arduino esp32 ble app案例

当使用Arduino ESP32和BLE时，你可以开发很多有趣的应用程序。下面是一个简单的Arduino ESP32 BLE应用程序案例，它使用一个智能手机应用程序来控制LED灯的开关。

硬件所需材料：
- Arduino ESP32开发板
- 一个LED灯
- 一个220欧姆电阻
- 面包板和杜邦线

软件所需材料:
- Arduino IDE
- Blynk App

步骤：

1. 使用Arduino IDE将以下代码上传到你的ESP32开发板中：

#include <BLEDevice.h>
#include <BLEServer.h>
#include <BLEUtils.h>
#include <BLE2902.h>

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

BLECharacteristic *pCharacteristic;
bool deviceConnected = false;
bool oldDeviceConnected = false;
int ledPin = 2; // GPIO 2

class MyServerCallbacks: public BLEServerCallbacks {
    void onConnect(BLEServer* pServer) {
      deviceConnected = true;
    };

    void onDisconnect(BLEServer* pServer) {
      deviceConnected = false;
    }
};

void setup() {
  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, LOW);

  Serial.begin(115200);

  BLEDevice::init("LED Controller");
  BLEServer *pServer = BLEDevice::createServer();
  pServer->setCallbacks(new MyServerCallbacks());

  BLEService *pService = pServer->createService(SERVICE_UUID);
  pCharacteristic = pService->createCharacteristic(
                     CHARACTERISTIC_UUID,
                     BLECharacteristic::PROPERTY_READ |
                     BLECharacteristic::PROPERTY_WRITE |
                     BLECharacteristic::PROPERTY_NOTIFY |
                     BLECharacteristic::PROPERTY_INDICATE
                   );

  pCharacteristic->addDescriptor(new BLE2902());

  pService->start();

  BLEAdvertising *pAdvertising = pServer->getAdvertising();
  pAdvertising->addServiceUUID(pService->getUUID());
  pAdvertising->setScanResponse(true);
  pAdvertising->setMinPreferred(0x06);
  pAdvertising->setMinPreferred(0x12);
  BLEDevice::startAdvertising();
  Serial.println("Waiting for a client connection to notify...");
}

void loop() {
  // notify changed value
  if (deviceConnected) {
    pCharacteristic->setValue("1");
    pCharacteristic->notify();
    digitalWrite(ledPin, HIGH);
  } else {
    digitalWrite(ledPin, LOW);
  }

  // disconnecting
  if (!deviceConnected && oldDeviceConnected) {
    delay(500); // give the bluetooth stack the chance to get things ready
    pServer->startAdvertising(); // restart advertising
    Serial.println("start advertising");
    oldDeviceConnected = deviceConnected;
  }
  // connecting
  if (deviceConnected && !oldDeviceConnected) {
    // do stuff here on connecting
    oldDeviceConnected = deviceConnected;
  }
}

2. 打开Blynk App，并创建一个新的项目。在该项目中添加一个按钮小部件，并将其设置为控制器模式。将控制器的输出引脚设置为虚拟引脚V1。

3. 将以下代码添加到Arduino IDE中：

#define BLYNK_PRINT Serial

#include <WiFi.h>
#include <WiFiClient.h>
#include <BlynkSimpleEsp32_BLE.h>

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = "YourAuthToken";

// Your WiFi credentials.
// Set password to "" for open networks.
char ssid[] = "YourNetworkName";
char pass[] = "YourPassword";

void setup()
{
  Serial.begin(115200);
  Blynk.begin(auth, ssid, pass);
}

void loop()
{
  Blynk.run();
}

BLYNK_WRITE(V1) {
  int buttonState = param.asInt();
  if (buttonState == 1) {
    Serial.println("LED ON");
    BLEDevice::getAdvertising()->stop();
    BLEDevice::getAdvertising()->start();
  } else {
    Serial.println("LED OFF");
  }
}

4. 将项目编译并上传到ESP32开发板中。

5. 在Blynk App中，点击按钮控制器来控制LED灯的开关。

这个应用程序演示了如何使用Arduino ESP32和BLE来控制一个简单的电路。当你点击Blynk App中的按钮控制器时，它会向ESP32发送一个指令，以控制LED灯的开关。由于BLE的低功耗特性，这个应用程序非常适合于物联网应用，因为它可以运行在电池供电的设备上，而且具有长时间的使用寿命。