Here is my display.. 98 of them in a 2'x4' box controlled by a nodejs web app.

http://www.youtube.com/watch?v=PXahEYJX9-g

The cutting board diffuser on this 7x7 display is genius. My diffuser material cost $$.

(If anyone wants to buy 98 on the cheap. Let me know. I'm going nomadic and have no place for my creations)

That looks awesome - are you looking to get rid of the 98 lights alone, or the whole thing?

Edit: Was going to write a seperate comment to the thread but had a change of heart, so I'll add my congratulations to jgc to this comment rather than cluttering the place up. Things like this regularly make me want to start playing with Arduinos, hopefully someday my laziness / lack of time (depending on how you look at it) will ease off.

Thanks.. My laziness gets to me in finishing the projects. I do the fun part of getting it to work, then slack on the polish it needs to be complete.

Just selling the lights would be best. Shipping on the 2 foot by 4 foot panel wouldn't be worth it.

Do you have Skype rather than stretching this chain out? If so, hit me up - I'm CorinCole :)

Edit: I really don't understand up/down voters here sometimes. How can a message asking somebody to add me to Skype get voted up to 4 points??

That's very cool. Love how it's interactive.

The cutting board diffuser came about because I went to my local hardware shop (which is not a chain) and asked the owner about pieces of opaque plastic (I was thinking pricey perspex). He's always got good ideas and said the only thing he could think of was a cutting board.

I've linked to the one I bought (he doesn't have a web site so I've linked to a chain that sells the same board). Dirt cheap and cutable with a Stanley knife.

How do you get three different kinds of diffusion with the same board?

The distance away from the light source ;)

Good job with the display, looks great.

Question: when you separated and reattached the LEDs, did you keep them in original order when reattaching? I seem to recall each LED node having a unique address, but maybe I'm misinterpreting.

No, I did not keep the in the same order. In fact when the LEDs power up they are waiting for the first packet to arrive and they will use the address in that packet to set the address for that LED. Until an LED has received its first packet it will not forward packets on.

So that allows you to program the LEDs with arbitrary addresses. I make use of this to program addresses that are easy to encode for the 7x7 display (each address is six bits so I use 3 bits for X and 3 bits for Y). This is complicated by the physical snaking layout on the board. See the code sample in the blog post for how this works.

https://github.com/jgrahamc/gece/blob/master/gece/protocol.c...

Good to know. Was going to hack up a set of these post-Christmas, and was under the impression that order of the LEDs needed to be maintained -- as if the addresses we're hardwired.

Thanks for the post.

I had a lot of fun playing with these sets last Christmas, and it has been my lighting of choice over the last year. Quite a fun and rewarding hack, and I'm sure the parallelism of more and more sets of these RGB LED strips will lead to greater things in the hobby world. I've seen music and entertainment productions use these strips quite effectively over the last couple of years.

Another noob question about the grid. Suppose you wanted a 10x50 grid (let's not waste any LEDs!), or basically a non-square grid.

Would that difference cause considerable change elsewhere? At the code level? Or with the Arduino controller?

A non-square grid would itself not be an issue but if you want to do multiple LED strings as would be needed for a 10x50 grid the code might need to be modified to have multiple data outputs for each string. You should be able serially connect the strings but at some number you will have issues with the data/power wires, and may not get your desired refresh rate.

The address system used is 6 bits long with one address reserved for broadcast, thus the maximum on one string is 63 LEDs. You'd also need to supply enough power (49 LEDs took 1.7A @ 5V). If you wanted to do 10x50 then I expected the simplest way would be to use 10 separate I/O ports to address them.

I'm very interested with that kind of projects, but I'm always wondering what to do once the hardware part (and software controller) is done. By that I mean the artistic part of it.

For example, take this sculpture: http://vimeo.com/21904379. I was thinking it could make for a very cool sculpture at home. Hardware-wise, it's very straightforward, but I wouldn't know what to hook it up to software-wise and how to show interesting patterns.

If you could set the addresses any way you want, why the odd diagonal configuration? I'm sure it's in the write up, but I must have missed it.

Very cool stuff.

Actually it's not in the write up, but it's a good question. By going with the diagonal configuration it was easier to solder the LEDs together. There's a bit more space (if the horizontal and vertical spacing is one unit then the diagonal spacing is sqrt(2) units) diagonally than vertically and since the LEDs are asymmetric (have the wired sticking out on opposite sides) this made it mechanically easiest.

Thus I 'fixed' in software a 'problem' created because of the constraints of the physical world.