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.
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