#include <MQUnifiedsensor.h>


#define Board "ESP32"
#define Voltage_Resolution 5
#define pin A0 //Analog input 0 of your esp
#define type "MQ-7" //MQ7
#define ADC_Bit_Resolution 12 // esp
#define RatioMQ7CleanAir 27.5 //RS / R0 = 27.5 ppm 

//Declare Sensor
MQUnifiedsensor MQ7(Board, Voltage_Resolution, ADC_Bit_Resolution, pin, type);


void setup() {

  Serial.begin(9600); 

  
  MQ7.setRegressionMethod(1); //_PPM =  a*ratio^b
  MQ7.setA(99.042); MQ7.setB(-1.518); // Configure the equation to calculate CO concentration value

  /*
    Exponential regression:
  GAS     | a      | b
  H2      | 69.014  | -1.374
  LPG     | 700000000 | -7.703
  CH4     | 60000000000000 | -10.54
  CO      | 99.042 | -1.518
  Alcohol | 40000000000000000 | -12.35
  */
  
  MQ7.init(); 
  
  Serial.print("Calibrating please wait.");
  float calcR0 = 0;
  for(int i = 1; i<=10; i ++)
  {
    MQ7.update(); // Update data,read the voltage from the analog pin
    calcR0 += MQ7.calibrate(RatioMQ7CleanAir);
    Serial.print(".");
  }
  MQ7.setR0(calcR0/10);
  Serial.println("  done!.");
  MQ7.serialDebug(true);
}

void loop() {
    MQ7.update();
    int adc = analogRead(pin);
    float ppm = MQ7.readSensor(); // Sensor will read PPM concentration using the model, a and b values set previously or from the setup
    Serial.print("ADC: ");
    Serial.print(adc);
    Serial.print("\t");
    
    Serial.print("  CO (ppm): ");
    Serial.println(ppm);

    delay(500); 
  }