mirror of
https://github.com/miguel5612/MQSensorsLib.git
synced 2025-03-15 05:17:30 +03:00
104 lines
4.3 KiB
C++
104 lines
4.3 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
|
|
|
|
This example code is in the public domain.
|
|
|
|
*/
|
|
|
|
//Include the library
|
|
#include <MQUnifiedsensor.h>
|
|
|
|
//Definitions
|
|
#define placa "Arduino UNO"
|
|
#define Voltage_Resolution 5
|
|
#define pin A4 //Analog input 4 of your arduino
|
|
#define type "MQ-4" //MQ4
|
|
#define ADC_Bit_Resolution 10 // For arduino UNO/MEGA/NANO
|
|
#define RatioMQ4CleanAir 4.4 //RS / R0 = 4.4 ppm
|
|
//#define calibration_button 13 //Pin to calibrate your sensor
|
|
|
|
//Declare Sensor
|
|
MQUnifiedsensor MQ4(placa, Voltage_Resolution, ADC_Bit_Resolution, pin, type);
|
|
|
|
void setup() {
|
|
//Init the serial port communication - to debug the library
|
|
Serial.begin(9600); //Init serial port
|
|
|
|
|
|
|
|
|
|
/***************************** 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 ********************************************/
|
|
|
|
/*
|
|
//If the RL value is different from 10K please assign your RL value with the following method:
|
|
MQ4.setRL(10);
|
|
*/
|
|
|
|
/***************************** MQ Init ********************************************/
|
|
//Input: setup flag, if this function are on setup will print the headers (Optional - Default value: False)
|
|
//Output: print on serial port the information about sensor and sensor readings
|
|
//Remarks: Configure the pin of arduino as input.
|
|
/************************************************************************************/
|
|
MQ4.init();
|
|
|
|
Serial.println("** Values from MQ-4**********");
|
|
Serial.println("| LPG (Linear EQ) | LPG (Exponential EQ) |");
|
|
}
|
|
|
|
void loop() {
|
|
MQ4.update(); // Update data, the arduino will read the voltage from the analog pin
|
|
|
|
//https://jayconsystems.com/blog/understanding-a-gas-sensor
|
|
//Set math model to calculate the PPM concentration and the value of constants
|
|
MQ4.setRegressionMethod(0); //_PPM = pow(10, (log10(ratio)-b)/a)
|
|
MQ4.setA(-0.318); MQ4.setB(1.133); // A -> Slope, B -> Intersect with X - Axis
|
|
float LPG1 = MQ4.readSensor(); // Sensor will read PPM concentration using the model, a and b values set previously or from the setup
|
|
|
|
//Set math model to calculate the PPM concentration and the value of constants
|
|
MQ4.setRegressionMethod(1); //_PPM = a*ratio^b
|
|
MQ4.setA(1012.7); MQ4.setB(-2.786); // Configure the equation to to calculate CH4 concentration
|
|
float LPG2 = MQ4.readSensor(); // Sensor will read PPM concentration using the model, a and b values set previously or from the setup
|
|
|
|
// exposure to 2000 ppm of LPG gas is immediately dangerous to life and health. In this section
|
|
if(LPG1>=2000 || LPG2>=2000) Serial.println("Warning - Very high concentrations detected!");
|
|
|
|
Serial.print("| "); Serial.print(LPG1);
|
|
Serial.print(" | "); Serial.print(LPG2);
|
|
Serial.println(" |");
|
|
|
|
delay(500); //Sampling frequency
|
|
} |