1 // 包含所必需的库
  2 #include <BLEDevice.h>
  3 #include <BLEServer.h>
  4 #include <BLEUtils.h>
  5 #include <BLE2902.h>
  6 
  7 BLEServer *pServer = NULL;
  8 BLECharacteristic *pTxCharacteristic;
  9 bool deviceConnected = false;
 10 bool oldDeviceConnected = false;
 11 
 12 char BLEbuf[32] = {0};
 13 String data = "";
 14 
 15 // 定义收发服务的UUID（唯一标识）
 16 #define SERVICE_UUID           "6E400001-B5A3-F393-E0A9-E50E24DCCA9E" 
 17 // RX串口标识
 18 #define CHARACTERISTIC_UUID_RX "6E400002-B5A3-F393-E0A9-E50E24DCCA9E"
 19 // TX串口标识
 20 #define CHARACTERISTIC_UUID_TX "6E400003-B5A3-F393-E0A9-E50E24DCCA9E"
 21 
 22 
 23 class MyServerCallbacks: public BLEServerCallbacks {
 24     void onConnect(BLEServer* pServer) {
 25       deviceConnected = true;
 26     };
 27 
 28     void onDisconnect(BLEServer* pServer) {
 29       deviceConnected = false;
 30     }
 31 };
 32 
 33 class MyCallbacks: public BLECharacteristicCallbacks {
 34     void onWrite(BLECharacteristic *pCharacteristic) {
 35       std::string rxValue = pCharacteristic->getValue();
 36 
 37       if (rxValue.length() > 0) {
 38         Serial.println("*********");
 39         Serial.print("Received Value: ");
 40         for (int i = 0; i < rxValue.length(); i++){
 41                 Serial.print(rxValue[i]);
 42             }
 43         Serial.println();
 44         data =rxValue.c_str();
 45         //Serial.println(data);
 46         Serial.println("*********");
 47         Serial.println();    
 48       }
 49     }
 50 };
 51 
 52 // setup()在复位或上电后运行一次:
 53 void setup() {
 54   Serial.begin(115200);
 55   // 初始化蓝牙设备
 56   BLEDevice::init("ESP32 test");
 57   // 为蓝牙设备创建服务器
 58   pServer = BLEDevice::createServer();
 59   pServer->setCallbacks(new MyServerCallbacks());
 60   // 基于SERVICE_UUID来创建一个服务
 61   BLEService *pService = pServer->createService(SERVICE_UUID);
 62   pTxCharacteristic = pService->createCharacteristic(
 63                                         CHARACTERISTIC_UUID_TX,
 64                                         BLECharacteristic::PROPERTY_NOTIFY
 65                                     );                      
 66   pTxCharacteristic->addDescriptor(new BLE2902());
 67   BLECharacteristic * pRxCharacteristic = pService->createCharacteristic(
 68                                              CHARACTERISTIC_UUID_RX,
 69                                             BLECharacteristic::PROPERTY_WRITE
 70                                         );
 71   pRxCharacteristic->setCallbacks(new MyCallbacks());
 72   // 开启服务
 73   pService->start();
 74   // 开启通知
 75   pServer->getAdvertising()->start();
 76   Serial.println("Waiting a client connection to notify...");    
 77   Serial.println();
 78 }
 79 
 80 // loop()一直循环执行:
 81 void loop() {
 82 
 83     if (deviceConnected==1&data.length()>0) {
 84         memset(BLEbuf, 0, 32);
 85         memcpy(BLEbuf, data.c_str(), 32); 
 86         Serial.println(BLEbuf); 
 87         
 88         pTxCharacteristic->setValue(BLEbuf);   //收到数据后返回数据
 89         pTxCharacteristic->notify();
 90         data = "";  //返回数据后进行清空，否则一直发送data
 91     }
 92 
 93     // 没有新连接时
 94     if (!deviceConnected && oldDeviceConnected) {
 95         // 给蓝牙堆栈准备数据的时间
 96         delay(500); 
 97         pServer->startAdvertising(); 
 98         // 重新开始广播
 99         Serial.println("start advertising");
100         oldDeviceConnected = deviceConnected;
101     }
102     // 正在连接时
103     if (deviceConnected && !oldDeviceConnected) {
104         // 正在连接时进行的操作
105         oldDeviceConnected = deviceConnected;
106     }
107 }

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