I want to drive a number of LEDs in a panel (8x32). No problem, I have a suitable 5V supply which can also supply the plasma board.
However, I am concerned about having this connected while I also have a USB cable connected for development/debugging. Obviously, I don’t want to fry the USB port I am connecting to on the development machine…
Anyone have any advice?
I made myself a Data only USB cable which I use with my Interstate 75 and Plasma Stick’s etc. Setups that have a dedicated +5V supply.
I carefully cut the +5V (Red) wire, leaving just the Data +, Data- and Ground wires.
Another option is to do some maths and to measure current. I usually set the brightness to 10% or even 5%, which is still very bright. E.g. I have a 8x8 panel and with all 64 pixels pure white I still need strong sunglasses, so 10% is fine. Depending on your USB port, this might still be too much. So having a dedicated power source as described by @alphanumeric is a better solution.
Also helpful is something like this: https://de.aliexpress.com/item/1005007487372253.html
(also available from Amazon and others). You can plug these devices in-line and they really do a great job at measuring voltage and current.