Question

Write an AVR assembly program for the ATmega328PB that uses a loop to sum the decimal numbers 1, 2, 3, ..., 19, 20, noting where the result is stored as well as its value in hexadecimal and decimal.

Answer 1

    ORG OOOOh
    LJMP main
    ORG 0x40h
main:
    MOV R0,#14h      ; N=20 value to get Sum from 1 to 20
    MOV R1,#01h
loop:
    ADD A,R1
    INC R1
    DJNZ R0, loop
    MOV R4,A         ; Final Sum is stored in register R4
end