Hello. i am using Arduino mega 2560 and i have some questions:
1) if i connect both the usb cable to the arduino and the power supply to the arduino, which supply voltage the Arduino will choose?
2) the usb supply 5V and in the data sheet says that that less than 7v is not good, so i have to use power supply of 7-12v?
3) what is the difference if i plug power supply of 9 or 11? and what is the exact supply voltage recommended?