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

93 lines
4.4 KiB
C++

// This is an example of implementation using ESP8266
// Never connect the sensor direct to the ESP8266, sensor high level is 5V
// ADC of ESP8266 high level is 3.3
// To connect use a voltage divisor, where 5V will 3v3 on the middle point like
// this {{URL}}
/*
MQUnifiedsensor Library - reading an MQSensor using ESP8266 board
For this example wi will demonstrates the use a MQ3 sensor.
Library originally added 01 may 2019
by Miguel A Califa, Yersson Carrillo, Ghiordy Contreras, Mario Rodriguez
Added ESP8266 example
29.03.2020
Wiring:
https://github.com/miguel5612/MQSensorsLib_Docs/blob/master/static/img/MQ_ESP8266.PNG
This example code is in the public domain.
*/
//Include the library
#include <MQUnifiedsensor.h>
/************************Hardware Related Macros************************************/
#define Board ("ESP-32") // Wemos ESP-32 or other board, whatever have ESP32 core.
#define Pin (25) //IO25 for your ESP32 WeMos Board, pinout here: https://i.pinimg.com/originals/66/9a/61/669a618d9435c702f4b67e12c40a11b8.jpg
/***********************Software Related Macros************************************/
#define Type ("MQ-3") //MQ3 or other MQ Sensor, if change this verify your a and b values.
#define Voltage_Resolution (3.3) // 3V3 <- IMPORTANT. Source: https://randomnerdtutorials.com/esp32-adc-analog-read-arduino-ide/
#define ADC_Bit_Resolution (12) // ESP-32 bit resolution. Source: https://randomnerdtutorials.com/esp32-adc-analog-read-arduino-ide/
#define RatioMQ3CleanAir (60) // Ratio of your sensor, for this example an MQ-3
/*****************************Globals***********************************************/
MQUnifiedsensor MQ3(Board, Voltage_Resolution, ADC_Bit_Resolution, Pin, Type);
/*****************************Globals***********************************************/
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
MQ3.setRegressionMethod(1); //_PPM = a*ratio^b
MQ3.setA(4.8387); MQ3.setB(-2.68); // Configure the equation to to calculate Benzene concentration
/*
Exponential regression:
Gas | a | b
LPG | 44771 | -3.245
CH4 | 2*10^31| 19.01
CO | 521853 | -3.821
Alcohol| 0.3934 | -1.504
Benzene| 4.8387 | -2.68
Hexane | 7585.3 | -2.849
*/
/***************************** MQ Init ********************************************/
//Remarks: Configure the pin of arduino as input.
/************************************************************************************/
MQ3.init();
/*
//If the RL value is different from 10K please assign your RL value with the following method:
MQ3.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 ++)
{
MQ3.update(); // Update data, the arduino will read the voltage from the analog pin
calcR0 += MQ3.calibrate(RatioMQ3CleanAir);
Serial.print(".");
}
MQ3.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 ********************************************/
MQ3.serialDebug(true);
}
void loop() {
MQ3.update(); // Update data, the arduino will read the voltage from the analog pin
MQ3.readSensor(); // Sensor will read PPM concentration using the model, a and b values set previously or from the setup
MQ3.serialDebug(); // Will print the table on the serial port
delay(500); //Sampling frequency
}