PIC Microcontroller: Developed By General Instruments

PIC Microcontroller

Pic stands for (Peripheral Interface Controller)

Introduction

The pic microcontroller was developed by General Instruments in 1975. PIC was developed when Microelectronics Division of General Instruments was testing its 16-bit CPU CP1600. Although the CP1600 was a good CPU but it had low I/O performance. The PIC controller was used to offload the I/O the tasks from CPU to improve the overall performance of the system.

Where as in

In 1985, General Instruments converted their Microelectronics Division to Microchip Technology.

In 1993, Microchip Technology launched the 8-bit PIC16C84 with EEPROM which could be programmed using serial programming method. The improved version of PIC16C84 with flash memory (PIC18F84 and PIC18F84A)

PIC is a microcontroller which also consists of the ram, rom, CPU, timers, counter, ADC (analog to digital converters), DAC (digital to analog converter). Hence PIC also supports the protocols like CAN, SPI, UART for interfacing with other peripherals. PIC mainly used modified Harvard architecture and also supports RISC by the above specification RISC and Harvard we can easily that PIC is faster than the 8051 based controller which is made-up of Von-Newman architecture.

Here is the architecture as shown below.

Here the CPU is not different from other microcontrollers CPU. PIC microcontroller CPU consists of Arithmetic logic unit (ALU), memory unit (MU), control unit (CU), Accumulator etc. we know that ALU mainly used for arithmetic operations and taking the logical decisions, memory used for storing the instruction which is to processed and also storing the instructions after processing, Control unit is used for controlling the all the peripherals which are connected to the CPU both internal peripherals and external peripherals. Accumulator is used for storing the results and used for further processing. As I said earlier PIC micro controller supports the RISC architecture that is reduced instruction set computer, if a computer or controller is said that it supports reduced instruction set you should note the following points:

Unlike the 17 series, it has been proven to be very popular, with a large number of device variants presently in manufacture. In contrast to earlier devices, which were the more often than not programmed in assembly, C has become the predominant the development language.

The 18 series inherits most of the features and instructions of the 17 series. add a number of important features.

• call stack is 21 bits wide and much deeper (31 levels deep)

• the call stack may be read and written (TOSU:TOSH:TOSL registers)

• conditional branch instructions

• indexed addressing mode (PLUSW)

• extending the FSR registers to 12 bits, allowing them to linearly address the entire data address space

• The addition of another FSR registers (bringing the number up to 3).

PIC24 and dsPIC

In the 2001, Microchip introduced the dsPIC series of chips, which entered mass production in late 2004. They are Microchip's first inherently 16-bit microcontrollers. PIC24 devices are designed as general purpose microcontrollers. dsPIC devices include (DSP) digital signal processing capabilities in