[TriEmbed] AllPixel

Adam Haile email at adamhaile.net
Wed Aug 12 09:17:17 CDT 2015


You can absolutely do varying speeds.
Check out the ColorChase animation here:
https://github.com/ManiacalLabs/BiblioPixel/blob/master/strip_animations.py#L112

That will run a single pixel down the strip. You can change the speed in
two ways:

   - Modify the framerate: anim.run(fps=30) #Travel 30 pixels per second
   - Modify the amt parameter: anim.run(amt=2, fps=5) #5 steps per second,
   but light every second pixel

I would use the first option, since you will light every pixel. You could
also take the basic code in that animation out and run it manually and then
specify your own delay between each step. The animation classes are there
to provide very accurate timing, which you may not need.

For the LED choice, there are a few things to consider:

   - Price
   - Speed
   - Density
   - Voltage

NeoPixel (WS281x) and APA102 are the cheapest... NeoPixel is slow and
APA102 is fast but slightly more expensive. But I don't think you need very
high speed... APA102 is a better choice for high pixel counts requiring >
30FPS. But NeoPixel can keep up at low pixel counts.

You can also get the typical strips or the "christmas light" style. That
just depends on the aesthetic you are going for. But the christmas style
are only generally available in NeoPixel or WS2801.

Most strips are 5V but 12V is also an option, available in the WS2801 and
LPD8806 chipsets. But with 12V you generally have a strip where 1 IC
controls 3 RGB LEDs in series making 3-5" long "pixels", *or* you have half
ping pong ball sized dome lights with 3-5 RGB LEDs in a cluster making one
giant round pixel. Given you used to use incandescent lights, I think the
dome LEDs might just be the ticket for you. Just note that with the
AllPixel, you don't want to solder on that diode if using 12V. You can, and
that's why it's there, but if you know you are doing 12V just leave it off.
Then you can use the barrel jack to power the strip (up to 5A)

On Wed, Aug 12, 2015 at 9:50 AM, Grawburg via TriEmbed <
triembed at triembed.org> wrote:

> Some general questions about the AllPixel.
>
> I'm working on an exhibit that could easily use a 4 meter length of LEDs.
> The exhibit is a racing game for little kids where they pick an
> animal/insect to see if they can outrun it. (I already have a much larger
> one that uses a PLC and 48 colored incandescent lights.)
>
> Using the Allpixel and a Raspberry Pi can I program the lights to race
> from start to finish at different rates (presuming, of course, I can write
> good Python code)?
>
> How do I pick the LED strip since there seem to be many choices?
>
> What other things do I need to consider?
>
>
> Thanks,
> Brian Grawburg
>
>
>
>
>
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