Jurek and the Amazing Techno, Colored DreamWall

Jurek and the Amazing Techno, Colored DreamWall

The title is mostly a placeholder, as I haven't really figured out a name for it yet. This project is a wall hanging that consists of semi-large triangular pixels using discrete RGB LED's and PWM to control intensity levels of each LED, resulting in a 4096-color display.

Friday, June 03, 2005

Soldering and code update

Sorry for the delay in posting... It took me a day or two to get back into it after my vacation.

Vacation Report

Budweiser has this billboard in Times Square in Manhattan that uses triangular pixels. I didn't even know it existed until this last weekend when I noticed it there. It was on the south end of the 7th Ave/Broadway intersection, right below the Cup-o-Noodles billboard.
The triangle orientation was rotated 90 degrees compared to what I'm planning on doing and it had about 3 times as many pixels as mine (its width was about the same as the height for mine, but its height was about 3x my width... in raw pixels that is, not dimensions). Unfortunately, it was a Budweiser ad and the only colors they ever used were red, white, blue (for the flag, of course) and tan (for beer and foam, along with white). I was really hoping to see other colors from it, but alas... that was all.

When I went back to look at it at night, I noticed that each of the pixels was made up of about 50 or so smaller pixels. I couldn't tell if the subpixels were rectangular or triangular, but I'm willing to bet that they're rectangular. There were a rather large number of the subpixels that had one or more of the RGB component colors blown out. For example, magenta where it should have been white, indicating that the green component was blown. Still, it looked really awesome from a technical standpoint (I really couldn't care less about the actual content of the ad).


I got my new soldering iron and it works wonderfully. Wednesday night, I tried it out and I was amazed at how much easier the 1/64" (about 15 mils) tip was than the 50-mil tip I had before (imagine that). I was able to solder 2 driver chips onto 2 adapters without much problem. That being said, I still have some room for improvement. The first one I soldered had WAY too much solder on it and I had to use wick across all of the pins just to pull enough out. In the end, the worst cross-pin resistance I had was in the low MOhms. The second one faired much better (although I still had too much solder) and the cross-pin resistance increased an order of magnitude. Hopefully, by the time I actually start soldering the driver chips to the board, I won't get any resistance at all.


I spent the better part of this evening working on abstracting out some common tasks on the code to deal with programmatically setting pixel values better. At this point, I can call a function when I want to set any single register on a particular driver chip and I have a decent amount of automation in place for the 8-register writing necessary for all 15 LED intensity values.

I noticed that the code I had running before was resetting the driver chip each time it was writing out the intensity values, so by removing that code from the infinite loop, I was able to speed the code up immensely.

Currently, I have 2 driver chips hooked up and I can access each of them individually and assign a color to a particular pixel with relative ease.

I think I'm ready to lay out the driver chip board (should be easy... a header or two... the driver chip... and a couple of resistors) and possibly place an order on them. Progress continues!

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