Is it actually possible to drive 3000 ws2812 LEDs if 5 FPS is enough? Would there be control signal loss / degradation as it’s passed through the chain? Or some kind of hard limit on the time period to sync the entire chain?
Each ws2812 regenerates the signal when sending it on to the next chip - so as long as you’re taking care of power injection every 100 LEDs or so, it should work. If the timing of the 2812 output is off, however, the longer the set of LEDs to signal through, the more likely problems are to show up.
(Seriously though - get a teensy 3.x and use the 8 or 16 way parallel output
Thanks! I was thinking about using a RPi and the ws2812 DMA library because it’s easier to do image creation on something as fast as RPi.
How easy would it be with a Teensy?
I haven’t used an rPI for anything led related - I have driven 3000 leds off of a teensy, though, using the parallel output in the past. It really depends on what you’re doing for your image creation.
And - with 3000 leds, I would still strongly encourage you to look into parallel output options, whether you’re using MCU’s like a teensy 3.x, or going up to small computers running an OS like an rPI or a beaglebone black. Maybe a rPI driving a handful of fadecandy boards - or a beaglebone black with a 24 output led cape
I don’t think it will work flawlessly. I am having issues with getting 1500 ws2801s working.
the issues, from what I have been told, is that the long lengths make the wiring itself suseptable to transient voltage. That is causing blinks. I havnt found a solution yet.
parallel outputs probably are the say to go.
Using parallel output, a couple years ago we built a project with 4320 WS2812s updated at 30 Hz (controlled from a single Teensy 3.1). Just in case you’re wondering if it’s possible with only 3000, here’s an article with details and even a video. https://community.arm.com/groups/embedded/blog/2014/05/23/led-video-panel-at-maker-faire-2014
Oh… that project also played 44 kHz mono sound through the DAC pin with the Teensy Audio lib, while keeping those 4320 WS2812s refreshed at 30 Hz. All the data was read from a file on the SD card… no PC connected. Just to give you an example of what’s possible. Don’t settle for only 5 Hz update rate!
My question for Teensy was more oriented towards convenience than hardware performance: I can connect the RPi to WiFi, make it remote-controllable that way, etc. so I’m wondering if the smaller ARM in Teensy would be enough (for WiFi, it would go through esp8266, etc.).
One other question: I’ve seen many people and many resources saying to use parallel output instead of a long chain, and I tend to agree: at least it would be more predictable. However, I have rarely seen a mention of using demultiplexers to achieve this parallel output. Are demuxes avoided for this sort of thing?