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Broken LCD?

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edeca

Active Member
I've got a 16x2 LCD here that I salvaged. It didn't look like it had ever been soldered to anything, I just got it in a box of junk from someone.

I've got the basic power wired up and adjusted the 10K resistor so that I can see the individual pixels. I can only see the bottom row though, might this suggest it is broken?

I'm about to get it wired to a PIC to see if it works or not, just thought I'd check before trying to fix a broken LCD!
 

Krumlink

New Member
Is it a Hitachi HD44780 LCD? Depending on the LCD, it may have different power up protocols (no input, just power up). For example, my 16x2 Hitachi HD44780 LCD displays the entire top row as black.
 

edeca

Active Member
Yes, it is a HD44780 compatible controller. Only one of the lines is black, I can't tell which is the top!

I wrote a simple program in C18 using the library to test it but I haven't got it working yet, it spends all it's time in the busy loop. I'll check the wiring tonight and see.

Do you need to send any particular command to your LCD to initialise it?
 

Nigel Goodwin

Super Moderator
Most Helpful Member
It sounds perfectly fine, you're getting what you do on an uninitialised display.

If you don't initilise it exactly correctly, then that's all you get.

Check my PIC tutorials for details of what you need.
 

edeca

Active Member
Thanks Nigel. I'm using the C18 libraries to access the LCD but the code seems to be stuck waiting for busy to clear. I'll check the wiring tonight and if that fails, try some ASM from your tutorial.

I don't think it would matter but I tied RW to ground as instructed in a few schematics, as I don't plan on reading from the LCD.
 
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