mq9_tester.ino

void setup() {
  Serial.begin(9600);
}

void loop() {
  float sensor_volt;
  float RS_air; //  Get the value of RS via in a clear air
  float R0;  // Get the value of R0 via in LPG
  float sensorValue;

  /*--- Get a average data by testing 100 times ---*/
  for (int x = 0 ; x < 100 ; x++)
  {
    sensorValue = sensorValue + analogRead(A0);
  }
  sensorValue = sensorValue / 100.0;
  /*-----------------------------------------------*/

  sensor_volt = sensorValue / 1024 * 5.0;
  RS_air = (5.0 - sensor_volt) / sensor_volt; // omit *RL
  R0 = RS_air / 9.9; // The ratio of RS/R0 is 9.9 in LPG gas

  Serial.print("sensor_volt = ");
  Serial.print(sensor_volt);
  Serial.println("V");

  Serial.print("R0 = ");
  Serial.println(R0);
  delay(1000);

} void setup() {
  Serial.begin(9600);
}

void loop() {
  float sensor_volt;
  float RS_air; //  Get the value of RS via in a clear air
  float R0;  // Get the value of R0 via in LPG
  float sensorValue;

  /*--- Get a average data by testing 100 times ---*/
  for (int x = 0 ; x < 100 ; x++)
  {
    sensorValue = sensorValue + analogRead(A0);
  }
  sensorValue = sensorValue / 100.0;
  /*-----------------------------------------------*/

  sensor_volt = sensorValue / 1024 * 5.0;
  RS_air = (5.0 - sensor_volt) / sensor_volt; // omit *RL
  R0 = RS_air / 9.9; // The ratio of RS/R0 is 9.9 in LPG gas

  Serial.print("sensor_volt = ");
  Serial.print(sensor_volt);
  Serial.println("V");

  Serial.print("R0 = ");
  Serial.println(R0);
  delay(1000);

}