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Particle swarm LED lamp

Discussion in 'LEDs and Optoelectronics' started by Hugo, Jul 18, 2017.

  1. Hugo


    Jul 18, 2017
    I am currently designing a kinda LED matrix that will display a particle swarm (around 2000 particles).

    The inspiration for this project is the Random International Swarm Study VI

    In this picture one can see that it was built using small PCB boards. The interesting thing is that "columns" of this boards are chained using 3 power/communication lines (to our knowledge, VCC, GND y SIGNAL) and the "cables" are 2.4mm diameter brass rods (this has been confirmed)

    I believe that the way they're chaining the boards is using an WS2812 or something similar, because each led in every column is addressable. As I want to implement more complex algorithms and even a bit of AI in the future, this kind of driver is not the best option for me.


    Currently I've determined that versatility will be paramount while dimming, controlling the LEDs and implementing some behavioral algorithms that require each particle to have its own memory, rules and overall behave as a "neuron" (this is different from the original design) Considering that, I've decided that I'll be using an MCU in each board and I already bought 2,500 ATMEGA16/QFN for 0.25USD each (they are currently very cheap in Digikey, starting 0.5 USD for 1-10 pieces batch)

    I already made some tests and it is possible to interface 12 boards in a column connected by a 4 feet length brass rod (its diameter is around 0.1 inches) using the MCU UART at 9600bps (up to know at least); that means we are interfacing 12 RX -MCU addressable "slave" lines to a single TX line from a "master" MCU. I am aware UART is designed to be point to point but I am on a budget and the least quantity of components, the better (and also considering I have only one line for communication > VCC, GND, *DSIGNAL <)

    1) The first question I would kindly ask to all of you is if you believe using a buffer in the TX line from the controller will allow me to get a faster baudrate. If not, what kind of signal conditioning would I need? I am aiming for the 115kbps baudrate but I am worried about the output current and noise tolerance along the single communication line.

    2) If I want to interface more than 12 slaves on the described chain, would it be possible? Imagine each column connects 12 boards, so we will require one MCU "master" for each o them ( we would be talking about 96 independent columns) . The best possible scenario is to at least control 8 columns per "master", that would drop the amount of "master boards" needed to only 12. I am considering using a demultiplexer to demux the TX "master" signal (with a BiCMOS 8 channel demux), but I would also ask all of you if there's a better alternative.

    3) For communicating the master boards that control 8 columns each, I am thinking on SPI. I have already read about long distance SPI over RS-422/RS-485, and that would be desirable because this screen must have a refresh rate of at least 60Hz in order to avoid flickering. That means 1Mbps to communicate the masters would be incredible for exchanging about 5Kb of data every 1/60 seconds.

    Please forgive my rusty english and that I am not an electronics expert (my BSc. is in robotics and automation and my MSc. is in financial engineering) Thanks a lot in advance for your comments and suggestions.
    Last edited: Jul 18, 2017
  2. BobK


    Jan 5, 2010
    Interesting project.

    It might be interesting to think of a purely local algorithm, where each node communicated only with near neighbors. I would think swarming behavior could be modelled that way.

  3. Hugo


    Jul 18, 2017
    Thanks for the response. It is exactly that way, neighbors are fundamental to calculate a particle position in space. It is also known as "flocking".
  4. JWHassler


    Dec 22, 2014 has a WS2812-driver board that, combined with one of their CPU boards, can drive hundreds of LEDs via DMA. leaving the CPU nearly idle.
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