Question

Assemble the Following AVR instructions into machine code (express your answer in binary). If you find an error, explain why it is an error. (Show steps)

a) mul r5, r16

b) ldi r22, 65

Answer 1

a) mul r5,r16

for MUL instruction format would be

1001 11rd dddd rrrr

mul opcode: 1001

and then 11rd = 1100

dddd = destination register = r5 = 0101

but rrrr = r16 which is error it shoul be within r0,r15. So it can't be converted to machine code.  

for LDI instruction format would beb) ldi r22,65

1110 KKKK dddd KKKK

where 1110 - LDI code

and in the instruction r22 is used which 6th register so dddd - 0110

and KKKK - 6 - 0110

and KKKK - 5 - 0101

so machine code would be: 1110 0110 0110 0101