### Project 33 ESP32 Read Data **1. Description** We learned how to control the led light throught ESP32 wifi and display the IP address on the LCD1602. Next, we will use the esp32 board read the sensor data and transmit it to the web page. **Notes** 1. You need to prepare your a 2.4GHz frequency WIFI, not 5GHz frequency. It can be a mobile hotspot or a router. 2. The ESP32 board consumes more power when connected to the network, so you need to connect an external power supply to this kit. We provide you with a 6XAA Battery Holder (battery not included), which you can connect to the DC port of the ESP32 integrated board. ![](media/B58.png)![](media/B59.png) 3. When using other devices to control this kit, the ESP32 board needs to be connected to the same network as your control device. 4. Remember your wifi network name and password and fill it into the code before uploading it. ``` const char* ssid = "your_SSID"; // Fill in WiFi name, for example,= "KEYES" const char* password = "your_password"; // Fill in WiFi password, for example,= "123456" ``` **2. Wiring Diagram** ![](media/B60.png) **3. Upload Code** ``` #include #include #include #include LiquidCrystal_I2C lcd(0x27, 16, 2); // WiFi configuration const char* ssid = "your-SSID"; // your WiFi name const char* password = "your-PASSWORD"; // your WiFi password // Create a Web Server AsyncWebServer server(80); // DHT11 configuration xht11 xht(26); //set DHT11 sensor pin to IO26 unsigned char dat[] = { 0, 0, 0, 0 }; //Define an array to store temperature and humidity values int i = 0; // photoresistor configuration #define LDRPIN 34 // connect photoresistor to GPIO34(analog input) void setup() { lcd.init(); // initialize the lcd lcd.backlight(); lcd.setCursor(0, 0); lcd.print("IP:"); // WiFi connection WiFi.begin(ssid, password); while (WiFi.status() != WL_CONNECTED) { lcd.setCursor(i, 1); lcd.print("."); delay(500); i++; if (i > 15) { i = 0; lcd.setCursor(0, 1); lcd.print(" "); } } lcd.setCursor(0, 1); lcd.print(" "); lcd.setCursor(0, 1); lcd.print(WiFi.localIP()); // Process the client request and return to the page server.on("/", HTTP_GET, [](AsyncWebServerRequest* request) { String html = generateHTML(); request->send(200, "text/html", html); }); // Start the Web server server.begin(); } String generateHTML() { // acquire photoresistor value int lightValue = analogRead(LDRPIN); // read photoresistor analog value // Generate HTML page String html = ""; // add automatic refresh, refresh the page every 5 seconds html += ""; html += ""; // diaplay temperature and humidity html += "

"; html += "

Temperature

"; html += "

" + String(dat[2]) + " °C

"; html += "

Humidity

"; html += "

" + String(dat[0]) + " %

"; html += "

"; // diaplay photoresistor resistance value html += "

"; html += "

Luminance

"; html += "

" + String(lightValue) + "

"; html += "

"; html += ""; return html; } void loop() { // Update temperature, humidity and light intensity every 2 seconds if (!xht.receive(dat)) { Serial.println("sensor error"); } delay(2000); } ``` **4. Test Result** After uploading the code, LCD1602 shows the IP address. Use a computer or mobile phone that is connected to the same network as the ESP32 board, open the browser and enter the IP address, you can see the sensor values on the control page which refresh every 5 seconds. ![](media/B61.png)