Modified fctn to get voltage

examples/MQ-Board-Calibration/MQ-Board-Calibration.ino

@@ -96,7 +96,7 @@ void setup() {
   Serial.println("MQ2 to MQ9 - Calibracion");
   Serial.println("Note - Make sure you are in a clean room and the sensor has pre-heated almost 4 hours");
   Serial.println("Note - All values are in KOhms");
-  Serial.println("Autonumeric, MQ2(R0), MQ3(R0), MQ4(R0), MQ5(R0), MQ6(R0), MQ7(R0)");
+  Serial.println("Autonumeric, MQ2(R0), MQ3(R0), MQ4(R0), MQ5(R0), MQ6(R0), MQ7(R0), MQ8(R0), MQ9(R0), v2(VDC), v3(VDC), v4(VDC), v5(VDC), v6(VDC), v7(VDC), v8(VDC), v9(VDC)");
   //Wait one second to continue
   delay(timeDelay/10);
 }
@@ -113,6 +113,16 @@ void loop() {
   float lecture8 =  MQ8.calibrate();
   float lecture9 =  MQ9.calibrate();
 
+    //Read voltage the sensor
+  float v2 =  MQ2.getVoltage(false);
+  float v3 =  MQ3.getVoltage(false);
+  float v4 =  MQ4.getVoltage(false);
+  float v5 =  MQ5.getVoltage(false);
+  float v6 =  MQ6.getVoltage(false);
+  float v7 =  MQ7.getVoltage(false);
+  float v8 =  MQ8.getVoltage(false);
+  float v9 =  MQ9.getVoltage(false);
+
   
   //Print in serial monitor
   Serial.print(contador);Serial.print(",");
@@ -123,7 +133,17 @@ void loop() {
   Serial.print(lecture6);Serial.print(",");
   Serial.print(lecture7);Serial.print(",");
   Serial.print(lecture8);Serial.print(",");
-  Serial.println(lecture9);
+  Serial.println(lecture9);Serial.print(",");
+  //Print voltages
+  Serial.print(v2);Serial.print(",");
+  Serial.print(v3);Serial.print(",");
+  Serial.print(v4);Serial.print(",");
+  Serial.print(v5);Serial.print(",");
+  Serial.print(v6);Serial.print(",");
+  Serial.print(v7);Serial.print(",");
+  Serial.print(v8);Serial.print(",");
+  Serial.println(v9);Serial.print(",");
+  
 
   //Print in LCD
   lcd.clear();

src/MQUnifiedsensor.cpp

@@ -527,7 +527,7 @@ int MQUnifiedsensor::readPPM(int m, int b) {
   double ppm = pow(10, ppm_log); //Convert ppm value to log scale
   return floor(ppm);
 }
-float MQUnifiedsensor::calibrate(boolean print) {
+long MQUnifiedsensor::calibrate(boolean print) {
   //More explained in: https://jayconsystems.com/blog/understanding-a-gas-sensor
   /*
   V = I x R 
@@ -541,9 +541,8 @@ float MQUnifiedsensor::calibrate(boolean print) {
   RS = [(VC x RL) / VRL] - RL
   */
   _sensor_volt; //Define variable for sensor voltage
-  float RS_air; //Define variable for sensor resistance
+  long RS_air; //Define variable for sensor resistance
-  float R0; //Define variable for R0
+  long R0; //Define variable for R0
-  float sensorValue; //Define variable for analog readings
   _sensor_volt = this->getVoltage(); //Convert average to voltage
   RS_air = ((_VOLT_RESOLUTION*_RLValue)/_sensor_volt)-_RLValue; //Calculate RS in fresh air 
   R0 = RS_air/_ratioInCleanAir; //Calculate R0 
@@ -560,15 +559,17 @@ float MQUnifiedsensor::calibrate(boolean print) {
   }
   return R0;
 }
-double MQUnifiedsensor::getVoltage() {
+double MQUnifiedsensor::getVoltage(int read) {
+  double voltage = _sensor_volt;
+  if(read)
+  {
     double avg = 0.0;
     for (int i = 0; i < retries; i ++) {
       avg += analogRead(this->_pin) / retries;
       delay(retry_interval);
     }
-
+    voltage = avg * _VOLT_RESOLUTION / (pow(2, ADC_RESOLUTION) - 1);
-  double voltage = avg * _VOLT_RESOLUTION / (pow(2, ADC_RESOLUTION) - 1);
+  }
-
   return voltage;
 }
 void MQUnifiedsensor::setR0(double R0) {

src/MQUnifiedsensor.h

@@ -274,8 +274,8 @@ class MQUnifiedsensor
     int readSensor(String nameLectureRequeired = "", bool print = false);
     int readPPM(int m, int b);
     
-    float calibrate(boolean print = false);
+    long calibrate(boolean print = false);
-    double getVoltage();
+    double getVoltage(int read =  true);
     double stringToDouble(String & str);
 
     String getnameLecture();