ESP32 Ble

 

近期做了一个项目需要用到微信小程序蓝牙与ESP32进行配网及数据设置，因此在一个前辈提供的demo上进行一部分优化和修改，踩了一些坑，因此记录一下

 

 ESP32 代码：

// 包含所必需的库
#include <BLEDevice.h>
#include <BLEServer.h>
#include <BLEUtils.h>
#include <BLE2902.h>

BLEServer *pServer = NULL;
BLECharacteristic *pTxCharacteristic;
bool deviceConnected = false;
bool oldDeviceConnected = false;

char BLEbuf[32] = {0};
String data = "";

// 定义收发服务的UUID（唯一标识）
#define SERVICE_UUID           "6E400001-B5A3-F393-E0A9-E50E24DCCA9E" 
// RX串口标识
#define CHARACTERISTIC_UUID_RX "6E400002-B5A3-F393-E0A9-E50E24DCCA9E"
// TX串口标识
#define CHARACTERISTIC_UUID_TX "6E400003-B5A3-F393-E0A9-E50E24DCCA9E"


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

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

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

      if (rxValue.length() > 0) {
        Serial.println("*********");
        Serial.print("Received Value: ");
        for (int i = 0; i < rxValue.length(); i++){
                Serial.print(rxValue[i]);
            }
        Serial.println();
        data =rxValue.c_str();
        //Serial.println(data);
        Serial.println("*********");
        Serial.println();    
      }
    }
};

// setup()在复位或上电后运行一次:
void setup() {
  Serial.begin(115200);
  // 初始化蓝牙设备
  BLEDevice::init("ESP32 test");
  // 为蓝牙设备创建服务器
  pServer = BLEDevice::createServer();
  pServer->setCallbacks(new MyServerCallbacks());
  // 基于SERVICE_UUID来创建一个服务
  BLEService *pService = pServer->createService(SERVICE_UUID);
  pTxCharacteristic = pService->createCharacteristic(
                                        CHARACTERISTIC_UUID_TX,
                                        BLECharacteristic::PROPERTY_NOTIFY
                                    );                      
  pTxCharacteristic->addDescriptor(new BLE2902());
  BLECharacteristic * pRxCharacteristic = pService->createCharacteristic(
                                             CHARACTERISTIC_UUID_RX,
                                            BLECharacteristic::PROPERTY_WRITE
                                        );
  pRxCharacteristic->setCallbacks(new MyCallbacks());
  // 开启服务
  pService->start();
  // 开启通知
  pServer->getAdvertising()->start();
  Serial.println("Waiting a client connection to notify...");    
  Serial.println();
}

// loop()一直循环执行:
void loop() {

    if (deviceConnected==1&data.length()>0) {
        memset(BLEbuf, 0, 32);
        memcpy(BLEbuf, data.c_str(), 32); 
        Serial.println(BLEbuf); 
        
        pTxCharacteristic->setValue(BLEbuf);   //收到数据后返回数据
        pTxCharacteristic->notify();
        data = "";  //返回数据后进行清空，否则一直发送data
    }

    // 没有新连接时
    if (!deviceConnected && oldDeviceConnected) {
        // 给蓝牙堆栈准备数据的时间
        delay(500); 
        pServer->startAdvertising(); 
        // 重新开始广播
        Serial.println("start advertising");
        oldDeviceConnected = deviceConnected;
    }
    // 正在连接时
    if (deviceConnected && !oldDeviceConnected) {
        // 正在连接时进行的操作
        oldDeviceConnected = deviceConnected;
    }
}

小程序的代码需要有几个需要注意的地方：

 1. 启用低功耗蓝牙设备特征值变化时的 notify 功能，订阅特征值。注意：必须设备的特征值支持notify或者indicate才可以成功调用。另外，必须先启用notifyBLECharacteristicValueChange才能监听到设备characteristicValueChange事件

  

 2.数据发送时所发的CHARACTERISTIC_UUID一定要与ESP32端的ID对应，否则会发送失败。

#define CHARACTERISTIC_UUID_RX "6E400002-B5A3-F393-E0A9-E50E24DCCA9E"  // RX串口标识

 

小程序源代码地址：

https://gitee.com/hejinlv/WeChat-Ble-To-ESP32-Ble/tree/master