16x2 LCD white squares (not working)

Forum 2005-2010 (read only) Hardware Interfacing
1

Hey everyone,

I've had a 2x16 LCD screen for some time now. I've even gotten it to work before around a year ago, so I'm wondering if something's changed with the LCD library?

Here's the datasheet: Elektroniikan verkkokauppa ja myymälä Vantaalla - PARTCO

All I get is the infamous 'one row of white squares'.

I'm using the 4 bit example, even tried 8 with no luck.

I have a feeling that either the library has changed and is incompatible, or something's physically wrong with the LCD.

R/W and V0 are going to ground.

Any ideas?

2

Often this is a problem of the data pins the wrong way round (or just a few mixed up). The liquid crystal library is also much better than the 4bit library.

Mowcius

3

Have you worked through the ladyada tutorial?
http://www.ladyada.net/learn/lcd/charlcd.html

It helped me when I had problems, largely because it's step-by-step and tells you what to expect.

4

I'm using the 4 bit example, even tried 8 with no luck.

Have you tried the LiquidCrystal library from Arduino v0018? Many of the older libraries are flawed. See: http://arduino.cc/en/Tutorial/LiquidCrystal

Don

5

Yes, I've actually only tried it with the library that comes with v0018.

The last time I got it to work was with an older version of the library/arduino IDE.

One of the data pins (DB) had its copper plating (the small piece of copper covering the pin hole) fall off, propably due to excess heat, but there's another copper plating on the other side, so it shouldn't be a connection issue.

Is there a way to use a different set of the data pins? As in when using only 4 data pins, you could for example the first four?

I'm also a bit confused since there seems to be multiple versions of the LCD library under "Tutorial". The Liquid Crystal library uses 4 pins instead of 8, right?

It's unlikely that the pins are the wrong way around, but nonetheless, I'll have another go at it.

PS. I've gone through ladyadas tutorial

6

Is there a way to use a different set of the data pins? As in when using only 4 data pins, you could for example the first four?

Not as far as I'm aware, its either DB4,DB5,DB6,DB7 or all 8.

The Liquid Crystal library uses 4 pins instead of 8, right?

The LiquidCrystal libray can use either 4 or 8 data pins depending on how you define the LiquidCrystal contruct in the sketch.

7

"One of the data pins (DB) had its copper plating (the small piece of copper covering the pin hole) fall off, propably due to excess heat, but there's another copper plating on the other side, so it shouldn't be a connection issue."

You also started off saying that you thought something was physically wrong with it. I suspect that there may be something deeper that you see.

It might be worth trying this version of LiquidCrystal:
http://www.healthriskappraisal.org/LiquidCrystalBulletproof.zip

it worked with a particularly finicky LCD.