#define MQ2_PIN 34
#define THRESHOLD 50
void setup()
{
  Serial.begin(115200);
  pinMode(MQ2_PIN, INPUT);
}
void loop()
{
  int sensorvalue=analogRead(MQ2_PIN);
  float voltage=(sensorvalue/4095.0)*3.3;
  float gaslevel=voltage*100;
  Serial.print("gas level:");
  Serial.println(gaslevel);
  if (gaslevel<THRESHOLD)
  {
    Serial.println("high");
  }
  else
  {
    Serial.println("low");
  }
}