Author Topic: BBB + ws2812 questions  (Read 280 times)

Offline yohannp

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BBB + ws2812 questions
« on: October 19, 2018, 07:33:20 AM »

Hello,


Last year i set up a christmas light show using a RPi 3, Falcon FPP and some ssr relay to simply control lights by siwthing it on or off.
This year i would to use ws2812 stripes to make a more impressive lightshow.


I read that a RPI can only control a maximum of 2 ws2812 stripes using GPIO.
Reading the fpp wiki i saw that a BBB can control more ws2812 stripes.


So i have some questions for you :


1) Can i control about 10 ws2812 stripes of 150 pixels (in 5V) each directly with GPIO's of a BBB ?
2) Do i need other electronic component/controler ?
3) Can you give me a link or a schema for wiring the ws2812 stripes on my BBB ?


Thank you very much for your help  :) :)

Online dkulp

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Re: BBB + ws2812 questions
« Reply #1 on: October 19, 2018, 08:33:41 AM »



A BBB can technically control 54 strips, but the software currently limits it to 48 mostly because no-one has designed a cape needing more than that.


To answer the questions:
1) Not DIRECTLY off the BBB.  You will need some buffer chip to up the GPIO's from 3.3v to the 5V the ws281x chips expect.  You MAY be able to directly connect to the GPIO, but the distance would be fairly short.   This is similar to the Pi as the Pi has the same issues and the capes all provide a buffer chip for this.


2) You don't NEED one, but there are already capes designed for this.  I sell a F8B cape that has 8 fused pixel outputs, 3 differential outputs that can be strings (ws281x via differential expansion boards from falcon) or DMX outputs, and a 16 port expansion port for even more strings. (from falcon)


3) The complete KiCad project for my F8B is at:
https://www.dropbox.com/sh/pwsbvn7x5gwshc4/AAAa2xBQwgMzEYFS-n_b-5UFa?dl=0


Not sure if that helps at all.  :)




Offline yohannp

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Re: BBB + ws2812 questions
« Reply #2 on: October 19, 2018, 11:09:52 AM »
Hi and thank you very much for your fast answer.


The dropdbox link that you sent to me is empty ...  :'(


So if i understand, to do what i want i need :
 - 1 x BBB
 - 2 x F8B (because i need to control 10 stripes)


am i right ?


Yohann





Online dkulp

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Re: BBB + ws2812 questions
« Reply #3 on: October 19, 2018, 11:20:20 AM »
Try this link:


https://www.dropbox.com/sh/7zv0t5n78wjogzw/AAB9K3ppnpir10AhnxTUMOeta?dl=0


Of course that assumes you are comfortable with KiCad (and it's updated to KiCad 5).




No, the F8B is a cape that sits on a BBB.  You cannot put two of them on a single BBB.   Thus, the options are kind of:
1) Use the kicad files and such to design your own output board/whatever.   Seriously, some jumpers to a breadboard and 2 buffer chips and 100ohm resistors would work.   Grab the pins from the schematics.


2) Buy an F8B (from me) + a differential receiver board (from pixelcontroller.com) and a cat5 cable to connect them.  That would give you 12 ports.


3) Use two BBB's and two F8B's. 




Offline yohannp

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Re: BBB + ws2812 questions
« Reply #4 on: October 19, 2018, 01:32:12 PM »
I m really not confortable with Kicad (in fact i have never heard of or before today 😀😀)

What is the price of the F8B and do you ship it in France ?

Thx

 

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