LED Grid Issue - Solved, thanks

CassLan

*** Update ****
As it turns out, I neglected to place a % symbol in the OUTA commands when attempting to clear the screen
Thanks for the responses.
Working Properly:
http://www.youtube.com/watch?v=gylFS5L2bLI
*************




Hi all,

Working on a desktop clock for myself comprised of a 7x5 led matrix.

Made from a hacked USB Proto board, and a DS1302.

Presently I've just been working on getting some scrolling animations going, at which point I would like to make a character driver for this display..and then get the time/date displaying.

I'm having a wierd issue where whenever I start to do fast updating of the LEDs, I get a ghosting effect, and some LEDs come on that should not be on.
They come on dimmer than the intended LEDs, but are still visible. I have tried clearing all LEDs before lighting up the next one, thias does not help.

Does anyone have any idea what this could be or how to solve it?


Video showing 3 collumns having this effect while attempting a Saw-tooth animation
http://www.youtube.com/user/casslan#p/a/u/0/MVm2h0DEcGI

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Post Edited (CassLan) : 11/29/2009 10:15:38 PM GMT

Leon

Schematic?

Leon

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JonnyMac

Leon's correct, a schematic would be helpful. In similar projects I always clear the current column before going on to the next to prevent ghosts -- maybe that will help.

MagIO2

Looks like it could be a hardware problem. Soldering flux can be a bridge - clean it. Shortcut anywhere?

Try it in slow-motion. I mean switching the LEDs at a speed you can follow with your eyes. If it's a problem in the program you should see that. If you set pins high/low one after another you can measure what you get on the display.

CassLan

I have put up a Schematic of the LED Portion, Rvalues are 47Ohms.
Also some pictures of the Board.

Mag, I am trying to pin-point the exact circumstance to which this occurs.

Thanks,

Rick

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MagIO2

In your code you light several LEDs in one column at the same time. You are aware that this type of code will result in columns which are darker than other columns? The more LEDs are lit in a column the darker it will be.

CassLan

As it turns out, I neglected to place a % symbol in the OUTA commands when attempting to clear the screen. That solved it.
Thanks for the responses. I uploaded a vid of it working properly but youtube is taking forever to process it.
http://www.youtube.com/watch?v=gylFS5L2bLI

Mag,
Yeah I am aware of that, I'm really just starting this project with the hardware portion complete now I will venture into the coding that will allow me to time the single LED lighting that will yeild a smooth look.
I'm trying to end up with some code that will take my row/collumn data blocks and safely light only one LED at a time but will populate the entire display to appear on.
I'm not too sure of what the delay between switching LEDs should be.

Then beyond that, I'm hoping to write some code that will alter the once static row/collumn data blocks with dynamic data to do scrolling...etc.
I dont think this is worth doing until the proper display driver (lighting one LED at a time is done)

Should I plan the timing to assume that all 35 LEDs will be used? This would keep the speed constant I guess.

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Post Edited (CassLan) : 11/29/2009 10:16:19 PM GMT

jazzed

Hey Rick! Good to see you post here. Cheers.

Jay Kickliter

Thanks for sharing.

I was just working on a similar project when I read your post, 8x8 LED's. I'm attaching what I have so far.

I'm back in town (Queens), still having Gotham Prop Club meetings?

Jay

mikediv

cassLan very cool thank you for sharing

Toby Seckshund

Jay

I live 2 miles south of the "original" Gotham, Notts. the locals call it " Goat-um". Its main claim to fame is that they all pretended to be mad so that the King wouldn't travel that way ( in cas he got "infected" ). This meant that it wasn't a royal route and the road maintenance tax wouldn't be levyed.

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Hugh

Toby Seckshund said...
Jay

I live 2 miles south of the "original" Gotham, Notts. the locals call it " Goat-um". Its main claim to fame is that they all pretended to be mad so that the King wouldn't travel that way ( in cas he got "infected" ). This meant that it wasn't a royal route and the road maintenance tax wouldn't be levyed.

Perhaps someone ought to tell them that they can stop pretending now...

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Hugh - the thinking woman's Geoffrey Pyke.

CassLan

Jay,

Its been off, but coming back [noparse]:)[/noparse]

Rick

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