We are using an Arduino Micro and need to have it (only) boot from an external supply. It cannot boot from USB power. We need this because the Arduino must preset an IC on power up that is connected to the same external supply. If the USB cable stays connected to the Arduino, the Arduino receives power from the bus and will not reboot to preset the IC.
Our attempt was to pull the resettable fuse in series with the USB power line on the Arduino Micro board. With that "fix" we were unable to upload to the Arduino or even see the Arduino on a com port.
Any suggestions would be appreciated.