Extract MCU PIC18F442 Code out from the memory which include the flash and eeprom, then copy the firmware into blank Microcontroller PIC18F442 through disable the security fuse bits which can be spotted through Microcontroller reverse engineering technique.
During reset, all I/O registers are set to their initial values. The SRAM content is not reset. Application execution starts from the Reset Vector. The instruction placed at the Reset Vector should be an Absolute Jump (JMP) instruction to the reset handling routine. By default the Reset Vector address is the lowest Flash program memory address, ‘0’, but it is possible to move the Reset Vector to the first address in the Boot Section.
The I/O ports of the AVR are immediately tri-stated when a reset source goes active. The reset functionality is asynchronous, so no running clock is required to reset the device. After the device is reset, the reset source can be determined by the application by reading the Reset Status Register when code of mcu being extracted.
The MCU is reset when the supply voltage VCC is below the Brown-Out Reset threshold voltage and the Brown-out Detector is enabled. The Brown-out threshold voltage is programmable.
The XMEGA A1 has a Watchdog Timer (WDT). The WDT will run continuously when turned on and if the Watchdog Timer is not reset within a software configurable time-out period, the microcontroller will be reset. The Watchdog Reset (WDR) instruction must be run by software to reset the WDT, and prevent microcontroller reset if the mcu code has been extracted.
The WDT has a Window mode. In this mode the WDR instruction must be run within a specified period called a window. Application software can set the minimum and maximum limits for this window. If the WDR instruction is not executed inside the window limits, the microcontroller will be reset.
A protection mechanism using a timed write sequence is implemented in order to prevent unwanted enabling, disabling or change of WDT settings. For maximum safety, the WDT also has an Always-on mode. This mode is enabled by programming a fuse. In Always-on mode, application software can not disable the WDT.
