Arduino - Flame Sensor

The flame sensor is capable of detecting and measuring infrared level emited from the flame, It can be used to detect fire. It is also called infrared flame sensor, or fire sensor. The infrared flame sensor provides two outputs: a digital output (LOW/HIGH) and an analog output.

In this tutorial, we will learn how to use an Arduino and an flame sensor to detect and measure the flame and fire. Specifically, we will cover the following:

arduino flame sensor

Afterward, you can modify the code to activate a warning horn (via a relay) when it detects fire.

Hardware Required

1×Arduino UNO or Genuino UNO
1×USB 2.0 cable type A/B
1×Flame Sensor
1×Jumper Wires
1×(Optional) 9V Power Adapter for Arduino
1×(Recommended) Screw Terminal Block Shield for Arduino Uno
1×(Optional) Transparent Acrylic Enclosure For Arduino Uno

Or you can buy the following sensor kit:

1×DIYables Sensor Kit 30 types, 69 units
Please note: These are Amazon affiliate links. If you buy the components through these links, We will get a commission at no extra cost to you. We appreciate it.

About Flame Sensor

The infrared flame sensor can be utilized to detect the presence of flame or measure the infrared level emited by the flame. Therefore, The flame sensor can be used to detect the fire. The flame sensor provides two options via a digital output pin and analog output pin.

The infrared flame sensors are designed to be selective in the wavelengths of infrared radiation they detect, focusing on the specific wavelengths associated with flames. They are engineered to minimize the likelihood of false alarms from other sources of infrared radiation, such as human body heat or artificial lighting. However, like any sensor, they have limitations, and under certain conditions, they might be susceptible to false positives or false negatives.

Pinout

The flame sensor includes four pins:

  • VCC pin: It needs to be connected to VCC (3.3V to 5V).
  • GND pin: It needs to be connected to GND (0V).
  • DO pin: It is a digital output pin. It is HIGH if the flame is not detected and LOW if detected. The threshold value for flame detection can be adjusted using a built-in potentiometer.
  • AO pin: It is an analog output pin. The output value decreases as the infraed level is decreased, and it increases as infraed level is increased.
Flame Sensor Pinout
image source: diyables.io

Furthermore, it has two LED indicators:

  • One PWR-LED indicator for power.
  • One DO-LED indicator for the flame state on the DO pin: it is on when flame is present.

How It Works

For the DO pin:

  • The module has a built-in potentiometer for setting the infrared threshold (sensitivity).
  • When the infrared intensity is above the threshold value, the flame is detected, the output pin of the sensor is LOW, and the DO-LED is on.
  • When the infrared intensity is below the threshold value, the flame is NOT detected, the output pin of the sensor is HIGH, and the DO-LED is off.

For the AO pin:

  • The higher the infrared intensity in the surrounding environment, the higher the value read from the AO pin.
  • The lower the infrared intensity in the surrounding environment, the lower the value read from the AO pin.

Note that the potentiometer does not affect the value on the AO pin.

Wiring Diagram

Since the flame sensor module has two outputs, you can choose to use one or both of them, depending on what you need.

  • The wiring diagram between Arduino and the flame sensor when using DO only.
Arduino Flame Sensor wiring diagram

This image is created using Fritzing. Click to enlarge image

  • The wiring diagram between Arduino and the flame sensor when using AO only.
Arduino fire sensor wiring diagram

This image is created using Fritzing. Click to enlarge image

  • The wiring diagram between Arduino and the flame sensor when using both AO an DO.
Arduino infrared flame sensor wiring diagram

This image is created using Fritzing. Click to enlarge image

Arduino Code - Read value from DO pin

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-flame-sensor */ #define DO_PIN 2 // Arduino's pin connected to DO pin of the flame sensor void setup() { // initialize serial communication Serial.begin(9600); // initialize the Arduino's pin as an input pinMode(DO_PIN, INPUT); } void loop() { int flame_state = digitalRead(DO_PIN); if (flame_state == HIGH) Serial.println("The flame is NOT present => The fire is NOT detected"); else Serial.println("The flame is present => The fire is detected"); }

Quick Steps

  • Copy the above code and open with Arduino IDE
  • Click Upload button on Arduino IDE to upload code to Arduino
  • Direct the flame sensor to a flame.
  • See the result on Serial Monitor.
COM6
Send
The flame is present => The fire is detected The flame is present => The fire is detected The flame is NOT present => The fire is NOT detected The flame is NOT present => The fire is NOT detected The flame is NOT present => The fire is NOT detected The flame is present => The fire is detected The flame is present => The fire is detected The flame is present => The fire is detected
Autoscroll Show timestamp
Clear output
9600 baud  
Newline  

Please keep in mind that if you notice the LED status remaining on constantly or off even when the sensor faces to a flame, you can adjust the potentiometer to fine-tune the sensitivity of the sensor.

Arduino Code - Read value from AO pin

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-flame-sensor */ #define AO_PIN A0 // Arduino's pin connected to AO pin of the flame sensor void setup() { // initialize serial communication Serial.begin(9600); } void loop() { int flameValue = analogRead(AO_PIN); Serial.println(flameValue); }

Quick Steps

  • Copy the above code and open with Arduino IDE
  • Click Upload button on Arduino IDE to upload code to Arduino
  • Direct the flame sensor to a flame.
  • See the result on Serial Monitor.
COM6
Send
245 246 246 573 677 949 955 1004 1007 1013 1018 641 543 340 179
Autoscroll Show timestamp
Clear output
9600 baud  
Newline  

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