A Multi-Layered Spin On Persistence Of Vision

By taking advantage of persistence in human vision, we can use modest bits of hardware to create an illusion of a far larger display. We’ve featured many POV projects here, but they are almost always an exploration in two dimensions. [Jamal-Ra-Davis] extends that into the third dimension with his Volumetric POV Display.

Having already built a 6x6x6 LED cube, [Jamal] wanted to make it bigger, but was not a fan of the amount of work it would take to grow the size of a three-dimensional array. To sidestep the exponential increase in effort required, he switched to using persistence of vision by spinning the light source and thereby multiplying its effect.

The current version has six arms stacked vertically, each of which presents eight individually addressable APA102 LEDs. When spinning, those 48 LEDs create a 3D display with an effective resolution of 60x8x6.

We saw an earlier iteration of this project a little over a year ago at Bay Area Maker Faire 2018. (A demo video from that evening can be found below.) It was set aside for a while but has now returned to active development as an entry to Hackaday Prize 2019. [Jamal-Ra-Davis] would like to evolve his prototype into something that can be sold as a kit, and all information has been made public so others can build upon this work.

We’ve seen two-dimensional spinning POV LED display in a toy top, and we’ve also seen some POV projects taking steps into the third dimension. We like where this trend is going.

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Flashing LEDs With MIDI, Note By Note

Musical keyboards that light up the correct notes to play have long been touted as a quick and easy way to learn how to play. They’re also fun to look at. [Shootingmaker] has developed a similar concept, with a keyboard lookalike, covered in LEDs (Youtube video, embedded below).

The project consists of a PCB, in which the design of the mask imitates the white and black notes of a piano. This makes it look like a keyboard, but as far as we can tell, it doesn’t actually work as one. All the notes are fitted with APA102 addressable LEDs, under the control of a Teensy 3.2 board, operating in USB-MIDI mode. The Teensy receives MIDI data, and then directs the individual LEDs to flash in different colors based on which MIDI channel fired the note.

It’s a fun way to visualise MIDI data, and we think it would be even more fun combined with a basic synthesis engine to make some noise. We suspect it wouldn’t be too hard to integrate the project into an existing instrument, either. Software is available on Github for those interested in replicating the project. You can use MIDI to control neon lights, too.
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Gyro Controlled RGB Blinky Ball Will Light Up Your Life

[James Bruton], from the XRobots YouTube channel is known for his multipart robot and cosplay builds. Occasionally, though, he creates a one-off build. Recently, he created a video showing how to build a LED ball that changes color depending on its movement.

The project is built around a series of 3D printed “arms” around a hollow core, each loaded with a strip of APA102 RGB LEDs. An Arduino Mega reads orientation data from an MPU6050 and changes the color of the LEDs based on that input. Two buttons attached to the Mega modify the way that the LEDs change color. The Mega, MPU6050, battery and power circuitry are mounted in the middle of the ball. The DotStar strips are stuck to the outside of the curved arms and the wiring goes from one end of the DotStar strip, up through the middle column of the ball to the top of the next arm. This means more complicated wiring but allows for easier programming of the LEDs.

Unlike [James’] other projects, this one is a quickie, but it works as a great introduction to programming DotStar LEDs with an Arduino, as well as using an accelerometer and gyro chip. The code and the CAD is up on Github if you want to create your own. [James] has had a few of his projects on the site before; check out his Open Dog project, but there’s also another blinky ball project as well.

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When Are Dumb LEDs The Smart Choice?

A couple years ago I got into making electronic conferences badges by building a device for DEFCON 25 shaped like a dragonfly. Like all badges the most important design factor was quite literally how flashy it was, and two years ago I delivered on that with ten RGB LEDs. At the time I planned to hand-assemble each and every of the 105 badges at my kitchen table. Given those constraints, and a desire for electrical and programmatic simplicity, I landed on using APA102s (DotStar’s in Adafruit parlance) in the common 5050 sized package. They were easy to place, easy to design with electrically, simple to control, and friendly to a human pick-n-place machine. Though by the end of the production run I had discovered a few problems, the APA102s were a success.

This year I made a new and improved version of the dragonfly, but applying my lessons learned led me to choose a very different LED architecture than 2017. I swapped out the smart LEDs for dumb ones.

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Are Patent Claims Coming For Your WS2812?

There are some components which are used within our sphere so often as to become ubiquitous, referred to by their part number without the need for a hasty dig through a data sheet to remind oneself just what we are talking about. You can rattle a few of them off, the 555, the 741, the ESP8266, and so on.

In the world of LEDs, the part that most immediately springs to mind is the Worldsemi WS2812 addressable LED. This part consists of three LEDs in red, green, and blue, all in the same package with a serial interface allowing a chain of individually addressable multicolour lights to be created. We’ve seen them in all sorts of places, and if you don’t recognise the part number then perhaps you will by one of the names they’re sold under: Neopixel.

Yesterday we received an email from our piratical friends at Pimoroni, the British supplier of all forms of electronic goodies. Among their range they have a reasonable number of products containing WS2812s, and it was these products that had formed the subject of an unexpected cease-and-desist letter. APA Electronic are the manufacturer of the APA102 addressable LED (which you may know as the Dotstar), and their cease-and-desist asking for the products to be withdrawn from sale rests on their holding a patent for an addressable multicolour LED. We’d be very interested to hear whether any other suppliers of WS2812-based parts have received similar communications.

US patent number 8094102B2 is indeed a patent for a “Single full-color LED with driving mechanism”, which does look a lot like a WS2812. But as always, such things are not as cut-and-dried as they might first appear. The LED in the patent for example relies upon a clock line for its operation, while the Worldsemi part doesn’t. I am not a lawyer so I’d hesitate to call this a baseless and speculative move, but I suspect that there will be plenty over which the two semiconductor companies can duke it out in the courtroom.

It’s fair to say that a large part of the ethos of our movement shares something with that of the world of open-source, so news of legal manoeuvres such as this are never likely to go down well. We’re small fry in this context and our commercial influence on APA102 or WS2812 sales will be minimal, but inevitably APA’s standing in our eyes will be diminished. Companies such as Pimoroni are not the target but a piece of collateral damage in a battle between manufacturers.

Whether the patent has been violated or not can only be decided by the courts. It is not uncommon for patent holders to go after companies selling the “infringing” products in hopes that rather than risk a costly court battle, they simply adhere to the demands, in this case buying parts from APA and not from Worldsemi.

So, if you rely on addressable LEDs, watch out! There may be trouble ahead.

Header image: Tristan Robitaille [CC BY-SA 4.0].

Look Out DotStar, Here Comes Lumenati

Adafruit has long been the undisputed ruler of the smart LED product, with their WS2812B (NeoPixel) and APA102C (DotStar) product lines dominating due to the robust assortment of sizes and form factors, as well as their ease of use. SparkFun Electronics recently announced Lumenati, their new line of APA102C breakouts that feature some intriguing features which do a good job of distinguishing the two lines.

First, the screen-printing on the boards include pixel numbers. We were working on NeoPixel assemblies the other day and keeping track of pixels was a nightmare. In addition, the Lumenati boards are meant to combine into larger creations, allowing you to make complicated shapes. SparkFun supports this by giving the boards castellated headers — far better than the solder pads! If you are running into logic conflicts with the boards you can solder in jumpers to bypass the data connections and control individual boards separately. On the down side, SparkFun’s intitial offerings — 6 products — still can’t compete with Adafruit’s, like their 255-LED disk, shields, strips, matrices, and flexible PCBs.

We’ve published a few DotStar builds over the years, like this violin bow lightsaber and the Magicshifter POV stick. Maybe we’ll start seeing some Lumenati builds? Continue reading “Look Out DotStar, Here Comes Lumenati”

Badge From Diamond Age Comes To DEF CON

We’re huge fans of [Neal Stephenson’s] work and are usually looking to assign some of his vision to the gear that pops up in the real world. But there’s no stretching or squinting necessary with this one. [Kerry Scharfglass] has built a functioning Drummer’s Badge from the foundational Sci-Fi novel The Diamond Age.

The badge is called Sympetrum, which is a genus of dragonfly. In explaining what the badge is and does, [Kerry] instructs you to go and read the book first and we couldn’t agree more. This isn’t recommended reading; if you’re a geek you need to read this book.

The dragonfly badges are from a portion of the book that gets pretty weird, but the gist is that rod-logic (machines build from microscopic carbon nanotubes) is so pervasive that at all times you’re covered in mites that are actually machines. At a party, one of the characters notices everyone is wearing dragonfly pins that begin to pulse with the music and synchronize with each other. They’re actually indicators of what the mites within the wearers’ bodies are doing — synchronizing people with other people.

This badge is a working recreation of that, presumably without the billions of mites controlling people (but who knows, it is DEF CON). At the center of the badge is an STM32 driving ten APA102 modules. Interactivity is based on IR signaling. The badge will cycle random color animations when alone. But each badge also projects clock sync and metadata over infrared, so put some of them in the same room and they’ll tend to synchronize.

Simple, beautiful, and a great geeky backstory. This example of Badgelife proves that hardware badges don’t need to be packed with features, or have a huge BOM cost. If done well, you can do an awful lot with just a little hardware and strong dose of inspiration. It also makes hand-assembly a lot more approachable, which is what you can see in the images above. Thanks [Kerry] for giving us an early look at this badge, can’t wait to see them at the CON.


We’ll be looking for this and all other #Badgelife offerings at DEF CON 25. Join us for a Hackaday meetup on Sunday morning as we once again do Breakfast at DEF CON