Fixed MQ-131 Issue

.github/pull_request_template.md

@@ -0,0 +1,49 @@
+# Description
+
+Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. List any dependencies that are required for this change.
+
+Fixes # (issue)
+
+## Type of change
+
+Please delete options that are not relevant.
+
+- [ ] Bug fix (non-breaking change which fixes an issue)
+- [ ] New feature (non-breaking change which adds functionality)
+- [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
+- [ ] This change requires a documentation update
+
+# How Has This Been Tested?
+
+Please describe the examples that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration
+
+- [ ] MQ-3
+- [ ] MQ-4
+- [ ] MQ-5
+- [ ] MQ-6
+- [ ] MQ-7
+- [ ] MQ-8
+- [ ] MQ-9
+- [ ] MQ-131
+- [ ] MQ-135
+- [ ] MQ-303
+- [ ] MQ-309
+- [ ] ESP8266
+- [ ] ESP-32
+
+**Test Configuration**:
+* Board:
+* Software (Version of your arduino):
+* Result (Good - Medium - Bad):
+* Your Comments:
+
+# Checklist:
+
+- [ ] My code follows the style guidelines of this project
+- [ ] I have performed a self-review of my own code
+- [ ] I have commented my code, particularly in hard-to-understand areas
+- [ ] I have made corresponding changes to the documentation
+- [ ] My changes generate no new warnings
+- [ ] I have added tests that prove my fix is effective or that my feature works
+- [ ] New and existing unit tests pass locally with my changes
+- [ ] Any dependent changes have been merged and published in downstream modules

README.md

@@ -17,7 +17,7 @@
 
 # MQSensorsLib
 
-This is a unified library to use sensors MQ: 2, 3, 4, 5, 6, 7, 8, 9, 131, 135, 303A and 309A.
+We present a unified library for MQ sensors, this library allows to read MQ signals easily from Arduino, Genuino, ESP8266, ESP-32 boards whose references are MQ2, MQ3, MQ4, MQ5, MQ6, MQ7, MQ8, MQ9, MQ131, MQ135, MQ303A, MQ309A.
 
 <!-- TABLE OF CONTENTS -->
 ## Table of Contents
@@ -26,8 +26,8 @@ This is a unified library to use sensors MQ: 2, 3, 4, 5, 6, 7, 8, 9, 131, 135, 3
 * [Wiring](#Wiring)
   * [Sensor](#Sensor)
   * [Arduino](#Arduino)
-  * [ESP8266](#ESP8266)
+  * [ESP8266 or ESP-32](#ESP8266-ESP32)
-* [User Manual](#usage)
+* [User Manual](#Manuals)
 * [Sensor manufacturers](#Sensor-manufacturers)
 * [Contributing](#Contributing)
 * [Authors](#Authors)
@@ -75,13 +75,16 @@ float ppmCH4 = MQ4.readSensor();
 ![Graph from datasheet](https://raw.githubusercontent.com/miguel5612/MQSensorsLib_Docs/master/static/img/Graph_Explanation.jpeg)
 ### Arduino
 ![Arduino_Wiring_MQSensor](https://raw.githubusercontent.com/miguel5612/MQSensorsLib_Docs/master/static/img/MQ_Arduino.PNG)
-
+#### MQ-7 / MQ-309A
-### ESP8266
+** Note ** [issue](https://github.com/miguel5612/MQSensorsLib/issues/26): MQ-7 and MQ-309 needs two different voltages for heater, they can be supplied by PWM and DC Signal controlled by your controller, another option is to use two different power sources, you should use the best option for you, next i will show the PWM option and on the examples this will be the way .
+![MQ-7_MQ-309](https://raw.githubusercontent.com/miguel5612/MQSensorsLib_Docs/master/static/img/MQ-309_MQ-7.PNG)
+### ESP8266-ESP32
 ![ESP8266_Wiring_MQSensor](https://raw.githubusercontent.com/miguel5612/MQSensorsLib_Docs/master/static/img/MQ_ESP8266.PNG)
 
-### User Manual (v1.0) 12.2019
+### Manuals
+#### User Manual (v1.0) 12.2019
 [Manual](https://drive.google.com/open?id=1BAFInlvqKR7h81zETtjz4_RC2EssvFWX)
-### User Manual (v2.0) 04.2020
+#### User Manual (v2.0) 04.2020
 [Manual](https://github.com/miguel5612/MQSensorsLib_Docs/blob/master/Docs/MQSensorLib_2.0.pdf)
 
 

examples/MQ-131/MQ-131.ino

@@ -17,6 +17,8 @@
   https://github.com/miguel5612/MQSensorsLib_Docs/blob/master/static/img/MQ_Arduino.PNG
   Please take care, arduino A0 pin represent the analog input configured on #define pin
 
+  Note: high concentration MQ-131 sensor.
+
  This example code is in the public domain.
 
 */
@@ -83,11 +85,12 @@ void setup() {
   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 ********************************************/ 
   MQ131.serialDebug(true);
+  Serial.println("Ignore Ratio = RS/R0, for this example we will use readSensorR0Rs, the ratio calculated will be R0/Rs. Thanks :)");
 }
 
 void loop() {
   MQ131.update(); // Update data, the arduino will be read the voltage on the analog pin
-  MQ131.readSensor(); // Sensor will read PPM concentration using the model and a and b values setted before or in the setup
+  MQ131.readSensorR0Rs(); // Sensor will read PPM concentration using the model and a and b values setted before or in the setup
   MQ131.serialDebug(); // Will print the table on the serial port
   delay(500); //Sampling frequency
 }

examples/MQ-309A/MQ-309.ino

@@ -31,14 +31,16 @@
 #define type "MQ-309" //MQ309
 #define ADC_Bit_Resolution 10 // For arduino UNO/MEGA/NANO
 #define RatioMQ309CleanAir 11 //RS / R0 = 11 ppm 
-//#define calibration_button 13 //Pin to calibrate your sensor
+#define PWMPin 5 // Pin connected to mosfet
 
 //Declare Sensor
 MQUnifiedsensor MQ309(placa, Voltage_Resolution, ADC_Bit_Resolution, pin, type);
+unsigned long oldTime = 0;
 
 void setup() {
   //Init the serial port communication - to debug the library
   Serial.begin(9600); //Init serial port
+  pinMode(PWMPin, OUTPUT);
 
   //Set math model to calculate the PPM concentration and the value of constants
   MQ309.setRegressionMethod(1); //_PPM =  a*ratio^b
@@ -86,8 +88,28 @@ void setup() {
 }
 
 void loop() {
+  // 60s cycle
+  oldTime = millis();
+  while(millis() - oldTime <= (30*1000))
+  {
+    // VH 0.9 Volts
+    analogWrite(5, 2); // 255 is 100%, 2.295 is aprox 0.9% of Duty cycle for 60s
     MQ309.update(); // Update data, the arduino will be read the voltage on the analog pin
     MQ309.readSensor(); // Sensor will read PPM concentration using the model and a and b values setted before or in the setup
     MQ309.serialDebug(); // Will print the table on the serial port
     delay(500); //Sampling frequency
   }
+
+  // 90s cycle
+  oldTime = millis();
+  while(millis() - oldTime <= (120*1000))
+  {
+    // VL 0.2 Volts
+    analogWrite(5, 1); // 255 is 100%, 0.51 is aprox 0.2% of Duty cycle for 120s
+    MQ309.update(); // Update data, the arduino will be read the voltage on the analog pin
+    MQ309.readSensor(); // Sensor will read PPM concentration using the model and a and b values setted before or in the setup
+    MQ309.serialDebug(); // Will print the table on the serial port
+    delay(500); //Sampling frequency
+  } 
+  // Total: 30 + 120s =  2.5 minutes.
+}

examples/MQ-7/MQ-7.ino

@@ -13,6 +13,10 @@
   modified 26 March 2020
   by Miguel Califa 
 
+  Updated example of MQ-7 AND MQ-309A
+  modified 20 April 2020
+  by Miguel Califa
+
   Wiring:
   https://github.com/miguel5612/MQSensorsLib_Docs/blob/master/static/img/MQ_Arduino.PNG
   Please take care, arduino A0 pin represent the analog input configured on #define pin
@@ -31,14 +35,16 @@
 #define type "MQ-7" //MQ7
 #define ADC_Bit_Resolution 10 // For arduino UNO/MEGA/NANO
 #define RatioMQ7CleanAir 27.5 //RS / R0 = 27.5 ppm 
-//#define calibration_button 13 //Pin to calibrate your sensor
+#define PWMPin 5 // Pin connected to mosfet
 
 //Declare Sensor
 MQUnifiedsensor MQ7(placa, Voltage_Resolution, ADC_Bit_Resolution, pin, type);
+unsigned long oldTime = 0;
 
 void setup() {
   //Init the serial port communication - to debug the library
   Serial.begin(9600); //Init serial port
+  pinMode(PWMPin, OUTPUT);
 
   //Set math model to calculate the PPM concentration and the value of constants
   MQ7.setRegressionMethod(1); //_PPM =  a*ratio^b
@@ -87,8 +93,28 @@ void setup() {
 }
 
 void loop() {
+  // 60s cycle
+  oldTime = millis();
+  while(millis() - oldTime <= (60*1000))
+  {
+    // VH 5 Volts
+    analogWrite(5, 255); // 255 is DC 5V output
     MQ7.update(); // Update data, the arduino will be read the voltage on the analog pin
     MQ7.readSensor(); // Sensor will read PPM concentration using the model and a and b values setted before or in the setup
     MQ7.serialDebug(); // Will print the table on the serial port
     delay(500); //Sampling frequency
   }
+
+  // 90s cycle
+  oldTime = millis();
+  while(millis() - oldTime <= (90*1000))
+  {
+    // VH 1.4 Volts
+    analogWrite(5, 20); // 255 is 100%, 20.4 is aprox 8% of Duty cycle for 90s
+    MQ7.update(); // Update data, the arduino will be read the voltage on the analog pin
+    MQ7.readSensor(); // Sensor will read PPM concentration using the model and a and b values setted before or in the setup
+    MQ7.serialDebug(); // Will print the table on the serial port
+    delay(500); //Sampling frequency
+  } 
+  // Total: 60 + 90s =  2.5 minutes.
+}

examples/MQ-Board/MQ-Board.ino

@@ -29,6 +29,7 @@
 #define         Pin7                     (A7)  //Analog input 7 of your arduino
 #define         Pin8                     (A8)  //Analog input 8 of your arduino
 #define         Pin9                     (A9)  //Analog input 9 of your arduino
+#define         PWMPin                   (5)   // Pin connected to mosfet
 /***********************Software Related Macros************************************/
 #define         RatioMQ2CleanAir          (9.83) //RS / R0 = 9.83 ppm 
 #define         RatioMQ3CleanAir          (60) //RS / R0 = 60 ppm 
@@ -52,6 +53,8 @@ MQUnifiedsensor MQ7(Board, Voltage_Resolution, ADC_Bit_Resolution, Pin7, Type);
 MQUnifiedsensor MQ8(Board, Voltage_Resolution, ADC_Bit_Resolution, Pin8, Type);
 MQUnifiedsensor MQ9(Board, Voltage_Resolution, ADC_Bit_Resolution, Pin9, Type);
 
+unsigned long oldTime = 0;
+
 void setup() {
   //Init serial port
   Serial.begin(9600);
@@ -168,6 +171,27 @@ void setup() {
 }
 
 void loop() {
+  oldTime = millis();
+  while(millis() - oldTime <= (60*1000))
+  { 
+    // VH 5 Volts
+    analogWrite(5, 255); // 255 is DC 5V output
+    readAllSensors();
+    delay(500);
+  }
+  // 90s cycle
+  oldTime = millis();
+  while(millis() - oldTime <= (90*1000))
+  {
+    // VH 1.4 Volts
+    analogWrite(5, 20); // 255 is 100%, 20.4 is aprox 8% of Duty cycle for 90s
+    readAllSensors();
+    delay(500);
+  }
+}
+
+void readAllSensors()
+{
   //Update the voltage lectures
   MQ2.update();
   MQ3.update();

src/MQUnifiedsensor.cpp

@@ -143,6 +143,24 @@ float MQUnifiedsensor::readSensor()
   //if(_PPM > 10000) _PPM = 99999999; //No negative values accepted or upper datasheet recomendation.
   return _PPM;
 }
+float MQUnifiedsensor::readSensorR0Rs()
+{
+  //More explained in: https://jayconsystems.com/blog/understanding-a-gas-sensor
+  _RS_Calc = ((_VOLT_RESOLUTION*_RL)/_sensor_volt)-_RL; //Get value of RS in a gas
+  if(_RS_Calc < 0)  _RS_Calc = 0; //No negative values accepted.
+  _ratio = this->_R0/_RS_Calc;   // Get ratio RS_air/RS_gas <- INVERTED for MQ-131 issue 28 https://github.com/miguel5612/MQSensorsLib/issues/28
+  if(_ratio <= 0)  _ratio = 0; //No negative values accepted or upper datasheet recomendation.
+  if(_regressionMethod == 1) _PPM= _a*pow(_ratio, _b); // <- Source excel analisis https://github.com/miguel5612/MQSensorsLib_Docs/tree/master/Internal_design_documents
+  else 
+  {
+    // https://jayconsystems.com/blog/understanding-a-gas-sensor <- Source of linear ecuation
+    double ppm_log = (log10(_ratio)-_b)/_a; //Get ppm value in linear scale according to the the ratio value  
+    _PPM = pow(10, ppm_log); //Convert ppm value to log scale  
+  }
+  if(_PPM < 0)  _PPM = 0; //No negative values accepted or upper datasheet recomendation.
+  //if(_PPM > 10000) _PPM = 99999999; //No negative values accepted or upper datasheet recomendation.
+  return _PPM;
+}
 float MQUnifiedsensor::calibrate(float ratioInCleanAir) {
   //More explained in: https://jayconsystems.com/blog/understanding-a-gas-sensor
   /*

src/MQUnifiedsensor.h

@@ -30,6 +30,7 @@ class MQUnifiedsensor
     //user functions
     float calibrate(float ratioInCleanAir);
     float readSensor();
+    float readSensorR0Rs();
     float validateEcuation(float ratioInput = 0);
     
     //get function for info