Can somebody tell me why my LCD Display won't turn on

Projects General Guidance
1

Here is the circuit:
http://imgur.com/M5WrVcs
http://imgur.com/18AxuT8

and here are my codes

#include <LiquidCrystal.h>

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

void setup()
{
lcd.begin(16,2);
lcd.clear();
}

void loop()
{
lcd.print("printing text");

delay(3000);

lcd.clear();
lcd.setCursor(0,1);
lcd.print("setting cursor");

delay(3000);

lcd.clear();
lcd.print("blink cursor");
lcd.blink();

delay(3000);

lcd.clear();
lcd.noBlink();
lcd.print("uline cursor");
lcd.cursor();

delay(3000);

lcd.clear();
lcd.print("no cursor");
lcd.noCursor();

delay(3000);

lcd.clear();
lcd.print("no display");

delay(1000);

lcd.noDisplay();

lcd.clear();
lcd.print("display on");

delay(3000);
lcd.display();

delay(3000);
}

======================================================

#include <LiquidCrystal.h>

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

byte customchar[8] =
{
B00000,
B00000,
B00000,
B00000,
B00000,
B00000,
B00000
};

void setup()
{
lcd.begin(16,2);
lcd.clear();
lcd.createChar(1,customchar);
lcd.print("Custom!");
}

void loop()
{
lcd.setCursor(0,1);
lcd.write(1);
}

2

Pin number one of the display (the one that's marked VSS)
I can't see anything going to that. It should be connected to GND of the arduino.
In fact I can't see ANYTHING connected to your uno GND yet Pin 1 and Pin 5 of the display should BOTH be connected to GND

You've connected those two pins together, You just need to add the connection to the Arduino GND.

3

it is connected to RW pin, then to the potentiometer, and to the ground pin on my arduino. I'm using black jumper wires for everything, other than an orange wire between the potentiometer, RW and VSS

4

The header pins need to be soldered to the display.

5

If you don't have a potentiometer handy, you can get away with a 3K resistor between GND and pin 3 of the display (marked V0 in your picture).

Although you won't be able to adjust the contrast, you'll probably find it works just fine.

6

KenF:
Although you won't be able to adjust the contrast, you'll probably find it works just fine.

Run a for(i -> 255) loop on a PWM pin to adjust contrast. Slow it down to see what the value actually is through Serial.print or LCD.print, and then always have a PWM pin set your contrast for that display.

7

Thank you my friend I will solder it when I get back to school.
The GND pin is connected already but nothing is happening.
http://imgur.com/BGl6Mep

Marmotjr: I think the PWM pin isn't connnect to my UNO board

8

You still haven't got the backlight connected. The last two pins on the display are for the backlight. Pin 15 should be connected to 5v (through a 47 ohm resistor to be safe) and the last one (pin 16) should also go to GND.

It's quite possible that your display is already up and running, but you'll never know without the backlight working.

9

http://imgur.com/3uSqklK
I'm using a 220 ohm resistor, but I think it should be correct now, it still won't turn on

10

Pin 15 of your display ( marked A in your image) should be going to 5v NOT AREF

11

The resistor may already be in place on the back of the board in position R8. Sometimes it may be labeled R7 or R9 but you should be able to see a trace running from the resistor over to the backlight.

12

don't have another 5V pin, so I'm using the 3.3V pin, nothing happening
http://imgur.com/kJJBto4

http://imgur.com/w7dBUEX is this going to work?

13

jackylee328:
don't have another 5V pin, so I'm using the 3.3V pin, nothing happening
http://imgur.com/kJJBto4

http://imgur.com/w7dBUEX is this going to work?

Probably not. The backlight on that display is actually a bunch of LEDs in series. I think they need something like 4.6v to overcome their forward voltage threshold. If you're giving them just 3.3v i don't think they'll conduct at all.

Take the 5v of your UNO to one of the rails of that breadboard. Then anything that needs 5v (including your backlight) just needs a connection to that rail.

14

the display lit up using the second diagram, but the letters aren't showing

#include <LiquidCrystal.h>
LiquidCrystal lcd
void setup()
{
lcd.begin(16,2);

lcd.setCursor(0,0);
lcd.print("Hello World");
lcd.setCursor(0,2);
lcd.print("Arduino is fun");
}
void loop()
{}

what to do now?
edit: all 3 codes don't do anything to the display, I am using 5V for the backlight now

15

First I note that you've taken my advice to use a fixed value resistor to control the contrast. The one in your image, however is just 1K. This will not work very well, you need somewhere between 3k to 5k

Secondly, the fifth pin from the left of your display should normally go to GND yet i notice you have it connected to pin 11 of the UNO.

Thirdly, all the wires connected to you UNO pins 4,5,6 and 7 are redundant, as they go to connections on the display that are usually left open circuit.

Finally, you need to let the LiquidCrystal library know, which pins you are usiing for what.

So replace this ( the second line of code)

LiquidCrystal lcd

With this

LiquidCrystal lcd(12, 2, 7, 8, 9, 10);

And just to be sure we're talking about the same diagram. This is the one I'm referring to.

16

Hi, please read;

Please use code tags.. See section 7 http://forum.arduino.cc/index.php/topic,148850.0.html

You can also add files as attachments,this helps us keep all the info together.

Tom..... :slight_smile:

17

yup we're getting there
http://imgur.com/O40Tfmp
still can't get it to display text tho

Thanks Tom! I'll do that next time,

18

Those white boxes on the top line are typical of what you see when that contrast resistor is too small. What is the actual resistance you are using?

19

I'm using 1k, I only have 220, 1k, and 10k available.
Can I use 3 1K resistors? ._.

20

jackylee328:
I'm using 1k, I only have 220, 1k, and 10k available.
Can I use 3 1K resistors? ._.

Three 1k resistors in series is fine. (not parallel though).