HISTORY OF THE PIC MICROCONTROLLER
In 1989 microchip technology corporation introduced an 8-bit micro-controller Called PIC Microcontroller which stands for Peripheral Interface Controller. This micro-controller had small amount of data RAM , a few hundred bytes of on-chip ROM for the program ,one timer, and a few pins for I/O ports ,all on a single chip . Some PIC Microcontroller families are 10xxx, 12xxx, 14xxx, 16xxx, 17xxx and 18xxx. They are all 8 bit processor means CPU can work on only 8 bit data at a time and data larger than 8 bit are broken into 8-bit pieces to be processed by the CPU.
Features of pic 18 family
- It has RISC (reduced instruction set computer) architecture.
- It contain ROM (read only memory) of size 2M (megabytes).
- It has On chip program (code) ROM (read only memory) in the form of flash memory.
- It contain RAM (random access memory) between 256 bytes to 4096 bytes.
- It has Data EEPROM (Electrical Erasable Programmable Read Only Memory).
- It include Timers.
- It has ADC (analog to digital converter).
- It include USART PROTOCOL for PC communication.
- It contains I/O port between 16 to 72 pins.
- All I/O port register are bit accessible and port accessible both.
- It include SPI PROTOCOL and I2C PROTOCOL for memory communication.
- There is 2-stage pipeline in PIC18F458.
Pin Diagram of PIC18F458
There are 5 PORT registers, PORTA, PORTB, PORTC, PORTD, PORTE. In PORTB, PORTC, PORTD are 8 bit register, PORTA Is of 7 bit register and PORTE of 3 bit register.
Hardware connection(Basic Connection) to start PIC18F458
- In the below fig we can see that PIN 11 and 32 are connected to +ve terminal of battery B and PIN 12 and 13 are connected to -ve terminal of battery B to provide the power supply to the controller.
- Crystal oscillator (XTAL) connected at PIN no 13 and 14 to provide basic clock to the micro-controller so that it is able to execute its instruction in stable, periodic way.
- Capacitors of 22pf is connected to overcome the distortion arises in the crystal frequency.
- At pin 1 capacitor(c), switch(sw) and resistor(R) is connected, capacitor is for power on reset and switch is for manual reset and resistor bypass extra current arises on pin 1.