NeoPixel Rings and Arduino Due

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rubidium
 
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Joined: Sun Nov 18, 2012 10:36 am

NeoPixel Rings and Arduino Due

Post by rubidium »

I'm driving 8 of the small NeoPixel rings (total of 8*12=96) with an Arduino Due. (I'm using the Due to sample an audio signal and crank a lot of signal processing math in real time.) The driving of the NeoPixels is *basically* following my desired algorithms, but there are random "flashes" occuring every few seconds on average. These random flashes also occur when running the "strandtest" code in the Adafruit library. I checked my power supply, and the voltages at each ring are within 10 mV of each other, and I have a 1000uF electrolytic between 5V and GND at the lead Neopixel in the chain. Also, my data line is passing through a 470 ohm resistor to the lead Din pin, and I have a 10Kohm between the lead Din pin and GND.

Could the problem I'm experiencing be due to my data line from the Due being a 3.3V signal? Is it necessary to shift the level to 5V?

Thanks,
Jim

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pburgess
 
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Re: NeoPixel Rings and Arduino Due

Post by pburgess »

Level-shifting is recommended, yes.

A quick-and-dirty workaround is to slightly lower the voltage to the rings.

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rubidium
 
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Re: NeoPixel Rings and Arduino Due

Post by rubidium »

OK, I shifted the data line level to 5V and the problem persisted. So it's time to bring out the ol' trusty oscilloscope. It turns out that my home-brew 5V supply had a 100mV RMS noise on it. Replacing a bad regulator chip eliminated that and all is well. Oh, and all is well with either a 3.3V or 5V data line. These NeoPixels are very tempermental.

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