Added examples for MQ138

examples/easyC/MQ-138-ALL-easyC/MQ-138-ALL-easyC.ino

@@ -0,0 +1,128 @@
+/*
+ MQUnifiedsensor Library - reading an mq138
+
+ Demonstrates the use a mq138 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
+
+ Example is modified by Soldered.com
+
+ 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 "MQ-Sensor-SOLDERED.h"
+
+// Predefined microcontroller pins for AO sensor pin (microcontroller dependent)
+// You can change the pin to suit your setup.
+#if defined(__AVR__) || defined(STM32)
+#define SENSOR_ANALOG_PIN A1
+#elif defined(ESP32)
+#define SENSOR_ANALOG_PIN 34
+#else
+#define SENSOR_ANALOG_PIN 5
+#endif
+
+#define Ratiomq138CleanAir 3.6 // RS / R0 = 3.6 ppm
+
+// Create library object for this specific sensor.
+MQ138 mq138(SENSOR_ANALOG_PIN);
+
+void setup()
+{
+ // Init the serial port communication at 115200 bauds. It's used to print out measured data.
+ Serial.begin(115200);
+
+ // Set math model to calculate the PPM concentration and the value of constants
+ mq138.setRegressionMethod(1); //_PPM = a*ratio^b
+
+ /***************************** MQ Init ********************************************/
+ // Remarks: Configure the pin of arduino as input.
+ /************************************************************************************/
+ mq138.begin(0x30); // If you have easyC version of this sensor
+ // you should add here I2C address of sensor
+ // which is 0x30 by default and can be changed
+ // by onboard switches labeled with ADDR
+ /*
+ //If the RL value is different from 10K please assign your RL value with the following method:
+ mq138.setRL(10);
+ */
+ /***************************** MQ CAlibration ********************************************/
+ // Explanation:
+ // In this routine the sensor will measure the resistance of the sensor supposing before was pre-heated
+ // and now is on clean air (Calibration conditions), and it will setup R0 value.
+ // We recomend execute this routine only on setup or on the laboratory and save on the eeprom of your arduino
+ // This routine not need to execute to every restart, you can load your R0 if you know the value
+ // Acknowledgements: https://jayconsystems.com/blog/understanding-a-gas-sensor
+ Serial.print("Calibrating please wait.");
+ float calcR0 = 0;
+ for (int i = 1; i <= 10; i++)
+ {
+ mq138.update(); // Update data, the arduino will be read the voltage on the analog pin
+ calcR0 += mq138.calibrate(Ratiomq138CleanAir);
+ Serial.print(".");
+ }
+ mq138.setR0(calcR0 / 10);
+ Serial.println(" done!.");
+
+ if (isinf(calcR0))
+ {
+ Serial.println("Warning: Conection issue founded, R0 is infite (Open circuit detected) please check your "
+ "wiring and supply");
+ while (1)
+ ;
+ }
+ 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)
+ ;
+ }
+ /***************************** MQ CAlibration ********************************************/
+ Serial.println("** Readings from MQ-138 ****");
+ Serial.println("| H2S | Ethanol | Toulene |");
+}
+
+void loop()
+{
+ mq138.update(); // Update data, the arduino will be read the voltage on the analog pin
+
+ mq138.setA(9.4784);
+ mq138.setB(-2.334); // Configurate the ecuation values to get H2S concentration
+ float H2S = mq138.readSensor(); // Sensor will read PPM concentration using the model and a and b values setted
+ // before or in the setup
+
+ mq138.setA(33.119);
+ mq138.setB(-2.847); // Configurate the ecuation values to get Ethanol concentration
+ float Ethanol = mq138.readSensor(); // Sensor will read PPM concentration using the model and a and b values setted
+ // before or in the setup
+
+ mq138.setA(168.48);
+ mq138.setB(-3.116); // Configurate the ecuation values to get Toulene concentration
+ float Toulene = mq138.readSensor(); // Sensor will read PPM concentration using the model and a and b values setted
+ // before or in the setup
+
+ Serial.print("| ");
+ Serial.print(H2S);
+ Serial.print(" | ");
+ Serial.print(Ethanol);
+ Serial.print(" | ");
+ Serial.print(Toulene);
+ Serial.println(" | ");
+
+ delay(500); // Sampling frequency
+}

examples/native/MQ-138-ALL/MQ-138-ALL.ino

@@ -0,0 +1,128 @@
+/*
+ MQUnifiedsensor Library - reading an mq138
+
+ Demonstrates the use a mq138 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
+
+ Example is modified by Soldered.com
+
+ 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 "MQ-Sensor-SOLDERED.h"
+
+// Predefined microcontroller pins for AO sensor pin (microcontroller dependent)
+// You can change the pin to suit your setup.
+#if defined(__AVR__) || defined(STM32)
+#define SENSOR_ANALOG_PIN A1
+#elif defined(ESP32)
+#define SENSOR_ANALOG_PIN 34
+#else
+#define SENSOR_ANALOG_PIN 5
+#endif
+
+#define Ratiomq138CleanAir 3.6 // RS / R0 = 3.6 ppm
+
+// Create library object for this specific sensor.
+MQ138 mq138(SENSOR_ANALOG_PIN);
+
+void setup()
+{
+ // Init the serial port communication at 115200 bauds. It's used to print out measured data.
+ Serial.begin(115200);
+
+ // Set math model to calculate the PPM concentration and the value of constants
+ mq138.setRegressionMethod(1); //_PPM = a*ratio^b
+
+ /***************************** MQ Init ********************************************/
+ // Remarks: Configure the pin of arduino as input.
+ /************************************************************************************/
+ mq138.begin(); // If you have easyC version of this sensor
+ // you should add here I2C address of sensor
+ // which is 0x30 by default and can be changed
+ // by onboard switches labeled with ADDR
+ /*
+ //If the RL value is different from 10K please assign your RL value with the following method:
+ mq138.setRL(10);
+ */
+ /***************************** MQ CAlibration ********************************************/
+ // Explanation:
+ // In this routine the sensor will measure the resistance of the sensor supposing before was pre-heated
+ // and now is on clean air (Calibration conditions), and it will setup R0 value.
+ // We recomend execute this routine only on setup or on the laboratory and save on the eeprom of your arduino
+ // This routine not need to execute to every restart, you can load your R0 if you know the value
+ // Acknowledgements: https://jayconsystems.com/blog/understanding-a-gas-sensor
+ Serial.print("Calibrating please wait.");
+ float calcR0 = 0;
+ for (int i = 1; i <= 10; i++)
+ {
+ mq138.update(); // Update data, the arduino will be read the voltage on the analog pin
+ calcR0 += mq138.calibrate(Ratiomq138CleanAir);
+ Serial.print(".");
+ }
+ mq138.setR0(calcR0 / 10);
+ Serial.println(" done!.");
+
+ if (isinf(calcR0))
+ {
+ Serial.println("Warning: Conection issue founded, R0 is infite (Open circuit detected) please check your "
+ "wiring and supply");
+ while (1)
+ ;
+ }
+ 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)
+ ;
+ }
+ /***************************** MQ CAlibration ********************************************/
+ Serial.println("** Readings from MQ-138 ****");
+ Serial.println("| H2S | Ethanol | Toulene |");
+}
+
+void loop()
+{
+ mq138.update(); // Update data, the arduino will be read the voltage on the analog pin
+
+ mq138.setA(9.4784);
+ mq138.setB(-2.334); // Configurate the ecuation values to get H2S concentration
+ float H2S = mq138.readSensor(); // Sensor will read PPM concentration using the model and a and b values setted
+ // before or in the setup
+
+ mq138.setA(33.119);
+ mq138.setB(-2.847); // Configurate the ecuation values to get Ethanol concentration
+ float Ethanol = mq138.readSensor(); // Sensor will read PPM concentration using the model and a and b values setted
+ // before or in the setup
+
+ mq138.setA(168.48);
+ mq138.setB(-3.116); // Configurate the ecuation values to get Toulene concentration
+ float Toulene = mq138.readSensor(); // Sensor will read PPM concentration using the model and a and b values setted
+ // before or in the setup
+
+ Serial.print("| ");
+ Serial.print(H2S);
+ Serial.print(" | ");
+ Serial.print(Ethanol);
+ Serial.print(" | ");
+ Serial.print(Toulene);
+ Serial.println(" | ");
+
+ delay(500); // Sampling frequency
+}