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Connecting WS2811 strips to Raspberry Pi and the common grou
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Connecting WS2811 strips to Raspberry Pi and the common grou

by turboki on Fri Nov 20, 2020 3:03 am

Hi all,

Im hoping someone could help me out here as Im pretty lost. Last year for Christmas I got a bunch of WS2811 5V strands of LED lights and to control them I got a cheap little controller box. This set up works fine, but the controller box really only lets me set a solid color or a handful of repeating patterns. This year I thought about replacing it with a raspberry pie, which I can program to show all kinds of patterns. This is what my current set up looks like:
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I followed the tutorial on adafruit for wiring up the GPIO pins to control the strip but immediately ran into a problem...well a fire...The wire that connects the PS ground to the gpio gnd had quickly melted my breadboard. Luckily the pi seems fine.
Image

This seemed very strange to me...why would connecting 2 grounds cause the wire to overheat. So I measured the voltage...and there is 5v difference between the GPIO GND and my PSU GND....how in the hell is this possible....At that point I disconnected the pi from the psu completely and went to measure the difference and again found a difference of 5v.
Image

I thought the point of sharing the ground was that both the signal and the strips would be powered from the same baseline, but this voltage difference was causing a short. So I tried removing the power adapter for the pi out of the equation. Instead I got a usbc dongle I had, stripped it open and connected the power and ground from the psu to it. Keep in mind I measured the voltage of the psu and it was at 5.2v. Connecting the Pi to the PSU directly, I got the boot screen followed very quickly by the lightning bolt and then black screen. Checking the USB-C plug, it was very hot as well.
Image

Here is the thing I don't get tho. I hook up the original setup (the cheap controller) and everything works great. There seems to just be some issue between my large psu and the Pi. If anyone has any ideas, please let me know.

turboki
 
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Joined: Fri Nov 20, 2020 2:11 am

Please be positive and constructive with your questions and comments.