有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);
          digitalWrite(motor1Pin2, HIGH);
          digitalWrite(motor2Pin1, HIGH);
          digitalWrite(motor2Pin2, LOW);
        }
        if (value[0] == '3') {
          dutyCycle = 100;
          Serial.println("Motor left");
          digitalWrite(motor1Pin1, HIGH);
          digitalWrite(motor1Pin2, LOW);
          digitalWrite(motor2Pin1, LOW);
          digitalWrite(motor2Pin2, HIGH);
        }
        if (value[0] == '0') {
          Serial.println("Motor stopped");
          digitalWrite(motor1Pin1, LOW);
          digitalWrite(motor1Pin2, LOW);
          digitalWrite(motor2Pin1, LOW);
          digitalWrite(motor2Pin2, 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() {

}

我如何通过蓝牙将数据从我的 android 应用程序发送到 esp32？

Answer 1

为了使这项工作正常进行，如果我是您，我会执行以下操作:-
A部分 :让这个与现有的 Android 应用程序一起工作(例如 nRF Connect - 也许你已经完成了这部分)

从 Play 商店下载并安装 nRF Connect 应用程序。

启动 nRF Connect 应用程序并扫描设备。

如果找到，请连接到您的 ESP32。

浏览 GATT 表并找到控制 ESP32 的特性的 UUID 和句柄。这很重要，因为它将在 B 部分中使用。

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。如果您已经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 应用程序使其正常工作:-

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 .

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.

一旦找到正确的特征及其句柄(这是您在上面的步骤 4 中记下的那个)，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?另请查看 this .

Are you using the right Android write operation?

Are you maybe using reliable writes instead of normal write?

您是否发送整数数据而不是字符串数据？该应用程序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