I have a hopefully more straightforward issue than my last.

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I have a hopefully more straightforward issue than my last. :slight_smile: I’m driving a two 4 meter strips of APA102 LEDs. The Teensy + Teensy LC shield (proving a 5V buffer) are about 4 meters from the start of the first strips (so data and clock traveling that far before the first LED). This strip is working PERFECTLY. Then I run another line (16awg stereo wire) about 3 meters from the end of the first strip to a SECOND 4 meter strip. This strip gets extremely glitchy!

To try and improve the situation, I put a split in the Clock out from the Teensy, running it directly to the second strip as well as the first. This definitely improved the situation, allowing me to set the color of the second strip much more reliably, but still with minor artifacts, and fading stays completely glitchy (possibly getting into the speed I’m pushing data, which is whatever the default is in FastLED for APA102 on a Teensy).

First off, is using stereo wire like I am (one of the wires for clock, the other for data) across the 3+ meters a problem? Would I be much better off to switch to ethernet cable? If clock and data are getting through the first strip without issue, can I expect them to be buffering and forwarding the data along reliably? It seems like the Clock splice is (understandably) sometimes glitching the end of the first strip, since it is likely conflicting with the clock being received from the other end.

I just want to get them all working with nice fades, but don’t want to do a big rewiring until I get some feedback that it would make a difference. Thanks for the help!

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Have you tried turning down the data rate?

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@Jeremy_Spencer I tried setting it down to 12 or 10Mhz when I initialize FastLED, but to no discernible effect. Not sure how low I can go, or if there are values to avoid, or if I need to change anything else for this value to work.

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How about running the problem strip off a different pair of pins? You can always combine the strips into one array in setup. (I think the default data rate for APA102s is 12Mhz)

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@Jerry_Belich_jerrytr There’s no harm in trying lower MHz rates, you can try whatever you like.
If you try using ethernet cable use a twisted pair for data and ground, and anther pair for clock and ground, something like this:

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@Jeremy_Spencer That would be a problem at this point, both the Teensy shield driving the LEDs currently (which provides the 5V buffer) and the software already in place. :confused: At least, I hope it doesn’t come to that, but a good idea if I can’t get it figured out!

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@marmil Thanks for the tips. I may give this a shot first to see if it helps with stability.