Arduino Project
Gas Leak Monitor
Course Introduction
This Arduino project simulates a basic gas leak detection system using an MQ-2 gas sensor, a red LED, and a buzzer.
The sensor continuously monitors gas concentration. If the reading exceeds a set threshold, the buzzer sounds and the LED blinks to indicate danger.
Otherwise, the system remains silent and the LED stays off.
Note
If this is your first time working with an Arduino project, we recommend downloading and reviewing the basic materials first.
1.1 Install Arduino IDE(Important)
1.2 Introduction of Arduino IDE
Wiring
Common Connections:
MQ-2 Gas Sensor Module
A0: Connect to A0 on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC: Connect to breadboard’s red power bus.
Buzzer Modudle
I/O: Connect to 9 on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC:Connect to breadboard’s red power bus.
LED
Connect the LED anode to 2 on the Arduino, and the cathode to a 220Ω resistor, then to the negative power bus on the breadboard.
Writing the Code
Note
You can copy this code into Arduino IDE.
Don’t forget to select the board(Arduino UNO R4 Minima) and the correct port before clicking the Upload button.
/*
Demo program: Arduino Uno + MQ-2 gas sensor + red LED + buzzer.
Purpose: Simulate gas leak detection.
- If gas concentration > threshold (300): buzzer sounds, red LED blinks.
- Otherwise: buzzer is silent, red LED is off.
Hardware:
- MQ-2 gas sensor connected to A0
- Buzzer connected to D9
- Red LED connected to D2 (via resistor)
*/
const int sensorPin = A0; // MQ-2 sensor analog pin
const int buzzerPin = 9; // Buzzer pin
const int redLEDPin = 2; // Red LED pin
int sensorValue = 0; // Variable to store sensor value
const int threshold = 90; // Gas detection threshold
void setup() {
Serial.begin(9600); // Initialize serial monitor
pinMode(buzzerPin, OUTPUT); // Set buzzer pin as output
pinMode(redLEDPin, OUTPUT); // Set red LED pin as output
}
void loop() {o
sensorValue = analogRead(sensorPin); // Read sensor value
Serial.print("Analog output: ");
Serial.println(sensorValue);
if (sensorValue > threshold) {
tone(buzzerPin, 500); // Turn on buzzer
digitalWrite(redLEDPin, HIGH); // LED ON
delay(250); // Wait 250 ms
digitalWrite(redLEDPin, LOW); // LED OFF
delay(250); // Wait 250 ms (total blink cycle = 500 ms)
} else {
noTone(buzzerPin); // Turn off buzzer
digitalWrite(redLEDPin, LOW); // LED OFF
delay(50); // Short delay
}
}