We can Copy Microprocessor PIC16C74B Firmware, please view the Microprocessor PIC16C74B features for your reference:
The Timer2 module has an 8-bit period register, PR2. Timer2 increments from 00h until it matches PR2 and then resets to 00h on the next increment cycle. PR2 is a readable and writable register. The PR2 register is initialized to FFh upon Reset when copying microprocessor firmware.
The comparator module contains two analog comparators. The inputs to the comparators are multiplexed with I/O port pins RA<3:0>, while the outputs are multiplexed to pins RA<5:4>. An on-chip Comparator Voltage Reference (CVREF) can also be applied to the inputs of the comparators if microprocess firmware copying.
The CMCON0 register (Register 8-1) controls the comparator input and output multiplexers. A block diagram of the various comparator configurations before copy firmware.
A single comparator is shown in Figure 8-1 along with the relationship between the analog input levels and the digital output. When the analog input at VIN+ is less than the analog input VIN-, the output of the comparator is a digital low level after microprocessor copy software.
When the analog input at VIN+ is greater than the analog input VIN-, the output of the comparator is a digital high level. The shaded areas of the output of the comparator in Figure 8-1 represent the uncertainty due to input offsets and response time.
The polarity of the comparator output can be inverted Output by setting the CxINV bits (CMCON0<5:4>). Clearing CxINV results in a non-inverted output. A complete table showing the output state versus input conditions and the polarity bit is shown in microprocessor firmware.
A simplified circuit for an analog input is shown in Figure 8-2. Since the analog pins are connected to a digital output, they have reverse biased diodes to VDD and VSS. The analog input, therefore, must be between VSS and VDD. If the input voltage deviates from this range by more than 0.6V in either direction, one of the diodes is forward biased and a latch-up may occur. A maximum source impedance of 10 kÙ is recommended for the analog sources. Any external component connected to an analog input pin, such as a capacitor or a Zener diode, should have very little leakage from microprocessor copying.
There are eight modes of operation for the comparators. The CMCON0 register is used to select these modes. Figure 8-3 shows the eight possible modes. If the Comparator mode is changed, the comparator output level may not be valid for the specified mode change delay shown in Section 19.0 “Electrical Specifications” when copy microcontroller.
