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Problem with multiple LED strips
#1
I finally installed my LED's today, and what worked on my breakfast table does not work on my Christmas tree!

I have encountered a slight problem with the following configuration.
* Two strips of 120 LED's (DotStar APA102's from Adafruit).  
* Each strip is powered by a PowerTap.
* Both PowerTaps are connected to the same 10 amp, 5V power supply (also from Adafruit).  
* Both strips share a common ground with the AllPixel.
* Both clock and data outputs from AllPixel are connected to each strip.

It works for both strips on the breakfast table, works for one strip or the other on the Xmas tree, but does not work for both strips on the Xmas tree!  

The only difference between the breakfast table and the Xmas tree is about 5 feet of shielded, 4 conductor, 24 gauge wire for each strip.  Any thoughts?  I am at a total loss.

While on the topic, it's obvious from looking at the tree that I am going to need a lot more LED's or a lot fewer LEDs / Inch, My RPi3 is already having trouble keeping up with some of the animations on 120 LEDs at 45 - 60 fps.  Any thoughts on how to scale the number of LEDs?  Multiple AllPixels?  Multiple RPis?

Best Wishes,

ks


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#2
Sounds like a power issue. 24 gauge is WAY to small to deliver the currents required over 5 feet. My guess is that the voltage at the end of the wire is too low to do anything. When I have to run power more than a few inches, I always use at least 16 gauge to deliver power.

Pi 3 should be able to handle the full limit of the AllPixel (about 690 pixels for APA102) no problem. What animations are you running?
#3
(04-21-2016, 05:00 PM)Adam Wrote: Sounds like a power issue. 24 gauge is WAY to small to deliver the currents required over 5 feet. My guess is that the voltage at the end of the wire is too low to do anything. When I have to run power more than a few inches, I always use at least 16 gauge to deliver power.

Pi 3 should be able to handle the full limit of the AllPixel (about 690 pixels for APA102) no problem. What animations are you running?

Adam,

Thanks again for your help.  There is no power being delivered via the AllPixel.  The 5 feet of wire is connecting the ground, data, and clock only.  The power is being delivered by a 10A / 5V power supply from Adafruit (https://www.adafruit.com/product/658) via a splitter (http://www.monoprice.com/Product?p_id=9911&gclid=CMCj-JTWo8wCFQIKaQodW3QDLw) to each of the strips.  Both strips and the allpixel are connected to a common ground.  I will re-wire with 16 gauge this weekend and give it a try.

Best Wishes,

ks
#4
I shortened the run between the allpixel and the two LED strips and it is working fine now!


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