Correct typos in source and example files

Allow setting the ADC pin of a MQUnifiedsensor object.

.github/pull_request_template.md

@@ -12,6 +12,8 @@ Please delete options that are not relevant.
 - [ ] 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
+- [ ] I have updated the version in `library.properties` to reflect my changes (advance by 0.01 for minor changes, or a whole number for new features)
+- [ ] I have submitted the pull request
 
 # How Has This Been Tested?
 

CONTRIBUTING.md

@@ -20,3 +20,7 @@ Pull request will be check by three main authors who are linked in
 [REAMDE.md](https://github.com/miguel5612/MQSensorsLib/README.md) and they determine to merge to
 master branch. Later than assessment and debbuging procedures was completed, the contribution 
 will be released.
+
+## Versioning
+
+When making a pull request, please remember to update the `library.properties` file to reflect the changes you've made. If your change is minor, consider advancing the version by 0.01. If you're adding a new feature, you may want to advance the version by a whole number.

README.md

@@ -121,15 +121,15 @@ You'll need Arduino desktop app 1.8.9 or later.
 ### Sensor manufacturers:
 | Sensor | Manufacture | URL Datasheet |
 |----------|----------|----------|
-| MQ-2 | Pololulu| [datasheet](https://www.pololu.com/file/0J309/MQ2.pdf) |
-| MQ-3 | Sparkfun | [datasheet](https://www.sparkfun.com/datasheets/Sensors/MQ-3.pdf) |
-| MQ-4 | Sparkfun | [datasheet](https://www.sparkfun.com/datasheets/Sensors/Biometric/MQ-4.pdf) |
-| MQ-5 | parallax | [datasheet](https://www.parallax.com/sites/default/files/downloads/605-00009-MQ-5-Datasheet.pdf) |
-| MQ-6 | Sparkfun | [datasheet](https://www.sparkfun.com/datasheets/Sensors/Biometric/MQ-6.pdf) |
-| MQ-7 | Sparkfun | [datasheet](https://www.sparkfun.com/datasheets/Sensors/Biometric/MQ-7.pdf) |
-| MQ-8 | Sparkfun | [datasheet](https://dlnmh9ip6v2uc.cloudfront.net/datasheets/Sensors/Biometric/MQ-8.pdf) |
-| MQ-9 | Haoyuelectronics | [datasheet](http://www.haoyuelectronics.com/Attachment/MQ-9/MQ9.pdf) |
-| MQ-131 | Sensorsportal | [datasheet](http://www.sensorsportal.com/DOWNLOADS/MQ131.pdf) |
+| MQ-2 | HANWEI Electronics| [datasheet](https://www.pololu.com/file/0J309/MQ2.pdf) |
+| MQ-3 | HANWEI Electronics | [datasheet](https://www.sparkfun.com/datasheets/Sensors/MQ-3.pdf) |
+| MQ-4 | HANWEI Electronics | [datasheet](https://www.sparkfun.com/datasheets/Sensors/Biometric/MQ-4.pdf) |
+| MQ-5 | HANWEI Electronics | [datasheet](https://www.parallax.com/sites/default/files/downloads/605-00009-MQ-5-Datasheet.pdf) |
+| MQ-6 | HANWEI Electronics | [datasheet](https://www.sparkfun.com/datasheets/Sensors/Biometric/MQ-6.pdf) |
+| MQ-7 | HANWEI Electronics | [datasheet](https://www.sparkfun.com/datasheets/Sensors/Biometric/MQ-7.pdf) |
+| MQ-8 | HANWEI Electronics | [datasheet](https://dlnmh9ip6v2uc.cloudfront.net/datasheets/Sensors/Biometric/MQ-8.pdf) |
+| MQ-9 | HANWEI Electronics | [datasheet](http://www.haoyuelectronics.com/Attachment/MQ-9/MQ9.pdf) |
+| MQ-131 | HANWEI Electronics | [datasheet](http://www.sensorsportal.com/DOWNLOADS/MQ131.pdf) |
 | MQ-135 | HANWEI Electronics | [datasheet](https://www.electronicoscaldas.com/datasheet/MQ-135_Hanwei.pdf) |
 | MQ-136 | HANWEI Electronics | [datasheet](https://github.com/miguel5612/MQSensorsLib_Docs/blob/master/Datasheets/MQ136%20-%20Hanwei.pdf) |
 | MQ-303A | HANWEI Electronics | [datasheet](http://www.kosmodrom.com.ua/pdf/MQ303A.pdf) |

examples/Alcoholimeter/Alcoholimeter.ino

@@ -66,7 +66,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -80,8 +80,8 @@ void setup() {
   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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/  
 }
 

examples/ESP32/ESP32_WROOM_32D/ESP32_WROOM_32D.ino

@@ -86,7 +86,7 @@ void setup()
   // 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.
+  // We recommend 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.");
@@ -100,8 +100,8 @@ void setup()
   MQ2.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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
   //MQ2.serialDebug(true); uncomment if you want to print the table on the serial port
 

examples/ESP32/esp32.ino

@@ -65,7 +65,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -79,8 +79,8 @@ void setup() {
   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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
   MQ3.serialDebug(true);
 }

examples/ESP8266/ESP8266.ino

@@ -65,7 +65,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -79,8 +79,8 @@ void setup() {
   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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
   MQ3.serialDebug(true);
 }

examples/LinearVsExponential/LinearVsExponential.ino

@@ -45,7 +45,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -59,8 +59,8 @@ void setup() {
   MQ4.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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
 
   /* 

examples/MQ-131/MQ-131.ino

@@ -67,7 +67,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -81,8 +81,8 @@ void setup() {
   MQ131.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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts 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 :)");

examples/MQ-135-ALL/MQ-135-ALL.ino

@@ -55,7 +55,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -69,8 +69,8 @@ void setup() {
   MQ135.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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
   Serial.println("** Values from MQ-135 ****");
   Serial.println("|    CO   |  Alcohol |   CO2  |  Toluen  |  NH4  |  Aceton  |");  

examples/MQ-135-CorrectionFactorDHT11/MQ-135-CorrectionFactorDHT11.ino

@@ -106,7 +106,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -120,8 +120,8 @@ void setup() {
   MQ135.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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
   MQ135.serialDebug(true);
   // Set delay between sensor readings based on sensor details.

examples/MQ-135/MQ-135.ino

@@ -67,7 +67,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -81,8 +81,8 @@ void setup() {
   MQ135.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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
   MQ135.serialDebug(true);
 }

examples/MQ-136/MQ-136.ino

@@ -60,7 +60,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -74,8 +74,8 @@ void setup() {
   MQ136.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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
   MQ136.serialDebug(true);
 }

examples/MQ-2/MQ-2.ino

@@ -64,7 +64,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -78,8 +78,8 @@ void setup() {
   MQ2.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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
 
   MQ2.serialDebug(true);

examples/MQ-3/MQ-3.ino

@@ -66,7 +66,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -80,8 +80,8 @@ void setup() {
   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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
   MQ3.serialDebug(true);
 }

examples/MQ-303A/MQ-303A.ino

@@ -64,7 +64,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -78,8 +78,8 @@ void setup() {
   MQ303.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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
   MQ303.serialDebug(true);
 }

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

@@ -67,7 +67,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -81,8 +81,8 @@ void setup() {
   MQ309.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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
   MQ309.serialDebug(true);
 }

examples/MQ-4-ALL/MQ-4-ALL.ino

@@ -55,7 +55,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -69,8 +69,8 @@ void setup() {
   MQ4.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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
 
   Serial.println("*************** Values from MQ-4 **********************");

examples/MQ-4-LINEAR/MQ-4-LINEAR.ino

@@ -54,7 +54,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -68,8 +68,8 @@ void setup() {
   MQ4.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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
 
   Serial.println("** Values from MQ-4**********");

examples/MQ-4/MQ-4.ino

@@ -65,7 +65,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -79,8 +79,8 @@ void setup() {
   MQ4.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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
   MQ4.serialDebug(true);
 }

examples/MQ-5/MQ-5.ino

@@ -65,7 +65,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -79,8 +79,8 @@ void setup() {
   MQ5.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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
   MQ5.serialDebug(true);
 }

examples/MQ-6/MQ-6.ino

@@ -65,7 +65,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -79,8 +79,8 @@ void setup() {
   MQ6.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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
   MQ6.serialDebug(true);
 }

examples/MQ-7/MQ-7.ino

@@ -72,7 +72,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -86,8 +86,8 @@ void setup() {
   MQ7.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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
   MQ7.serialDebug(true);
 }

examples/MQ-8/MQ-8.ino

@@ -66,7 +66,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -80,8 +80,8 @@ void setup() {
   MQ8.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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
   MQ8.serialDebug(true);
 }

examples/MQ-9-ALL/MQ-9-ALL.ino

@@ -55,7 +55,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -69,8 +69,8 @@ void setup() {
   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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
   Serial.println("** Values from MQ-9 ****");
   Serial.println("|    LPG   |  CH4 |   CO  |");  

examples/MQ-9/MQ-9.ino

@@ -67,7 +67,7 @@ void setup() {
   // 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.
+  // We recommend 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
@@ -101,8 +101,8 @@ void setup() {
   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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
   MQ9.serialDebug(true);
 }

examples/MQ-Board/MQ-Board.ino

@@ -103,7 +103,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -158,8 +158,8 @@ void setup() {
   Serial.print(MQ8calcR0/10); Serial.print(" | ");
   Serial.print(MQ9calcR0/10); Serial.println(" |");
 
-  if(isinf(MQ2calcR0) || isinf(MQ3calcR0) || isinf(MQ4calcR0) || isinf(MQ5calcR0)  || isinf(MQ6calcR0) || isinf(MQ7calcR0) || isinf(MQ8calcR0) || isinf(MQ9calcR0)) {Serial.println("Warning: Conection issue founded, R0 is infite (Open circuit detected) please check your wiring and supply"); while(1);}
-  if(MQ2calcR0 == 0 || MQ3calcR0 == 0 || MQ4calcR0 == 0 || MQ5calcR0 == 0 || MQ6calcR0 == 0 || MQ7calcR0 == 0 || MQ8calcR0 == 0 || MQ9calcR0 == 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);}
+  if(isinf(MQ2calcR0) || isinf(MQ3calcR0) || isinf(MQ4calcR0) || isinf(MQ5calcR0)  || isinf(MQ6calcR0) || isinf(MQ7calcR0) || isinf(MQ8calcR0) || isinf(MQ9calcR0)) {Serial.println("Warning: Connection issue found, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(MQ2calcR0 == 0 || MQ3calcR0 == 0 || MQ4calcR0 == 0 || MQ5calcR0 == 0 || MQ6calcR0 == 0 || MQ7calcR0 == 0 || MQ8calcR0 == 0 || MQ9calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin with short circuit to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
  
   //Print in serial monitor

examples/MQ135-ADS1115/MQ135-ADS1115.ino

@@ -62,8 +62,8 @@ void setup(void)
   MQ135.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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
   Serial.println("** Values from MQ-135 ****");
   Serial.println("|    CO   |  Alcohol |   CO2  |  Toluen  |  NH4  |  Aceton  |");  

examples/external_A2D/external_A2D.ino

@@ -37,7 +37,7 @@
 //Definitions
 #define placa "Arduino UNO"
 #define Voltage_Resolution 5
-#define pin A0 //Analog input 0 -> This value can have any number, we recomend use A0
+#define pin A0 //Analog input 0 -> This value can have any number, we recommend use A0
 #define type "MQ-3 With A2D External connected" //MQ3
 #define ADC_Bit_Resolution 10 // Resolution of your external A2D
 #define RatioMQ3CleanAir 60   //RS / R0 = 60 ppm 
@@ -74,7 +74,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -89,8 +89,8 @@ void setup() {
   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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
 
   MQ3.serialDebug(true);

examples/smokeDetector/smokeDetector.ino

@@ -59,7 +59,7 @@ void setup() {
   // 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.
+  // We recommend 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.");
@@ -73,8 +73,8 @@ void setup() {
   MQ4.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);}
+  if(isinf(calcR0)) {Serial.println("Warning: Connection issue, R0 is infinite (Open circuit detected) please check your wiring and supply"); while(1);}
+  if(calcR0 == 0){Serial.println("Warning: Connection issue found, R0 is zero (Analog pin shorts to ground) please check your wiring and supply"); while(1);}
   /*****************************  MQ CAlibration ********************************************/ 
   MQ4.serialDebug(true);
 }

src/MQUnifiedsensor.cpp

@@ -1,9 +1,12 @@
 #include "MQUnifiedsensor.h"
 
+#define retries 2
+#define retry_interval 20
+
 MQUnifiedsensor::MQUnifiedsensor(String Placa, float Voltage_Resolution, int ADC_Bit_Resolution, int pin, String type) {
   this->_pin = pin;
   Placa.toCharArray(this->_placa, 20);
-  type.toCharArray(this->_type, 6);
+  type.toCharArray(this->_type, 7);
   //this->_type = type; //MQ-2, MQ-3 ... MQ-309A
   //this->_placa = Placa;
   this-> _VOLT_RESOLUTION = Voltage_Resolution;
@@ -11,7 +14,7 @@ MQUnifiedsensor::MQUnifiedsensor(String Placa, float Voltage_Resolution, int ADC
 }
 MQUnifiedsensor::MQUnifiedsensor(String Placa, String type) {
   Placa.toCharArray(this->_placa, 20);
-  type.toCharArray(this->_type, 6);
+  type.toCharArray(this->_type, 7);
 }
 void MQUnifiedsensor::init()
 {
@@ -38,6 +41,9 @@ void MQUnifiedsensor::setVoltResolution(float voltage_resolution)
 {
   _VOLT_RESOLUTION = voltage_resolution;
 }
+void MQUnifiedsensor::setPin(int pin) {
+  this->_pin = pin;
+}
 void MQUnifiedsensor::setRegressionMethod(int regressionMethod)
 {
   //this->_regressionMethod = regressionMethod;
@@ -143,16 +149,16 @@ float MQUnifiedsensor::readSensor(bool isMQ303A, float correctionFactor, bool in
   if(_RS_Calc < 0)  _RS_Calc = 0; //No negative values accepted.
   if(!injected) _ratio = _RS_Calc / this->_R0;   // Get ratio RS_gas/RS_air
   _ratio += correctionFactor;
-  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
+  if(_ratio <= 0)  _ratio = 0; //No negative values accepted or upper datasheet recommendation.
+  if(_regressionMethod == 1) _PPM= _a*pow(_ratio, _b); // <- Source excel analysis https://github.com/miguel5612/MQSensorsLib_Docs/tree/master/Internal_design_documents
   else 
   {
-    // https://jayconsystems.com/blog/understanding-a-gas-sensor <- Source of linear ecuation
+    // https://jayconsystems.com/blog/understanding-a-gas-sensor <- Source of linear equation
     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.
+  if(_PPM < 0)  _PPM = 0; //No negative values accepted or upper datasheet recommendation.
+  //if(_PPM > 10000) _PPM = 99999999; //No negative values accepted or upper datasheet recommendation.
   return _PPM;
 }
 float MQUnifiedsensor::readSensorR0Rs()
@@ -161,16 +167,16 @@ float MQUnifiedsensor::readSensorR0Rs()
   _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
+  if(_ratio <= 0)  _ratio = 0; //No negative values accepted or upper datasheet recommendation.
+  if(_regressionMethod == 1) _PPM= _a*pow(_ratio, _b); // <- Source excel analysis https://github.com/miguel5612/MQSensorsLib_Docs/tree/master/Internal_design_documents
   else 
   {
-    // https://jayconsystems.com/blog/understanding-a-gas-sensor <- Source of linear ecuation
+    // https://jayconsystems.com/blog/understanding-a-gas-sensor <- Source of linear equation
     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.
+  if(_PPM < 0)  _PPM = 0; //No negative values accepted or upper datasheet recommendation.
+  //if(_PPM > 10000) _PPM = 99999999; //No negative values accepted or upper datasheet recommendation.
   return _PPM;
 }
 float MQUnifiedsensor::calibrate(float ratioInCleanAir) {

src/MQUnifiedsensor.h

@@ -6,10 +6,6 @@
 
 /***********************Software Related Macros************************************/
 
-#define ADC_RESOLUTION 10 // for 10bit analog to digital converter.
-#define retries 2
-#define retry_interval 20
-
 class MQUnifiedsensor
 {
   public:
@@ -26,6 +22,7 @@ class MQUnifiedsensor
     void setB(float b);
     void setRegressionMethod(int regressionMethod);
     void setVoltResolution(float voltage_resolution =  5);
+    void setPin(int pin = 1);
     void serialDebug(bool onSetup = false); //Show on serial port information about sensor
     void setADC(int value); //For external ADC Usage
     
@@ -51,7 +48,7 @@ class MQUnifiedsensor
 
   private:
     /************************Private vars************************************/
-    byte _pin;
+    byte _pin = 1;
     byte _firstFlag = false;
     float _VOLT_RESOLUTION  = 5.0; // if 3.3v use 3.3
     float _RL = 10; //Value in KiloOhms
@@ -61,7 +58,7 @@ class MQUnifiedsensor
     float _adc, _a, _b, _sensor_volt;
     float  _R0, RS_air, _ratio, _PPM, _RS_Calc;  
     
-    char _type[6];
+    char _type[7];
     char _placa[20]; 
 };