mirror of
https://github.com/miguel5612/MQSensorsLib.git
synced 2025-03-15 05:17:30 +03:00
121 lines
4.8 KiB
C++
121 lines
4.8 KiB
C++
/*
|
|
MQUnifiedsensor Library - reading an MQ9
|
|
|
|
Demonstrates the use a MQ9 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 (A0) //Analog input 4 of your arduino
|
|
/***********************Software Related Macros************************************/
|
|
#define Type ("MQ-9") //MQ9
|
|
#define Voltage_Resolution (5)
|
|
#define ADC_Bit_Resolution (10) // For arduino UNO/MEGA/NANO
|
|
#define RatioMQ9CleanAir (9.6) //RS / R0 = 60 ppm
|
|
#define PreaheatControlPin5 (3) // Preaheat pin to control with 5 volts
|
|
#define PreaheatControlPin14 (4) // Preaheat pin to control with 1.4 volts
|
|
/*****************************Globals***********************************************/
|
|
//Declare Sensor
|
|
MQUnifiedsensor MQ9(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
|
|
pinMode(PreaheatControlPin5, OUTPUT);
|
|
pinMode(PreaheatControlPin14, OUTPUT);
|
|
|
|
//Set math model to calculate the PPM concentration and the value of constants
|
|
MQ9.setRegressionMethod(1); //_PPM = a*ratio^b
|
|
MQ9.setA(1000.5); MQ9.setB(-2.186); // Configure the equation to to calculate LPG concentration
|
|
|
|
/*
|
|
Exponential regression:
|
|
GAS | a | b
|
|
LPG | 1000.5 | -2.186
|
|
CH4 | 4269.6 | -2.648
|
|
CO | 599.65 | -2.244
|
|
*/
|
|
|
|
/***************************** MQ Init ********************************************/
|
|
//Remarks: Configure the pin of arduino as input.
|
|
/************************************************************************************/
|
|
MQ9.init();
|
|
/*
|
|
//If the RL value is different from 10K please assign your RL value with the following method:
|
|
MQ9.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
|
|
// ISSUE 44 - MQ9 needs a low/high temperature cycle like MQ7 #44
|
|
|
|
Serial.println("Preheating, please wait 2.5 minutes");
|
|
digitalWrite(PreaheatControlPin5, HIGH);
|
|
digitalWrite(PreaheatControlPin14, LOW);
|
|
delay(60000);
|
|
digitalWrite(PreaheatControlPin5, LOW);
|
|
digitalWrite(PreaheatControlPin14, HIGH);
|
|
delay(90000);
|
|
digitalWrite(PreaheatControlPin5, HIGH);
|
|
digitalWrite(PreaheatControlPin14, LOW);
|
|
delay(60000);
|
|
digitalWrite(PreaheatControlPin5, LOW);
|
|
digitalWrite(PreaheatControlPin14, HIGH);
|
|
delay(90000);
|
|
digitalWrite(PreaheatControlPin5, HIGH);
|
|
digitalWrite(PreaheatControlPin14, LOW);
|
|
|
|
// End pre-heat cycle
|
|
|
|
Serial.print("Calibrating please wait.");
|
|
float calcR0 = 0;
|
|
for(int i = 1; i<=10; i ++)
|
|
{
|
|
MQ9.update(); // Update data, the arduino will read the voltage from the analog pin
|
|
calcR0 += MQ9.calibrate(RatioMQ9CleanAir);
|
|
Serial.print(".");
|
|
}
|
|
MQ9.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 ********************************************/
|
|
MQ9.serialDebug(true);
|
|
}
|
|
|
|
void loop() {
|
|
digitalWrite(PreaheatControlPin5, LOW);
|
|
digitalWrite(PreaheatControlPin14, HIGH);
|
|
delay(90000);
|
|
digitalWrite(PreaheatControlPin5, HIGH);
|
|
digitalWrite(PreaheatControlPin14, LOW);
|
|
|
|
MQ9.update(); // Update data, the arduino will read the voltage from the analog pin
|
|
MQ9.readSensor(); // Sensor will read PPM concentration using the model, a and b values set previously or from the setup
|
|
MQ9.serialDebug(); // Will print the table on the serial port
|
|
|
|
} |