Break IC, Recover MCU, Microcontroller Reverse Engineering

Posts Tagged ‘extract dsp ic program’

Extract PIC16F84 MCU Firmware from Microcontroller PIC16F84 flash and eeprom memory, reset the microprocessor status to unlocked one by crack MCU fuse bit and copy MCU’s code to new one;

Another example is an old PIC16F84 microcontroller from Microchip. The chip erase operation removes the security protection but at the same time erases the contents of program and data memories on the chip. The hardware design of the security protection circuit is made such that the memory is always erased before the security fuse is reset to the initial state.

However it was found that if during the chip erase operation the power supply voltage is increased to about 10 V for a few milliseconds it causes the memory erase process to terminate but the security fuse reset finishes as usual making it possible to read the contents of the memory. Such a high voltage pulse should be applied carefully as increasing its length could permanently damage the chip. The later revision of this microcontroller, PIC16F84A, has protection against under- and over-voltage attacks. Any memory modification operations performed via the programming interface are immediately terminated if the power supply voltage goes below 3 V or above 6 V.