MQ135 sensor

Hello everybody,

I am working with an Arduino Uno and a MQ135 module arduino :

I can get back data from this sensor, I got between 100-900 ppm when I launched serial terminal after compiling and uploading this code below.

int sensorValue;

void setup()
  Serial.begin(9600);      // sets the serial port to 9600

void loop()
  sensorValue = analogRead(0);       // read analog input pin 0
  Serial.println(sensorValue, DEC);  // prints the value read
  delay(100);                        // wait 100ms for next reading

But, I would like to get back data from gases like NH3, NOx, alcohol, benzene, smoke and CO2 . I read a lot of topics and the datasheets of the sensor but I don't see how to do.

Some interesting links :
Davide Gironi: Cheap CO2 meter using the MQ135 sensor with AVR ATmega
If someone could help me, it will be great.


You mean you want it to show how much of each of detectable gases, in a mixture is present? won't happen. It just is sensitive to several gases and any of them affects it.

Think of it as a scale. You can weigh flour, you can weigh water, but it won't tell you how much flour and how much water is on the plate.

You right, in fact it's not possible to get back data from each of the gases.
Now, I have to do the calibration of this sensor.
I think, I will take an example of this video :Getting right PPM from MQ sensors - YouTube
Iit's seems easier than with this method : Davide Gironi: Cheap CO2 meter using the MQ135 sensor with AVR ATmega
Or, I think I can adapt this method to the MQ135 module sensor : MQ-2 Smoke/LPG/CO Gas Sensor Module | Sandbox Electronics

What do you think ?

Hey guys ..
I got reading from mq 135 as..300,325,326,321,324,332,333,.....etc
so how can i convert them into ppm?? or anything else in unit??