Extract Microcontroller PIC16F685 Code from MCU PIC16F685 flash memory, crack MCU fuse bit by locate its position through Microcontroller reverse engineering technique;

The STATUS register, shown in Register 2-1, contains:

• the arithmetic status of the ALU
• the Reset status
• the bank select bits for data memory (GPR and SFR)

The STATUS register can be the destination for any instruction, like any other register. If the STATUS register is the destination for an instruction that affects the Z, DC or C bits, then the write to these three bits is disabled when read mcu at89c51cc03 program.

These bits are set or cleared according to the device logic. Furthermore, the TO and PD bits are not writable. Therefore, the result of an instruction with the STATUS register as destination may be different than intended.

The Program Counter (PC) is 13 bits wide. The low byte comes from the PCL register, which is a readable and writable register. The high byte (PC<12:8>) is not directly readable or writable and comes from PCLATH.

On any Reset, the PC is cleared. Figure 2-9 shows the two situations for the loading of the PC. The upper example in Figure 2-9 shows how the PC is loaded on a write to PCL (PCLATH<4:0> → PCH). The lower example in Figure 2-9 shows how the PC is loaded during aCALL or GOTO instruction (PCLATH<4:3> → PCH) after extract microcontroller AT89C51IC2 program.

The PIC16F631/677/685/687/689/690 devices have an 8-level x 13-bit wide hardware stack (see Figures 2-2 and 2-3). The stack space is not part of either program or data space and the Stack Pointer is not readable or writable.

The PC is PUSHed onto the stack when a CALL instruction is executed or an interrupt causes a branch. The stack is POPed in the event of a RETURN, RETLW or a RETFIE instruction execution. PCLATH is not affected by a PUSH or POP operation.

The stack operates as a circular buffer. This means that after the stack has been PUSHed eight times, the ninth push overwrites the value that was stored from the first push. The tenth push overwrites the second push (and so on).