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Simple HD44780
hardware : by Nate - November 7th 2005, 09:56AM
Tommy gave me a parallel character LCD that he's had stashed away for a long time. He was on the right track, just never finished it. I looked at what he'd made, based on the original schematic. I hooked the LCD to a DB25 connector that was already soldered to a ribbon cable, hooked it up and it worked.

I noticed that the brightness and contrast knobs were set and didn't need to be adjusted. One pot was even set to 0! After a few minutes I was able to boil down the circuit to just use one 50-ohm resistor.
Here is the final "simple" schematic:
simple HD44780

This schematic should work on any Hiatchi HD44780-based character LCD, so long as it only has a single 8-bit connection, like the Seiko L2014.

update: You may also use this LCD screen test app to check your LCD: http://www.neodux.com/projects/lcd/LCDsetup.zip

Grendel sez: You da man, sir. Thanks. Here is a picture of the LCD in action. Videos are here (2.5Mb, avi) and here (6.9,avi).

update: I (grendel) just got the LCD working under linux using lcdproc/LCDd. Now, if only I could figure out how to get lcdvc to work with it, I'll be even more pleased.


+ anonymous
  Nov 07, 2005 19:50
awsome, where can i get the LCD though...


+ Tommy G.
  Nov 07, 2005 20:24
Character LCDs, like the Seiko L2014, are available from EIO.

May I also suggest using an old parallel port connector from an old computer(preferably with the ribbon cable already soldered to the DB25).


+ anonymous
  Nov 09, 2005 20:37
sweet .... i so want one that'll do 640x480 (good luck!!)


+ Tommy G.
  Nov 10, 2005 08:16
I have a small 4" LCD, but I can't remember where I got it. It's completely different from this though. This LCD is a "character LCD" which mean it isn't measured in pixels, or even capable of displaying color. Instead, this one only displays a single per-defined character per space.

The 4" LCD that I have, I bought ages ago when I read about it on this guy's page. It came from PartsExpress.com, but it appears they have no more. You might also browse MP3Car.com, since there's a whole community in search of small, cheap displays.


+ Tommy G.
  Nov 10, 2005 08:22
Anyone using WinAmp with their LCD might like this link.


+ anonymous
  Nov 28, 2005 10:45
Hi, I found your site in my referrer log because your Digg story links to Anyterm. Then I scrolled down and found this. I've also been playing with an LCD module and have connected a 4x20 display to my "slug" Linux box. I wrote a terminal program for it, the details of which are all here: http://chezphil.org/slugterm/. I used USB, but you could hack it to work with your parallel port. It uses the same terminal emulation library (ROTE) as Anyterm.

Cheers, Phil.


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