2022-03-20 12:53:36 -05:00

115 lines
5.1 KiB
C++

/*
MQUnifiedsensor Library - reading an MQ4
Demonstrates the use a MQ4 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 make sure arduino A0 pin represents the analog input configured on #define pin
This example code is in the public domain.
*/
//Include the library
#include <MQUnifiedsensor.h>
/************************Hardware Related Macros************************************/
#define Board ("Arduino UNO")
#define Pin (A4) //Analog input 4 of your arduino
/***********************Software Related Macros************************************/
#define Type ("MQ-4") //MQ4
#define Voltage_Resolution (5)
#define ADC_Bit_Resolution (10) // For arduino UNO/MEGA/NANO
#define RatioMQ4CleanAir (4.4) //RS / R0 = 60 ppm
/*****************************Globals***********************************************/
//Declare Sensor
MQUnifiedsensor MQ4(Board, Voltage_Resolution, ADC_Bit_Resolution, Pin, Type);
void setup() {
//Init the serial port communication - to debug the library
Serial.begin(9600); //Init serial port
//Set math model to calculate the PPM concentration and the value of constants
MQ4.setRegressionMethod(1); //_PPM = a*ratio^b
/***************************** MQ Init ********************************************/
//Remarks: Configure the pin of arduino as input.
/************************************************************************************/
MQ4.init();
/*
//If the RL value is different from 10K please assign your RL value with the following method:
MQ4.setRL(10);
*/
/***************************** MQ CAlibration ********************************************/
// Explanation:
// In this routine the sensor will measure the resistance of the sensor supposedly before being pre-heated
// and on clean air (Calibration conditions), setting up R0 value.
// We recomend executing this routine only on setup in laboratory conditions.
// This routine does not need to be executed on each restart, you can load your R0 value from eeprom.
// Acknowledgements: https://jayconsystems.com/blog/understanding-a-gas-sensor
Serial.print("Calibrating please wait.");
float calcR0 = 0;
for(int i = 1; i<=10; i ++)
{
MQ4.update(); // Update data, the arduino will read the voltage from the analog pin
calcR0 += MQ4.calibrate(RatioMQ4CleanAir);
Serial.print(".");
}
MQ4.setR0(calcR0/10);
Serial.println(" done!.");
if(isinf(calcR0)) {Serial.println("Warning: Conection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
if(calcR0 == 0){Serial.println("Warning: Conection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
/***************************** MQ CAlibration ********************************************/
Serial.println("*************** Values from MQ-4 **********************");
Serial.println("| LPG | CH4 | CO | Alcohol | Smoke |");
}
void loop() {
MQ4.update(); // Update data, the arduino will read the voltage from the analog pin
/*
Exponential regression:
Gas | a | b
LPG | 3811.9 | -3.113
CH4 | 1012.7 | -2.786
CO | 200000000000000 | -19.05
Alcohol| 60000000000 | -14.01
smoke | 30000000 | -8.308
*/
MQ4.setA(3811.9); MQ4.setB(-3.113); // Configure the equation to to calculate CH4 concentration
float LPG = MQ4.readSensor(); // Sensor will read PPM concentration using the model, a and b values set previously or from the setup
MQ4.setA(1012.7); MQ4.setB(-2.786); // Configure the equation to to calculate CH4 concentration
float CH4 = MQ4.readSensor(); // Sensor will read PPM concentration using the model, a and b values set previously or from the setup
MQ4.setA(200000000000000); MQ4.setB(-19.05); // Configure the equation to to calculate CH4 concentration
float CO = MQ4.readSensor(); // Sensor will read PPM concentration using the model, a and b values set previously or from the setup
MQ4.setA(60000000000); MQ4.setB(-14.01); // Configure the equation to to calculate CH4 concentration
float Alcohol = MQ4.readSensor(); // Sensor will read PPM concentration using the model, a and b values set previously or from the setup
MQ4.setA(30000000); MQ4.setB(-8.308); // Configure the equation to to calculate CH4 concentration
float Smoke = MQ4.readSensor(); // Sensor will read PPM concentration using the model, a and b values set previously or from the setup
Serial.print("| "); Serial.print(LPG);
Serial.print(" | "); Serial.print(CH4);
Serial.print(" | "); Serial.print(CO);
Serial.print(" | "); Serial.print(Alcohol);
Serial.print(" | "); Serial.print(Smoke);
Serial.println(" |");
delay(500); //Sampling frequency
}