But what if the chips is taken out from the circuit with intention to steal the code by opening lock bits by giving the chip supply dips faster than allowed?
Is there any thing that can help the chip and the code writer in such an event.
I do not know why the extreme worry about code being stolen. I once had to recreate code for a factory that burned down and, stupidly, did not have off-site copies (they bought a unit back for me to work with) and after much work with disassembly etc threw it all away and started from scratch. Of course, I do set the lock bits, but that's just to avoid the competition to have a glance, it may give them a hint here or there (you can load it in a debugger and see the disassmbly when running) but, again, it will cost them more time that starting from scratch. I doubt even 'the glance' will make it worth it to break the lock bits. Oh, the code I had to recreate was written in assembly, I would not even attempt to 'read' disassembled C. Of course there will be the extremely rare case where some algorithm (e.g. a lookup table that took weeks to get right) would be of some value, but still not worth the effort. One exception would be where, for some reason (I can not imagine one on a microprocessor) a very valuable password would be in the flash.

Erik

a Danish proverb "thief thinks everyone steals"