   unsigned long chars;
   unsigned short sentences, failed;
 #endif 
-  //gps_serial.listen(); // select the GPS softserial port for listening
   
   // For one second we parse GPS data and report some key values
   for (unsigned long start = millis(); millis() - start < 1000;) {

  Serial.print(sentences);
  Serial.print(" CSUM ERR=");
  Serial.println(failed);
  if (chars == 0)
    Serial.println("** No characters received from GPS: check wiring **");
#endif


  // **************** FOR MQ7 SENSOR ****************
  pinMode(CO_PWR_SEL_PIN, OUTPUT);
  digitalWrite(CO_PWR_SEL_PIN, LOW);// 5v phase
  heaterInHighPhase = true;
  CO_timer_start = millis();
  CO_switch_time = CO_timer_start + CO_HEAT_TIME;

  // **************** FOR TEMP & HUMIDITY SENSOR ****************
  dht.begin();
