To get started, let’s assume you have some model of Arduino microcontroller connected to the computer’s USB port. We’ll elaborate on the finer points of powering NeoPixels later, but in general you’ll usually be using a 5V DC power supply (e.g. “wall wart”) or — for wearable projects — a 3.7 Volt lithium-polymer battery.
Identify the “input” end of your NeoPixel strip, pixel(s) or other device. On some, there will be a solder pad labeled “DIN” or “DI” (data input). Others will have an arrow showing the direction that data moves. The data input can originate from any digital pin on the Arduino, but all the example code is set up for digital pin 6 by default. The NeoPixel shield comes wired this way.
If using a Flora, Feather or other microcontroller board with an attached lithium-polymer battery: connect the +5V input on the strip to the pad labeled VBAT or BAT on the board, GND from the strip to any GND pad on the microcontroller board, and DIN to Flora pin D6. If the board doesn’t have a pin #6, you’ll need to modify the example code to change the pin number.
For other Arduino boards with a separate +5V DC power supply for the NeoPixels: connect the +5V input on the strip to the + (positive) terminal on the power supply (don’t connect to the Arduino), DIN to digital pin 6 on the Arduino, and – (minus or GND) on the strip must connect to both the minus (–) terminal on the DC supply and a GND pin on the Arduino (there are usually several — any will do).
The 144 pixel strips are so tightly packed, there’s no room for labels other than –, + and the data direction arrows. Data is the un-labeled pad.
Can NeoPixels be powered directly from the Arduino’s 5V pin?
Sometimes. The Arduino can continuously supply only about 500 milliamps to the 5V pin. Each NeoPixel can draw up to 60 milliamps at full brightness. So yes, you can skip the separate DC supply and power directly off the Arduino as long as just a few pixels are used, more if the colors and overall brightness are low. When in doubt, give the pixels a separate power supply.