PIC Microcontrollers

The PIC is a family of microcontrollers developed by Microchip technology. It's derived from the name of the microcontroller(PIC1650) originally developed by general instrument's micro electronics division. The name PIC initially referred to pheripheral interface controller. It's now expanded to Programmable Intelligent Computer. 

It's controlled by software and programmed in such a way that it performs different tasks and controls a generation line. PIC microcontrollers are used in different new applications such as smartphones, audio, accessories, and advanced medical devices.

Many types of PIC are available in the market ranging from PIC16F84 to PIC16C84. These types of PICs are affordable flash PICs.  Microchip has recently introduction flash chips with different types such as 16F628, 16F877 and 18F452.  The 16F877 cosst 

 

  The 16F877 costs twice the price of the old 16F84, but it is eight times more than the code size, with more RAM and much more I/O pins, a UART, A/D converter and a lot more features.

PIC Microcontrollers Architecture

The PIC microcontroller is based on RISC architecture. Its memory architecture follows the Harvard pattern of separate memories for program and data, with separate buses.

PIC microcontroller architecture

1. Memory Structure

The PIC architecture consists of two memories: Program memory and Data memory.

Program Memory: This is a 4K*14 memory space. It is used to store 13-bit instructions or the program code. The program memory data is accessed by the program counter register that holds the address of the program memory. The address 0000H is used as reset memory space and 0004H is used as interrupt memory space.

Data Memory: The data memory consists of the 368 bytes of RAM and 256 bytes of EEPROM. The 368 bytes of RAM consists of multiple banks. Each bank consists of general-purpose registers and special function registers.

The special function registers consist of control registers to control different operations of the chip resources like Timers, Analog to Digital Converters, Serial ports, I/O ports, etc. For example, the TRISA register whose bits can be changed to alter the input or output operations of the port A.

The general-purpose registers consist of registers that are