Can Controller for LCD be changed to control LED board?

vollord

This is just a very general question.· I do not have any experience dealing with BASIC Stamp and the LCD's.· I was just curious if I put LED's on a circuit board with the same amount as the pixels on the given LCD board controller id use.· Is it possible to do this?· Basically trying to make a custom sign for my business...the cheap and labor intensive way.· Any thoughts on the idea would be appreciative, thanks.

Chris Savage

·· The short answer is, "no."· The controller chips on the back side of an LCD display do more than just store the data and CG ram and handle the instructions.· The chips were designed to drive very low current LCD panels mapped in a very specific way.· The LCD's crystal panel is scanned in a very specific manner at a varying rate, and it would never be able to drive discrete LEDs.



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Chris Savage

Parallax Tech Support
csavage@parallax.com

allanlane5

You can't do this and use the Hitachi HD47780 driver chip, which is what the previous response is saying. You certainly CAN build a unit, driven by a Maxim 7218 LED driver, with the same number and position of pixels as a comparable LCD panel. It will be much bigger, of course, and the code to talk to it would be much different than the LCD -- but you can get the same effect.

It will also pull more power. An LCD is a very low power device compared to an LED driven sign. But that's a good thing -- the LED version will be much more visible.

Note they do manufacture small LED blocks of 5x7 LED's each which can be used for this purpose. That's what commercial scrolling signs use.

In all fairness you should be told it's probably much easier and cheaper in the long run to get one of the commercial units -- I think CostCo has them for less than $300. Not nearly as much fun, or as much control though.

Chris Savage

·· After reading Allan's post, I re-read the original post, and Allan, I can't help but wonder, if it's a matter of using the same amount of real-estate as an LCD, wouldn't a VFD Display be a better choice?· I guess I am unclear whether vollord is looking for the same size as the LCD, or the same resolution, but on a larger scale.



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Chris Savage

Parallax Tech Support
csavage@parallax.com

Tom-Matrix Orbital

Have you considered using a Matrix Orbital VFD. They are bright and easy to send data too, since they serial interface devices. You can also use a PLED too. You can check out the units at www.matrixorbital.com . Questions related to the units can be answered on the forums at http://lcdforums.com/forums/index.php .

Best Regards,

Paul Baker

vollord said...
Basically trying to make a custom sign for my business...the cheap and labor intensive way.

VFD does not satisfy this considering VFD's are typically 2 or more times expensive than LCD. And he is talking about a pixel equivalency, meaning larger size.

Vollord, you may want to look into using LED display modules like shown here: http://www.parallax.com/detail.asp?product_id=28099·but again an LCD controller could not control one of these.

Post Edited (Paul Baker) : 3/24/2005 5:17:25 PM GMT

Chris Savage

Paul,

·· My question was based on pixel equivalency...Which means that VFD Displays qualify, since they're basically the same pixel configuration as LCD, except that they're lit up.· In that context, VFD could almost be compared to an LED version of LCD, if you were somehow able to make pixel-sized LEDs that were on the board.

·· As for cost, a VFD display would be a lot cheaper than discrete LEDs trying to do the same thing with the same resolution.· Again, this is based on the assumption that the OP was looking for an LED version of LCD Displays.· Just as some people prefered the older LED Wrist Watches to the new LED ones, since you could read those at night without a light.

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Chris Savage

Parallax Tech Support
csavage@parallax.com