Home Chipkit Chipkit Uno and MQ-9 gas sensor

Chipkit Uno and MQ-9 gas sensor

by shedboy71

The MQ-9 Analog Gas Sensor has high sensitity to Carbon Monoxide, Methane and LPG. The sensor can be used to detect different gases containing CO and combustible gases, it is low cost and suitable for a variety of applications.

The core sensing material of MQ-9 gas sensor is SnO2, which has a lower conductivity in clean air. It makes detection by cycling high and low temperature, and detects CO when low temperature (heated by 1.5V). The sensor’s conductivity is higher along with the gas concentration rising. When temperature rises (heated by 5.0V), it detects Methane, Propane, combustible gas,etc  and cleans the other gases adsorbed under low temperature.

The sensitivity of the sensor can be adjusted by using the potentiometer.



* Good sensitivity to CO/Combustible gas
* High sensitivity to Methane, Propane and CO
* Long life and low cost
* Simple drive circuit




here are the connections for my sensor

Wemos Gas Sensor
3v3 VCC
Analog A0 AOUT



[codesyntax lang=”cpp”]

void setup() 
void loop() 
  float sensorVoltage; 
  float sensorValue;
  sensorValue = analogRead(A0);
  sensorVoltage = sensorValue/1024*3.3;
  Serial.print("sensor voltage = ");
  Serial.println(" V");




Again look at the serial monitor, you need to let the sensor stabilise. Remember it consists of a heating element, so you effectively have to let the sensor ‘heat up’.

sensor voltage = 0.40 V
sensor voltage = 0.40 V
sensor voltage = 0.40 V
sensor voltage = 0.42 V
sensor voltage = 0.41 V
sensor voltage = 0.41 V
sensor voltage = 0.41 V
sensor voltage = 0.41 V
sensor voltage = 0.40 V



Mq-9 datasheet
MQ-9 Combustible Gas Detector Carbon Monoxide CO Sensor Module for Arduino


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