Controlling multiple addressable strips without BBB Cape

[lyrewolf]

Hi!

I am brand new to this forum, so if I am stepping out of line by posting this question please let me know and feel free to point me in the right direction of existing threads.


I have been tasked with a rather unique project involving wearable led displays.

Essentially, I need to be able to control multiple addressable RGB strips as a matrix, with the capability to play video files and animations using Falcon Player.

The equipment I have at hand is as follows:

• BeagleBone Black
• Octoscrolla (Hanson)
• Many many UltraSkinny Neopixel strips (WS2812)
• 20A 5V Regulators
• 18V Batteries

Basically, I had purchased the Octoscrolla in the opinion that I could use it to control multiple addressable LED strips wired up like a matrix (end-to-end) however the more I read, the more I doubt that I will be able to do this.

The reasoning behind using strips rather than P10 panels is that I need the matrices to be flexible as per the wearable nature of the project.

My question is, is it possible to have an Octoscrolla control multiple LED strips wired as a matrix, or are they strictly for use with P10 matrices?

If I am unable to use an Octoscrolla, is it possible to wire the data lines of the LED strips directly to the I/O of a BeagleBone (5V supplied separately of course) and if so, how many pixels could I theoretically drive using this method?


Many thanks!

 

[Skymaster]

Hi Lyrewolf,

As you elude to, the Octoscrolla is for P10 panels, which use a different signalling format to WS2812 strip.
For the BBB, Hanson has the HE123 controller which outputs the right data, however that may not end up being particularly "wearable" given the physical size of the board.
There are other hats for the raspberry pi, such as the rPi-28D which will give you two outputs for up to 800 pixels per port at 40fps.
Alternatively, there are the Kulp controllers from the US which will achieve what you want to.

As for direct drive - the BBB (and rPi) use 3.3V GPIO pins, whereas the WS281x expect a 5V signal. That said, if the distance from the SBC to the first pixel is kept very short, they'll generally be fine with it, and each pixel regenerates the signal, so it's just getting to the first one that's important.

 

[lyrewolf]

Thanks for your help both here and on the chat Skymaster! I feel a renewed confidence in the project!

As per your advice, I will drive the strips directly from the BBB at the BBB's signal 3.3v signal level, and if that proves unreliable I will try a logic level converter to bump the signal up to 5v.

For anyone else stuck with this, Skymaster has been very helpful in pointing me towards the applicable pinout of the BBB for driving WS2812 strips with Falcon Player in mind.

Pinout as per this documentation:
https://github.com/FalconChristmas/fpp/blob/master/capes/bbb/strings/RGBCape48F.json

What it would look like in Falcon Player 5 when you set up the non-existant "cape":


Note that the BBB's logic output is at 3.3v so it may be necessary to run the 3.3v signals through logic level convertors to bump up to 5v if the first LED in the sequence is longer than 1 metre from the signal source.

 

[Notenoughlights]

I can confirm that you can directly drive 2815 and 2812 strips directly from the output of a BBB. You may not get a long distance from the controller however.
Have been running it non-stop 24/7 without issues for the last year almost.
Here is what it looks like in FPP when set up with the cape that isn't actually there.

View: https://i.imgur.com/sHbqjqr.png

 

[Indigogyre]

How flexible do the panels need to be? They do make semi flexible panels that can be worn. Without know the full design they might or might not be an options. I bought one of these to play with and it flops along pretty well although it is mostly in a single direction but has flex also.

32x8 Flexible Mini Matrix

32x8 Flexible Mini Matrix

www.wiredwatts.com

Dean