Course 10：Env_Detector ====================== .. image:: _static/COURSE/29.env.png :align: center ---- Learning Objectives ------------------- - Learn environmental sensor data acquisition techniques, master the use of DHT11, photosensors, and raindrop sensors, and understand JSON data communication. - Learn to achieve multi-source data acquisition through ADC analog input and digital signal reading. ---- Required Component ------------------ - DHT11 Sensor、Light Sensor、Raindrop Sensor ---- Working Principle ----------------- - Light Sensor:The core component of a photosensitive brightness sensor is a photoresistor, a semiconductor device whose resistance changes with light intensity. When the light intensity increases, photons are absorbed by the material, generating more free electrons, thus reducing resistance and increasing current; when the light intensity decreases, the number of free electrons decreases, increasing resistance and decreasing current. - Raindrop Sensor:A rain sensor mainly consists of a sensing plate and a comparison module（signal processing circuit）. The surface of the sensing plate has a layer of conductive lines. When water droplets fall on the surface, the conductive liquid（water）creates a path between the electrodes, resulting in a decrease in resistance and an increase in current. ---- Wiring -------- - DHT11 Sensor —— ESP32 IO15 - Light Sensor —— ESP32 IO34 - Raindrop Sensor —— ESP32 IO35 .. image:: _static/COURSE/30.env.png :align: center ---- Example Code ------------ .. code-block:: cpp #include #include #include #include // ===== Pin Definitions ===== #define DHTPIN 15 #define DHTTYPE DHT11 #define LIGHT_PIN 34 #define RAIN_PIN 35 DHT dht(DHTPIN, DHTTYPE); WebServer server(80); // ===== Sensor Data ===== float temperature = 0; float humidity = 0; int lightPercent = 0; int rainPercent = 0; // ===== WiFi Configuration ===== const char* apSSID = "Env_Detector"; // Access Point SSID (no password) const char* apPassword = NULL; // No password String wifiSSID = ""; // Store target WiFi SSID String wifiPassword = ""; // Store target WiFi password bool isConfigMode = true; // Configuration mode flag bool wifiConnected = false; // WiFi connection status // ===== Preferences for storing WiFi credentials ===== Preferences preferences; // ===== Read Sensors ===== void readSensors() { temperature = dht.readTemperature(); humidity = dht.readHumidity(); int lightVal = analogRead(LIGHT_PIN); lightPercent = map(lightVal, 0, 4095, 0, 100); if(lightPercent>100) lightPercent=100; int rainVal = analogRead(RAIN_PIN); rainPercent = map(rainVal, 0, 4095, 0, 100); if(rainPercent>100) rainPercent=100; } // ===== Return Data JSON ===== void handleData() { readSensors(); String json = "{"; json += "\"temperature\":" + String(temperature) + ","; json += "\"humidity\":" + String(humidity) + ","; json += "\"light\":" + String(lightPercent) + ","; json += "\"rain\":" + String(rainPercent); json += "}"; server.send(200,"application/json",json); } // ===== HTML Configuration Page ===== String configHTMLPage() { return R"rawliteral( ESP32 WiFi Configuration

WiFi Configuration

)rawliteral"; } // ===== Control Web Page ===== String controlHTMLPage() { return R"rawliteral( ESP32 Environment Detection System

ESP32 Environment Detection System

Temperature: 0°C

0°C

Humidity: 0%

Light: 0%

Rain: 0%

)rawliteral"; } // ===== Route Handlers ===== void handleRoot() { if (isConfigMode) { server.send(200, "text/html", configHTMLPage()); } else { server.send(200, "text/html", controlHTMLPage()); } } void handleConfigure() { wifiSSID = server.arg("ssid"); wifiPassword = server.arg("password"); // Save credentials to preferences preferences.putString("ssid", wifiSSID); preferences.putString("password", wifiPassword); server.send(200, "text/html", "

Connecting to WiFi...

" "

SSID: " + wifiSSID + "

" "

Device will restart and attempt connection.

" "" ""); delay(2000); ESP.restart(); } // ===== Connect to WiFi ===== bool connectToWiFi() { if (wifiSSID == "") return false; Serial.println("Attempting to connect to WiFi: " + wifiSSID); WiFi.begin(wifiSSID.c_str(), wifiPassword.c_str()); int attempts = 0; while (WiFi.status() != WL_CONNECTED && attempts < 20) { delay(500); Serial.print("."); attempts++; } if (WiFi.status() == WL_CONNECTED) { Serial.println("\nWiFi connected successfully!"); Serial.println("IP address: " + WiFi.localIP().toString()); return true; } else { Serial.println("\nFailed to connect to WiFi"); return false; } } // ===== Setup Access Point ===== void setupAccessPoint() { Serial.println("Setting up Access Point..."); WiFi.softAP(apSSID, apPassword); Serial.println("Access Point started"); Serial.println("SSID: " + String(apSSID)); Serial.println("Password: None (Open Network)"); Serial.println("IP address: " + WiFi.softAPIP().toString()); } // ===== Setup ===== void setup(){ Serial.begin(115200); dht.begin(); pinMode(LIGHT_PIN, INPUT); pinMode(RAIN_PIN, INPUT); // Initialize preferences preferences.begin("wifi-config", false); // Try to load saved WiFi credentials wifiSSID = preferences.getString("ssid", ""); wifiPassword = preferences.getString("password", ""); Serial.println("=== ESP32 Environment Detection System ==="); if (wifiSSID != "" && connectToWiFi()) { // Successfully connected to WiFi isConfigMode = false; wifiConnected = true; Serial.println("Mode: Station (Connected to WiFi)"); } else { // Enter configuration mode (Access Point) isConfigMode = true; wifiConnected = false; setupAccessPoint(); Serial.println("Mode: Access Point (Configuration)"); } server.on("/", handleRoot); server.on("/data", handleData); server.on("/configure", HTTP_POST, handleConfigure); server.begin(); Serial.println("Web server started"); } void loop(){ server.handleClient(); } ---- **Code burning options** 1. You can directly copy the code provided above into the Arduino IDE for burning. 2. Find the **10.Env_Detector.ino** file in the provided folder, download it, open it with the **Arduino IDE**, and burn the program to the ESP32 development board. 3. Find the **10.Env_Detector.bin** file in the provided folder, download it and use **Flash Download Tool** to flash the program to the ESP32 development board. ---- Effects Demonstration --------------------- 1. The web interface displays temperature, brightness, and raindrop values in real time. .. image:: _static/COURSE/31.env.png :width: 800 :align: center ----