display 4x20 y modlo I2C

https://www.youtube.com/watch?v=4mTRnRwDnF8
http://4tronix.co.uk/arduino/I2C_LCD_Module.php
https://arduino-info.wikispaces.com/LCD-Blue-I2C
https://www.youtube.com/watch?v=DCoaX2owAgg
https://www.dfrobot.com/product-590.html
http://forum.arduino.cc/index.php?topic=203965.0
https://forum.arduino.cc/index.php?topic=352362.0
https://www.youtube.com/watch?v=F9IVtKa8C7Q
https://github.com/fdebrabander/Arduino-LiquidCrystal-I2C-library/blob/master/examples/HelloWorld/HelloWorld.ino
-----------------------------------------------------------16x2 displays con i2c
http://www.instructables.com/id/I2C-LCD-Controller-the-easy-way/
https://www.sunfounder.com/learn/Sensor-Kit-v2-0-for-Arduino/lesson-1-display-by-i2c-lcd1602-sensor-kit-v2-0-for-arduino.html

----------------
ejrmplo   de   http://www.4tronix.co.uk/arduino/sketches/I2C_LCD02.ino

/*-----( Import needed libraries )-----*/
#include <Wire.h>  // Comes with Arduino IDE
// Get the LCD I2C Library here: 
// www.4tronix.co.uk/arduino/sketches/LiquidCrystal_V1.2.1.zip
// Move any other LCD libraries to another folder or delete them
// See Library "Docs" folder for possible commands etc.
#include <LiquidCrystal_I2C.h>

/*-----( Declare Constants )-----*/
/*-----( Declare objects )-----*/
// set the LCD address to 0x27 for a 20 chars 4 line display
// Set the pins on the I2C chip used for LCD connections:
//                    addr, en,rw,rs,d4,d5,d6,d7,bl,blpol
LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);  // Set the LCD I2C address

/*-----( Declare Variables )-----*/
//NONE

void setup()   /*----( SETUP: RUNS ONCE )----*/
{
  Serial.begin(9600);  // Used to type in characters

  lcd.begin(20,4);   // initialize the lcd for 20 chars 4 lines, turn on backlight

// ------- Quick 3 blinks of backlight  -------------
  for(int i = 0; i< 3; i++)
  {
    lcd.backlight();
    delay(250);
    lcd.noBacklight();
    delay(250);
  }
  lcd.backlight(); // finish with backlight on  

//-------- Write characters on the display ------------------
// NOTE: Cursor Position: (CHAR, LINE) start at 0  
  lcd.setCursor(0,0); //Start at character 4 on line 0
  lcd.print("Hello, world!");
  delay(1000);
  lcd.setCursor(0,1);
  lcd.print("4tronix I2C LCD"); // Print text on 2nd Line
  delay(1000);
  lcd.setCursor(0,2);
  lcd.print("0123456789ABCDEFGHIJ"); //Print 20 characters on 3rd line
  delay(1000);
  lcd.setCursor(0,3);
  lcd.print("4th Line of Text");
  delay(8000);  

// Wait and then tell user they can start the Serial Monitor and type in characters to
// Display. (Set Serial Monitor option to "No Line Ending")
/*  lcd.clear();
  lcd.setCursor(0,0); //Start at character 0 on line 0
  lcd.print("Use Serial Mon");
  lcd.setCursor(0,1);
  lcd.print("Type to display"); */


}/*--(end setup )---*/


void loop()   /*----( LOOP: RUNS CONSTANTLY )----*/
{
  {
    // when characters arrive over the serial port...
    if (Serial.available()) {
      // wait a bit for the entire message to arrive
      delay(100);
      // clear the screen
      //lcd.clear();
      // read all the available characters
      while (Serial.available() > 0) {
        // display each character to the LCD
        //lcd.write(Serial.read());
      }
    }
  }

}/* --(end main loop )-- */


/* ( THE END ) */