Smoke Detector with Arduino & MQ2 Sensor

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Mechatronics Engineering

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Smoke Detector with Arduino & MQ2 Sensor

• First of all, we need to connect some jumper wires between Arduino and MQ2 smoke sensor shield.
• Here's the image of our Gas sensor and you can see, it has four pins in total.

• This gas sensor has four pins in total, which are:
  • Vcc: We need to provide +5V.
  • GND: We need to ground it.
  • D0: Digital Output.
  • A0: Analog Output.
• So now you will need four male to female jumper wires and connect them as shown in below figure:

• Sensor's pins are labelled on the back side and I have connected these four pins as follows:
  • White Wire: Vcc of Sensor connected with +5V of Arduino.
  • Black Wire: GND of Sensor connected with GND of Arduino.
  • Grey Wire: D0 of Sensor connected with Pin # 8 of Arduino.
  • Orange Wire: A0 of Sensor connected with A0 of Arduino.
• So, now let's design our code in Arduino software in which we will detect whether there's smoke around or not.
• I'm gonna use the analog output of our sensor and will first display the analog value in my Serial Monitor.
• I have used the below code, so copy it and upload in your Arduino board:

int Input = A0;
int SensorVal = 0;

void setup() {
  Serial.begin(9600);
  pinMode(Input, INPUT);
  Serial.println("Interfacing of Smoke Sensor with Arduino");
  Serial. println("Design by www.TheEngineeringProjects.com");
  Serial.println();
}

void loop() {

  SensorVal = analogRead(Input);
  Serial.println(SensorVal);
  delay(500);
}

• Now open the Serial Monitor of Arduino to check the analog values coming from our sensor.
• If everything goes fine then you will get something like this in your Serial Monitor:

• You can see we are getting the values in range of 420 to 450.
• You should read How to do Arduino Serial Communication, if you don't know how to get data serially.
• Now let's place a burning cigarette near it for smoke. (Cigarettes are injurious to health :P )
• When the sensor will sense smoke in its surroundings then its value will start to increase and in my case it reached to around 650.
• So, let's place a check in our Arduino coding to detect whether there's smoke or not.
• So add below code in your Arduino software and upload it to your Arduino board.

int Input = A0;
int SensorVal = 0;

int Check = 0;

void setup() {
  Serial.begin(9600);
  pinMode(Input, INPUT);
  Serial.println("Interfacing of Smoke Sensor with Arduino");
  Serial. println("Design by www.TheEngineeringProjects.com");
  Serial.println();
}

void loop() {

  SensorVal = analogRead(Input);
  if((SensorVal > 500) && (Check == 1))
  {
    Serial.println("Smoke Detected . . .");
    Check = 0;
  }

  if((SensorVal < 500) && (Check == 0))
  {
    Serial.println("All Clear . . .");
    Check = 1;
  }
  //Serial.println(SensorVal);
  delay(500);
}

• After uploading the code to Arduino, open your Serial Monitor.
• If everything goes fine then you will get something as shown in below figure:

• Now let me bring the cigarette close to get some smoke. (Cigarettes are injurious to health :P )
• You will get the warning as soon as it will detect smoke as shown in below figure:

• We got the detection of smoke in our Serial Terminal.