The ATmega4809 organizes I/O registers by module and puts all the registers in C structures. The older AVR microcontrollers have a flat organization. For instance, take the Data Direction register for port B. In the ATmega328P this is simply defined: #define DDRB _SFR_IO8(0x04) This puts the register at location 0x04. In the ATmega4809, all the …