Interfacing MQ-2 Gas Sensor with Arduino and 16×2 LCD (I2C)

Gas sensors play a crucial role in detecting harmful gases and ensuring safety. In this blog, we will interface the MQ-2 gas sensor with Arduino Uno and display the readings on a 16×2 LCD with I2C. We will also discuss wiring, errors, and troubleshooting tips.

🛠 Components Used

1. Arduino Uno – Microcontroller board
2. MQ-2 Gas Sensor – Detects gases like LPG, butane, methane, CO, etc.
3. 16×2 LCD (I2C) – Displays gas readings
4. I2C Module for LCD – Reduces wiring complexity
5. Jumper Wires – For connections
6. Breadboard – To make stable connections

🔌 Wiring Diagram

MQ-2 Gas Sensor to Arduino

16×2 LCD (I2C) to Arduino

💻 Arduino Code

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

#define MQ2_PIN A0  // MQ-2 analog output connected to A0

LiquidCrystal_I2C lcd(0x27, 16, 2);  // Initialize LCD with I2C address 0x27

void setup() {
    Serial.begin(9600);
    lcd.init();       // Initialize LCD
    lcd.backlight();  // Turn on LCD backlight

    lcd.setCursor(0, 0);
    lcd.print("MQ-2 Gas Sensor");
    delay(2000);  // Display message for 2 seconds
}

void loop() {
    int gasValue = analogRead(MQ2_PIN);  // Read MQ-2 sensor
    float voltage = gasValue * (5.0 / 1023.0);  // Convert to voltage

    // Convert to estimated PPM (for reference only)
    float ppm = gasValue * (1000.0 / 1023.0);  // Approximate ppm calculation

    // Display values on Serial Monitor
    Serial.print("Gas Value: ");
    Serial.print(gasValue);
    Serial.print(" | Voltage: ");
    Serial.print(voltage);
    Serial.print("V | PPM: ");
    Serial.println(ppm);

    // Display data on LCD
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Gas: ");
    lcd.print(gasValue);  // Raw ADC value

    lcd.setCursor(0, 1);
    lcd.print("PPM: ");
    lcd.print(ppm, 1);  // Display PPM value with 1 decimal place

    delay(1000);  // Update every second
}

📟 Understanding the Output

The LCD and Serial Monitor will display three key values:

• Gas Value (0-1023): The raw analog output from the sensor
• Voltage (0-5V): Converts the gas value into voltage
• PPM (Approximate): An estimation of gas concentration

Example Output

📟 LCD Display

Gas: 300
PPM: 293.0

🖥 Serial Monitor

Gas Value: 300 | Voltage: 1.47V | PPM: 293.0
Gas Value: 310 | Voltage: 1.52V | PPM: 302.0

🔧 Common Errors & Solutions

1️⃣ LCD Not Displaying Anything

✔️ Check if the I2C address (0x27) is correct. Run an I2C scanner sketch to find the correct address. ✔️ Ensure lcd.init(); and lcd.backlight(); are used. ✔️ Double-check SDA (A4) and SCL (A5) connections.

2️⃣ MQ-2 Sensor Always Showing the Same Value

✔️ Ensure the sensor is preheated for at least 20 seconds before reading. ✔️ Check wiring connections (VCC, GND, A0). ✔️ Use delay(1000); to allow stable readings.

3️⃣ PPM Readings Not Accurate

✔️ This is a rough estimation. To get precise values, use a calibrated gas chamber. ✔️ Consider using MQ-2 sensor libraries for better accuracy.

🚀 Conclusion

By following this guide, you can successfully interface the MQ-2 gas sensor with Arduino and display the readings on a 16×2 LCD. This project is useful for gas leakage detection in homes and industries.

📢 Next Steps: Want to add a buzzer or IoT integration? Let me know in the comments! 🚀🔥