EMBEDDED SYSTEM

What is embedded system?

It is a electronic and electrical device which is use for microcontroller and microprocessor for performing a specific tasks is called embedded system. And it is combination if hardware and software.

 

Difference between microcontroller and microprocessor:-

Microcontroller is a single chip that has everything in built.

Ex- RAM, ROM, I/O devices , timers and counters etc.

 But in Microprocessor we are using externally RAM, ROM, I/O devices etc. And by this region microprocessor system required more hardware.

 

Here we are talking about microcontroller :-

The microcontroller has on-chip peripheral device. it has ROM, RAM, Serial I/O, Parallel I/O, timer/counters, interrupts and clock. Microcontrollers were developed to avoid the drawbacks of microprocessor.

·       In Microcontroller due to less hardware its PCB size is small.

·       It has smaller access time. Hence, speed is high.

 

Types of microcontroller:-

·       MCS51(8051)

·       AVR

·       PIC

·       ARM but this is a microprocessor.

 

Introduction :-

 

8051:- The 8051 was introduced  by Intel in 1980. It is a 8-bit microcontroller.

 

AVR (Advance virtual risk machine) :- The AVR was introduced by ATMEL in 1996. It is a 8-bit, 16-bit and 32-bit microcontroller.

 

PIC (Peripheral interface computer) :- The PIC was introduced by microchip technology  in 1976. It is a 8-bit, 16-bit and 32-bit microcontroller.

 

ARM (Advance risk machine):- the ARM was introduced by Philips in 1985. It is a 32-bit and 64-bit microprocessor.

 

 

             --: 8051 :--

 

The main features are available in 8051 chips:-

 

1.   8-bit CPU

2.  4-kb on chip programmable memory

3.  128 bytes RAM

4.  Four ports of each 8-bit

5.  Two 16-bit Timers

6.  Full duplex Serial port

7.  On chip clock oscillator

 

Applications:-

Appliances, lighting control, security system, printers, toys, musical instrument etc.

                          - -:  AVR :--

 

Series                    ROM

 

ATmega8                     8kb

ATmega16                   16kb

Atmega32                    32kb

ATmega64                   64kb

ATmega128                128kb

 

It has four I/O ports:-

 

PORTA, PORTB, PORTC, PORTD

 

Each port is 8-bit and has 8 pins.

 

PORTA (Pa0……Pa7)

 

PORTB (Pb0……Pb7)

 

PORTC (Pc0……Pc7)

 

PORTD (Pd0……Pd7)

 

    Each Pins are 1 bit. We can use every pin as an input or output.

 

In AVR we are using a register DDR for select the PORT as input or output .

 

DDR (Data Direction register):-

 

For PORTA-

 

DDRA=0xff; Means this port is select for OUTPUT.

DDRA=0x00; Means this port is select for INPUT.

And selection is same for all Ports.

 

DDRB=0B11111111; means this in binary form for output.

DDRB=0xff; means this in hex form.

DDRB=0B00000000; means this in binary form for input.

DDRB=0x00; means this in hex form for input.

 

   And same in DDRC and DDRD.

 

Applications:- ROBOTICS.