The “magic” of these pixels is that they're digitally controlled…even though there are only two control lines, you can have as many pixels as you’d like in a single long strand, yet each remains independently controllable.
Though it looks like the 4-conductor ribbon cable is continuous, it isn't! The pixels have a distinct “in” and “out” side. Data from the microcontroller arrives on the input side, where it’s received by the driver chip. The output side then connects to the input of the next pixel, all the way down the line.When connecting these pixels to a microcontroller, make sure you're connecting to the strand's input pins! On these large pixels, it's easy to spot: examine the circuit board, looking for the "IN" label and an arrow indicating the direction of data flow. If connecting multiple strands together, make sure the output of one strand goes to the input of the next.
Wiring is pretty easy since there are only 4 wires. The only important thing is that you should not try to power the LED strand from the Arduino's 5V line — these LEDs require a dedicated 12V source separate from the microcontroller.
Use this diagram with the red wire going to +12V from the power supply, green (serial clock) to Arduino digital pin 3, yellow (serial data) to digital pin 2, and black to both the ground connection on the power supply and any available GND pin on the Arduino.
Our Arduino library can use any two pins, but the examples are written to use pins 2 and 3 as above.