user3454: Recently I have linked up a typical 16*2 LCD (Liquid Crystal Display) display to my Arduino Uno and have linked all the pins up.
Here is my connection:(LCD pin first)
1=GND, 2=+5v, 4=11, 6=12, 11=5, 12=4, 12=3, 14=2, 15=backlight positive, 16=backlight negative
#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  // set up the LCD's number of columns and rows: 
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("hello, world!");
}

void loop() {
  // set the cursor to column 0, line 1
  // (note: line 1 is the second row, since counting begins with 0):
  lcd.setCursor(0, 1);
  // print the number of seconds since reset:
  lcd.print(millis()/1000);
}

This is the code that is the default for the LCD, I didn't write it.
So I have done all this and when I turn it on the screen is blank and nothing is happening. Could anyone explain what I have done wrong?

user19228: What is connected to LCD pin 3? Pin 3 is the contrast V0 and needs to be connected with a 10 KOhm potentiometer.
Some LCD's need a negative contrast voltage, check the datasheet of the display.
If the contrast voltage is not correct the display will stay blank. 
I came across the same problem until i saw the negative voltage must be applied :-)

user490: Check out this tutorial on Adafruit. It will walk you through setting it up. In the tutorial they change the pins, which I believe is the issue here. Here is a snippet.

And change your pins:
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);


user19695: Recently I also faced similar problem, with connection as:
1=GND, 2=+5v, 4=11, 6=12, 11=5, 12=4, 12=3, 14=2, 15=backlight positive, 16=backlight negative
Solution: I just connected VEE (pin 3) of LCD to Ground (GND) without use of potentiometer as it worked.

3454: <p>Recently I have linked up a typical 16*2 LCD (Liquid Crystal Display) display to my Arduino Uno and have linked all the pins up.</p>

<p>Here is my connection:(LCD pin first)</p>

<p>1=GND, 2=+5v, 4=11, 6=12, 11=5, 12=4, 12=3, 14=2, 15=backlight positive, 16=backlight negative</p>

<pre><code>#include &lt;LiquidCrystal.h&gt;

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  // set up the LCD's number of columns and rows: 
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("hello, world!");
}

void loop() {
  // set the cursor to column 0, line 1
  // (note: line 1 is the second row, since counting begins with 0):
  lcd.setCursor(0, 1);
  // print the number of seconds since reset:
  lcd.print(millis()/1000);
}
</code></pre>

<p>This is the code that is the default for the LCD, I didn't write it.</p>

<p>So I have done all this and when I turn it on the screen is blank and nothing is happening. Could anyone explain what I have done wrong?</p>
 19228: <p>What is connected to LCD pin 3? Pin 3 is the contrast V0 and needs to be connected with a 10 KOhm potentiometer.</p>

<p>Some LCD's need a negative contrast voltage, check the datasheet of the display.</p>

<p>If the contrast voltage is not correct the display will stay blank. 
I came across the same problem until i saw the negative voltage must be applied :-)</p>
 490: <p>Check out this tutorial on <a href="https://learn.adafruit.com/adafruit-arduino-lesson-11-lcd-displays-1" rel="noreferrer">Adafruit</a>. It will walk you through setting it up. In the tutorial they change the pins, which I believe is the issue here. Here is a snippet.</p>

<p><img src="https://i.stack.imgur.com/pmgMg.jpg" alt="Fritzing Diagram"></p>

<p>And change your pins:</p>

<pre><code>LiquidCrystal lcd(7, 8, 9, 10, 11, 12);
</code></pre>
 19695: <p>Recently I also faced similar problem, with connection as:</p>

<p>1=GND, 2=+5v, 4=11, 6=12, 11=5, 12=4, 12=3, 14=2, 15=backlight positive, 16=backlight negative</p>

<p>Solution: I just <strong>connected VEE (pin 3) of LCD to Ground (GND)</strong> without use of potentiometer as it worked.</p>
