External power vs usb power

Question

I built a sample of my project on a breadboard using little 700mh leds and other components that easily ran off my computers usb. Now I’m building my project to full size. This includes 12 7w leds, soundboard and amps. It’s still going to be controlled by a arduino mega, obviously, the power consumption is substantially higher than the usb or even the arduino can provide. I’m using a high amp power supply that can drive everything including the arduino.

The question is... how will I be able to alter my sketch later??? Is it feasible to use a panel mount usb cord modified to only allow tx and rx, (cut the red and black)? Or will I have to isolate the mega each time I need to send a change to it?

Answer 1

You can modify a USB cable by cutting the power (red) wire. You'll still need the ground wire with RX and TX.

Answer 2

Using an altered USB cable and a separate power supply will work but isn't really necessary. I usually put a connector on my high-current devices like LEDs and whatnot so I can remove them from the equation while I upload code, and for debugging I leave the external power supply attached and use a regular USB cable to the PC (see What happens if I power the Arduino with both the USB and external power voltage simultaneously?).