Arduino UNO, LCD HD44780 20x4, backlight working, no characters showing

I’m following the instructions from this link, and the specifications from this link.

I’m using a 4,7 k Ohm on lcd pin 3 and a 100 Ohm on lcd pin 15 that’s used for the backlight. I have followed the instructions to the letter (at least I think I have) and my setup looks identical to the one from the first link (except I use arduino pin 7 instead of 13 for the backlight), and yet I get no characters to show up.

What am I missing/doing wrong?

Here’s the sketch I’m using. I’ve tried it without the clear screen command but nothing changed.

#include <LiquidCrystal.h>

LiquidCrystal lcd(12, 11, 10, 5, 4, 3, 2);

int backLight = 7;    // pin 13 will control the backlight

void setup() {
  pinMode(backLight, OUTPUT);
  digitalWrite(backLight, HIGH); // turn backlight on. Replace 'HIGH' with 'LOW' to turn it off.
  lcd.begin(20,4);              // columns, rows.  use 16,2 for a 16x2 LCD, etc.
  lcd.clear();                  // start with a blank screen
  lcd.setCursor(5,2);           // set cursor to column 0, row 0 (the first row)
  lcd.print("Hello, World");    // change this text to whatever you like. keep it clean.
  lcd.setCursor(0,1);           // set cursor to column 0, row 1
  lcd.print("hacktronics.com");
 
  // if you have a 4 row LCD, uncomment these lines to write to the bottom rows
  // and change the lcd.begin() statement above.
  lcd.setCursor(0,2);         // set cursor to column 0, row 2
  lcd.print("Row 3");
  lcd.setCursor(0,3);         // set cursor to column 0, row 3
  lcd.print("Row 4");
}

void loop() {
}

Start from the basics and work up

http://learn.adafruit.com/character-lcds/character-vs-graphical-lcds

int backLight = 7;    // pin 13 will control the backlight

How does that work? that just confusion to the people that try to help.

I'm using a 4,7 k Ohm on lcd pin 3 ...

That's not the correct way to provide the contrast voltage. Use a potentiometer as shown on page 2 of your data sheet.

... and yet I get no characters to show up.

Does anything show up?

What happens if you pull out all the yellow wires?

Be careful if you follow the tutorial at the link in reply #1. Although the text material talks about the series resistor for the backlight the photographs do not show that resistor.

Don