Description
MQ9 - CO and Combustible Gas Sensor Module
The MQ9 Gas Sensor Module is a versatile sensor used to detect Carbon Monoxide (CO), Methane (CH₄), and LPG gases. It provides both analog and digital outputs, making it suitable for gas leak detection and air quality monitoring. The sensor requires a short warm-up time and is ideal for use in safety alarms and IoT-based environmental monitoring systems.
Technical Specifications:
-
Operating Voltage: 5V DC
-
Gases Detected: CO (Carbon Monoxide), CH₄ (Methane), LPG
-
Detection Range: 10 – 1000 ppm (CO), 300 – 10,000 ppm (CH₄, LPG)
-
Analog Output (A0): Varies with gas concentration
-
Digital Output (D0): HIGH/LOW (based on threshold knob)
-
Heater Power: ~900 mW
- Warm-up Time: 2 – 5 minutes (for stable readings)
Pinouts:
Connection with Arduino:
Module |
Arduino UNO |
VCC |
5V |
GND |
GND |
A0 |
A0 |
D0 |
D2(Optional) |
Sample code:
Analog reading:
int mq9Pin = A0; // Analog output of MQ9 connected to Arduino A0
void setup() {
Serial.begin(9600); // Start Serial Monitor
}
void loop() {
int gasValue = analogRead(mq9Pin); // Read analog value from sensor
Serial.print("Gas Level (CO/CH4/LPG): ");
Serial.println(gasValue); // Display gas level
delay(1000); // Delay 1 second
}
Alert with a Buzzer if Gas is Detected
int mq9Pin = A0; // Analog pin
int buzzerPin = 8; // Buzzer connected to digital pin 8
int threshold = 400; // Set based on testing
void setup() {
Serial.begin(9600);
pinMode(buzzerPin, OUTPUT);
}
void loop() {
int gasLevel = analogRead(mq9Pin);
Serial.print("Gas Level: ");
Serial.println(gasLevel);
if (gasLevel > threshold) {
digitalWrite(buzzerPin, HIGH); // Turn on buzzer
} else {
digitalWrite(buzzerPin, LOW); // Turn off buzzer
}
delay(500);
}