[dorkbotpdx-blabber] Advice on large LED matrix

[Hans Lindauer]

As Mykle already mentioned, shift registers seem to be the way to go for 
this.  There are ones like the Texas Instruments 5940 which are 
specifically made for controlling LEDs - they have on-board pulse width 
modulation for controlling brightness and are able to drive a high 
enough load that you don't need external drivers (for standard LEDs).  
There are other versions without the PWM, if you don't need the 
brightness control.  You can chain them together to get as many pinouts 
as you need.  There may be simpler options than the 5940 - I 
experimented with them a little bit, but I thought they were a little 
more cumbersome than they needed to be.

There's a kit available for a 25x25 LED array, although it's not RGB: 
http://evilmadscience.com/tinykitlist/35-tinykitcat/75-peggy2
That one must be doing multiplexing, because you'd need forty 5940 chips 
to control each LED directly.  For RGB you'd need 120, and that might be 
prohibitive.  Of course, multiplexing cuts your brightness at the same 
time as it decreases the number of pinouts you need.

You could also do a grid of ShiftBrite modules: 
http://www.macetech.com/blog/

LED dance floor projects might be a good place to look.  There are 
others trying to do large RGB grids - I've seen a lot of similar 
inquiries on other forums when doing my own research.

-Hans


dalas v. wrote:
> I'm thinking of building a matrix of RGB LEDs. Brightness is a priority. Size would be maybe 1 or 2 square feet. Battery power would be preferred, but if there is a need for AC power, I'd need to use a prebuilt power supply, because I don't want to attempt making one. Minimum control would be 32 color options (preferably more), maybe you can program 8 - 12 sequences and switch between them?
>
> It seems like the arduino might be able to handle this? It would be my first arduino project. I know that it can control LED matrices and sequences, how would it be for a large matrix and how big / bright can I get?
>
> I'm in the really early stages with this, so any advice or links to kits would be appreciated.
>
> -dalas