More on the matrix/array

Date: April 13, 2010 | Comment

It’s been a few months since I last posted here … I don’t think there are any constant visitors who’ve been bummed out about the lack of activity, but I apologize nonetheless.

Since we last spoke I threw the LED matrix project out to the Do It Yourself Christmas community to see if I could get some others interested and willing to help. I got a couple of bites and have spent the last few months working with them, trying to further my goal of building an LED star that has 60 lamps, three colors and can be driven by DMX-512. You can see the discussions.

The current circuit is based on the Atmel ATTiny2313, two 74HC595 shift registers and a ULN2803 Darlington array to handle sink current (plus an RS485 chip to handle DMX signals and associated resistors and capacitors).

Unfortunately, I haven’t been able to make as much progress as I would have liked. I have a breadboarded circuit that works, but unfortunately, it works backwards. That is, when the DMX application sends a signal to an LED to light, it is dark; when there is a DMX signal but sent to have the LED dark, it lights.

Big brains in the DIYC community haven’t been able to figure this one out, so for now I remain mired in my own ignorance.

That’s all I know right now. Stay tuned for more information.

    
Tags: Atmel | DMX-512 | LED

3 comments. Add yours ...

  • Chris
    1:09 am on October 18th, 2010

    I just stumbled upon your site and so am reading this post WAY after you posted it, so probably you’ve solved this problem long ago. But if not…
    Maybe I was misunderstanding your problem, but could you not simply invert the signal post-microprocessor? I know it’s an ugly hack, but, if you just put an inverter chip in (like a CMOS 4069) you could run your signal lines out of the Atmel into the 4069 and then to your LED’s and if your code said “light”, and the atmel said “dark”, the 4069 would switch that back to “light”, and light the LED.
    But like I said, I’m probably not actually understanding the real problem.
    Cheers,
    Chris

  • dmcole
    11:27 am on November 10th, 2010

    Chris:

    Thanks for your insight. I’ve put this project on hold for the next couple of months; when I return to it, I will explore the 4069 as an answer.

    \dmc

  • smartalec
    9:17 am on August 11th, 2011

    Hi there, I just finished my Star http://vimeo.com/27579263 using the renard64 with uln2803′s an 12v RGB Led Strip.

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