PIC16F877A 10..

The PIC16F877A micro controller is used to control the whole system. It is designed using flash technology. So the PIC can read/write program for more than 100,00 times. The PIC16F877A has 8K words or program memory. Since each word in the mid range family is 14 bits long the program memory can also be expressed as 14K bytes. The unit has 368 bytes of data ram and 256 bytes of EEPROM. It has 8 channels of A/D with 10 bit resolution. The unit has 2 8bit Timer?Counters and a single 16 bit Timer/Counter. in addition to this, it has several different types of serial communication functions such as SPI, 12C, and normal PC type serial communication functions.

PIC16F877A port.

OSC1 and OSC2 pins are connected to 20MHZ crystal to execute every single program line in the system. 20MHz crystal is used because this is the maximum frequency that the PIC can support. If over frequency the PIC will burn. Else if crystal speed is less than 20MHz the the PIC response speed will slower. The MCLR pin of the PIC is pull up to 5V through a 10KR resistor. The PIC can operate using 4.5V to 6.0V DC voltage. In the project is operating at 5.0V (by using 7805). It is DIP layout (dual in line package) and suitable for student project. It has 40 pins but only 33 I/O pins can be set as digital input or digital output. The digital output of the PIC is 5V (for signal) and 0V (for signal 0) these signals will be directly connected to actuators for control purpose. When the PIC pin is set as digital input. it will detect input voltage 5V as signal 1 and 0V as signal 0. Any voltage less than 0V or more than 5V will damage PIC.