I tried connecting some 1 meter LPD8806 strips parallel and I'm having a strange

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I tried connecting some 1 meter LPD8806 strips parallel and I’m having a strange issue.

I use cable connectors, the type that comes with the strip to divide power and signal from Arduino to 3 different branches with connectors at end. Basically the torso and arms of a stickman. However somehow only any 2 of these connectors work at the same time. If I connect the third strip they all light up random bright white colors. Any combination of 2 works but the 3rd messes up things. I run a very simple animation of a few leds traversing, and power them from a simple powerbank. Anyone know what I should do?

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what MCU ? do you need level shifters ??

A picture (of the wiring…) is worth 1,000 words but a video showing details of the problem is much much more…

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Im using Arduino Nano. Things work without the level shifters so I did not use any. Will try to send a video. When I connect the third strip, the strips turn white entirely yet I can barely see the pattern traversing the strips… Behind the white, if that makes sense.

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Ok, the NANO has 5V digital outputs so there is no need for level shifters.

I am only guessing at how you are wiring the 2 or 3 strips that could explain why you have problems when a 3rd strip is added so a few detailed wiring pictures may help.

Never used them but I see the LPD8806 is a clocked device. Have you tried significantly reducing the data frequency ?

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Another quick suggestion would be to confirm your power bank is up to the task of supplying all the current for 3 strips ??

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missing/deleted image from Google+

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missing/deleted image from Google+

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Thank you, I will check into how I can reduce the data frequency. The animation is just 5 legs travelling the strips but I will try a different power source. Above are photos, top is working fine, bottom is the issue when I connected the third strip.

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Another issue happened when I powered Arduino through Vin pin rather than Usb. One strip works fine. The longest strip, no matter which cable connector I plug it into, works fine. Then some random blinks. missing/deleted image from Google+

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I think I figured it out, I connected a single strip to arduino, then forked out 3 strips from the end of that strip and all 4 are working now. Somehow I needed to pass through a strip of lpd8806 before divinding the strips in parallel…

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@turgan_s You can try a different data rate like this:
FastLED.addLeds<LPD8806,11,13,RGB,DATA_RATE_MHZ(4)>(leds,NUM_LEDS);

I believe the default for LPD8806 is 12MHz.

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@turgan_s Ok that would suggest that your power bank is not the problem and somehow the digital drivers of the NANO is not able to drive 3 parallel strips but the LPD8806 device clock and/or data outputs can. The LPD8806 does specify strong clock signal regeneration !

Do try the clock reduction that Marc specified. I am only guessing that the capacitive load from all 3 strips in parallel has enough influence on the clock signal to distort its shape and cause havoc. Maybe reducing the clock frequency can help !?

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Assuming I’ve understood the wiring correctly :wink:
It sounds like you’re driving all three strips from one pair of pins. This could be pulling the voltage down so it’s just too low.

If you have enough spare pins, drive the strips on separate pairs of pins rather then all on the same pair. You can always copy the data to them if you want them to all be the same…