I am following this guide. Now I want to create the Create the "ArduinoCore library". But when I am creating a new project, I can not select ATmega16U2 as MCU type.
But my Arduino Due R3-E and UNO SMD R3 both use ATmega16U2.
What shall I do O_o???
ATmega16U2 on those boards isn't intended to be programmable by the end-user. It's only there to help convert from USB to TTL serial, which lets your computer communicate with the board's main microcontroller. It replaces the FTDI chip which was used on some older boards.
In the case of the Uno, the main microcontroller is the
ATmega328. For the Due, it's the
AT91SAM3X8E. If you want to program them from the Arduino IDE, you can usually just select the board by name from the drop-down menu.