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I am trying to drive a small (20x2) LCD screen from a Parallax Propeller board/chip. Can't find a decent manual anywhere. This is the LCD:

http://www.jameco.com/1/1/24982-hc20216nyu-lyvo-20-2-black-yellow-parallel-lcd-display-green-backlight.html

On that page there is a PDF which gives the pinouts:

http://www.jameco.com/Jameco/Products/ProdDS/2155372.pdf

...which is better than nothing.

But I can't find anything about what kind of data I'm supposed to push over those data pins, frequency/timing, and some detail about what the other pins do.

I've googled quite a bit.

EDIT: After a bit more googling (with the proper wording - tks @Joe Hass), it seems like a lot of the same parts are used in these things (e.g. Samsung S6A0069), so I'm thinking one of this propeller object might work with it: http://obex.parallax.com/object/337

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That lcd is a typical dime a dozen, hd44780 or ks0066 compatible Character LCD display. The HD44780 is a standard parallel input display controller, with well documented information, and 99 out of 100 character lcd displays will use the same protocol. Heck, even some serial, i2c, and spi character displays are really HD44780 displays with a secondary chip (often called a backpack) acting as a middleman.

And Yes, that Propeller object you link to will work for it. In fact, here is more: http://obex.parallax.com/search/HD44780

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  • \$\begingroup\$ Right - that makes sense. After looking at several of these they all basically have the same pins, similar voltage, etc. I wired it all up now and tried running the propeller object tests but it's still dead as a doornail. My propeller board is running at 4.25v, I'm using it's power to power the LCD says it requires 5v (maybe a little less but I guess 4.25 doesn't cut it - or s/t else is wrong)... \$\endgroup\$ – bgp Sep 15 '13 at 1:28
  • \$\begingroup\$ You can power the lcd from 5v but connect the data pins to a lower voltage. I've done this with a 3.5v MSP430 Launchpad. Also, you need to make sure you have the contrast pin connected properly (I just tied mine to ground). \$\endgroup\$ – Passerby Sep 15 '13 at 1:33
  • \$\begingroup\$ Good point. For now I found another similar LCD that has slightly lower voltage requirements, but will try that if I have time to give it another shot. You're most definitely right that these things are pretty much the same, just have to play with the addresses and the rowXcol layout and things like that. \$\endgroup\$ – bgp Sep 15 '13 at 18:09
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What you have is not an LCD "screen", it's an LCD character display. Googling for "LCD character display propeller" provides 1,900,000 hits. I've done this with ARM processors and it's not terribly difficult but it's more than can be summarized here.

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Here are two places that have the command set for LCDs.

My tip is that using it in 4 bit mode is fine, there's no point in using all 8.

http://www.8051projects.net/lcd-interfacing/commands.php

http://www.csus.edu/indiv/p/pangj/166/handout/Handout_Character_16x2_LCD.pdf

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  • \$\begingroup\$ Thanks - I don't see a 4-bit option on this particular one I'm using, but still deciphering here. \$\endgroup\$ – bgp Sep 14 '13 at 23:21

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