diff --git a/examples/MQ4/MQ4.ino b/examples/MQ4/MQ4.ino
index 154f4e4..613a5a8 100644
--- a/examples/MQ4/MQ4.ino
+++ b/examples/MQ4/MQ4.ino
@@ -1,12 +1,41 @@
+/*
+  MQUnifiedsensor Library - reading an MQ4
+
+  Demonstrates the use a MQ4 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 
+
+ This example code is in the public domain.
+
+*/
+
+//Include the library
 #include <MQUnifiedsensor.h>
 
+//Definitions
+#define pin A0 //Analog input 0 of your arduino
+#define type 4 //MQ4
+
+//Declare Sensor
+
+MQUnifiedsensor MQ4(pin, type);
 
 void setup() {
-  // put your setup code here, to run once:
-
+  //init the sensor
+  MQ4.inicializar(); 
 }
 
 void loop() {
-  // put your main code here, to run repeatedly:
-
+  //Read the sensor
+  int read =  MQ4.readSensor();
+  //Print measurements
+  Serial.print("MQ4: ");
+  Serial.print(read);
+  Serial.println(" PPM");
+  //delay 1s to next measure
+  delay(1000);
 }
diff --git a/src/MQUnifiedsensor.cpp b/src/MQUnifiedsensor.cpp
index 7794a3d..e7b98cd 100644
--- a/src/MQUnifiedsensor.cpp
+++ b/src/MQUnifiedsensor.cpp
@@ -65,7 +65,10 @@ int MQUnifiedsensor::readSensor(String nameLectureRequeired = "")
   setSensorCharacteristics(nameLectureRequeired);
   return readPPM(_m, _b);
 }
-
+void MQUnifiedsensor::inicializar()
+{
+  pinMode(_pin, INPUT);
+}
 void MQUnifiedsensor::setSensorCharacteristics(String nameLectureRequeired)
 {
   int wantedpos = 0;
diff --git a/src/MQUnifiedsensor.h b/src/MQUnifiedsensor.h
index dfba88e..4c4bddf 100644
--- a/src/MQUnifiedsensor.h
+++ b/src/MQUnifiedsensor.h
@@ -16,6 +16,7 @@ class MQUnifiedsensor
     
     int readSensor(String nameLectureReqeuired = "");
     int readPPM(int m, int b);
+    void inicializar();
 
     /**
      * Calibrates the start point of 400