MQ-2 not detecting lpg gas or smoke

Projects General Guidance
1

I already pre- heated the MQ-2 all the components in my circuit is functional. The code seems to work but the sensor is not detecting lpg gas or smoke. I even changed the sensor used a new one. Currently the arduino is directly connected to my laptop for power supply.

int red_led=3;//indicates gas
int green_led=2;//indicates normal
int smokeA0 = A0;//indicates sensor is connected to A5
int buzzer=4;
int sensorThres=400;//The threshold value

void setup() {
pinMode(red_led,OUTPUT);//red led as output
pinMode(green_led,OUTPUT);//green led as output
pinMode(buzzer,OUTPUT);
pinMode(A0,INPUT);//sensor as input
Serial.begin(9600);//starts the code
}

void loop() {
  int gas_avalue=analogRead(smokeA0);//reads sensor value
  if (gas_avalue > sensorThres) {//sees if it reached threshold value 
  digitalWrite(red_led, HIGH);//turns on red led
  digitalWrite(green_led, LOW);//turns off green led
  digitalWrite(buzzer, HIGH);//turn buzzer on
  }
  else//if it hasn't reached threshold value
  {
  digitalWrite(red_led, LOW);//turns red led off
  digitalWrite(green_led, HIGH);//turn green led on
  digitalWrite(buzzer, LOW);//turn buzzer off
  }
delay(100);//delay 0.1 sec
}
2

Welcome to the forum

What value do you see if you print the value returned by the sensor ?

3

It doesnt print anything

4

That makes no sense

Please post the loop() function showing how you tried to print it. Have you checked that the baud rate of the Serial monitor matches that of the Serial.begin() ?

5

I am actually new to this so I didnt understand however I updated the code

int red_led=3;//indicates gas
int green_led=2;//indicates normal
int smokeA0 = A0;//indicates sensor is connected to A5
int buzzer=4;
int sensorThres=400;//The threshold value

void setup() {
pinMode(red_led,OUTPUT);//red led as output
pinMode(green_led,OUTPUT);//green led as output
pinMode(buzzer,OUTPUT);
pinMode(A0,INPUT);//sensor as input
Serial.begin(9600);//starts the code
}

void loop() {
  int gas_avalue=analogRead(smokeA0);//reads sensor value
  if (gas_avalue > sensorThres) {//sees if it reached threshold value 
  digitalWrite(red_led, HIGH);//turns on red led
  digitalWrite(green_led, LOW);//turns off green led
  digitalWrite(buzzer, HIGH);//turn buzzer on
  Serial.println("GAS LEAKING");
  }
  else//if it hasn't reached threshold value
  {
  digitalWrite(red_led, LOW);//turns red led off
  digitalWrite(green_led, HIGH);//turn green led on
  digitalWrite(buzzer, LOW);//turn buzzer off
  Serial.println("NORMAL");
  }
delay(100);//delay 0.1 sec
}

In serial monitor it prints "Normal"
Is this what you are referring to?

6

No. What I had in mind was printing the value returned by the sensor before you test it. Like this

void loop()
{
    int gas_avalue = analogRead(smokeA0);  //reads sensor value
    Serial.print("sensor value : ");    //print the sensor value
    Serial.println(gas_avalue);
    if (gas_avalue > sensorThres)
    {                                  //sees if it reached threshold value
etc, etc
8

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