How do I disable the Mega2560 from powering up via USB? I am supplying external power VIN and only want to use that, as the current drain is too high for USB. The voltages are too low when USB is connected.
As long as the Vin voltage is applied before plugging in the USB cable, then USB power will not be drawn. However Vin voltage goes only to the on-board +5vdc regulator so it will not supply all that more current then using USB power, perhaps 800ma with Vin Vs 500ma for USB. Also the specific voltage of Vin can limit the current avalible from the on board regulator as if too high a voltage then heat dissapation of the regulator could become the limiting factor.