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Topic: WS2801, Fast SPI or Adafruit library? (Read 1 time) previous topic - next topic

dtokez

Dec 02, 2013, 06:34 pm Last Edit: Dec 02, 2013, 07:17 pm by dtokez Reason: 1
Hi all, I have a string of WS2801 LEDs that I would now like to use. I have tested them with the Adafruit library before and they worked well, but a few days ago I came across the Fast SPI library which appears to be compatible with WS2801 drivers.

I'm now wondering if I would be better off wiring the string to the SPI pins of the Arduino pro mini that I planned to use or just stick to the Adafruit method?

fungus

No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

dtokez

True  :P

Just wondering if there is any advantage in one over the other? I guess the fast spi library might be faster and able to drive more pixels?

Thanks

dgarcia42

So with the WS2801 chipsets, you're capped out at a data rate of about 1Mbps, which is slower than the max SPI data rate that the arduinos can push out, so there's not a lot of benefit on that front.  What the FastSPI_LED library has (at least, in the second version which we've been pushing out release candidate builds for the past month or few) is inline (0 extra CPU cost) brightness control/dimming, a wide batch of optimized 8-bit math functions for working with leds, a faster (and somewhat more correct) HSV to RGB converter, and a random handful of other useful things.  If any of that sounds like it might be useful to you, it might be worth flipping over.  However, on the flip side, if you have something that's working and you aren't going to be adding more to it, there's something to be said for not changing what's existing.
--

FastLED (formerly FastSPI_LED) -- new home http://fastled.io

fungus


Just wondering if there is any advantage in one over the other? I guess the fast spi library might be faster and able to drive more pixels?


Maybe, but there's no reason to change unless you're pixel-limited.
No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

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