#include <DHT.h>

#define DHTPIN 12
#define DHTTYPE DHT22
DHT dht(DHTPIN, DHTTYPE);

#define MQ_PIN 34  // Analog input pin for MQ sensor

void setup() {
  Serial.begin(115200);
  dht.begin();
  delay(1000);
  Serial.println("Time(ms),Gas,Temperature,Humidity");
}

void loop() {
  int gasValue = analogRead(MQ_PIN);                     // Read gas sensor (0-4095)
  float temp = dht.readTemperature();                    // Temperature in °C
  float hum = dht.readHumidity();                        // Humidity in %

  // If DHT fails, skip plotting
  if (isnan(temp) || isnan(hum)) {
    Serial.println("DHT22 read error");
  } else {
    // Print values in CSV format: useful for Serial Plotter
    Serial.print(millis()); Serial.print(",");
    Serial.print(gasValue); Serial.print(",");
    Serial.print(temp);     Serial.print(",");
    Serial.println(hum);
  }

  delay(1000);  // 1-second update
}