Datasheets AVR Instruction Set Manual ATmega328 Datasheet Stackblitz demos avr8js-minimal avr8js-6leds - this is where we added the AVRUSART Peripheral ATMega328 + Arduino Pinout Issues Serial port (USART TX) should respect the given baud rate Tools The Online Disassembler - Click on the Platform button, and select "avr" in the Arch dropdown list.