esp32蓝牙连接手机代码

你可以尝试以下代码：

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

// 定义服务和特征
#define SERVICE_UUID        "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"

BLECharacteristic *characteristic;
bool deviceConnected = false;

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

void setup() {
  // 创建 BLE 设备
  BLEDevice::init("ESP32 BLE Server");

  // 创建 BLE 服务
  BLEServer *pServer = BLEDevice::createServer();
  pServer->setCallbacks(new MyServerCallbacks());

  // 创建 BLE 特征
  BLEService *pService = pServer->createService(SERVICE_UUID);
  characteristic = pService->createCharacteristic(
                      CHARACTERISTIC_UUID,
                      BLECharacteristic::PROPERTY_READ |
                      BLECharacteristic::PROPERTY_WRITE |
                      BLECharacteristic::PROPERTY_NOTIFY |
                      BLECharacteristic::PROPERTY_INDICATE
                    );
                    
  // 开始服务
  pService->start();

  // 开始广播
  BLEAdvertising *pAdvertising = pServer->getAdvertising();
  pAdvertising->start();
}

void loop() {
  if (deviceConnected) {
    // 更新特征
    characteristic->setValue("Hello, World!");
    characteristic->notify();
  }
  delay(1000);
}

这是一个基本的 ESP32 BLE Server 代码示例，建立了一个名为 "ESP32 BLE Server" 的 BLE 设备，并创建了一个服务和特征。可以通过特征进行读写操作，并可以通知和指示特征变化。

如果您想要连接到这个服务，您需要使用一个 BLE 客户端应用程序，并扫描设备。一旦发现设备，您可以连接到该设备并与特征进行通信。