Copy Microcontroller PIC16F684 Firmware from its flash memory and then re-programme the program into blank MCU PIC16F684 to provide the same functions as original MCU which can be viewed as IC cloning.

An input change on PORTB<7:4> sets flag bit RBIF (INTCON<0>). The interrupt can be enabled/disabled by setting/clearing enable bit RBIE (INTCON<4>).

During an interrupt, only the return PC value is saved on the stack. Typically, users may wish to save key registers during an interrupt (i.e., W, PCLATH and STATUS registers). This will have to be implemented in software before Copy MCU AT89C5131A software.

For the PIC16F73/74 devices, the register W_TEMP must be defined in both banks 0 and 1 and must be defined at the same offset from the bank base address (i.e., If W_TEMP is defined at 20h in bank 0, it must also be defined at A0h in bank 1.).

The registers, PCLATH_TEMP and STATUS_TEMP, are only defined in bank 0. Since the upper 16 bytes of each bank are common in the PIC16F76/77 devices, temporary holding registers after extract Microcontroller at89ls8252 code.

W_TEMP, STATUS_TEMP and PCLATH_TEMP should be placed in here. These 16 locations don’t require banking and, therefore, make it easier for context save and restore. The same code shown in Example 12-1 can be used.

The Watchdog Timer is a free running on-chip RC oscillator, which does not require any external components. This RC oscillator is separate from the RC oscillator of the OSC1/CLKIN pin.

That means that the WDT will run, even if the clock on the OSC1/CLKIN and OSC2/CLKOUT pins of the device has been stopped, for example, by execution of a SLEEP instruction.

During normal operation, a WDT time-out generates a device RESET (Watchdog Timer Reset). If the device is in SLEEP mode, a WDT time-out causes the device to wake-up and continue with normal operation (Watch-dog Timer Wake-up).

The TO bit in the STATUS register will be cleared upon a Watchdog Timer time-out. The WDT can be permanently disabled by clearing configuration bit, WDTE.