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Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
@Gordon
Yes - with 256 LEDs you're looking at potentially 256*3*0.02A if all LEDs are lit - which is 15 amps! :)
You'll want to connect GND and Data to Espruino, and GND + Power to an external 5v power supply.
Also, it's worth connecting Power and GND right from the end of your LEDs, back to the beginning. That'll really help with the dimming you're seeing. If you want to do it really nicely you could connect the power and GND of each row back to one place...