Wokwi - Online ESP32, STM32, Arduino Simulator

#include <Arduino.h>
#include <WiFi.h>
#include "DHT.h"

// ------------------- Pin Definitions -------------------
#define DHTPIN 4          // DHT11 data pin
#define DHTTYPE DHT11
#define LDR_PIN 34        // LDR analog pin
#define LED_PIN 10        // Optional indicator

// ------------------- Wi-Fi / ThingSpeak -------------------
String SSID = "Wokwi-GUEST";
String PASSWORD = "";
String SERVER_IP = "api.thingspeak.com";
String API_KEY = "DJS2GKXB9K02BWZG";

// ------------------- Globals -------------------
DHT dht(DHTPIN, DHTTYPE);
WiFiServer server(80);

float g_temperature = 0;
float g_humidity = 0;
int g_LDR = 0;

// ------------------- Setup -------------------
void setup() {
  Serial.begin(115200);
  pinMode(LED_PIN, OUTPUT);

  dht.begin();
  setupWiFi();

  server.begin(); // Optional web server
}

// ------------------- Main Loop -------------------
void loop() {
  digitalWrite(LED_PIN, LOW); // Indicate reading

  // Read DHT11
  float temperature = dht.readTemperature();
  float humidity = dht.readHumidity();

  if (isnan(temperature) || isnan(humidity)) {
    Serial.println("DHT read error!");
    temperature = 0;
    humidity = 0;
  }

  // Read LDR
  int ldrValue = analogRead(LDR_PIN);

  // Save globals
  g_temperature = temperature;
  g_humidity = humidity;
  g_LDR = ldrValue;

  // Send to ThingSpeak
  sendToThingSpeak(temperature, humidity, ldrValue);

  digitalWrite(LED_PIN, HIGH);

  // Handle optional web server
  handleWebServer();

  delay(5000); // Adjust reading interval
}

// ------------------- Wi-Fi Setup -------------------
void setupWiFi() {
  Serial.print("Connecting to Wi-Fi...");
  WiFi.begin(SSID.c_str(), PASSWORD.c_str());
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("\nWi-Fi connected!");
  Serial.print("ESP32 IP Address: "); Serial.println(WiFi.localIP());
}

// ------------------- ThingSpeak -------------------
void sendToThingSpeak(float temp, float hum, int ldr) {
  WiFiClient client;
  if (!client.connect(SERVER_IP.c_str(), 80)) {
    Serial.println("Connection to ThingSpeak failed");
    return;
  }

  String url = "/update?api_key=" + API_KEY;
  url += "&field1=" + String(temp, 1);
  url += "&field2=" + String(hum, 1);
  url += "&field3=" + String(ldr);

  client.print("GET " + url + " HTTP/1.1\r\nHost: " + SERVER_IP + "\r\nConnection: close\r\n\r\n");

  Serial.println("Data sent to ThingSpeak:");
  Serial.println(url);

  client.stop();
}

// ------------------- Web Server -------------------
void handleWebServer() {
  WiFiClient client = server.available();
  if (!client) return;

  String request = client.readStringUntil('\r');
  client.flush();

  client.println("HTTP/1.1 200 OK");
  client.println("Content-Type: text/html");
  client.println("Connection: close");
  client.println();
  client.println("<!DOCTYPE HTML>");
  client.println("<html>");
  client.println("<h1>ESP32 Sensor Data</h1>");
  client.print("Temperature: "); client.print(g_temperature); client.println(" °C<br>");
  client.print("Humidity: "); client.print(g_humidity); client.println(" %<br>");
  client.print("LDR Value: "); client.print(g_LDR); client.println("<br>");
  client.println("</html>");

  client.stop();
}