Contrast Problem

Other Hardware Displays
1

Hello,

I have bought a LCD screen this one:

And hook't it up like this:

http://www.ladyada.net/learn/lcd/charlcd.html

But when i upload the sketch i don't see anything on the screen.. thats ok because when i move the pot meter (that was standing on full) down to about 1 voltage you see the text.. but when i upload a new text or the text change's i don't see anything anymore.. i have to put the pot meter to full en turn it down after the sketch upload is done..

I made a video about what happend's and a photo off my setup and the code:

The video:

The picture's:

By josvink666 at 2011-09-11

By josvink666 at 2011-09-11

The code:

/*

// include the library code:
#include <LiquidCrystal.h>

// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);

void setup() {
lcd.begin(16, 2);
// set up the LCD's number of columns and rows:
// Print a message to the LCD.
lcd.print("hello, world!");
lcd.setCursor(0,1);
lcd.print("Line 2");
}

void loop() {

}

can anyone help me?

sorry for my bad english i'm dutch

2

Your English is good enough to understand the case.

You are one of the few who actually post a vid of the problem!!

Think the problem is that the display does not get enough power, can you connect a separate power supply to it?

Do not forget to connect the ground of the Arduino with the ground of the display so they share the same reference ground.

Let us know the result,
Rob

3

Your backlight seems very bright and your connections to it are unclear. According to the data sheet it should have a 4.2v supply and can tolerate 4.6v maximum. It looks like you may be driving it with the full 5v from the Arduino supply. If you scroll down through the comments section of your first link you will see some discussion about a suitable current limiting resistor. Without a current limiting resistor you could be drawing enough current to give the power problems that Rob mentioned.

Once you get the backlight current down to where it is supposed to be your display may work properly. Normally you should be able to set the contrast control once and then not have to adjust it again.

Don

4

Tnx for your reply's

i've tried to put a resistor betweet the +5 and the backlight (pin 15)
The resistor was a 100? resistor
I even tried 2 but the light stay't the same and i still have the same problem

5

I recommend that you disconnect all of your wires and then follow the first part of the tutorial at Arduino Tutorial - connecting a parallel LCD to verify your connections. Start from the beginning and make sure that your power, contrast, and backlight are working correctly. You should see something like the photo just before the section on 'Bus Wiring' (the display in that photo is upside down).

EDIT: The Adafruit display has a 5v backlight and does not require a current limiting resistor. Make sure that you remember to put yours in.

When that is working then connect the rest of the LCD wires and run your sketch. I think your version is better for testing than the standard one that displays a changing count. If you are still having problems then post another photo like your third one above, except this time make sure that the wires are not blocking the view of the pins that they are connected to.

Don