Password protection code for AVR MC code

[Silent_Miracle]

i am using ATmega16L with 4bit mode of LCD and keypad using C. i want to protect the code with a password with option to change password. Could anyone please help me with this. i dnt knw what should be the code for password protection.

 

[kalbun]

Which "code" are you referring? The firmware inside the MPU? In this case I'm not aware of ways to password-protect it. You can yet set fuses so that memory is no longer readable and no one can steal your executable.
Or are you designing an electronic lock and you want to set a master code that allows you to change access code?
Please explain.

 

[Silent_Miracle]

actually what i meant is i have a code that displays option on LCD i.e,"Enter time " and when a user presses the key from the keypad the motor is run for that particular time. and what i want is that first there is an authentication option.User enters the password. if the password is correct then the "enter time" option is displayed to him.so i don't know how to write the code for this authentication