/*

  MQUnifiedsensor Library - reading an MQ7

  Demonstrates the use a MQ7 sensor.

  Library originally added 01 may 2019

  by Miguel A Califa, Yersson Carrillo, Ghiordy Contreras, Mario Rodriguez

  Added example

  modified 23 May 2019

  by Miguel Califa 

  Updated library usage

  modified 26 March 2020

  by Miguel Califa 

  Wiring:

  https://github.com/miguel5612/MQSensorsLib_Docs/blob/master/static/img/MQ_Arduino.PNG

  Please take care, arduino A0 pin represent the analog input configured on #define pin

 This example code is in the public domain.

 Soure: https://github.com/miguel5612/MQSensorsLib

*/

#include <MQUnifiedsensor.h>

MQUnifiedsensor MQ7("Arduino UNO", 5, 10, A0, "MQ-7");

void setup() {

  Serial.begin(9600);

  MQ7.setRegressionMethod(1); //_PPM =  a*ratio^b

  MQ7.setA(99.042); MQ7.setB(-1.518); // Configurate the ecuation values to get CO concentration

  MQ7.init(); 

  Serial.print("Calibrating please wait.");

  float calcR0 = 0;

  for(int i = 1; i<=10; i ++)

  {

    MQ7.update(); // Update data, the arduino will be read the voltage on the analog pin

    calcR0 += MQ7.calibrate(27.5);

    Serial.print(".");

  }

  MQ7.setR0(calcR0/10);

  Serial.println("  done!.");

  if(isinf(calcR0)) {Serial.println("Warning: Conection issue founded, R0 is infite (Open circuit detected) please check your wiring and supply"); while(1);}

  if(calcR0 == 0){Serial.println("Warning: Conection issue founded, R0 is zero (Analog pin with short circuit to ground) please check your wiring and supply"); while(1);}

  MQ7.serialDebug(true);

}

void loop() {

  MQ7.update(); // Update data, the arduino will be read the voltage on the analog pin

  float COppm =MQ7.readSensor(); // Sensor will read PPM concentration using the model and a and b values setted before or in the setup

  Serial.print("CO= ");

  Serial.print(COppm);

  Serial.println(" ppm");

  delay(500); //Sampling frequency

}