ATMEGA328P-AU is small chip used in Arduino Nano, and chip can be purchased and used for own projects. When designing circuit board, I don’t want to waste space for pattern just to burn bootloader, which is usually only used once for most of the time. I use kit sold from aitendo store in Japan to burn bootloader (sorry, not shipped overseas). http://www.aitendo.com/product/15799 This kit comes with socket for ATMEGA328P-AU and circuit board and some parts. After building kit, connect with Arduino with bootloader burn sketch, then place chip on socket and burn bootloader to ATMEGA328P-AU chip. Since original sketch output result to serial port, I added OLED display so it …