System and method for protecting contents of microcontroller memory by providing scrambled data in response to an unauthorized read access without alteration of the memory contents

摘要: A microcontroller fabricated on a semiconductor chip has an on-chip EPROM program memory. The is selectively configurable to operate in any one of plurality predetermined operating modes, including at least secure mode. configuration fuses used for configuring the and protecting its memory from read, verify or write through instruction initiated other than area chip, are mapped into as bits respective address locations thereof. value bit representing said effective determine condition fuse. That observed by reading that fuse stored security enabled code protected mode programming desired effectively blow erase each according configuration.