LED Matrix Hack Chat

Let's see how deep this rabbit hole goes.

Wednesday, June 9, 2021 12:00 pm PDT Local time zone:
Hack Chat
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Garrett Mace will host the Hack Chat on Wednesday, June 9 at noon Pacific.

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It's pretty amazing how quickly light-emitting diodes went from physics lab curiosity to a mainstream commodity product made in the millions, if not billions. Everything about LEDs has gotten better, smaller, and cheaper over the years, going from an "any color you want as long as it's red" phase to all the colors of the rainbow and beyond in a relatively short time. LEDs have worked their way into applications that just didn't seem likely not that long ago, like architectural lighting, automotive applications, and even immense displays covering billboards, buildings, and sporting venues with multicolor, high-resolution displays.

It's that latter application that seems to have provided a boon to electronics hobbyists, in the form of cheap and plentiful LED matrix modules. These are easily sourced at the usual places, and with their tightly packed pinpoints that can show any color at any intensity, they have a ton of fun and useful applications for the hacker. But how exactly do you put them to use? Usually the electronics end is pretty straightforward, but some of the math involved in figuring out how to address all these LEDs can be a little mind-bending.

To help us sort all this out, Garrett Mace will drop by the Hack Chat. You've probably seen Garrett's cool LED matrix shades, which have gone through a ton of revisions and are a much-copied fashion accessory among the cool hackers. They look simple, but there are tricks to making them work right, and Garrett will share his secrets. Come with your questions on putting LED matrix modules to work, especially those odd-size modules and strange arrangements that defy simple Cartesian coordinates.

  • Hack Chat Transcript, Part 2

    Dan Maloney06/09/2021 at 19:55 0 comments

    Steve Pomeroy12:23 PM
    @Jason Moungey that's a disco stick if I've ever seen one!

    Jason Moungey12:23 PM
    Either way I am in love with it

    Jason Moungey12:23 PM
    @Steve Pomeroy :)))))

    Garrett Mace12:24 PM
    Once you do your transforms, you can step through the physical pixels you have, pull out their coordinates of interest, and feed that into your generation algorithm

    Garrett Mace12:24 PM

    Steve Pomeroy12:24 PM
    I'm loving these explainer gifs!

    Garrett Mace12:25 PM
    I definitely recommend perusing some old math texts, maybe Khan Academy or really helps! And I do love my Python and matplotlib!

    Orlando Hoilett12:25 PM
    @Dan Maloney are we still saving HackChat transcripts?

    Ben Hencke12:25 PM
    @Garrett Mace what did you end up using to make these explainer gifs? good stuff

    reynolds.garrett12:26 PM
    What software are you using to simulate your end result?

    Garrett Mace12:26 PM
    Most of the patterns on that LED Nonagon are very simple. I have it run through the pixels and feed coordinates to generator classes. The core algorithm for many patterns is a oneliner

    Garrett Mace12:26 PM



    CRGB render(pixel_info pix) {


        int8_t color = (int32_t)(pix.r/12*(int32_t)(sin16(angle))/256) + pix.angle*256/PI*1;


        CRGB ret_color;


        ret_color = ColorFromPalette(palette, color+hue, 255);


        return ret_color;



    Garrett Mace12:27 PM
    Ben: I'm rendering them in Matplotlib, frame by frame, from within jupyter notebook

    Garrett Mace12:27 PM
    reynolds: I usually dev actual patterns on the device itself. However, there are some great FastLED simulator projects on github

    Garrett Mace12:28 PM
    I know hackaday posted one pretty recently?

    Garrett Mace12:28 PM
    I would like to figure out how to feed LED algorithms directly into Blender and render the results in EEvee

    Garrett Mace12:29 PM
    In any case....if you precalculate the math, use a "shader" style approach to generating physical-space patterns, you might forget the actual complexity looks like this:

    reynolds.garrett12:29 PM
    That would be slick, and thanks I will have a look around on github for some simulators

    Garrett Mace12:29 PM

    Steve Pomeroy12:29 PM
    Do you do most of your project mockups/renders in Blender?

    reynolds.garrett12:29 PM

    Garrett Mace12:30 PM
    Steve: I've done a few, but definitely not most. Lots of pencil sketches, and some guesstimations

    Steve Pomeroy12:30 PM
    Gotcha. I've been trying to figure out a good workflow for LED-based sim there. Sounds like Eevee? :-)

    Garrett Mace12:30 PM
    You can build the thing, and then measure where the pixels are, or where a strip starts and ends and what the pixel spacing is

    LqqkOut12:31 PM
    🤯 Incredible images! Maybe a chicken and egg question, but did you have the mathematics background when you started doing animations or did it evolve from these projects?

    Garrett Mace12:31 PM
    Eevee is a graphics-card based render option in newest Blender releases, it's a lot faster

    Garrett Mace12:32 PM
    LqqkOut I graduated as an EE with pretty heavy math along the way, but that was almost 20 years ago. Knowing where to look helped (hence this hack chat) but I did have to relearn a lot

    Garrett Mace12:34 PM
    Any other questions about the above projects, approaches to LED mapping, how to even use this, or random thoughts about the state of LED tech today?

    Ben Hencke12:34 PM
    I found this bit to be really good at explaining transformation matrix math:

    Garrett Mace12:36 PM
    That looks pretty good! I'm thinking about switching to Javascript (as in your link) because I think it'll be a bit more performant, easier to share, interactive

    Garrett Mace12:36 PM
    I mean look at all this cool stuff:

    LqqkOut12:36 PM
    (hold for later if it's coming up!) Any lessons-learned or tips re: power and power distribution? I imagine these can be pretty...

    Read more »

  • Hack Chat Transcript, Part 1

    Dan Maloney06/09/2021 at 19:54 0 comments

    Dan Maloney12:00 PM
    OK, people are still coming in but I think we can get started. Hello everyone, thanks for coming out today. I'm Dan and I'll be moderating along with Dusan today as we welcome Garrett Mace to the Hack Chat. We'll be talking about cool tricks to making LED matrix project easier and better.

    Garrett Mace12:00 PM
    Hey everyone!

    Dan Maloney12:00 PM
    Hi Garrett! Can you tell us a little about how LEDs became your thing?

    Dusan Petrovic12:00 PM
    Hello and welcome!

    Garrett Mace12:01 PM
    They always were! I started experimenting with electronics while LEDs existed, so my first circuits of course blinked an LED or two

    Dan Maloney12:01 PM
    "Hello world" of hardware, right?

    Garrett Mace12:01 PM
    Once you go from one LED to two LEDs, it's a slippery slope. You never come back!

    Garrett Mace12:02 PM
    I have some intro material if it's OK to launch it?

    Dan Maloney12:02 PM
    Yeah, go for it

    Tim Slagle joined  the room.12:02 PM

    Garrett Mace12:02 PM
    Hi, I'm Garrett Mace of I work on lots of projects, but in this chat will focus on LED stuff. Specifically LED matrixes, non-rectangular LED arrays, and LED matrixes in non-rectangular arrays ;) Here are some examples of projects I've worked on:

    Garrett Mace12:03 PM

    Darrin B joined  the room.12:03 PM

    Garrett Mace12:03 PM

    Steve Pomeroy joined  the room.12:03 PM

    Garrett Mace12:03 PM

    Garrett Mace12:03 PM

    Garrett Mace12:04 PM
    So you can see that while some of them involve 1D and 2D LED arrays, they may not confirm to regular grids

    Dan Maloney12:04 PM
    Whoa - just the logisitics of installing that ceiling project must be a story worth telling.

    Garrett Mace12:04 PM
    This poses several problems, if you want to make your LED animations make sense in the physical world

    Jason Moungey joined  the room.12:05 PM

    Garrett Mace12:05 PM
    The ceiling install was a lot of fun: I got to design and order custom extrusion for example!

    Pete Willard12:05 PM

    Garrett Mace12:05 PM
    We used about 35 networked Teensy 3.6's (thanks Paul)

    Paul Stoffregen12:05 PM

    Garrett Mace12:06 PM
    And 3D mapping done with Touch Designer. This was a collab with Tangible Interaction up in Vancouver BC

    Nick joined  the room.12:06 PM

    Orlando Hoilett12:06 PM
    Who did you design the ceiling light show for?

    reynolds.garrett joined  the room.12:06 PM

    Steve Pomeroy12:07 PM
    Nice! Do you have any tips/tricks for LED mapping with TouchDesigner? Or resources that explain it well to beginners? (I'm teaching a workshop on doing LED art with TouchDesigner now and looking for intro resources)

    reynolds.garrett12:07 PM
    TD definitely seems to be the leader in lots of LED projects I see. They keep popping up. A bit of a learning curve, but it's soooo powerful!

    Garrett Mace12:07 PM
    That was a sort of office HQ for a development up in the Squamish wilds. We had a bear alert on site and had to hide!

    TyIsI joined  the room.12:07 PM

    Garrett Mace12:07 PM
    Steve: On Touch Designer we had someone else do the intense 3D mapping

    Steve Pomeroy12:08 PM
    Gotcha. Understandable, it can get pretty hairy!

    grcornwe12:08 PM
    Besides TD, any other tools/techniques you find useful for working with non-rectangular matrices?

    Garrett Mace12:08 PM
    It was a very complex setup that mapped stick points into 3D space, mapped patterns onto a model of the actual install

    Orlando Hoilett12:08 PM
    @Dan Maloney can we ask questions here or do we have to fill out the Google Sheet (if we still do that)?

    Garrett Mace12:08 PM
    I believe he was projecting textures onto the sticks and extracting them to LED colors

    Dan Maloney12:09 PM
    @Orlando Hoilett - ask away! No formalities here!

    Ben Hencke12:09 PM
    nice ceiling effect! was that mapped to some kind of cartesian space or work on some kind of connection topology?

    Garrett Mace12:09 PM
    grcornwe: I have lots of material on that aspect :)

    Garrett Mace12:09 PM
    You can draw shapes pretty easily using (x,y) coordinates just like a computer screen. But what if your project...

    Read more »

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