NeoPixels

 

 

Improper use can damage your NeoPixels. Before diving in, be aware of the following:

• Before connecting NeoPixels to any large power source (DC “wall wart” or even a large battery), add a capacitor (500–1000 µF at 6.3V or higher) across the + and – terminals as shown above. The capacitor buffers sudden changes in the current drawn by the strip.
• Place a 300 to 500 Ohm resistor between the Arduino data output pin and the input to the first NeoPixel. The resistor should be at the end of the wire closest to the NeoPixel(s), not the microcontroller. Some products already incorporate this resistor…if you’re not sure, add one…there’s no harm in doubling up! Nothing’s needed at the “out” end of a strip…you can leave the data out “floating.”
• Try to minimize the distance between the Arduino and first pixel, so the signal is clear. A meter or two is usually no problem. Much longer and things can become unreliable. Individual NeoPixels can act as repeaters for long runs.
• Avoid connecting NeoPixels to a live circuit. If you simply must, always connect ground first, then +5V, then data. Disconnect in the reverse order.
• If powering the pixels with a separate supply, apply power to the pixels before applying power to the microcontroller. Otherwise they’ll try to power “parasitically” through the data line, which could spell trouble for the microcontroller.
• Observe the same precautions as you would for any static-sensitive part; ground yourself before handling, etc.
• NeoPixels powered by 5v require a 5V data signal. If using a 3.3V microcontroller you must use a logic level shifter such as a 74AHCT125 or 74HCT245. (If you are powering your NeoPixels with 3.7v directly from a LiPoly cell, a 3.3v data signal is OK)
• Make sure that your connections are secure. Alligator clips do not make reliable connections to the tiny solder pads on NeoPixel rings. Better to solder a small pigtail wire to the ring and attach the alligator clips to that.
• If your microcontroller and NeoPixels are powered from two different sources (e.g. separate batteries for each), there must be a ground connection between the two.

Some of our projects don’t make the above precautions…these are typically small battery-powered devices and power spikes aren’t a big concern. Any project with a lot pixels or a large power source should definitely include the power capacitor and data line resistor.