FC-22 Module with MQ-2 Sensor for Smoke, Methane and LPG Flammable Gas Detection for Arduino

Description

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🧾 Description of FC-22 Module with MQ-2 Sensor

The FC-22 Module is a gas sensor based on theMQ-2, designed to detect smoke, methane (CH₄), LPG (liquefied petroleum gas) and other flammable gases present in the air.

📦 Main Features

• Sensor: MQ-2
• Detection Type: Smoke, Methane, LPG, Hydrogen, Alcohol, Propane
• Operating Voltage: 5V DC
• Interface:
  • Analog (A0): output proportional to gas concentration
  • Digital (D0): HIGH/LOW output based on set threshold
• Potentiometer integrated for threshold adjustment (digital output)
• LED indicator for power supply and digital status
• Preheating time: 20-30 seconds
• Dimensions: approximately 32 x 22 x 27 mm

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⚙️ FC-22 Module Connections with Arduino

FC-22 Pin	Function	Recommended Arduino Pin
VCC	Power Supply (5V)	5V
GND	GND	GND
D0	Digital Output	Any Digital Pin
A0	Analog Output	A0 (or any other analog pin)

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🧪 How the MQ-2 Sensor Works

The MQ-2 sensor contains a sensitive material (SnO₂) that changes resistance in the presence of flammable gases. This change is converted into an electrical signal.

• Analog Output (A0): provides a value proportional to the gas concentration.
• Digital Output (D0): returns HIGH (1) if the concentration exceeds the threshold, LOW (0) otherwise.

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🔧 Arduino Programming Guide

🔌 1. Basic Connections

Arduino     FC-22
--------     -----
5V          → VCC
GND         → GND
A0          → A0 (uscita analogica)
D2          → D0 (uscita digitale)

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🧑‍💻 2. Example Code: Analog Read (A0)

const int analogPin = A0;

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

void loop() {
  int gasValue = analogRead(analogPin);
  Serial.print("Valore gas rilevato: ");
  Serial.println(gasValue);
  delay(1000);
}

📝 Note: Read values can range from 0 to 1023. Higher the value, higher the gas concentration detected.

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🧑‍💻 3. Example Code: Threshold Detection with Digital Output (D0)

const int digitalPin = 2;
const int ledPin = 13;

void setup() {
  pinMode(digitalPin, INPUT);
  pinMode(ledPin, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  int gasDetected = digitalRead(digitalPin);

  if (gasDetected == LOW) {
    Serial.println("⚠️ Gas rilevato!");
    digitalWrite(ledPin, HIGH);
  } else {
    Serial.println("✅ Aria pulita.");
    digitalWrite(ledPin, LOW);
  }
  delay(1000);
}

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🧰 Practical Tips

• ⚠️ Warm-up: the sensor needs 20-30 seconds of warm-up time before providing reliable readings.
• 🔧 Digital Threshold Adjustment: use the potentiometer on the module to set the digital threshold sensitivity.
• 🧪 Calibration: for more precise measurements, compare values with professional tools and use a calibration algorithm.
• 🔋 Power Supply: works best when powered by a stable 5V source (e.g., Arduino or external power supply with common GND).

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💡 Common Applications

• DIY Smoke Detectors
• Home Gas Leak Alarms
• Environmental Monitoring Systems
• IoT Projects with Gas Notification

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📈 Project Expansion

You can extend the project with:

• LCD/OLED Display to show values
• Buzzer/Sound Alarm
• Wi-Fi Module (ESP8266/ESP32) for remote notification or logging
• Relay to turn off valves or activate fans

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Here is a connection diagram module description FC‑22 with MQ‑2 sensor connected to Arduino, followed by a step-by-step guide for integration on Arduino IoT Cloud.

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🧑‍🔧 Electrical diagram (wiring)

Required components:

• FC‑22 (MQ‑2)
• Arduino UNO or compatible
• LED (green and red) + resistors 220 Ω
• Buzzer (optional)
• Breadboard and jumpers

Connections:

FC‑22 module	Function	Arduino UNO
VCC	5V power supply	5V
GND	Mass	GND
A0	Analog Output	Pin A0
D0	Digital Output	Ex. Pin 8 (optional LED)

For LED and buzzer:

• Red LED with 220 Ω resistor → Digital Pin (example 8)
• Green LED with resistor → Pin 13 (on board) or other
• Buzzer if applicable, on pin 9 (GND to common)

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☁️ Integration on Arduino IoT Cloud

1. Setting up the “Thing”

• Log in to Arduino IoT Cloud, create a new Thing named “GasSensor”.
• Add variable:
  • GasLevel (type Float), permission: Read Only, policy On Change.

2. Configure device (e.g. Arduino MKR or Nano IoT)

Connect and register the device (Arduino MKR/Nano IoT). Arduino Cloud will provide a file thingProperties.h to include in your sketch.

3. Hardware connections on IoT board

Similar to Arduino UNO: A0 → uscita analogica MQ-2, VCC/GND common (teachmemicro.com, Random Nerd Tutorials, Arduino Project Hub, Arduino Intro, Instructables).

4. Example Code

#include "thingProperties.h"

const int gasPin = A0;
float gasLevel = 0;

void setup() {
  Serial.begin(115200);
  delay(1500);
  initProperties();
  ArduinoCloud.begin(ArduinoIoTPreferredConnection);
  while (!ArduinoCloud.connected()) {
    ArduinoCloud.update();
    delay(500);
  }
  Serial.println("Connesso a Arduino IoT Cloud");
}

void loop() {
  gasLevel = analogRead(gasPin);
  gasLevel = map(gasLevel, 0, 1023, 0, 5000) / 10.0; // opzionale: converti value in mV o scala personalizzata
  ArduinoCloud.update();
  Serial.print("Valore gas (A0): ");
  Serial.println(gasLevel);
  delay(1000);
}

5. Cloud Dashboard

• Add Widget Value for variable GasLevel.
• Add Widget Indicator to signal threshold:
  Configure logic green if value below threshold, red if above.

If you use Status Indicator, you can base it on gasLevel or a boolean variable derived from the analog value (teachmemicro.com, Arduino Introduction, Arduino Forum).

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🧾 Detailed Explanation

• Wiring: standard connections Vcc-GND-A0-D0 as described by various tutorials (diyi0t.com).
• Analog usage (A0) provides continuous readings, while digital (D0) is used only if a fixed threshold alarm is needed.
• Pre-amplifies the sensor for 2–5 minutes (or 24–48 hours for initial calibration) before taking reliable measurements (Arduino Introduction).

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✅ In summary

• The FC-22 module (MQ-2) easily connects to Arduino to detect flammable gases and smoke.
• The connection diagram is simple and standard.
• On Arduino IoT Cloud, it is possible to send the analog value GasLevel and create a remote dashboard with security indicators.
• The code shown allows for an analog read and cloud upload every second.

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Tutorial: How to use FC-22 Module with MQ-2 Sensor

The FC-22 module with MQ-2 sensor is a useful device for detecting smoke, methane, and other flammable gases. Ideal for home or industrial security projects.

What you need

• Arduino
• USB Type B cable
• Soldering iron

Steps

1. Connect the FC-22 module to the Arduino using the VCC, GND, and SIG pins.
2. Download and install the Adafruit_Sensor library if it is not already installed.
3. Insert the example sketch provided with the library into your Arduino IDE.
4. Compile and upload the source code to your Arduino.
5. Open the serial monitor to view the sensor values.
6. Check that the sensor reacts appropriately to changes in gas concentration.
7. Adjust the alarm threshold according to your needs.
8. Test the system with test gases (if available).

Example code

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

void loop() {
  int val = analogRead(A0); // Verifica sul datasheet per la corretta lettura del pin SIG.
  Serial.println(val);
}

Mini project

Create a home alarm system with the MQ-2 sensor and a Wi-Fi module. The device sends an email or message notification when it detects gas.

Common mistakes

• Do not connect the sensor pins correctly.
• Ignore the initial calibration of the sensor.
• Use excessively high gas concentrations to test the device.
• Omit the installation of the necessary library for the sensor.

Recommended accessories

• ESP8266 Wi-Fi Module
• Li-Po Batteries for Portable Power
• Relay to Activate Alarm Devices
• OLED Display to Show Sensor Data

Frequently asked questions

Can the sensor detect specific gases like CO?
Check the datasheet to see if the MQ-2 sensor supports carbon monoxide.

How can I improve the accuracy of my tests?
Calibrate the sensor in environments with known gas concentrations and adjust the alarm thresholds.