I have written a code for password based door lock on Atmel Studio 7. I am using external interrupt INT0 to change the password at anytime according to user's wish. But, this interrupt gets executed automatically every time simulation on Proteus is run. As a result, it prompts user to change password every time the simulation is run, which should not happen! I wish the ISR to be executed only when I apply INT0 signal. Kindly help!