With the ESC powered and connected to a motor, and you plug in a live USB connection to the processor, a spurious full RPM signal is sent to the motors.
If the processor is externally powered from the control box (12v), and then you plug in the USB cable, all’s well.
The problem with having to have the control box power on is when you forget to center the motor speed control on the box. In any event it is a problem that could prove destructive.
I don’t want to have to remove an end cap and disconnect ESC power every time I make a program change.
During my PID testing a lot of changes are being made.