I’m starting work on a project for Burning Man to build a large-scale POV Display. The idea is to have single strand of SK9822A leds (APA102 compatible), somewhere around 500 leds, driven by an ESP32. This would be a POV display, so the frame rate would need to be as high as possible.
I see that for release 0.13.0 that the SPI frequency was reduced to 5MHz due to issues related to distance between LEDs, but we’ll have these be 10cm/4in apart with a proper line level driver at the start. So I’m planning on cranking this clock rate as high as is reliable.
I also see that WLED is limited to 120fps in several places in the code. What limits am I running up against if I increase the frame rate above this?
Assuming I can get the LEDs working reliably at 20MHz I should be able to do 1200fps, at which I expect that I’ll start hitting CPU limits on the ESP32.
I’d love to hear any thoughts on what pitfalls I’m likely to encounter if I try to get this working with WLED…
Thanks, @kilrah, it’s a fair question. I like WLED for the web API and interface for configuration and controllability, OTA upgrades, etc. I suppose the underlying display engine isn’t really designed for high frame rate graphics like POV, but I thought I’d ask for advice on how adaptable it would be to this application.
I like Burningman 2Times Member
The Man is more a analog then a Digital Event
You may get some shitstrom on the Display as special as movin Theme car
WHAT is to be displayes Image Text ??
Considering the Envirerment at BRC better to go for the WS2811
You can drive this with a Simple battery 12V 10aH for the entire event
at BRC "seeing only the EXESS is missing the freedom "
Thanks for that reference, @ALDIY, it looks promising!
I should have explained more about the project, @Magig_Wled
The idea is that this is going to be attached to a large balloon, running the LEDs down the line (100-200ft/40-60m long). The balloon will also be illuminated. We’re planning to provide a way to interact with it on the ground. We’d like for it to be a POV display from far away where the image would appear as the viewer’s eye moves across the line. Also provide various animations like lightning st.rikes and color wheels
The first challenge is building a robust and safe wire that provides enough power over the distance and isn’t too heavy. Using a higher voltage is probably going to be necessary, but I don’t think the 800kHz signal rate will allow for a fast enough frame update for POV images. The current (ha!) plan is to run up 48vdc and then have small DC-DC converters powering segments along the line.
A 48V bus over ~60m for LED power is a reasonable solution (potentially).
One of the key issues is going to be the total LED count and thereby the max power draw.
Total power of ~300W would definitely be reasonable => ~7A on the main bus.
That means 600W => 14A on the main bus (hmmmm)
As total power approaches 1000W, you’re talking about 20A+ on the main bus and that will imply some hefty cabling to support that current load.
Data supply over that distance is almost guaranteed to require differential TxRx boards, especially if you’re worried about refresh rates over a long LED strip. Subdividing the full strip into 8 driven sections gives 8 x 7.5m subsections that should be reasonable to drive quickly.
2 pieces of Cat5e cable will give you 8 pairs suitable for this setup.
huge projekt
you shoudt consider THE MEGA tree Projekts from Xlights
as of a baloon 32stripes x50 led WS2811 woudt give you a impressiv Display
if you like it more sphere better to go 32x100
at BRC you can run 100LED at 200mA as it is realy dark out there even at 50mA 8100LED) thats WLED 8brightness it is fully visable for 1mile
There are on ALI mow Pearls available in diferent length / distances
this is made for things like Baloon Sphere or els and they are IP67 what makes them envirerment friendly under very hard conditions https://de.aliexpress.com/item/1005005545423588.html
as the Pixel count i the same but length difer they are very good for spheres Display
Good idea, @TokyoDave ! Trying to balance out the weight of the wires, electronics, etc. against the cost of a larger balloon that can carry a bigger payload.
Ah, looks interesting. They don’t seem to have clock/data LEDs with the necessary refresh rate to get the POV, but looking at the different designs is inspiring. Thanks, @Magig_Wled
Please tell me that was you guys… I love that ballon… it tripped me out because I thought it was a static installation. until I saw it on deep playa. Loved the ldea… I hope it makes it to 2025.
I didn’t make it to the playa, but my brother flew the thing we built, he called it Lumitether.
There ended up being two versions being flown.
The first one was designed as the main attraction, but only flew for a few hours. That one was POV capable and he was uploading photos and graphics on the fly to be displayed across the playa, along with a bunch of custom animations. Also had a high-striker game with a big hammer and sound effects part of the time.
This string has 576 SK9822A LEDs over 60m broken up in to 12 segments of 5m length, each with 48 LEDs, plus about 70 LEDs on the balloon. This string was hand wired with custom PCBs, little diffuser balls. There was a 48v power supply at the ground and each segment had a small, lightweight 48v → 5v DCDC converter. We drove it at 8MHz as a single string of logically 192 pixels (every 3 pixels shared an input from the previous set of 3 pixels). That way we were able to get POV working at that the full length, though with reduced resolution. This was being driven by a Raspberry Pi Zero with some custom Python code. Unfortunately the controller failed early on, probably due to a power glitch that came back down from the string.
The backup system was a factory made string with 1000 12v WS2812b compatible LEDs at 100m length, plus another 75 LEDs on the balloon. Same 48V supply and a few 48v->12v DCDC inserters along the way. More LEDs, each running less bright. This was driven by a Pixelblaze which we had on hand. That system ran for most of the week and didn’t do POV but had a few animations.
He’s planning to fly it again next year, and hopefully we’ll make the primary system more reliable and have the full POV on display with improved animations!
I learned to learn in making a back up… My bike controller died the second day by being yeeted from my bike when some one knock it over. they picked up and then plugged it in backwards… Fried my 12v to usb and the microcontroller. I luckly thought to set up a few. For encase I wanted to use the 2 other strings i brought for just because.
We totally enjoyed it. Looking to see it out on the playa every day. We really couldnt tell its POV but it was still very lovely to see it out there.
Ha, yes. Big believer in backups. After the second Raspberry Pi died, he switched to the backup of the backup which was the PixelBlaze.
The POV was only up for about an hour at twilight for two nights. Talked to my brother today, he’s committed to bringing it back more robust and improved next year. Look for it!
Alas, I wasn’t able to get the POV working with WLED.
We needed a much higher update rate than WLED was able to provide out of box (we ended up with an 8MHz clock rate to 192 pixels for a frame rate of about 1300fps!)
We also needed to be able do full color images with the POV, up to about a megabyte per image.
In theory the ESP32 could have handled this with a ton of software work, but it was quite easy to bring up on a Raspberry Pi in Python.
