CHAPTER 1INTRODUCTION

1

1.1 Aim of the project:

The main objective of this project is to develop an Automatic

Door opening system using IR sensors which will reduce the

need of manual labor.

1.2 Methodology:

According to our project requirements, the following modules

are essential.

Power supply

Microcontroller

Stepper Motor

IR sensors

1.3 Significance and applications:

Automatic door opening systems using IR sensors plays a very

important role in domestic applications. The elimination of

manual supervision adds up as an additional advantage for its

usage. Its significance can be proved by considering the

following specialties of kit designed by us

Reliability: Reliability is one such factor that every

electrical system should have in order to render its

services without malfunctioning over along period of

time. We have designed our kit using AT89C52 micro

controller which is itself very reliable and also operates

very efficiently under normal condition

Cost: The design is implemented at an economical

price.

Hassle-free maintenance: Automatic door opening

systems using IR sensors offers a round the clock

2

service which reduces the requirement of shifting

watchmen.

Simple Technology: This project uses a relatively

simple technology, thus reducing the strain to a good

extent.

1.4 Organization of the report:

The report totally consists of seven chapters - Chapter 1 gives the

introduction to the project, Chapter 2 provides an overview of the project

with the help of a block diagram, Chapter 3 gives a note of embedded

systems usage, Chapter 4 explains about the circuitry and the

interconnections of the project, Chapter 5 explains in detail about the

components used in our project, chapter 6 provides a compact project

description, chapter 7 makes use of a flowchart , and then followed by the

conclusion.

3

CHAPTER 2OVERVIEW

4

2.1 OVERVIEW OF THE PROJECT

2.1.1 Block Diagram of an IR door opening system

2.1.2 Block diagram description

The block diagram of the embedded security system consists of

the following modules.

555 timer : The 555 timer has been employed to generate a

square wave of 56KHz frequency. The output signal for this

module is used to drive the Infrared Emitting Diode.

IR Receiver: This project makes use of an infrared sensor

module, which consists of an Infrared emitting IR receiver

TSOP 1356. The output of IR receiver is connected to pin 1 of

the microcontroller 8952.

5

Microcontroller: This project employs the 8-bit

microcontroller from ATMEL (AT89S52). The microcontroller

in our security system is used for sending signals to the auto

dialer and buzzer alarm.

Stepper motor: The stepper motor used here is for the

movement of the door connected to it, through a particular

specified angle in steps in precise positions.

Power supply: Supply of 230V, 50Hz ac signal from main

supply board is given to a step down transformer. The

transformer is selected such that its output ranges from 10V to

12V, used for the various components in the project, as per

their needs.

ULN 2803: As the microcontrollers maximum voltage is 5V,

this component is used for supplying the 12V to run the stepper

motor. It provides the 12V to the motor to run it, as it receives

the signal from the microcontroller.

6

CHAPTER 3EMBEDDED SYSTEMS

7

3.1 INTRODUCTION TO EMBEDDED SYSTEM

An Embedded system is a special-purpose computer system

designed to perform one or a few dedicated functions, sometimes with

real time computing constraints. it is usually embedded as a part of a

complete device including hardware and mechanical parts. Since the

embedded system is dedicated to few specific tasks, design engineers

can optimize it, reducing the size and the cost of the product or

increasing the reliability and performance.

For example, handheld computers share some elements with

embedded system= such as the operating systems and microprocessors

which power them –but are not truly embedded system, because they

allow different applications to be loaded and peripherals to be

connected. The program is written to the system memory in this case

rather than being loaded into the RAM, as programs on a personal

computer are.

The main purpose of the microprocessors are simplify the

system design and improve flexibility. In the embedded systems, the

software is often stored in a read only memory (RAM) chip.Embedded

systems provide several major functions including monitoring of the

analog environment by reading data from sensors and controlling

actuators.

Inputs (sensor) Outputs

(actuator)

Fig 3.1 A real time system interacts with environment

8

Embedded

System

3.1.1 Examples of embedded systems

Embedded systems are found in wide range of application

areas. Originally they were used only for expensive industrial control

applications, but as technology brought down the cost of dedicated

processors, they began to appear in moderately expensive applications

such as automobiles, communication and office equipments and

television Today's embedded systems are so inexpensive that they are

used in almost every electronic product in our life. Embedded systems

are often designed for mass production.

Some examples of embedded systems:

Automatic Teller Machines

Engine controllers and antilock break controllers for

automobiles

Measurement equipment

Multifunction printers

Mobile phones with additional capabilities

Programmable Logic Controllers

3.2MICROPROCESSOR AND MICROCONTROLLER

Microprocessors and microcontrollers are used in embedded

system products. An embedded product uses a microprocessor (or

microcontroller) to do one task and one task only.

Microprocessor as the term come to be known is a general

purpose digital computer central processing unit. Although popularly

known as a "computer on chip", the microprocessor is in no sense a

complete digital computer.

9

Microprocessor CPU contains Arithmetic Logical Unit, a

program counter, a stack pointer, some working registers, a clock

timing circuits and interrupt circuit.

To make complete microcomputer memory must add, usually

Read Only Memory, Random Access Memory, memory decoders and

an Input/ Output devices. In addition special purpose devices such as

interrupts, counters may be added to relieve the CPU from time

consuming counting or timing chores.

The hardware design of microprocessor CPU is arranged so

that a small or very large system can be configured around the CPU as

the application demands. The internal CPU architecture as well as the

resultant machine level code that operates that architecture is

comprehensive but as flexible as possible.The prime use of

microprocessor is to read data perform extensive calculations on that

data and store those calculations in mass storage devices or display the

results for user use. The program is used by microprocessor are stored

in the mass storage devices and loaded into RAM as the user directs.

A microcontrollers is a computer on a single chip .Micro

suggest that the device is small and controller tells that the device is

used to control objects, process or events

Microcontroller is a highly integrated chip that contains all the

devices comprising a computer. Typically this includes a CPU, RAM,

Input/ Output ports, timers, interrupts. So microcontroller is also called

as "true computer on a chip". Unlike a general purpose computer

which also includes all of these devices. A microcontroller is designed

for a very specific task to control a particular system.

10

A microcontroller is a general purpose device but one that is

meant to read data, perform limited calculations on that data and

control its environment based on those calculations.The prime use of

microcontroller is to control the operation of machine using a fixed

program that is stored in ROM that does not change over the life time

of the system.

The advantages of microcontroller over microprocessor are

cost is less

speed is more

power consumption is less

compact device

11

3.3 Criterion for choosing a microcontroller

The first criterion for choosing a microcontroller is that it must

meet the tasks at hand efficiently and cost effectively. In analyzing the

needs of a microcontroller based project we must see whether it’s a

8bit,16bit or a 32bit microcontroller and how best it can handle the

computing needs of the task most effectively.

The other considerations in this category are:

(a) speed : the highest speed that the microcontroller can support

(b) Packaging: is it a 40-pin DIP, QPF or some other packaging

format? This is important in terms of space, assembling and

prototyping the end-product.

(c) Power consumption: this is especially critical for battery

powered products.

(d) The amount of RAM and ROM space on chip.

(e) The number of I/O pins and timers on the chip.

(f) How easy it is to upgrade to higher performance or lower

power consumption versions.

(g) Cost per unit: this is important in terms of final product in

which a microcontroller is used.

The second criterion depends on how easy it is to develop

products around it.

The third criterion is regarding the availability of the tools in

needed quantities both now and in future.

12

Counter

inpu

3.4 8051 MICROCONTROLLER

3.4.1 8051 Architecture

The generic 8051 architecture contains two separate buses for

both program and data. So, it has two distinctive memory spaces of

64× 8 size for both programmed and data. It is based on an 8-bit CPU

with an 8-bit accumulator and another 8-bit B register as main

processing blocks. Other portions of the architecture include few 8 bit

registers and 8 bit memory locations.

Each 8051 device has some amount of data Ram built in the

device for internal processing. This area is used for stack operations

and temporary storage of data. This bus architecture is supported with

on-chip peripheral functions like I/O ports, timers/counters, versatile

serial communication port.

FEATURES OF 8051 ARCHITECTURE

Optimised 8 bit CPU for control applications.

64K program Memory address space.

64K program Data address space.

128 bytes of on chip Data memory.

32 bi-directional and individually addressable I/O lines.

Two 16 bit timer/counters.

Full Duplex UART.

6-source/5-vector interrupts structure with priority levels.

On chip clock oscillator.

13

Rxd

CHAPTER 4

CIRCUIT DIAGRAM

14

4.1 CIRCUIT DESCRIPTION

Fig 4.1 Circuit Diagram of IR door opening system

4.1.1 MICROCONTROLLER:

The microcontroller used in this project is AT89S52, which is a

40 pin IC

Pin 40 is connected to +5v power supply

Reset circuit is connected to pin 9 of 8952 to provide reset

condition when the microcontroller is powered off. The reset

circuitry comprises of 10 micro farads (C6) and a resistor (R5)

of 8.2k ohms.

Pin 31 (EA\VPP) is tied to VCC for internal program

15

execution.

The crystal oscillator (11.0592MHz) is connected across pin 18

and pin19.

Pin 1 (port 1.0) is connected to the output (pin 3) of the IR

receiver (TSOP 1356).

Pin 3 (port 1.2) is connected to the Chip Enable input (pin 2) of

the DTMF generator (UM95089).

Port 2 of the microcontroller is used to drive the stepper motor

using ULN 2803.

4.1.2 555TIMER:

NE 555 is a highly stable controller capability of producing

accurate timing pulses. In this circuit, 555timer has been connected in

astable mode to accurately generate a square wave of frequency 56

KHz. For the astable mode, we connect two external resistors (R1,

R2) and one capacitor (C1).

Pin 8 is connected to +5V power supply.

Pin 1 is grounded.

Pin 4 is tied to +5V power supply.

A 220 ohm (Ra) is connected between pin 8 and pin 7.

A 10.2K pot is connected between pin 7 and pin 6

A capacitor (C1) of 0.05uf is connected between pin 2 and pin1

Pin 5 is connected to the ground through a capacitor (C2)

of .01uf.

The output of 555timer at pin 3 which is connected to the

Infrared emitting diode (TSAL 6200).

4.1.3 INFRARED EMITTING DIODE (TSAL 6200):

16

TSAL 6200 is a high efficiency infrared emitting diode

modeled in clear gray tinted plastic packages. The pulse current

through the LED can vary from 100mA to well over 1A. In order to

get an acceptable control distance, the LED currents have to be as high

as possible. A trade-off should be made between LED parameters and

maximum control distance. Average power dissipation of the LED

should not exceed the maximum value though.

We adopt modulation technique to ensure that our IR message

gets across to the receiver without errors. With modulation, we make

the IR light source blink in a particular frequency. The IR receiver will

be tuned to that frequency, so it can ignore everything else.

In our IR sensor module, we have chosen a carrier frequency of

56 kHz. Hence the current pulses are at a frequency of 56 kHz. There

are several manufacturers of IR receivers in the market. Siemens,

Vishay and Telefunken are main suppliers. Vishay has its TSOP

product series (TSOP 13xx, TSOP 48xx, TSOP 62xx where xx

indicates the modulation frequency of 30, 33,36,38,40 or 56 kHz)The

anode of LED is connected to pin 3 of 555 timer and the cathode of the

LED is grounded through a resistor (R3) of 500 ohms.

4.1.4 IR RECEIVER (TSOP 1356):

TSOP 13xx series are miniaturized receivers for infrared

remote control systems. PIN diode and preamplifier are assembled on

lead frame, the epoxy package is designed as IR filter. The

demodulated output signal can directly be decoded by a

microprocessor.

TSOP 13xx is the standard IR remote control receiver series,

supporting all major transmission codes.

17

Pin 1 is grounded.

A capacitor (C3) of 4.7 micro farads connected between pin 1 and

pin 2.

Pin 2 is connected to a supply of +5V through a resistor (R4) of 1k

ohms.

When there is a proper transmission and reception between the

LED and IR receiver, the output of TSOP 1356 is logic high.

The carrier frequency should be close to 56 kHz. Whenever there

is no link between IR transmitter and receiver, the output pin 3 of

TSOP 1356 will be logic low.

4.1.5 POWER SUPPLY

Supply of 230V, 50Hz ac signal from main supply board is

given to a step down transformer. The transformer is selected such that

its output ranges from 10V to 12V, which is supplied to the power

supply block for making the output compatible with the TTL logic

supply. This TTL logic supply acts as the power supply for the

microcontroller, IR sensor, auto dialer, timer circuit and buzzer. Thus

the main function of the power supply is to give the voltage supply

required for the logic families, which is an output of +5V.

18

Fig 4.2 power supply block diagram

19

CHAPTER 5

COMPONENTS USED IN THE PROJECT

AND THEIR DESCRIPTION

5.1 MICROCONTROLLER

20

5.1.1 Description of AT89S52

The AT89S52 is a low power, high performance CMOS 8bit

microcontroller with 8K bytes of in-system programmable flash

memory, manufactured using Atmel’s high density non-volatile

memory technology and is compatible wih the industry-standard

80C51 instruction set. The on chip flash allows the program

memory to be reprogrammed in-system or by a conventional non-

volatile memory programmer. By combining a versatile 8bit CPU

with in-system programmable flash on a monolithic chip, the

Atmel’s AT89S52 is a powerful microcontroller providing high-

flexibility to embedded control applications.

The AT89S52 provides the following standard features:

Compatible with MCS-51 Products

8 Kbytes of In-System Reprogrammable Flash Memory

Endurance: 1,000 Write/Erase Cycles

4.0 to 5.5V Operating range

Fully Static Operation: 0 Hz to 33 MHz

Three-Level Program Memory Lock

256 x 8-Bit Internal RAM

32 Programmable I/O Lines

Three 16-Bit Timer/Counters

Eight vector two level Interrupt Sources

Full Duplex UART Serial Channel

Interrupt Recovery from Power-down Modes

Programmable Serial Channel

Low Power Idle and Power Down Modes

Watchdog Timer

Dual Data Pointer

21

Power-Off Flag

Fast Programming Time

Flexible ISP programming(Byte and Page mode)

In addition, the AT89C52 is designed with static logic for operation

down to zero frequency and supports two software selectable power

saving modes.

The Idle Mode stops the CPU while allowing the RAM,

timer/counters, serial port and interrupt system to continue

functioning. The Power down Mode saves the RAM contents but

freezes the oscillator disabling all other chip functions until the next

hardware reset.

Fig 5.1.2 Pin diagram of 8052

22

Fig 5.1.3 Block diagram of 8052

5.1.2 Pin Description

23

VCC

Pin 40 provides Supply voltage to the chip. The voltage source

is +5v.

GND .

Pin 20 is the grounded

Port 0

Port 0 is an 8-bit open drain bidirectional I/O port from pin 32

to 39. As an output port each pin can sink eight TTL inputs. When 1s

are written to port 0 pins, the pins can be used as high-impedance

inputs. Port 0 may also be configured to be the multiplexed low-order

address/data bus during accesses to external program and data

memory. In this mode P0 has internal pull-ups.Port 0 also receives the

code bytes during Flash programming, and outputs the code bytes

during program verification. External pull-ups are required during

program verification.

Port 1

Port 1 is an 8-bit bidirectional I/O port with internal pull-ups

from pin 1 to 8. The Port 1 output buffers can sink/source four TTL

inputs. When 1s are written to Port 1 pins they are pulled high by the

internal pull-ups and can be used as inputs. As inputs, Port 1 pins that

are externally being pulled low will source current (IIL) because of the

internal pull-ups. In addition, P1.0 and P1.1 can be configured to be

the timer/counter 2 external count input(P1.0/T2) and the

timer/counter 2 trigger input (P1.1/T2EX), respectively as shown

below

24

Fig 5.1 Alternate function of the ports

Port 2

Port 2 is an 8-bit bidirectional I/O port with internal pull-ups

from pin 21 to 28. The Port 2 output buffers can sink / source four

TTL inputs. When 1s are written to Port 2 pins they are pulled high by

the internal pull-ups and can be used as inputs. As inputs, Port 2 pins

that are externally being pulled low will source current (IIL) because

of the internal pull-ups.

Port 2 emits the high-order address byte and fetches from

external program memory and during accesses to external data

memory that use 16-bit addresses (MOVX @ DPTR). In this

application it uses strong internal pull-ups when emitting 1s. During

accesses to external data memory (that use 8-bit addresses (MOVX @

RI), Port 2 emits the contents of the P2 Special Function Register. Port

2 also receives the high-order address bits and some control signals

during Flash programming and verification.

Port 3

Port 3 is an 8-bit bidirectional I/O port with internal pull-ups

from pin 10 to 17. The Port 3 output buffers can sink / source four

TTL inputs. When 1s are written to Port 3 pins they are pulled high

by the internal pull-ups and can be used as inputs. As inputs, Port 3

pins that are externally being pulled low will source current (IIL)

25

because of the pull-ups. Port 3 also serves the functions of various

special features of the AT89C51 as listed below:

Table 5.2 Special Features of 89C5

RST

Pin 9 is the Reset input. It is active high. Upon applying a high

pulse to this pin, the microcontroller will reset and terminate all

activities. A high on this pin for two machine cycles while the

oscillator is running resets the device.

ALE/PROG

Address Latch Enable output pulse for latching the low byte of

the address during accesses to external memory. In normal

operation ALE is emitted at a constant rate of 1/6 the oscillator

frequency, and may be used for external timing or clocking

purposes. Note, however, that one ALE pulse is skipped during

each access to external Data Memory.

If desired, ALE operation can be disabled by setting bit 0 of

SFR location 8EH. With the bit set, ALE is active only during a

MOVX or MOVC instruction. Otherwise, the pin is weakly pulled

high. Setting the ALE-disable bit has no effect if the

microcontroller is in external execution mode.

26

PSEN

Program Store Enable is the read strobe to external program

memory. When the AT89C52 is executing code from external program

memory, PSEN is activated twice each machine cycle, except that two

PSEN activations are skipped during each access to external data

memory.

EA/VPP

External Access Enable. EA must be strapped to GND in order

to enable the device to fetch code from external program memory

locations starting at 0000H up to FFFFH. Note, however, that if lock

bit 1 is programmed, EA will be internally latched on reset. EA should

be strapped to VCC for internal program executions. This pin also

receives the 12-volt programming enable voltage (VPP) during Flash

programming, for parts that require 12-volt VPP.

XTAL1

Input to the inverting oscillator amplifier and input to the internal

clock operating circuit.

XTAL2

Output from the inverting oscillator amplifier.

Oscillator Characteristics

XTAL1 and XTAL2 are the input and output, respectively, of

an inverting amplifier which can be configured for use as an on chip

oscillator, as shown in Figure 5.3. Either a quartz crystal or ceramic

resonator may be used. To drive the device from an external clock

source, XTAL2 should be left unconnected while XTAL1 is driven as

shown in Figure 5.4.

27

Fig 5.1.4 crystal connections

Figure 5.1.5 External Clock Drive Configuration

There are no requirements on the duty cycle of the external

clock signal, since the input to the internal clocking circuitry is

through a divide-by two flip-flop, but minimum and maximum voltage

high and low time specifications must be observed.

28

TIMERS

o Timer 0 and 1

Timer 0 and Timer 1 in the AT89S52 operate the same way as

Timer 0 and Timer 1 in the AT89S51.

o Timer 2

Timer 2 is a 16-bit Timer/Counter that can operate as either a

timer or an event counter. The type of operation is selected by bit C/T2

in the SFR T2CON. Timer 2 has three operating modes: capture, auto-

reload (up or down counting), and baud rate generator. The modes are

selected by bits in T2CON, as shown in Table 5.2. Timer 2 consists of

two 8-bit registers, TH2 and TL2. In the Timer function, the TL2

register is incremented every machine cycle. Since a machine cycle

consists of 12 oscillator periods, the count rate is 1/12 of the oscillator

frequency.

Table 5.1.3. Timer 2 Operating Modes

In the Counter function, the register is incremented in response

to a 1-to-0 transition at its corresponding external input pin, T2. In this

function, the external input is sampled during S5P2 of every machine

cycle. When the samples show a high in one cycle and a low in the

next cycle, the count is incremented. The new count value appears in

the register during S3P1 of the cycle following the one in which the

29

transition was detected. Since two machine cycles (24 oscillator

periods) are required to recognize a 1-to-0 transition, the maximum

count rate is 1/24 of the oscillator frequency. To ensure that a given

level is sampled at least once before it changes, the level should be

held for at least one full machine cycle.

There are no restrictions on the duty cycle of external input

signal, but it should for at least one full machine to ensure that a given

level is sampled at least once before it changes

Interrupts

The AT89S52 has a total of six interrupt vectors: two external

interrupts (INT0 and INT1), three timer interrupts (Timers 0, 1, and 2),

and the serial port interrupt. These interrupts are all shown in Figure

5.5

Fig 5.1.6 Interrupts source

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Each of these interrupt sources can be individually enabled or

disabled by setting or clearing a bit in Special Function Register IE. IE

also contains a global disable bit, EA, which disables all interrupts at

once. Note that Table 5.3 shows that bit position IE.6 is

unimplemented. In the AT89C51, bit position IE.5 is also

unimplemented. User software should not write 1s to these bit

positions, since they may be used in future AT89 products.

Table 5.4 Interrupts Enable Register

Timer 2 interrupt is generated by the logical OR of bits TF2

and EXF2 in register T2CON. Neither of these flags is cleared by

hardware when the service routine is vectored. In fact, the service

31

routine may have to determine whether it was TF2 or EXF2 that

generated the interrupt, and that bit will have to be cleared in software.

The Timer 0 and Timer 1 flags, TF0 and TF1, are set at S5P2

of the cycle in which the timers overflow. The values are then polled

by the circuitry in the next cycle. However, the Timer 2 flag, TF2, is

set at S2P2 and is polled in the same cycle in which the timer

overflows.

Idle Mode

In idle mode, the CPU puts itself to sleep while all the on-chip

peripherals remain active. The mode is invoked by software. The

content of the on-chip RAM and all the special functions registers

remain unchanged during this mode. The idle mode can be terminated

by any enabled interrupt or by a hardware reset. It should be noted that

when idle is terminated by a hardware reset, the device normally

resumes program execution, from where it left off, up to two machine

cycles before the internal reset algorithm takes control.

Power down Mode

In the power down mode the oscillator is stopped, and the

instruction that invokes power down is the last instruction executed.

The on-chip RAM and Special Function Registers retain their values

until the power down mode is terminated. The only exit from power

down is a hardware reset. Reset redefines the SFRs but does not

change the on-chip RAM.

32

Table 5.5 Status Of External Pins During Idle and Power Down Mode

Program Memory Lock Bits

The AT89S52 has three lock bits which can be left

unprogrammed(U) or can be programmed (P) to obtain the additional

features listed in the following table. When lock bit 1 is programmed,

the logic level at the EA pin is sampled and latched during reset. If the

device is powered up without a reset, the latch initializes to a random

value, and holds that value until reset is activated. The latched value

must agree with the current logic level at that pin in order for the

device to function properly.

Table 5.6 Lock Bit Protection Modes

33

5.2 INFRARED SENSOR

5.2.1 INFRARED EMITTING DIODE

TSAL 6200 is a high efficiency infrared emitting diode in Ga

Al As on Ga As technology modeled in clear, blue-grey tinted plastic

packages.

In comparison with standard Ga As on Ga As technology, these

emitters achieve more than 100% radiant power improvement at a

similar wavelength.The forward voltages at low current and at high

pulse current correspond to the values of the standard technology.

Therefore these emitters are ideally suitable as high performance

replacements of standard emitters. The transmitter usually is a battery

powered handset. It should consume as little power as possible, and

should be strong as possible to achieve an acceptable control distance.

Many chips are designed to be as IR transmitters. The older

chips were dedicated to only one of many protocols that were

invented. Nowadays very low power microcontrollers are used in IR

transmitters for the simple reason that they are more flexible in their

use.

FEATURES:

Extra high radiant power and radiant intensity and high

reliability

Low forward voltage

Suitable for high pulse current operation

Peak wavelength = 940nm

Good spectral matching to Si photo detectors

34

APPLICATIONS:

IR remote control units with high power requirements

Free air transmission systems

Infrared source for optical counters and readers

IR source for smoke detector

5.2.2 IR RECEIVER

Many different receiver circuits exists on the market. The most

important selection criteria are the modulation frequency used and the

availability in you region.

TSOP 1356 series are miniaturized receivers for IR remote

control systems. The demodulated output signal can directly be

decoded by a microcontroller. It is standard IR remote control receiver

series, supporting all major transmission codes.

Fig5.5.2.1 Block Diagram of an IR receiver

In the picture above you can see a typical block diagram of an

IR receiver. The received IR signal is picked up by the IR detection

diode on the left side of the diagram.

35

Amplifier Limiter B.P.F

DemodulatorIntegratorComparator

This signal is amplified and limited by the first two stages. The limiter

acts as an AGC circuits to get a constant pulse level, regardless of the

distance to the hand set.

As you can see only the AC signal is sent to the Band Pass

Filter. The B.P.F is tuned to the modulation of the handset unit.

Common frequencies range from 30 kHz to 60 kHz in consumer

electronics. The next stages are a detector, integrator and comparator.

The purpose of these three blokes is to detect the presence of the

modulation frequency. If the modulation frequency is present, the

output of the comparator will be pulled low.

All these blokes are integrated into a single electronic

component. There are many different manufactures of these

components on the market. And most devices are available in several

versions each of which are tuned to a particular modulation frequency.

The amplifier is set to a very high gain. Therefore the system

tends to start oscillating very easily. Placing a large capacitor of al

least 22 microfarads close to the receiver’s power connections is

mandatory to decouple of 330 ohms in series with the power supply to

further decouple the power supply from the rest of the circuit.

Fig5.2.2 IR Receiver (TSOP 1356)

36

BLOCK DIAGRAM OF TSOP 1356

Figure 5.2.3 Block diagram of TSOP 1356

FEATURES:

Phone detector and preamplifier in one package

Internal filter for PCM frequency

TTL and CMOS compatibility

Output active is low

High immunity against ambient light

Continuous data transmission possible

5.3 555 TIMER

37

A 555 timer IC is most versatile and highly reliable linear IC. It

is used for generating accurate time delay or oscillations. SIGNETICS

corporation first introduce the device SE\NE 555. This device is

available as 8 pin metal can, 8 pin mini DIP. The SE 555 is

designed for the operating temperature range from -55 degree

centigrade to +125 degree centigrade while the NE 555 operates on a

range from 0 degree centigrade to 70 degree centigrade. The NE

555 timer operates on +5v to +18v power supply. It has adjustable

duty cycle from micro seconds to hours. It has highly current output. It

can source or sink 200mA. It is compatible with both TTL and CMOS

logic circuits.

5.3.1 FUNCTIONAL BLOCK DIAGRAM OF 555 TIMER

The block diagram of 555 timer is shown in figure5.7 It

consists of two comparators resistive divider network flip-flop and a

discharge transistor. The upper comparator has a threshold input and a

control input. The control voltage is 2\3 VCC. When ever the

threshold voltage exceeds the control the high output from the

comparator will set the flip-flop. The collector of the discharge

transistor is goes to pin number 7. When this pin is connected to an

external timing capacitor, high Q output from the flip-flop will saturate

the transistor and discharge the capacitor. When Q is low transistor

opens and the capacitor will charge.

The complementary signal of the flip-flop is taken as output of

the 555 (pin no 3). The reset pin prevents the flip-flop from working.

Hence in most applications reset pin is connected to supply voltage.

38

The lower comparator is connected trigger input and a fixed

voltage 1\3 VCC. When the trigger voltage is slightly less than 1\3

VCC the comparator output goes high and reset the flip-flop. Pin no1

is known as ground the supply pin 8.

Fig5.3.1 Block Diagram of 555 Timer

5.3.2 PIN DIAGRAM OF 555 TIMER

39

Fig 5.3.2 Pin Diagram of 555

5.3.3 PIN DIAGRAM DESCRIPTION

Ground (Pin 1)

Not surprising this pin is connected directly to ground.

Trigger (Pin 2)

This pin is the input to the lower comparator and is used to set

the latch, which in turn causes the output to go high.

Output (Pin 3)

Output high is about 1.7V less than supply. Output high is

capable of Isource up to 200mA while output low is capable of

Isink up to 200mA.

Reset (Pin 4)

This is used to reset the latch and return the output to a low

state. The reset is an overriding function. When not used connect to

V+.

Control (Pin 5)

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Allows access to the 2/3V+ voltage divider point when the 555

timer is used in voltage control mode. When not used it is connected to

ground through a 0.01 uF capacitor.

Threshold (Pin 6)

This is an input to the upper comparator. See data sheet for

comprehensive explanation.

Discharge (Pin 7)

This is the open collector to Q14 in figure 4 below. See data

sheet for comprehensive explanation.

V+ (Pin 8)

This connects to VCC and the Philips data book states the

ICM7555 CMOS version operates 3V - 16V DC while the NE555

version is 3V - 16V DC. Note comments about effective supply

filtering and bypassing this pin below under "General considerations

with using a 555 timer" The 555 can be connected as monostable

multivibrator and astable multivibrator mode.

5.3.4 ASTABLE MULTIVIBRATOR USING 555 TIMERS

The 555 timer is connected is astable mode is shown in figure.

The astable multivibrator has two quasi stable states. Initially when the

output is high i.e. Q is low Q' is high, the capacitor C starts charging

towards VCC through R1 and R2 with time constant (R1+R2) C.

However as soon as voltage across the capacitor equals to 2\3 VCC,

comparator1 triggers the flip-flop and the output switches to low i.e. Q

is high and Q' is low. Because of this transistor acts as short circuit,

which results the capacitor starts discharging through R2 and

discharge transistor Q1. When the voltage across equal’s 1\3Vcc

41

comparator2 output resets the flip-flop and output goes high, again the

above cycle repeats.The time during which the capacitor charges from

1\3Vcc to 2\3Vcc is equal to the time the output is high and is given by

TC = 0.69 (RA+RB) C

Similarly, the time period during the capacitor discharges from

2\3Vcc to 1\3Vcc is equal to the time output is low and is given by

Td = 0.69RB*C

Thus the total time period is given by

T = TC +Td = 0.69(RA+2RB) C

Thus the astable multivibrator generates the asymmetric square

wave with frequency of oscillations and is given by

f = 1\T = 1.49\ (RA+2RB) C

And the duty cycle is given by

D = (RA+RB)\(R1+2RB)

Fig 5.3.4 555 as Astable operation

5.4 STEPPER MOTOR

42

A stepper motor is an electromechanical device which

converts electrical pulses into discrete mechanical movements. The

stepper motor is used for position control in applications like disk

drives and robotics. The name stepper is used because this motor

rotates through a fixed angular step in response to each input current

pulse received by its controller. In recent years, there has been a wide-

spread demand of stepper motors because of the explosive growth of

computer industry.

Their popularity is due to the fact that they can be controlled

directly by computers, microprocessors and programmable controllers.

Stepper motors are ideally suited for situations where precise position

and speed control are required without the use of a closed-loop

feedback. When a definite number of pulses are supplied, the shaft

turns through a definite known angle. This fact makes the motor well

suited for open-loop position control because no feedback is to be

taken from the output shaft.Every stepper motor has a permanent

magnet rotor also known as shaft surrounded by a stator poles. The

most common stepper motors have four stator windings that are paired

with a center-tapped.

This type of stepper motor is commonly referred to as a four-

phase stepper motor. The center tap allows a change of current

direction in each of two coils when a winding is grounded, there by

resulting in a polarity change of the stator.

43

Fig 5.4.1 Rotor diagram

The shaft or spindle of a stepper motor rotates in discrete step

increments when electrical command pulses are applied to it in the

proper sequence. The direction of the rotation is determined by the

stator poles. The stator poles are determined by the current sent

through the wire coils. As the polarity of the current is changed, the

polarity is also changed causing a reverse motion of the motor .The

sequence of the applied pulses is directly related to the direction of

motor shafts rotation. The speed of the motor shafts rotation is directly

related to the frequency of the input pulses and the length of rotation is

related to the number of input pulses applied.

While a conventional motor shaft moves freely, stepper motor

shaft moves in a fixed repeatable increment which helps in precise

positioning. This repeatable fixed movement is possible as a result of

basic magnetic theory where poles of the same polarity repel and

opposite poles attract.

The stepper motor converts digital signals into fixed

mechanical increment of motion. It thereby provides a natural interface

with the digital computer. It is a synchronous motor such that the rotor

rotates a specific incremental number of degrees for each pulse input

given to the motor system. These motors can provide accurate

44

positioning without the need of position feedback sensors when

compared to other motors.

The position is known simply by keeping track of the input

step pulses. Usually, position information can be obtained simply by

keeping count of the pulses sent to the motor thereby eliminating the

need of expensive position sensors and feedback controls Stepper

motors are rated by the torque they produce ,step angle ,steps per

second and the number of teeth on rotor.

The minimum degree of rotation with which the stepper motor

turns for a single pulse if supply to one wire or a pair is called step

angle. The minimum step angle is always a function of the number of

teeth on rotor i.e., the smaller the step angle the more teeth the rotor

possesses.

Steps per complete revolution = Number of phases (coils) x

Number of teeth on rotor

Smaller the step angle, greater the number of steps per revolution and

higher the resolution or the accuracy of positioning obtained. The step

angles can be as small as 0.72˚ or as large as 90˚. The motor speed is

measured in steps per second.

Steps per second = (Revolution per minute x steps per

Revolution)/ 60

Stepping motors have the extraordinary ability to operate at very high

speeds (up to 20,000 steps per second ) and yet to remain fully in

45

synchronism with the command pulses, when the pulse rate is high ,the

shaft rotation seems continuous.

If the stepping rate is increased too quickly, the motor loses

synchronism and stops. Stepper motors are designed to operate for

long periods with the rotor held in a fixed position and with rated

current flowing in the stator windings whereas for most of the other

motors, this results in collapse of back emf and a very high current

which can lead to a quick burn out.

A stepper motor is a special kind of motor that moves in individual

steps which are usually 0.9 degrees each. Each step is controlled by

energizing coils inside the motor causing the shaft to move to the next

position. Turning these coils on and off in sequence will cause the

motor to rotate forward or reverse. The time delay between each step

determines the motor's speed. Steppers can be moved to any desired

position reliably by sending them the proper number of step pulses.

Fig 5.4.2 Stepper mo

46

A stepper motor's shaft has permanent magnets attached to it.

Around the body of the motor is a series of coils that create a magnetic

field that interacts with the permanent magnets. When these coils are

turned on and off, the magnetic field causes the rotor to move. As the

coils are turned on and off in sequence the motor will rotate forward or

reverse.

47

CHAPTER 6PROJECT DESCRIPTION

48

PROJECT DESCRIPTION

Our aim is to design flexible and economical system. In this

system whenever the infrared sensor senses the obstacle and the signal

is sent to the microcontroller. Then the microcontroller sent the signal

to the stepper motor as in which the door is opened

In this particular application "EMBEDDED SYSTEM FOR

AUTO DOOR OPENING". When there is no obstacle, the TSOP

receive no signal and their output is high which is connected to port 1.

When there is an obstacle the signal gets reflected and TSOP receives

that and its output goes low. If the door is intact, there will be proper

transmission and reception between the IR transmitter and IR receiver

and the output of the IR receiver will be logic high.

Whenever the door is opened, the link between the IR

transmitter and IR receiver is obstructed and the IR sensor detects the

obstacle. The output of the IR receiver will go to logic low now. The

output of the IR receiver is connected to the P1.0 of the

microcontroller. Thus the microcontroller will be constantly

monitoring the output of the receiver.

FEATURES OF THE SECURITY SYSTEM

Built-in motion sensors can trigger alarms.

The IR transmitter and receiver have an automated generation

of the 38 kHz carrier signal.

8 bit microcontroller called the AT89C51 from Atmel

corporation, has on chip ROM in the of flash memory.

This system when senses the signal it turns the buzzer on and

dials the number directly

49

Your local phone can be used for normal use by using a DPDT

switch. So you need not use a separate telephone line for this

device controlling.

There is no risk of false switching.

50

CHAPTER 7FLOWCHART

51

FLOWCHART

#include<reg51.h>

sbit ir=P2^0;

sbit buzzer=P0^7;

stepper();

delay(unsigned int);

unsigned char i;

unsigned int z,s;

main()

{

buzzer=0;

while(1)

{

if(ir==0)

{

buzzer=1;

stepper();

buzzer=0;

}

52

else

{

buzzer=0;

}

}

}

stepper()

{

for(s=0;s<14;s++)

{

for(z=0x01;z<0x0a;z=z*2)

{

P3=z;

delay(5);

}

}

for(s=0;s<14;s++)

{

53

for(z=0x08;z>0x00;z=z/2)

{

P3=z;

delay(5);

}

}

}

delay(unsigned int time)

{

unsigned int i,j;

for(i=0;i<time;i++)

for(j=0;j<1275;j++);

}

54

CHAPTER 8RESULTS AND CONCLUSION

55

RESULTS

Fig8.1 The project kit photo

The above picture is the photo of the project kit that we created for our

project. It displays a model of an automatic door opening system

using IR sensors. It picturizes the following parts namely: power

supply, sensors, microcontroller board, driving circuit and the stepper

motor.

56

CONCLUSION

As this world is readily growing up for Era of automation

and global communication this concept of providing security remotely

regardless of load at which the device operates and the function s they

perform, will surly fuel the scope of technology. This concept can

definitely serve as a platform for new innovations and help us get

better with time.

We have presented a method for constructing and

modifying complex autonomous security model while accomplishing

the following goals:

Provide a means to interface security models with any other

model.

Provide an intuitive facility to modify models.

The main aim of this project is to detect an intrusion in the

premises of a building door opens. This system finds applications

in industries, banks and homes.

ADVANTAGES

The system is completely automatic and requires no human

supervision to carry out the necessary actions.

The main advantage of this system is it is economical and

reliable.

The system is best for guiding the perimeter of a house or a

business center the point s where an intruder would enter

the building

57

References:

1. Lee Reuben: “ Electronic Transformers and

circuits”,John Wiley & sons, Inc.,New York,1947

2. Glasoe,G.N,and J.V .Lebacqz:” Pulse Generators,”

Massachusetts Institute of technology radiation

Laboratory series ,vol 5, Mc Graw –hill Book

Company,New York,1948

3. Jacob Millman and Herbert Taub:”Pulse , digital and

switching waveforms” second edition, Mc Graw –hill

Book Company,New York,2000.

4. J.Millman and C.C Halkais ,”Integrated Electronics”,

Mc Graw –hill,first edition,1972.

5. Theodore F.Bogart jr.,J.s.Beasley and G.Rico,

“Electronic Devices and Circuits ”,Pearson

Education,sixth edition,2004

6. T.K.Nagasarkar and M.S.Sukhija,”Basic Electrical

Engineering”,Oxford University press,2006.

7. A.K.Ray and K.M.Bhurchandi,”Advanced

microprocessor and peripherials”,TMH,2000.

8. Raj Kamal,”Microcontrollers

Architecture,programming ,Interfacing and system

Design,pearson edition, 2005

9. www.knowledgebase.com

58

10.www.alldatasheets.com

11.www. Howsstuffworks.com

12.Datasheets of Microcontroller AT89C52

13.Datasheets of 555 timer

14.Datasheets of TSOP 1356

59

APPENDIX

60

SOURCE CODE

ORG 000H

MOV P1,#0FFH

HERE:JB P1.0,HERE

MOV P2,#11H

CALL DELAY

MOV P2,#22H

CALL DELAY

MOV P2,#44H

CALL DELAY

MOV P2,#88H

CALL DELAY

MOV P2,#00H

CALL DELAY

CALL DELAY

CALL DELAY

CALL DELAY

MOV P2,#88H

CALL DELAY

MOV P2,#44H

61

CALL DELAY

MOV P2,#22H

CALL DELAY

MOV P2,#11H

CALL DELAY

SJMP HERE

DELAY:

MOV R1,#255

HERE1: DJNZ R1, HERE1

RET

END

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