Smart pixel is a multi color LED (light emitting diode) containing individual red, green and blue (RGB) light emitting diodes. It's conveniently placed on a tiny PCB with pins available to solder easily. Inside the LED there is a very small chip that can understand data coming through the IN pin and pass along to other LEDs connected on the OUT pin.
The pixel needs a very precise timing to receive the data and convert it into one of RGB colors. Each R, G and B value can be in the range of [0..255]. BlinkStick Pro takes care of handling the LEDs and controlling up to 192 of them connected to a single controller.
On the bottom side of the smart pixel, the little black arrows display the direction in which the data is transferred. All smart pixels share +5V and GND lines and are connected between IN and OUT pins.
The first example shows the connection in series on the R channel of BlinkStick Pro. You can connect up to 64 smart pixels 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.