Persistence-of-vision displays come in all shapes and sizes. But when you get a couple of [Bruce Land’s] students involved, well let’s just say they tend to up the ante. When [Emily] and [Han] decided to make a POV display for their next class project, they did so with style. Unsatisfied with smaller displays they saw on YouTube – they decided to make a larger one out of an old box fan and a DotStar LED strip, which are similar to NeoPixels except they use SPI, which means you can update the LEDs at a much faster rate. This makes them perfect for a POV display!
As usual with projects out of Cornell’s EE class – this POV project is extremely well documented and it’s nice to see the fundamental details of a POV display explained. So be sure to check out this project if you’re rusty on the inner workings of POV displays.
We’ve seen some interesting POV displays here at Hackaday, including one strapped to a dog to display its running speed. What’s the coolest POV display you’ve seen?
I’m kinda partial to this one…
http://chrismillerstuff.com/2015/09/22/creating-a-1-meter-rgb-pov-display-with-raspberry-pi-and-lpd8806/
Was hoping they’d show it with the room lights turned down.
What about a 2m diameter POV mill ?
https://hackaday.io/project/6955-rosace
https://www.youtube.com/watch?v=v7z_S63g47M
Anyone else annoyed that it’s turning counter-clockwise?
OCD strikes again.
Tell yourself it’s a POV for the southern hemisphere ? :-P
You don’t watch many old B&W western movies.
https://wiki.das-labor.org/w/Borg_Ventilator
https://www.youtube.com/watch?v=rkMQSm3kIng
No style with zip ties, much less without sniping the waste ends off.
SPI LEDs you say, I must have those, let me check the price, aaaand I guess I will stick to ws2812 LEDs for now.
Check eBay for APA102/APA102C to avoid Adafruit’s “DotStar” branding premium.
APA102 LEDs are my current favorite, much more than the ugly LPD8806 stuff, as you can get it in a high-density 144 LEDs/meter strip. Communication is much less timing sensitive thanks to SPI, and the clock line is a welcome addition.
I still like WS2812 for small or non-POV projects, but driving more than a meter of it is a crapshoot. The new WS2813 is supposed to improve on this with a second data line, but the implementation seems…janky. Instead of a clock line, it has a “backup data” line, which itself seems like a hack (check the datasheet). I’m not sure if it’s fast enough to handle POV, though, and it’s still going to be more timing-sensitive than the SPI stuff like APA102.
I’m also partial to the APA102. The very high update rate, the easeness of control (I have a software library that uses SPI and DMA, so it takes up no processing power at all) and the ability to run them at a 1s lipo is totally awesome.
I have seen images of, but never found where to buy, strips with APA102 2020 LEDs (instead of the normal 5050). Does anyone know where to get them? The only I can find is loose LEDs (both Adafruit and Ebay sells them), and I don’t want to manufacture my own LED strip. There must be some Chinese that makes them.
“I still like WS2812 for small or non-POV projects, but driving more than a meter of it is a crapshoot.”
Why do you say this? I understand that WS2812 are FAAAR more timing sensitive than the APA102 or LPD8806, but why is driving more than a meter a problem?