Program Code Protection Method of Microprocessor Adopting Flash Memory

Abstract

A program code protection method for a microprocessor adopting a flash memory aims at a stage that a manufacture develops a product through an MCU (Micro Controller Unit) and burns a program code. The program code protection method for the microprocessor adopting the flash memory comprises steps of electrifying the MCU through a burning tool to enable the MCU enters a Mode 0 mode when burning starts; performing erasure operation on a parameter area and a data area of an integral Flash; writing a special parameter into the parameter area of the Flash and dividing the data area of the Flash into a P1 area, a P2 area and a P3 area; burning data for the P1 area and the P2 area, burning application program codes for the P1 area and burning bottom-driven and firmware upgrading control codes for the P2 area; writing a special parameter for the parameter area of the Flash, setting the P1 area and the P2 area to be read-only under a Mode 1 mode and setting the P3 area to be read-only, writeable and erasable under the Mode 1 mode; writing a special parameter into the parameter area of the Flash, opening a secret key verifying unit and setting a secret key for verifying and a verifying mechanism for the P1 area. The program code protection method for the microprocessor adopting the flash memory can avoid procedure damage or data loss caused by external disturbance to the Flash MCU and effectively protects an original code from reading and stealing.

Description

technical field [0001] The invention relates to the technical field of microprocessors, in particular, the invention relates to a program code protection method of a microprocessor using a flash memory. Background technique [0002] Compared with ROM (read-only memory) and RAM (random access memory), which are two common memory types, Flash (flash memory, referred to as flash memory) has the advantage of not losing data after power failure of ROM memory, and has the advantages of erasable and reusable The write function can be used to update the program code. Therefore, more and more MCU (microprocessor) manufacturers use Flash as the program memory in their MCU chips. [0003] Many electronic products may find some problems in the hands of consumers after leaving the factory. Some problems are caused by bugs (loopholes) in the program code of the internal MCU, and some may be caused by imperfect control of the MCU and external devices. In short, many of these problems can...

AI Technical Summary

Problems solved by technology

This will bring some risks and hidden dangers to products that use Flash MCU and provide firmware upgrade function

Since the Flash memory itself has the characteristics of being erasable and rewritable, and in order to provide the firmware upgrade function, the product must also have program codes for erasing and rewriting the Flash in the factory firmware, so when the program code instructions are executed due to interference When a disorder occurs, it may be because the instruction jumps to the instruction branch related to firmware upgrade, and the erase and write operations on the Flash are executed, resulting in the destruction of the program code itself stored in the Flash, and the product cannot be used normally. question

Although all products usually have more or less anti-interference protection and enhancement on hardware and software, it cannot completely guarantee that they will not be interfered. Therefore, compared with MCUs using ROM memory, Flash MCUs have problems in this regard. probability is higher

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