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https://github.com/miguel5612/MQSensorsLib.git
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121 lines
4.9 KiB
C++
121 lines
4.9 KiB
C++
/*
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MQUnifiedsensor Library - reading an MQ9
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Demonstrates the use a MQ9 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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Wiring:
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https://github.com/miguel5612/MQSensorsLib_Docs/blob/master/static/img/MQ_Arduino.PNG
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Please take care, arduino A0 pin represent the analog input configured on #define pin
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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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/************************Hardware Related Macros************************************/
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#define Board ("Arduino UNO")
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#define Pin (A0) //Analog input 4 of your arduino
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/***********************Software Related Macros************************************/
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#define Type ("MQ-9") //MQ9
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#define Voltage_Resolution (5)
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#define ADC_Bit_Resolution (10) // For arduino UNO/MEGA/NANO
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#define RatioMQ9CleanAir (9.6) //RS / R0 = 60 ppm
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#define PreaheatControlPin5 (3) // Preaheat pin to control with 5 volts
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#define PreaheatControlPin14 (4) // Preaheat pin to control with 1.4 volts
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/*****************************Globals***********************************************/
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//Declare Sensor
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MQUnifiedsensor MQ9(Board, 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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pinMode(PreaheatControlPin5, OUTPUT);
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pinMode(PreaheatControlPin14, OUTPUT);
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//Set math model to calculate the PPM concentration and the value of constants
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MQ9.setRegressionMethod(1); //_PPM = a*ratio^b
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MQ9.setA(1000.5); MQ9.setB(-2.186); // 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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LPG | 1000.5 | -2.186
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CH4 | 4269.6 | -2.648
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CO | 599.65 | -2.244
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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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MQ9.init();
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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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MQ9.setRL(10);
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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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// ISSUE 44 - MQ9 needs a low/high temperature cycle like MQ7 #44
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Serial.println("Preheating, please wait 2.5 minutes");
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digitalWrite(PreaheatControlPin5, HIGH);
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digitalWrite(PreaheatControlPin14, LOW);
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delay(60000);
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digitalWrite(PreaheatControlPin5, LOW);
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digitalWrite(PreaheatControlPin14, HIGH);
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delay(90000);
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digitalWrite(PreaheatControlPin5, HIGH);
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digitalWrite(PreaheatControlPin14, LOW);
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delay(60000);
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digitalWrite(PreaheatControlPin5, LOW);
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digitalWrite(PreaheatControlPin14, HIGH);
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delay(90000);
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digitalWrite(PreaheatControlPin5, HIGH);
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digitalWrite(PreaheatControlPin14, LOW);
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// End pre-heat cycle
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Serial.print("Calibrating please wait.");
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float calcR0 = 0;
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for(int i = 1; i<=10; i ++)
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{
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MQ9.update(); // Update data, the arduino will be read the voltage on the analog pin
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calcR0 += MQ9.calibrate(RatioMQ9CleanAir);
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Serial.print(".");
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}
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MQ9.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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MQ9.serialDebug(true);
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}
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void loop() {
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digitalWrite(PreaheatControlPin5, LOW);
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digitalWrite(PreaheatControlPin14, HIGH);
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delay(90000);
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digitalWrite(PreaheatControlPin5, HIGH);
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digitalWrite(PreaheatControlPin14, LOW);
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MQ9.update(); // Update data, the arduino will be read the voltage on the analog pin
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MQ9.readSensor(); // Sensor will read PPM concentration using the model and a and b values setted before or in the setup
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MQ9.serialDebug(); // Will print the table on the serial port
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delay(500); //Sampling frequency
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} |