IOT Base Gas Sensor - Wokwi ESP32, STM32, Arduino Simulator

#include <WiFi.h>
#include <WebServer.h>
#include "DHTesp.h"

#define GAS_PIN 34      // MQ-2 analog
#define DHT_PIN 15

#define LED_RED   26
#define LED_GREEN 27

const char* ssid = "Wokwi-GUEST";
const char* password = "";

WebServer server(80);
DHTesp dht;

float gasValue;
float temperature;

void handleRoot() {
  String page = "<!DOCTYPE html><html><head>";
  page += "<meta name='viewport' content='width=device-width, initial-scale=1'>";
  page += "<style>";
  page += "body{font-family:Arial;text-align:center;}";
  page += ".safe{color:green;font-size:24px;}";
  page += ".danger{color:red;font-size:24px;}";
  page += "</style></head><body>";

  page += "<h2>Engine Room Safety Monitor</h2>";
  page += "<p>Gas Level: " + String(gasValue) + "</p>";
  page += "<p>Temperature: " + String(temperature) + " °C</p>";

  if (gasValue > 300 || temperature >= 40) {
    page += "<p class='danger'>⚠️ DANGER – DO NOT RUN ENGINE</p>";
  } else {
    page += "<p class='safe'>✅ SAFE – ENGINE OK</p>";
  }

  page += "<meta http-equiv='refresh' content='2'>";
  page += "</body></html>";

  server.send(200, "text/html", page);
}

void setup() {
  Serial.begin(115200);

  pinMode(LED_RED, OUTPUT);
  pinMode(LED_GREEN, OUTPUT);

  dht.setup(DHT_PIN, DHTesp::DHT22);

  WiFi.begin(ssid, password);
  Serial.print("Connecting");
  while (WiFi.status() != WL_CONNECTED) {
    delay(300);
    Serial.print(".");
    Serial.println("Open http://10.10.0.2 in Wokwi Web View");

  }

  Serial.println("\nConnected!");
  Serial.print("IP: ");
  Serial.println(WiFi.localIP());

  server.on("/", handleRoot);
  server.begin();
}

void loop() {
  gasValue = analogRead(GAS_PIN);
  temperature = dht.getTemperature();

  if (gasValue > 300 || temperature >= 40) {
    digitalWrite(LED_RED, HIGH);
    digitalWrite(LED_GREEN, LOW);
  } else {
    digitalWrite(LED_RED, LOW);
    digitalWrite(LED_GREEN, HIGH);
  }

  server.handleClient();
  delay(500);
}