Driving WS2801 and similar LED controllers with BBB

Sulev-Madis Silber (ketas) madis555 at hot.ee
Fri Aug 15 12:43:46 UTC 2014

On 2014-08-14 21:30, John-Mark Gurney wrote:
> Sulev-Madis Silber (ketas) wrote this message on Thu, Aug 14, 2014 at 20:19 +0300:
>> Hello.
>> Maybe someone else works on things like this? I basically know how those
>> are controlled, however I'm unsure what should I choose. Maybe SPI,
>> maybe I should bitbang GPIO for clock / data? Last should work with that
>> specific model (WS2801). Others use weird protocols (or "protocols"). I
>> guess I should just try something. I just let people know that I'm
>> working on that. I won't be surprised if I'm the first one to get it
>> working.
> I'd look at using SPI...  From what I've read on the WS2801, SPI
> will do exactly what you need to do, and be the most straight forward
> solution...

Only problem is, I seem to be only one who wants to use SPI from
userland... No documentation, no code. I hope that it even works in BBB.
Maybe I'll try bitbanging GPIO from Perl first. That I understand fully,
at least. And that controller seems to allow one to be sloppy or slow.

>> I'm also aware that this platform contains PRU's, which are maybe better
>> for this task. Though, that seems like even more complex task. Like how
>> to get code compiled for that (there seems to be one open way for C),
>> how to get it running there and how to
>> assign IO pins.
> The PRU is probably more complicated than you need compared to using
> SPI...

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