Embedded System (2)

7/30/2019 Embedded System (2)

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By: AVTAR SINGH MALHI

Uni. Roll No:90510414053

NWIET, DHUDIKE. MOGA

In the name of God


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Embedded system means the processor is embedded

into that application.

An embedded product uses a microprocessor or

microcontroller to do one task only. In an embedded system, there is only one application

software that is typically burned into ROM.


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Perform a single task

Usually not general purpose.

Increasingly high performance.

Power, cost and reliability. HW-SW systems

Software is used for more features and flexibility

Hardware (processors, memory etc. are used forperformance and security.


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Exampleprinter, keyboard, video game player,

microwave oven etc.

Aircraft electronics

Trains

Medical systems


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Microprocessor vs. M icrocontrol ler

Microprocessor

CPU is stand-alone,

RAM, ROM,I/O,timer are separate

Designer can

decide on the

amount of ROM,

RAM and I/O ports.

Expansive

General-purpose

Microcontroller

CPU, RAM, ROM, I/O

and timer are all on asingle chip

fix amount of on-chip

ROM, RAM, I/O ports

for applications in which

cost, power and space

are critical

single-purpose


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Microcontroller

A microcontroller is an entirecomputer manufactured on a singlechip.

They have a high concentration ofon-chip facilities such as serial ports,parallel input/output ports, timers,counters, interrupt control, analog-to-digital converters, random accessmemory, read only memory, etc.

ExampleMotorolas 6811, Intels 8051,


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The 8051 M icrocontrol ler

The 8051 is the first microcontroller of the MCS-51 familyintroduced by Intel Corporation at the end of the 1970s.

The 8051 family characteristics:4K Bytes ROM128 Bytes RAMtwo timer/counters (16 bit)

A serial port4 general purpose parallel input/output portInterrupt controller

The 8051 can address 64K of external data memory and64K of External program memory.


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CPU

On-chip

RAM

On-chip

ROM for

program

code

4 I/O Ports

Timer 0

Serial

PortOSC

Timer 1

Timer/Counter

Bus

Control

TxD RxDP0 P1 P2 P3

Address/Data


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1234567

891011121314

151617181920

40393837363534

33323130292827

262524232221

P1.0P1.1P1.2P1.3P1.4P1.5P1.6

P1.7RST

(RXD)P3.0(TXD)P3.1

(T0)P3.4

(T1)P3.5

XTAL2XTAL1

GND

(INT0)P3.2(INT1)P3.3

(RD)P3.7(WR)P3.6

VccP0.0(AD0)P0.1(AD1)P0.2(AD2)P0.3(AD3)P0.4(AD4)P0.5(AD5)

P0.6(AD6)P0.7(AD7)EA

ALE

PSENP2.7(A15)P2.6(A14)

P2.5(A13)P2.4(A12)P2.3(A11)P2.2(A10)P2.1(A9)P2.0(A8)

8051

(8031)


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o Vccpin 40Vcc provides supply voltage

to the chip.The voltage source

is +5V.

o GNDpin 20ground

o XTAL1 and XTAL2pins

19,18. Using a crystaloscillator we can observe the

frequency on the XTAL2 pin..

C2

30pF

C1

30pF

XTAL2

XTAL1

GND


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RSTpin 9reset It is an input pin and is active highnormally low.

The high pulse must be high at least 2.

It is a power-on reset.

Upon applying a high pulse to RST, themicrocontroller will reset and all values in registers

will be lost.

All values of 8051 registers will be Reset.


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EApin 31external access There is no on-chip ROM in 8031 and 8032 .

The /EA pin is connected to GND to indicate the code isstored externally.

/PSENALE are used for external ROM.

For 8051, /EA pin is connected to Vcc.

/ means active low.

/PSENpin 29program store enable This is an output pin and is connected to the OE pin of the

ROM.


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ALEpin 30address latch enable

It is an output pin and is active high.

8051 port 0 provides both address and data.

The ALE pin is used for de-multiplexing the address anddata by connecting to the G pin of the 74LS373 latch.

I/O port pins

The four ports P0, P1, P2, and P3.

Each port uses 8 pins.

All I/O pins are bi-directional.

ALE, I /O port pins


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The 8051 has four I/O ports Port 0pins 32-39P0P0.0P0.7 Port 1pins 1-8 P1P1.0P1.7 Port 2pins 21-28P2P2.0P2.7 Port 3pins 10-17P3P3.0P3.7 Each port has 8 pins. These 8 bits form a byte.

Each port can be used as input or output (bi-direction).


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PROGRAMMING WITH THE

USE OF KEI L SOFTWARE

Write a program in embedded C language.

Execute it.

View the output of program on peripheral devices as

provided in Keil software.

Now burn the program on AT89C52 using flash magic

burner.

Now apply the chip with hardware.


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LED

Seven Segment Display

LCD Display

Relay

Switch

Buzzer

Devices which are Interfaced

with 8051 microcontroller


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A simple project using P89V51RD2

Here weve designed, built and programmed a digitalStop Watch that counts from 00:00:00 to 99:99:99on a LCD( liquid crystal display).


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Interfacing of 8051 microcontroller with lcd(liquid crystal display)


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Program to display STOP WATCH on liquid crystal display (LCD).#includesbit rs=P1^0; sbit e=P1^1; sbit sw1=P1^2; sbit sw2=P1^3;

unsigned char min[3]="Min"; unsigned char sec[3]="Sec";unsigned charhur[4]="Hour";void dat(); void delay(); void cmd(); void main(){ int g,h,i,j,k,l,a,b,c;P0=0x38; cmd(); delay();P0=0x0c; cmd(); delay();

P0=0x01; cmd(); delay();P0=0x06; cmd(); delay();P0=0x80; cmd(); delay();for(c=0;c


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Embedded System (2)

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