LCD BACK LIGHT NO WORKING

I have hooked my LCD up to my Arduino using the guide on hacktronics.com
http://www.hacktronics.com/Tutorials/arduino-character-lcd-tutorial.html

Works perfectly, apart from the Back light.

The LCD is 16 x 2 line LCD module Model: 162A0 by Emerging Display Technologies Corporation.

here is the code, but the only thing i can posablt think of is a problem with my Arduino pin13?

#include <LiquidCrystal.h>

// Connections:
// rs (LCD pin 4) to Arduino pin 12
// rw (LCD pin 5) to Arduino pin 11
// enable (LCD pin 6) to Arduino pin 10
// LCD pin 15 to Arduino pin 13
// LCD pins d4, d5, d6, d7 to Arduino pins 5, 4, 3, 2
LiquidCrystal lcd(12, 11, 10, 5, 4, 3, 2);

int backLight = 13;    // 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.clear();                  // start with a blank screen
  lcd.setCursor(0,0);           // 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 out these lines to write to the bottom rows
  //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()
{
}

Do you have 16 wired to GND?

Do you have 16 wired to GND?

Hello, Yes I have interface 16 going to the GND rail of my BB (thats hooked upto the Arduino GND)

here is my interface list

1 GND
2 + 5v
3 1k resistor to GND
4 pin 12
5 pin 11
6 pin 10
7
8
9
10
11 pin 5
12 pin 4
13 pin 3
14 pin 2
15 pin 13
16 GND

I can see you copied the code exactly from the site, so it’s most likely not code… try changing the code to backLight = 9; and moving the wire from 13 to 9, to test if it’s really the pin. If the problem still persists, it might be a faulty connection on the breadboard, in which case you should try moving the wire around a little (to a different “socket”), perhaps the one it’s using right now is damaged

changed the code to pin 9, but still no joy, tested it on a second BB and still no back light.

given the choice of me having missed something or the LCD being faulty, my money is on human error…just cant see what iv done wrong :frowning:

It looks like that tutorial has the backlight driven through arduino pin 13. An LCD backlight can draw more then the maximum current that an arduino pin can provide. Some of the older arduino boards had a current limiting resistor on pin 13 but most don’t.

Check the datasheet to see how much current the backlight requires and if it needs a current limiting resistor ( a quick look on goggle indicated that it does need a resistor to limit the current). If the backlight draws more than 40ma then you will need to use a transistor if you want to switch it on or off.

Thank you MEM,

I see on the Data sheet it looks like it draws 130mA.

So how and what transistor would I nee to attach :-/

You can use the circuit here: http://www.arduino.cc/playground/uploads/Learning/relays.pdf

  • but instead of driving a relay you will be driving the backlight
    the 2N2222 shown should be easy to find but almost any NPN transistor will work,

Connect the LCD positive side of the backlight to +5 volts, connect the negative side through a resistor (see your datasheet) to the collector of the transistor (you can ignore the relay and diode shown in that diagram)

Bear in mind that you may have damaged the pins you connected the backlight to directly, so try this with a different pin