LCD troubles

Forum 2005-2010 (read only) Hardware Interfacing
1

I know this may sound a little stupid, but I can't even get the lcd display to work. I'm using the liquid crystal library, but all I can visibly change is the contrast and the backlight. I've even copied and pasted examples from the LCD library examples and still nothing.

this is the LCD I'm using: Basic 20x4 Character LCD - Black on Green 5V - LCD-00256 - SparkFun Electronics

Thank you in advance!

2

Post your code.

3

Post your code.

Also post a photo that clearly shows the interconnections between your Arduino and your LCD module.

but I can't even get the lcd display to work

Post a photo that shows the display that you get when it is not 'working'.

Try following the tutorial at Arduino Tutorial - connecting a parallel LCD.

Don

4

I don't know how to add a picture, but my pin assignments are:
Arduino GRND to LCD 16 (backlight ground)
Arduino 13 to LCD 15 (backlight power supply)
Arduino 12 to LCD 4 (rs signal)
Arduino 11 to LCD 5 (r/w signal)
Arduino 10 to LCD 6 (enable signal)
Arduino 9 to LCD 3 (contrast adjust)
Arduino 5 to LCD 11 (DB4)
Arduino 4 to LCD 12 (DB5)
Arduino 3 to LCD 13 (DB6)
Arduino 2 to LCD 14 (DB7)

My code is:

#include <LiquidCrystal.h>

LiquidCrystal lcd(12, 11, 10, 5, 4, 3, 2);
int contrast = 0;

void setup()
{
  pinMode(9, OUTPUT);
  pinMode(13, OUTPUT);
  lcd.begin(20,4);
  lcd.print("hello, world!");
  digitalWrite(13, HIGH);
}

void loop() {
  if (contrast < 255) {
    contrast++;
    analogWrite(9, contrast);
    delay(20);
  }
  else if (contrast == 255) {
    contrast = 0;
  }

}

I did the contrast loop to verify the code was actually running. I did the same idea with the backlight of the LCD, and it worked both times, but I'm not getting any text.

5

Arduino GRND to LCD 16 (backlight ground)

Does the Arduino GND also go to LCD pin 1?

... but I'm not getting any text.

What are you getting? We really can't help you until we know what is happening.

Did you follow the tutorial? You should get that working before you try anything else (such as software control of the contrast).

Don

6

Have you checked the pinout for the specific LCD you have?

Of the 16 pins, the two power ones on the outside are sometimes at the other end.

7

I got it to work! Thanks for your help, guys. I think the issue was that all of the other tutorials I used didn't say anything about powering the LCD logic. I feel so stupid for not thinking of that myself...

Thanks for putting up with my noob-ness.