Building LED walls on the cheap

Around this time last year, [KopfKopfKopfAffe] was enlisted as a set designer and was told to build some sort of light effects for electronic music parties. The budget for the project wasn’t much at 200 Euros, but he did manage to build decent 5×5 RGB LED matrix that is fully controllable by a computer.

[KopfKopfKopfAffe] didn’t have the time or money to wait for manufactured PCBs, so a bunch of perfboard was placed in a CNC mill with a pen to act as a plotter. All the lines that needed soldered were drawn on by the mill, a feat that probably saved hours of looking at the design before committing solder to iron.

A total of five boards were constructed, each one capable of controlling five RGB LEDs. Each board can be dasiy-chained with an RS-232 serial connection for further expansion. The only thing that’s needed to control the matrix is 17 bits that includes an address and RGB color data for each LED. The system only cost about 10 Euros per node, but we think that could be significantly reduced by leaving out the Molex and DB-9 connectors. [Kopf] project turned out very nice, check it out after the break.

Comments

  1. Mike says:

    Now I’ve got to make one of THESE! I’m not whining, it just sounds that way.

  2. Sergio says:

    Hey.
    The specs say 24bit color (3×8).
    I’ve kinda figured out what the firmware does, and it seems to be outputting power (for each color channel) proportional to the number of HIGH bits in the 8 bit color value, wich leads to only 9 possible values (0 to 8 bits set) instead of 256.
    That’s below 10bit color.
    Or did I miss something?

  3. Brian says:

    Why not use the well-known DMX512 protocol instead of RS232?. It could probably have been done a little cheaper too.
    And if you have access to a CNC machine, why not just mill the PCBs?

    • Milling PCBs takes a lot of experience and/or the correct tools. We made some experiments a year ago but gave up along the way somehow. I went with perfboard in this project because I had no time left to be spent on milling experiments.

      About the protocol: I use the well-known RS232 because its easy to use on a PC. No DMX adapter necessary. No need for DMX adapter drivers. OS independent. Easy to implement on a microcontroller.

      • Brian says:

        I myself am an owner of small desktop CNC machine, and there is almost only one thing I can figure out how to use it for, and that is milling and drilling PCBs.

        A DMX adapter would be easy enough to build yourselve based on a small microcontroller, it could then be connected to a RS232 port or a USB port, it would cost approx $10 and with the right firmware it would run the existing PC software without any changes to the software.

  4. Sasha says:

    Have you tried addressable LED ‘pixels’? Basically you have an RGB LEDs connected directly to a DMX receiver . Like that, you can save all the fuss of programming it.

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