Adafruit NeoPixel strips consist of WS2812 LEDs on a flexible PCB.
All NeoPixel strings share PWR and GND lines with BlinkStick Pro. They are chained together with IN and OUT pins.
The first example shows the connection of one NeoPixel strip to the R channel of BlinkStick Pro. You can connect up to 64 LEDs on a single channel and you can use any of the channels available.
The second example shows how to use all channels on BlinkStick Pro.
Regular USB port can supply about 500mA of current. It's safe to run 8 LEDs from USB port directly at full brightness. About 50mA is required for BlinkStick Pro, so you can only use a safe 400mA to drive the LEDs.
Here is how you can calculate the maximum brightness limit of LEDs:
Brightness = 400mA / [Number of LEDs] / 50mA * 100%
Number of LEDs - is the maximum number of LEDs that will be turned on at any time.
For example, if you will be turning on 24 LEDs at the same time, then:
400mA / 25 / 50mA * 100% = 32%
This means that you will have to limit the brightness of LEDs to 32% in order to run them safely from USB. Please note that these pixels are bright even at 1%!
In order to control more than 8 pixels at full brightness, you will need an external power supply.
The power supply must provide 5V and the amperage rating depends on how many LEDs you are going to use. For example, to run maximum 192 LEDs at full brightness, you will need a 10A power supply. Here is how you can calculate the amperage of power supply to drive the LEDs:
Current = [Number of LEDs] * 50mA
For example, in order to drive 64 LEDs, you will need 64 * 50mA = 3.2A power supply.