Flash memory rewriting circuit for microcontroller

摘要

A flash memory rewriting circuit capable of rewriting a flash ROM without Presenting any problem from the viewpoint of security of programs. In a transfer Program storing region of the flash ROM is stored a program to activate a CPU of a microcontroller and to transfer a rewriting data from external devices to peripherals. On a mask ROM is written, in a fixed manner, a program to activate a CPU and to write the rewriting data on a region other than the flash ROM. Because the program stored in the transfer program storing region is installed by users, no on except user can read or rewrite the program.