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

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.

 Details Of PIN  Of PIC18F458 


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.

hardware connection of pic microcontroller


How we can program port