It is very critical to reset the security bits of Microcontroller W77E52 to disable its protection against the internal memory system which include flash and eeprom, only when the bits has been disable, the Attack Nutovon Microcontroller W77E52 Flash Memory will become a possibility, now we list some of the basic features of its security bits:
During the programmer operation mode, the Flash EPROM can be programmed and verified repeatedly. Until the code inside the Flash EPROM is confirmed OK, the code can be protected. The protection of Flash EPROM and those operations on it are described below.
The W77E52 has a Special Setting Register, the Security Register, which can be accessed in normal mode. The register can only be accessed from the Flash EPROM operation mode. Those bits of the Security Registers can not be changed once they have been programmed from high to low. They can only be reset through erase-all operation. The Security Register is addressed in the Flash EPROM operation mode by address #0FFFFh when Attack Nutovon Microcontroller W77E52 Flash Memory.
SPECIAL SETTING REGISTER
7.1 Lock Bit
This bit is used to protect the customer’s program code in the W78E51B. It may be set after the programmer finishes the programming and verifies sequence. Once this bit is set to logic 0, both the on-chip ROM data and Special Setting Registers can not be accessed again.
7.2 MOVC Inhibit
This bit is used to restrict the accessible region of the MOVC instruction. It can prevent the MOVC instruction in external program memory from reading the internal program code. When this bit is set to logic 0, a MOVC instruction in external program memory space will be able to access code only in the external memory, not in the internal memory. A MOVC instruction in internal program memory space will always be able to access the ROM data in both internal and external memory. If this bit is logic 1, there are no restrictions on the MOVC instruction after Attack Nutovon Microcontroller W77E52 Flash Memory.
7.3 Encryption
This bit is used to enable/disable the encryption logic for code protection. Once encryption feature is enabled, the data presented on port 0 will be encoded via encryption logic. Only whole chip erase will reset this bit before reverse engineering MICROCONTROLLER.