Break Locked MCU PIC16F870 Flash
Break Locked MCU PIC16F870 Flash memory protection and copy original source code from pic16f870 microcontroller encrypted to new chip, this is an important step to collecting the necessary data of reverse engineering circuit board;
In RCIO mode, the RC circuit is connected to the OSC1 pin. The OSC2 pin becomes an additional general purpose I/O pin. The I/O pin becomes bit 4 of PORTA (RA4). Figure 3-6 shows the RCIO mode connections.
The RC oscillator frequency is a function of the supply voltage, the resistor (REXT) and capacitor (CEXT) values and the operating temperature. Other factors affecting the oscillator frequency are:
- threshold voltage variation
- component tolerances
- packaging variations in capacitance
The user also needs to take into account variation due to tolerance of external RC components used.
The INTRC and INTRCIO modes configure the internal oscillators as the system clock source when the device is programmed using the Oscillator Selection (FOSC) bits in the Configuration Word register (Register 11-1).
In INTRC mode, the OSC1 pin is available for general purpose I/O. The OSC2/CLKOUT pin outputs the selected internal oscillator frequency divided by 4. The CLKOUT signal may be used to provide a clock for external circuitry, synchronization, calibration, test or other application requirements which are all required for printed circuit board duplication.
In INTRCIO mode, the OSC1 and OSC2 pins are available for general purpose I/O.