mirror of
https://github.com/miguel5612/MQSensorsLib.git
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94 lines
3.7 KiB
C++
94 lines
3.7 KiB
C++
/*
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MQUnifiedsensor Library - reading an MQ2
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Demonstrates the use a MQ2 sensor.
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Library originally added 01 may 2019
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by Miguel A Califa, Yersson Carrillo, Ghiordy Contreras, Mario Rodriguez
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Added example
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modified 23 May 2019
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by Miguel Califa
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Updated library usage
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modified 26 March 2020
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by Miguel Califa
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This example code is in the public domain.
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*/
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//Include the library
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#include <MQUnifiedsensor.h>
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//Definitions
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#define placa "Arduino UNO"
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#define Voltage_Resolution 5
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#define pin A0 //Analog input 0 of your arduino
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#define type "MQ-2" //MQ2
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#define ADC_Bit_Resolution 10 // For arduino UNO/MEGA/NANO
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#define RatioMQ2CleanAir 9.83 //RS / R0 = 9.83 ppm
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//Declare Sensor
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MQUnifiedsensor MQ2(placa, Voltage_Resolution, ADC_Bit_Resolution, pin, type);
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void setup() {
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//Init the serial port communication - to debug the library
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Serial.begin(9600); //Init serial port
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//Set math model to calculate the PPM concentration and the value of constants
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MQ2.setRegressionMethod(1); //_PPM = a*ratio^b
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MQ2.setA(574.25); MQ2.setB(-2.222); // Configurate the ecuation values to get LPG concentration
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/*
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Exponential regression:
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Gas | a | b
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H2 | 987.99 | -2.162
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LPG | 574.25 | -2.222
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CO | 36974 | -3.109
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Alcohol| 3616.1 | -2.675
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Propane| 658.71 | -2.168
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*/
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/***************************** MQ CAlibration ********************************************/
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// Explanation:
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// In this routine the sensor will measure the resistance of the sensor supposing before was pre-heated
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// and now is on clean air (Calibration conditions), and it will setup R0 value.
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// We recomend execute this routine only on setup or on the laboratory and save on the eeprom of your arduino
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// This routine not need to execute to every restart, you can load your R0 if you know the value
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// Acknowledgements: https://jayconsystems.com/blog/understanding-a-gas-sensor
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Serial.print("Calibrating please wait.");
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float calcR0 = 0;
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for(int i = 0; i<=10; i ++)
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{
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MQ2.update(); // Update data, the arduino will be read the voltage on the analog pin
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calcR0 += MQ2.calibrate(RatioMQ2CleanAir);
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Serial.print(".");
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}
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MQ2.setR0(calcR0/10);
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Serial.println(" done!.");
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if(isinf(calcR0)) {Serial.println("Warning: Conection issue founded, R0 is infite (Open circuit detected) please check your wiring and supply"); while(1);}
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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);}
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/***************************** MQ CAlibration ********************************************/
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/*
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//If the RL value is different from 10K please assign your RL value with the following method:
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MQ2.setRL(10);
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*/
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/***************************** MQ Init ********************************************/
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//Remarks: Configure the pin of arduino as input.
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/************************************************************************************/
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MQ2.init();
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/***************************** MQ Init ********************************************/
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//Input: setup flag, if this function are on setup will print the headers (Optional - Default value: False)
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//Output: print on serial port the information about sensor and sensor readings
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//Remarks: Configure the pin of arduino as input.
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/************************************************************************************/
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MQ2.serialDebug(true);
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}
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void loop() {
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MQ2.update(); // Update data, the arduino will be read the voltage on the analog pin
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MQ2.readSensor(); // Sensor will read PPM concentration using the model and a and b values setted before or in the setup
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MQ2.serialDebug(); // Will print the table on the serial port
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delay(500); //Sampling frequency
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} |