node mcu 32 and dht 11

sketch_nov12a_esp_32.ino

+#include <BLEDevice.h>
+#include <BLEServer.h>
+#include <BLEUtils.h>
+#include <BLE2902.h>
+#include <DHT.h>
+
+#define DHTPIN 4     
+#define DHTTYPE    DHT11
+
+DHT dht(DHTPIN, DHTTYPE);
+BLEServer* pServer = NULL;
+BLECharacteristic* pCharacteristic = NULL;
+bool deviceConnected = false;
+bool oldDeviceConnected = false;
+uint32_t value = 0;
+float prev_temp;
+float prev_humidity;
+
+
+#define SERVICE_UUID        "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
+#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"
+
+
+class MyServerCallbacks: public BLEServerCallbacks {
+    void onConnect(BLEServer* pServer) {
+      deviceConnected = true;
+      BLEDevice::startAdvertising();
+    };
+
+    void onDisconnect(BLEServer* pServer) {
+      deviceConnected = false;
+    }
+};
+
+void updateTemp(float temp){
+  if(prev_temp != temp){
+   
+
+    String tempString = "";
+    tempString += (int)temp;
+    tempString += "C";
+    prev_temp = temp;
+  }
+}
+
+void updateHumidity(float humidity){
+  if(prev_humidity != humidity){
+    String humidityString = "";
+    humidityString += (int)humidity;
+    humidityString += "%";
+    prev_humidity = humidity;
+  }
+}
+
+
+void setup() {
+  Serial.begin(115200);
+ dht.begin();
+  // Create the BLE Device
+  BLEDevice::init("ESP32 Test");
+
+  // Create the BLE Server
+  pServer = BLEDevice::createServer();
+  pServer->setCallbacks(new MyServerCallbacks());
+
+  // Create the BLE Service
+  BLEService *pService = pServer->createService(SERVICE_UUID);
+
+  // Create a BLE Characteristic
+  pCharacteristic = pService->createCharacteristic(
+                      CHARACTERISTIC_UUID,
+                      BLECharacteristic::PROPERTY_READ   |
+                      BLECharacteristic::PROPERTY_WRITE  |
+                      BLECharacteristic::PROPERTY_NOTIFY |
+                      BLECharacteristic::PROPERTY_INDICATE
+                    );
+
+  // Create a BLE Descriptor
+  pCharacteristic->addDescriptor(new BLE2902());
+
+  // Start the service
+  pService->start();
+
+  // Start advertising
+  BLEAdvertising *pAdvertising = BLEDevice::getAdvertising();
+  pAdvertising->addServiceUUID(SERVICE_UUID);
+  pAdvertising->setScanResponse(false);
+  pAdvertising->setMinPreferred(0x0);  // set value to 0x00 to not advertise this parameter
+  BLEDevice::startAdvertising();
+  Serial.println("Waiting a client connection to notify...");
+}
+
+void loop() {
+
+updateTemp(dht.readTemperature());
+updateHumidity(dht.readHumidity());
+
+
+    // notify changed value
+    if (deviceConnected) {
+        String str = "";
+      str += prev_temp;
+      str += ",";
+      str += prev_humidity;
+    pCharacteristic->setValue((char*)str.c_str());
+    pCharacteristic->notify();
+    
+  Serial.println(prev_humidity);
+  Serial.println(F("%  Temperature: "));
+  Serial.println(prev_temp);
+    }
+    // disconnecting Serial.println("start advertising");
+        oldDeviceConnected = deviceConnected;
+    if (!deviceConnected && oldDeviceConnected) {
+        delay(500); // give the bluetooth stack the chance to get things ready
+        pServer->startAdvertising(); // restart advertising
+       
+    }
+    // connecting
+    if (deviceConnected && !oldDeviceConnected) {
+        // do stuff here on connecting
+        oldDeviceConnected = deviceConnected;
+    }
+
+}