Atmega328p kicad subsystem headers Arduino schematic uno r3 diagram circuit atmega microcontroller electroschematics own vin build part physics original powering through updating firmware version Arduino from scratch part 12 – atmega328p schematic
Build your own arduino & bootload an atmega microcontroller
Arduino from Scratch Part 12 – ATMEGA328P Schematic
Build Your Own Arduino & Bootload an ATmega Microcontroller - part 1