L.E.D. Array

projectmayhem

alright, time to abuse your knowledge for my own gain

i'm wondering how easy/difficult it would be to make an LED array (say 3x3 or 5x5) that i can then run into my PC or an LED controller (if such a thing exists) that i can program to show various patterns. for example, a smiley face switching to a space invader guy.

if i can do this the idea is to program it into a winamp plug-in type of thing, just running through pre-programmed array structures (smiley faces et al).

i have the theory down alright, i've just no idea if it can be done, or if it's out of my league. i'm assuming maplin's sell the type of devices i need...

RoundyMooney

I'll leave the practical stuff to someone better qualified...

But, you'd be looking at a minimum resolution of 15*15 LEDs, I'd imagine, in order to end up with a usable image?

projectmayhem

RoundyMooney wrote: »

I'll leave the practical stuff to someone better qualified...

But, you'd be looking at a minimum resolution of 15*15 LEDs, I'd imagine, in order to end up with a usable image?

oh yeah i understand that i'll need to aim a lot higher then 5x5 to be proper, but i'd like to build a small one first so i know what i'm doing. trial and error etc.

RoundyMooney

Ah ok.

Nothing is impossible, let me do a bit of googling and see what's out there...

I remember something similiar was done with nixie tubes (think old LEDs-although they were in practise, completely different, and represented the numbers 1 thru 0 depending on the pins energised...)

Anyway I'm gone off on a tangent now.

10-10-20

You're looking at multiplexing - that's easy, it's the programming which is difficult....
Have a look at the datasheet for 74LS138 which is a 3 to 8 line decoder (€2).
http://ece.colorado.edu/~mcclurel/sn74ls138rev5.pdf

With this and a 4x4 LED array for example, you can write to the lines in the array. For example, writing to row A, column 1, you'll get the top-left LED to light, writing to row B, column 1, you get the LED under A1 to light...

Then what you have to do is get the LED's in the array to light in a scanned fashion, giving the impression of a static image.

projectmayhem

10-10-20 wrote: »

that's easy, it's the programming which is difficult....

hopefully the whole college thing comes in handy then

if i manage to do a small one correct i may motion this idea as my final year project. whether it's applicable to an computer science style degree is another thing altogether...

Stoner

sounds complicated lads TBH.

anyway
http://led.linear1.org/led.wiz

is handy for the basic LED Arrays I use., but no where near useful for this thread

10-10-20

That wizard doesn't use the same array setup I'm thinking of... You're not lighting a row of LED's at a time, you are lighting one at a time, but you do it so quickly that it appears to be multiple.

Here... this is better...
http://users.tpg.com.au/users/talking/Construction-Part1.html
Ignore the PIC (16F84) as you are doing this at a lower level.

Look at the scan control transistors, they link into the second 74LS138 and are addressed via the binary input.

So, you would write to one '138 as the column controller, and the second '138 as the row controller.

projectmayhem

thanks for all the info lads. when i get going on this i'll post some updates, let you know how i'm troubleshooting/programming. if i get to the finish line i'll post up the code for my winamp plug-in too

LeBash

This can be done with a pre-programmed "DMX" system. Alot a good quaility LED manufactures make them. If you are going with basic white it will be no problem, if you want colours you need RGB LED's and not trying to mix them. I seen something simular to what your trying to do when i was doing OEM training on LED and lighting controls.
If you can get your hands on the Osram corperate video you will see it done with DALI controls on an entire building. The DMX will do the same thing for LED, but because DMX will also dim LED's its an expensive enough piece of kit.
Also, look into OLED, its a new technology that will replace LCD tv's the old OLED's if cheap enough would be perfect for that