/*
  Wokwi | projects
  Can anyone help in doing this project by code
  and hardware, air quality using esp32

  Karthik September 11, 2025 at 1:15 PM
  Task - 1: Air Quality Safety Monitor
  Problem Statement: Indoor pollution often goes unnoticed.
  Build a system that checks air quality and alerts when unsafe using ESP32
  Requirements:
  Use a MQ- Gas Sensor to detect harmful gases.
  Use a DHTSensor for temperature & humidity.
  If the gas level is above threshold and humidity is high (>70%),
  turn on a simulated buzzer (LED).
  Show readings and alert status on Serial Monitor.
*/

#include "DHTesp.h"

const int DHT_PIN = 12;
const int MQ2_PIN = 13;
const int LED_PIN = 14;
const int BUZZ_PIN = 27;

DHTesp dhtSensor;

void setup() {
  Serial.begin(115200);
  dhtSensor.setup(DHT_PIN, DHTesp::DHT22);
  pinMode(MQ2_PIN, INPUT);
  pinMode(LED_PIN, OUTPUT);
  pinMode(BUZZ_PIN, OUTPUT);
}

void loop() {
  // read DHT
  TempAndHumidity  data = dhtSensor.getTempAndHumidity();
  Serial.println("Temp: " + String(data.temperature, 2) + "°C");
  Serial.println("Humidity: " + String(data.humidity, 1) + "%");
  // read MQ2
  if (digitalRead(MQ2_PIN)) {
    Serial.println("No gas sensed.");
  } else {
    Serial.println("Gas sensed!");
  }
  Serial.println("---");

  if (!digitalRead(MQ2_PIN) && data.humidity > 70)  {
    tone(BUZZ_PIN, 440);
    digitalWrite(LED_PIN, HIGH);
  } else {
    noTone(BUZZ_PIN);
    digitalWrite(LED_PIN, LOW);
  }

  delay(2000); // Wait for a new reading from the sensor (DHT22 has ~0.5Hz sample rate)
}