Air Quality Sensor (MQ135) [S037]

Air Quality Sensor (MQ135) [S037]

https://www.youtube.com/watch?v=JJonDVX8CYQ

*GitHub : https://github.com/rdiot/rdiot-s037.git

* Specs

Sensitive material of MQ135 gas sensor is SnO2, which with lower conductivity in clean air. When the

target combustible gas exist, The sensor’s conductivity is more higher along with the gas concentration

rising. Please use simple electrocircuit, Convert change of conductivity to correspond output signal of

gas concentration.

MQ135 gas sensor has high sensitity to Ammonia, Sulfide and Benze steam, also sensitive to smoke

and other harmful gases. It is with low cost and suitable for different application. 

* Contents

- Library : https://github.com/GeorgK/MQ135

- DataSheet : http://www.cooking-hacks.com/skin/frontend/default/cooking/pdf/MQ-135.pdf

- Connect

- Key Code

#include <MQ135.h>

#include <Wire.h> 

#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27,20,4);  // LCD2004

int pin = A0;

int sensorValue;

int ledPin = 13;

MQ135 gasSensor = MQ135(pin);

float rzero = gasSensor.getRZero();

int ppm = gasSensor.getPPM();

void loop()

{

 

  lcd.setCursor(0,0);

  lcd.print("S037:MQ135");

  sensorValue = analogRead(pin);

  lcd.setCursor(0,1);

  lcd.print("A0=" + (String)sensorValue + " Resis="+(String)gasSensor.getResistance() +" ");

  float rzero = gasSensor.getRZero();

  digitalWrite(ledPin, HIGH);      // turn the ledPin on

  delay(100);                      // stop the program for some time

  digitalWrite(ledPin, LOW);       // turn the ledPin off

  delay(100);  // stop the program for some time

 

  lcd.setCursor(0,2);

  lcd.print("rzero=" + (String)rzero + "    ");

 

  float co2_ppm = gasSensor.getPPM();

  int ppm = co2_ppm / 4;

  //Vrl = val * ( 5.00 / 1024.0  );      // V

  //Rs = 20000 * ( 5.00 - Vrl) / Vrl ;   // Ohm 

  //ratio =  Rs/Ro;     

  lcd.setCursor(0,3);

  lcd.print("co2 ppm=" + (String)co2_ppm + "    ");

    

  delay(1000);

}