Project Report RENJIT

Rajagiri School of Engineering & Technology, Kakkanad

ACKNOWLEDGMENT

I thank God almighty for His bountiful mercy and graces showered on us during the

period of project, without which nothing could have been possible. I thank the Principal

and the Management for lending us a helping hand & providing us lab and other technical

assistances. I would like to thank the Head of the Department, Prof. Madhava Panicker

and Ex-Head of the Department, Prof. S. Ramkumar, who have been our sources of

motivation and guidance at all times, especially throughout the period of project. I would

like to thank our project guide, Mr. Joval P.G. who always stood by us during the course

of the project and especially during the tougher times, motivating and guiding us in our

project. I extend sincere gratitude to all the Faculty of RASET who have helped us in our

project. I would also like to thank our Lab Assistant, Mr. Jince Mon. it would never have

been possible to accomplish whatever we have, without his ever helping hands.

1


INDEX INDEX

CHAPTE

R

No.

TITLEPage

No.

1. INTRODUCTION 3

2. TRANSMITTER/ RECEIVER DESIGN& DEVELOPMENT 6

3.MICRO CONTROLLER PROGRAMMING & LOGIC

DESIGN 16

4.MOTOR DRIVE MECHANISM AND HARDWARE

IMPLEMENTATION.22

5. CONCLUSION. 34

6. APPENDIX - A: MODULAR DIVISION OF WORK 37

7. APPENDIX – B: PROGRAM CODE 38

8. APPENDIX C: THE 8051 IDE 42

9. APPENDIX D: THE PCB DESIGN 44

2


CHAPTER – 1

I N T R O D U C T I O N

1.1) AIM ……………………..………………………………...Pg 4

1.2) CONCEPTUAL DESIGN-BLOCK SCHEMATIC

1.2.1) TRANSMITTING UNIT………………..……..Pg 4

1.2.2) RECEIVING UNIT….…………………………Pg 5

3


CHAPTER 1:

INTRODUCTION

1.1) Aim :

To develop a Personalized Automated Garage Door Opener, that uses key less entry to

one’s home’s garage, every time the owner initiates the remote.

The microcontroller unit (at the transmitter) services an interrupt service routine

when an interrupt (key press on remote) is being signaled. The microcontroller serially

outputs a specific code, preset in the microcontroller. The code that is been serially output

is then given as an input to the ASK transmitter module. The ASK transmitter module

now converts the digital output to an analog RF signal that is transmitted.

The ASK receiver module at the base station receives the ASK signal and the

decoded (digital) signal is input to the microcontroller at the receiver part. On being

interrupted by the serial input interrupt, the microcontroller services a routine that checks

whether the received code is an authorized (preset look up table) code. If the code is an

authorised code, then the motor is driven.

4


1.2) Conceptual Design-Block Schematic:

Trigger SignalMicro

Controller Unit I

RF Transmitter

A. S. K. Module I

Serial output

1.2.1) Transmitting Unit

1.2.2) Receiving Unit

Micro Controller

Unit II

A. S. K Module II

RF Receiver

Serial input

Motor Drive Unit

5


CHAPTER – 2

TRANSMITTER/ RECEIVER DESIGN, DEVELOPMENT

AND INTEGRATION.

2.1) INTRODUCTION ……………………………………………...……….Pg 7

2.1.1) ANALOG MODULATION TECHNIQUES….………………Pg 8

2.1.2) DIGITAL MODULATION TECHNIQUES…………………..Pg 8

2.1.3) BLOCK SCHEMATIC - AMPLITUDE SHIFT KEYING…..Pg 10

2.2) ON OFF KEYING:………………………………….…………………..Pg 10

2.3) SCHEMATIC DIAGRAM OF A.S.K…………….……………………..Pg 11

2.4) TRANSMITTER & RECEIVER MODULE FEATURES

2.4.1) FEATURES OF TRANSMITTER……………………………Pg 11

2.4.2) FEATURES OF RECEIVER……..…………………………..Pg 12

2.4.3) ISSUES ENCOUNTERED ……………………………….…..Pg 12

2.5) INTERFACING WITH AT89C51……………..…………………….Pg 14

6


CHAPTER 2

TRANSMITTER/ RECEIVER DESIGN, DEVELOPMENT AND

INTEGRATION.

2.1) In t roduc t ion

Modulation is the process of varying a carrier signal in order to use that signal to

convey information. The three key parameters of a sinusoid are its amplitude, its phase

and its frequency, all of which can be modified in accordance with an information signal

to obtain the modulated signal. There are several reasons to modulate a signal before

transmission in a medium. These include the ability of different users sharing a medium

(multiple access), and making the signal properties physically compatible with the

propagation medium. A device that performs modulation is known as a modulator and a

device that performs the inverse operation of demodulation is known as a demodulator. A

device that can do both operations is a modem (a contraction of the two terms).

In digital modulation, the changes in the signal are chosen from a fixed list (the

modulation alphabet) each entry of which conveys a different possible piece of

information (a symbol). The alphabet is often conveniently represented on a constellation

diagram.

In analog modulation, the change is applied continuously in response to the data

signal. The modulation may be applied to various aspects of the signal as the lists below

indicate.

Modulation is generally performed to overcome signal transmission issues such as

to allow

Easy (low loss, low dispersion) propagation as electromagnetic waves

Multiplexing — the transmission of multiple data signals in one frequency band,

on different carrier frequencies.

Smaller, more directional antennas

Carrier signals are usually high frequency electromagnetic waves.

7


2.1.1) Analog modulat ion techniques :

Angular modulation

o Phase modulation (PM)

o Frequency modulation (FM)

Amplitude modulation (AM)

o Single-sideband modulation (SSB, or SSB-AM), very similar to

single-sideband suppressed carrier modulation (SSB-SC)

o Vestigial-sideband modulation (VSB, or VSB-AM)

Sigma-delta modulation (∑Δ)

2 .1 .2 ) Dig i t a l modula t ion t echn iques

Any form of digital modulation necessarily uses a finite number of distinct signals

to represent digital data.

In the case of PSK, a finite number of phases are used.

In the case of FSK, a finite number of frequencies are used.

In the case of ASK, a finite number of amplitudes are used.

Each of these phases, frequencies or amplitudes are assigned a unique pattern of

binary bits. Usually, each phase, frequency or amplitude encodes an equal number of bits.

This number of bits comprises the symbol that is represented by the particular phase.

These are the general steps used by the modulator to transmit data:

1. Accept incoming digital data;

2. Group the data into symbols;

3. Use these symbols to set or change the phase, frequency or amplitude of the

reference signal appropriately;

4. Pass the modulated signal on for further processing, such as filtering and channel-

coding, before transmission.

8


At the receiver, the demodulator

1. Is passed the de-filtered and de-channel-coded signal;

2. Determines its phase, frequency or amplitude;

3. Maps the phase, frequency or amplitude to its corresponding symbol;

4. Translates the symbol into its individual bits;

5. Passes the resultant bit stream on for further processing such as removal of any

error-correcting codes.

As is common to all digital communication systems, the design of both the modulator

and demodulator must be done simultaneously. Digital modulation schemes are possible

because the transmitter-receiver pair have prior knowledge of how data is encoded and

represented in the communications system. In all digital communication systems, both

the modulator at the transmitter and the demodulator at the receiver are structured so that

they perform inverse operations.

The principal classes of modulation are:

Phase-shift keying (PSK)

Frequency-shift keying (FSK) and audio frequency-shift keying (AFSK)

o Minimum-shift keying (MSK)

o Gaussian minimum-shift keying (GMSK)

o Very minimum-shift keying (VMSK)

Amplitude-shift keying (ASK) and its most common form, on-off keying (OOK)

Quadrature amplitude modulation

9


2.1.3) Block Schematic - Amplitude Shift Keying

2.2) ON OFF KEYING:

On-off keying (OOK) is a type of modulation that represents digital data as the

presence or absence of a carrier wave. In its simplest form, the presence of a carrier for a

specific duration represents a binary one, while its absence for the same duration

represents a binary zero. Some more sophisticated schemes vary these durations to

convey additional information.

10


In ASK, the two binary values are represented by two different amplitudes of the

carrier frequency. Commonly, one of the amplitude is zero; that is, one binary digit is

represented by the presence, at constant amplitude, of the carrier, the other by absence of

carrier. Resulting signal is ASK

S{t} = Acos(2Πfct){binary=0}

= 0 {binary=1}

2 .3 ) Schemat ic d iagram of A .S .K

2.4) Transmitter & Receiver Module Features:

2.4.1) Features of transmitter

11


Features: Frequency: 433.92MHz • Operating Voltage: 2 to 12 Vdc • Data Rate: Up to

200K bps • Works directly with HT12E or similar encoder • Dimensions: Width -

10.3mm; Height - 13.3mm (Excluding Pins.)

2.4.2) Features of Receiver

2 .4 .3 ) I s sues encoun te red in th i s module o f the p ro jec t :

The initial idea was to make use of Frequency Shift Keyed modulation scheme

transmission, due to the advantages of FSK over ASK. The major advantage would have

been the least noise transmission and reception. The non-availability of the FSK

transmission circuits and associated accessories, our hopes of incorporating FSK

mechanism in our projects, were all in vain.

The ASK module (TLP/RLP 434A) couldn’t faithfully transmit the 8 bit code that

was serially output from the microcontroller, due to poor noise rejection. The

12

Operating supply voltage range: 3.3 - 6.0 V

Typical=5v

Operating Current - 4.5 mA

Channel Width=10khz

Receiver Turn On Time= 5 ms

Baseboard Data Rate= 4.8 KHz


experimental study conducted on the module revealed that pulse wave forms generated

from the function generated was more or less faithfully transmitted.

To improve the noise rejection ,a band pass filter was designed and connected at

the reception part, but the filter was unable to satisfy our need.

The failure of SAW based ASK module to faithfully transmit our code forced us

to replace the SAW model with a CRYSTAL based ASK module.

The crystal based ASK module and its features are as follows:

13


2 .5 ) In te r fac ing wi th AT89C51:

The receiver module output was found to have insufficient current driving capability, due

to which the received signal was not properly received at the microcontroller. The

transistor interface using the 2N2222 catered to the current requirements.

14


15


CHAPTER – 3

M I C R O C O N T R O L L E R P R O G R A M M I N G , L O G I C D E S I G N

A N D G E N E R A L C I R C U I T R Y .

3.1) TRANSMISSION PART.………………………………………...Pg 17

3.2) RECEPTION PART………………………………………...…….Pg 17

3.3) MOTOR DRIVE………………………………………………….Pg 17

3.4) A BRIEF HISTORY OF AT89C51………………………………Pg 18

3.5) FEATURES AND ARCHITECTURE OF AT89C51

3.5.1) FEATURES OF 8051………………………………..….Pg 19

3.5.2) ARCHITECTURE OF 8051………………………….…Pg 20

3.6) PROGRAMMING THE MICROCONTROLLER……………..…Pg 21

16


CHAPTER 3:

MICROCONTROLLER PROGRAMMING & LOGIC DESIGN

The major objective is to program the microcontroller so as to perform the desired

applications, listed below:

3 .1 ) Transmiss ion pa r t : the microcontroller plays a very significant part at the

transmitter part. The microcontroller senses a key press on the remote (as an interrupt)

and accordingly sends a particular initiating signal to the RF module (ASK) that transmits

it. The project also imitates a RC (rolling code) algorithm, so that it is hack proof. The

rolling code algorithm is a defined random number generator algorithm that generates

and sends a particular code each time the user initiates the remote key press.

The imitation of the rolling code is being done be presetting a set of ten codes in

consecutive address locations of the RAM. Each time the code has to be sent, one of the

ten codes are selected and sent.

The output of the microcontroller to the RF module is done serially and the

microcontroller program has to deal with the serial communication also.

3.2) Reception part: The microcontroller has a role to play, which is no less significant

than in any other part. The microcontroller receives the digital output from the RF

module and then checks the code received from the receiver with the preset look up table

that stores all the valid codes. The authorisation is hence the job of the microcontroller at

the reception part.

3.3) Motor Drive: The motor is a dc motor and hence has to be driven by providing

proper sequences ( 1 0 or 0 1 for clockwise or anti-clockwise, respectively), properly

delayed, so as to control the time duration of rotations. The microcontroller program code

also takes care of the number of rotations etc.

17


3.4) A brief history of the 8051

In 1981, Intel Corporation introduced an 8-bit microcontroller called the 8051.

This microcontroller had 128 bytes of RAM, 4K bytes of on-chip ROM, two timers, one

serial port, and four ports (each 8-bits wide) all on a single chip. At the time it was also

referred to as a "system on a chip." The 8051 is an 8-bit processor, meaning that the

CPU can work on only 8 bits of data at a time. Data larger than 8 bits has to be broken

into 8-bit pieces to be processed by the CPU. The 8051 has a total of four I/O ports, each

8 bits wide. Although the 8051 can have a maximum of 64K bytes of on-chip ROM,

many manufacturers have put only 4K bytes on the chip.

The 8051 became widely popular after Intel allowed other manufacturers to

make and market any flavor of the 8051 they please with the condition that they remain

code-compatible with the 8051. This has led to many versions of the 8051 with different

speeds and amounts of on-chip ROM marketed by more than half a dozen manufacturers.

There are different flavors of the 8051 in terms of speed and amount of on-chip ROM;

they are all compatible with the original 8051 as far as the instructions are concerned.

This means that if you write your program for one, it will run on any one of them

regardless of the manufacturer.

3.5) Features and architecture of AT89C51

The selection of the micro controller is based on a number of factors like size,

power consumption, packaging, number of pins, availability of assemblers, availability of

programmers to burn the codes onto the chip etc. The micro controller chosen as per the

afore said criterion was the Atmel89C51. The features that led to choosing the

microcontroller are:

18


3.5.1) Features of 8051:

Feature Quantity

ROM 4K bytes

RAM 128 bytes

Timer 2

I/O Pins 32

Power Supply 5V DC

Serial Port 1

Interrupt Sources 6

This popular 8051 chip has on-chip ROM in the form of flash memory. This is ideal for

fast development since flash memory can be erased in seconds compared to the twenty

minutes or more needed for the 8751. For this reason the AT89C51 is used in place of the

8751 to eliminate the waiting time needed to erase the chip and thereby speed up the

development time. To use the AT89C51 to develop a microcontroller-based system

requires a ROM burner that supports flash memory; however, a ROM eraser is not

needed. Notice that in flash memory you must erase the entire contents of ROM in order

to program it again. This erasing of flash is done by the PROM burner itself and this is

why a separate eraser is not needed. To eliminate the need for a PROM burner Atmel is

working on a version of the AT89C51 that can be programmed via the serial COM port

of an IBM PC.

19


3.5.2) The Architecture Of AT89C51:

20


3.6) Programming the microcontroller:

The micro controllers at the transmission part and the reception part were

programmed as per the requirements cited in sections 3.1 and 3.2. Yet another issue that

had to be taken care of was the time delay for which the motor drive mechanism was to

be excited. The delay was found out by trial and error method done on the prototype of

the garage prepared, and the micro controller was programmed as required. The detailed

coding involved in each section of the project has been given in the Appendix (Refer

Appendix B.)

The programming of the micro controller was done using 8051IDE, which is a

text editor cum assembler cum software simulator. The screen snap shots of the 8051 IDE

has also been detailed in Appendix. (Refer Appendix C).

21


CHAPTER – 4

M O T O R D R I V E M E C H A N I S M A N D H A R D W A R E

I M P L E M E N T A T I O N .

4.1) PRINCIPLE OF WORKING OF DC MOTOR……………………….….……….Pg 23

4.2) LOAD TEST OF DC SHUNT MOTOR…………………………………………....Pg 24

4.3) CHARACTERISTICS OF DC SHUNT MOTOR

4.3.1) VOLTAGE – SPEED CHARACTERISTICS………………………..……...Pg 25

4.3.2) TORQUE – CURRENT CHARACTERISTICS………………………..…..Pg 26

4.4) GEAR ARRANGEMENT……………………………….………………..…..Pg 27

4.5) INTERFACING THE DC MOTOR WITH 89C51…………………..……....Pg 28

4.6) TYPES OF RELAYS & CONTACTS:

4.6.A.) ELECTROMECHANICAL RELAYS……………………..Pg 30

4.6.B.) SOLID STATE RELAYS………………………………...…Pg 30

4.6.1) CONTACT ARRANGEMENTS…………………………………………….Pg 31

4.7) DRIVER IC USED FOR DRIVING THE RELAY……………………………Pg 32

4.8) ISSUES ENCOUNTERED ……………………………………………………Pg 32

22


CHAPTER 4 :

MOTOR DRIVE MECHANISM AND HARDWARE

IMPLEMENTATION.

4.1) Principle of Working of Dc Motor:

An Electric motor is a machine, which converts electric energy into mechanical energy.

Its action is based on the principle that when a current-carrying conductor is placed in a

magnetic field, it experiences a mechanical force whose direction is given by Fleming's

Left-hand Rule and whose magnitude is given by F = BIl newton.

As regard to the construction, there is no basic difference between a d.c. Generator

and a d.c. Motor. In fact, the same d.c, machine can be used interchangeably as a generator or

as a motor. d.c. motors are also like generators, shunt-wound or series-wound or

compound-wound.

The figure shown below is a part of multi polar d.c motor. When its field magnets

are excited and its armature conductors are supplied with current from the supply mains, they

experience a force tending to rotate the armature. Armature conductors under N-pole are

assumed to carry current downwards (crosses) and those under S-poles, to carry current

upwards (dots). By applying Fleming's Left-hand Rule, the direction of the force on each

conductor can be found. It is shown by small arrows placed above each conductor. It will be

seen that each conductor experiences a force F which tends to rotate the armature in the

anticlockwise direction. These forces collectively produce a driving torque, which sets the

armature rotating.

By reversing current in each conductor as it passes from one pole to another, the

commutator helps to develop a continuous and unidirectional torque.

23


4.2) Load Test Of Dc Shunt Motor

In order to determine the maximum torque and speed of a shunt motor, the load test is

performed. The motor is mounted and fixed on to a rigid base (wooden plank). A long thread tied on to

the shaft is suspended and the other end, tied onto a one-end fixed spring balance. For different voltages

the force is calculated and the current drawn correspondingly is noted. The reading of the spring balance

gives the weight and the weight multiplied by the acceleration due to gravity, gives the forces. The radius

of the shaft is now found out and the torque calculated as follows:

Torque, ( T ) = Weight x 9.8 x r Newton meter (N-m) ,

where r = radius of the shaft (3mm)

24

Fixed end


4.3) Characteristics Of Dc Shunt Motor

4.3.1) Voltage – Speed Characteristics:

The motor is rated for 150 rpm @ 12V. The plot shows the variation of

speed of the motor with input voltage at no load condition. It is seen that it is a

straight line varying linearly with the input voltage.

Voltage (v) Speed (rpm)

5 706 757 908 1009 11510 12811 14012 150

25

voltage-speed graph

0

20

40

60

80

100

120

140

160

0 2 4 6 8 10 12 14

Voltage (V)

Sp

ee

d (

rpm

)


4.3.2) Torque – Current Characteristics:

Assuming the Φ to be practically a constant, we find that Torque Armature

Current. Hence the electrical characteristics are as shown as in the plot. It is a straight line

through the origin.

Current (A) Torque (KNm)

0.5 .11760.55 .11760.6 .11760.68 .13230.77 .1470.85 .17640.91 .20581.01 .2352

26


4.4) Gear Arrangement:

Examination itself reveals the transfer functions. The (right) driving gear with 20 teeth,

1 inch radius and 2 ounce-inches torque rotates counter clockwise at 200 RPM and exerts

a 2 ounce force on the driven gear with forty teeth for a ratio of 2:1.

If the teeth are of equal size to permit proper mesh, the driven gear must have 2 inch

radius. During one revolution of the driver, 20 teeth pass 20 teeth on the driven, resulting

in only one half a revolution clock wise, which means the driver must turn twice for the

driven to turn once. This produces 100 RPM or a 2:1 speed reduction.

Since the driver output force is at a radius of 1 inch:

F = T / R = 2 / 1 = 2 oz.

This same force is applied to the driven at a radius of 2 inches:

T = F x R = 2 x 2 = 4 oz-in.

Thus the torque ratio is 2:1 increase.

27


The basic rules of gear systems are:

RPM is divided by the gear ratio.

TORQUE is multiplied by the gear ratio.

POWER does not change during the transfer.

4.5) Interfacing the DC Motor With The Micro Controller:

The motor on/off control by the micro controller is done by the help of electro-

magnetic relays. (with driver/buffer IC provided to drive the relays, as per the

microcontroller program.)

The relay used is JRC-27F/ 005 H where the explanation to the corresponding parts of

the part number is as per given below:

A relay is usually an electromechanical device that is actuated by an electrical

current. The current flowing in one circuit causes the opening or closing of another

circuit. Relays are like remote control switches and are used in many applications

28


because of their relative simplicity, long life, and proven high reliability. Relays are used

in a wide variety of applications throughout industry, such as in telephone exchanges,

digital computers and automation systems. Highly sophisticated relays are utilized to

protect electric power systems against trouble and power blackouts as well as to regulate

and control the generation and distribution of power. In the home, relays are used in

refrigerators, washing machines and dishwashers, and heating and air-conditioning

controls. Although relays are generally associated with electrical circuitry, there are many

other types, such as pneumatic and hydraulic. Input may be electrical and output directly

mechanical, or vice versa. All relays contain a sensing unit, the electric coil, which is

powered by AC or DC current. When the applied current or voltage exceeds a threshold

value, the coil activates the armature, which operates either to close the open contacts or

to open the closed contacts. When a power is supplied to the coil, it generates a magnetic

force that actuates the switch mechanism. The magnetic force is, in effect, relaying the

action from one circuit to another. The first circuit is called the control circuit; the second

is called the load circuit.

4.6) Types o f Re lays & Contac t s :

There are two basic classifications of relays: Electromechanical and Solid State.

Electromechanical relays have moving parts, whereas solid-state relays have no moving

parts. Advantages of Electromechanical relays include lower cost, no heat sink is

required, multiple poles are available, and they can switch AC or DC with ease.

29


4.6.A.) Electromechanical Relays

General Purpose Relay: The general-purpose relay is rated by the

amount of current its switch contacts can handle. Most versions of the

general-purpose relay have one to eight poles and can be single or double

throw. These are found in computers, copy machines, and other consumer

electronic equipment and appliances. Power Relay: The power relay is

capable of handling larger power loads – 10-50 amperes or more. They are

usually single-pole or double-pole units. Contactor: A special type of high

power relay, it’s used mainly to control high voltages and currents in

industrial electrical applications. Because of these high power

requirements, contactors always have double-make contacts. Time-Delay

Relay: The contacts might not open or close until some time interval after

the coil has been energized. This is called delay-on-operate. Delay-on-

release means that the contacts will remain in their actuated position until

some interval after the power has been removed from the coil. A third

delay is called interval timing. Contacts revert to their alternate position at

a specific interval of time after the coil has been energized. The timing of

these actions may be a fixed parameter of the relay, or adjusted by a knob

on the relay itself, or remotely adjusted through an external circuit.

4.6.B.) Solid State Relays:

These active semiconductor devices use light instead of magnetism

to actuate a switch.

30


4.6.1) Contact Arrangements:

The arrangement of contacts on a relay includes a form factor and a number of

poles. Each form factor is explained below:

4.6.1.A) Form A is a contact that is Normally Open (NO), or “make” contact. It is

open when the coil is de-energized and closes when the coil is energized. Form A

contacts are useful in applications that must switch a single power source of high current

from a remote location. An example of this is a car horn, which cannot have a high

current applied directly to the steering wheel. A Form A relay can be used to switch the

high current to the horn. Form B is a contact that is Normally Closed (NC), or “break”

contact. It is closed in the de-energized position and opens when the coil is energized.

4.6.1.B) Form B contacts are useful in applications that require the circuit to remain

closed, and when the relay is activated, the circuit is shut off. An example of this is a

machine’s motor that needs to run at all times, but when the motor must be stopped, the

operator can do so by activating a Form B relay and breaking the circuit.

4.6.1.C) Form C is a combination of Form A and B arrangement, sharing the same

movable contact in the switching circuit. Form C contact are useful in applications that

require one circuit to remain open; when the relay is activated, the first circuit is shut off,

and another circuit is turned on. An example of this is on a piece of equipment that runs

continually; when the relay is activated, it stops that piece of equipment and opens a

second circuit to another piece of equipment.

4.6.1.D) Make-before-break Contact: a contact arrangement in which part of the

switching section is shared between both a Form A and a Form B contact. When the relay

operates or releases, the contact that closes the circuit operates before the contact that

opens the circuit releases. Thus both contact are closed momentarily at the same time.

The inverse of a Make-before break contact is a Break-before-make contact. Poles are the

number of separate switching circuits within the relay.

31


4.7) Driver IC Used For Driving The Relay:

The output of the micro controller being in the range of a few mA, the output as

such becomes in sufficient to drive the relay. Hence the output of the microcontroller has

to be buffered so as to make the relay work. The driver IC used is, ULN2003A. The

ULN2003 are high voltage, high current Darlington arrays each containing seven open

collector Darlington pairs with common emitters. Each channel rated at 500mA and can

withstand peak currents of 600mA.

This versatile device is useful for driving a wide range of loads including

solenoids, relays, LED displays filament lamps, thermal print heads and high power

buffers.

The ULN2003A are supplied in 16 pin plastic DIP packages with a copper lead

frame to reduce thermal resistance.

4.8) ISSUES ENCOUNTERED IN THIS MODULE OF THE PROJECT:

Initially the motor chosen was SMJ 404880A, a stepper motor, to open the garage

door. The motor was so chosen because of many factors which are that, the

number of steps could be well controlled, by controlling the stepping sequence

generated by the microcontroller, for the stepper motor drive. The stepper motor

was known to have a reasonably good torque, which was another reason. The easy

availability and our little know-how also contributed to our procurement of the

stepper motor.

The advantages and features, that were the selection criteria, never met the

required specifications.

o The torque offered was too less to lift even the gate of the pro-type garage.

o The current requirement was very high, which the driver IC (L293D)

couldn’t source, which resulted in heating up of the driver IC as well as

the motor.

32


o The poor torque characteristics, called for addition of gears to the stepper

motor shaft, which was not viable, taking into consideration the cost as

well as the time frame.

o The usage of the stepper motor would imply that a separate supply be

designed for the operating voltage (12V) and the microcontroller. (5V).

The above said disadvantages were overcome by using the geared dc motor of

Sanko Electrical Co., Ltd. The motor is rated at 12V offering 150 rpm. The

current drawn were in the range of 100 mA.

Another issue, was the heating up of the driver IC (already mentioned above).

Substituting L293D with ULN2003A solved the issue. The substitution with

ULN2003A made way for another issue, which was insufficient torque, due to the

poor output characteristics. The new issue was finally resolved by using

electromagnetic relays for controlling the On/Off of the motor, so that the current

required could easily be sourced.

33


CHAPTER – 5

CONCLUSION

5.1) CONCLUSION………………………………………………..Pg. 35

5.2) FAILURE MODE EVALUATION…………………………...Pg. 35

5.3) SCOPE FOR FURTHER DEVELOPMENT………………….Pg. 36

5.4) BIBLIOGRAPHY……………………………………………..Pg. 36

34


CHAPTER - 5

CONCLUSION

The Mini Project was completed within constraints of time, availability of

resources and the scope of the subjects covered in the curriculum till the present

semester. A proto type model was made and the working of the Personalized Automatic

Garage Door Opener was implemented on it.

5.2) FAILURE MODE EVALUATION

ISSUE 1 : Stepper motor not catering to the required torque and getting excessively

heated up.

The issue was diagnosed as the incapacity of the driver IC to source the

required current.

Solution: Replaced ULN2003 with a higher capacity driver, L293D

ISSUE 2: Stepper motor not providing the required torque.

Solution: DC motor was tested for torque and selected.

ISSUE 3: RF transmission not performing faithful transmission/reception of the

microcontroller generated code.

The error was diagnosed as high noise and unwanted pick up. The

experimental study revealed that the RF module transmitted and received

pulses moreover faithfully. Hence the initial idea of transmitting the code has

been modified as transmitting a particular sequence of pulses, characteristic to

each transmitter and detecting the received pulses and checking them with the

value stored in the look up table of the receiver micro controller.

35


5.3) SCOPE FOR FURTHER DEVELOPMENT:

1. The mini project can be implemented on a real garage door,

provided a better communication module is devised, with better

range and noise rejection.

2. The project may be extended to a Digital Image Processing project

where the number plate is sensed and checked for authentication,

thereby reducing the noise & errors, as no RF Communication is

involved.

5.4) BIBLIOGRAPHY:

1. The 8051 Microcontroller and embedded Systems

Muhammed Ali Mazidi

Janice Gillispie Mazidi

2. The 8051 Microcontroller Architecture, Programming &

Application

Kenneth J. Ayala

3. Data & Computers Communications

William Stallings

4. Electric Machines

BL Theraja

5. The World Wide Web.

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APPENDIX – A

Modular Division of Work

Module I:

Transmitter/ receiver design, development and

integration.

Module II:

Microcontroller programming, logic

Development and general circuitry.

Module III:

Motor drive mechanism and hardware

implementation.

Team Member Module Allocated

1) Francis Scaria Module III (Chapter – 4))

2) George Teddy K. C. Module I (Chapter – 2)

3) Renjit Kurian Module II (Chapter – 3)

37


APPENDIX – B: PROGRAM CODE

THE TRANSMITTER MICROCONTROLLER CODE:

ORG 0000H

SJMP MAIN

ORG 0003H

JMP ISR2

ORG 0030H

MAIN:

MOV 55H,#01H

MOV IE,#91H

MOV 40H,#0AH

MOV 41H,#0BH

MOV 42H,#0CH

MOV 43H,#0DH

MOV 44H,#0EH

MOV 45H,#0FH

MOV 46H,#1AH

MOV 47H,#1BH

MOV 48H,#1CH

MOV 49H,#1DH

MOV R0,#40H

SETB TCON.0

THERE: JMP THERE

ISR2: MOV SCON,#40H

MOV TMOD,#20H

MOV TH1,#0FDH

SETB TR1

MOV A,@R0

38


MOV SBUF,A

HERE:JNB TI HERE

CLR P1.4

CLR TI

INC R0

CJNE R0,#4AH,EXT

MOV R0,#40H

EXT: RETI

THE RECEIVER MICROCONTROLLER CODE:

ORG 0000H

SJMP MAIN

ORG 0003H

AJMP FORWARD

ORG 0023H

SJMP ISR

ORG 0040H

MAIN: MOV P1,#00H

MOV 60H,#0AAH

MOV 40H,#0AH

MOV 41H,#0BH

MOV 42H,#0CH

MOV 43H,#0DH

MOV 44H,#0EH

MOV 45H,#0FH

MOV 46H,#1AH

MOV 47H,#1BH

MOV 48H,#1CH

MOV 49H,#1DH

39


MOV IE,#91H

MOV SCON,#50H

MOV TMOD,#20H

MOV TH1,#0FDH

SETB TR1

TH: JMP TH

ISR: MOV IE,#00H

HERE: JNB RI HERE

CLR RI

MOV A,SBUF

MOV 50H,A

MOV R2,#0BH

MOV R0,#40H

THERE: DEC R2

MOV A,R2

JZ EX

MOV A,@R0

INC R0

CJNE A,50H,THERE

ACALL FORWARD

EX: MOV IE,#91H

RETI

FORWARD:CLR IE0

MOV IE,#00H

MOV A,60H

MOV P1,A

CPL A

MOV 60H,A

ACALL DELAY

40


MOV P1,#00H

MOV P3,#0FFH

MOV IE,#91H

RETI

DELAY: MOV R2,#40H

L2:MOV R3,#0FFH

L3: MOV R4,#0FFH

L6: DJNZ R4,L6

DJNZ R3,L3

DJNZ R2,L2

RET

41


APPENDIX – C: THE 8051 IDE

8051 IDE window screen snapshot

The 8051 Integrated Development Environment (IDE) combines a text editor,

assembler and software simulator into a single program. All components needed to

develop 8051 programs (and its various derivatives) available and controllable from this

single IDE.

The steps that have to be performed for the 8051 programming are as follows:

Enter and modify the program source code from within the built in editor. Then assemble

the source code by selecting the Assemble command. If any errors are located the

42


appropriate source module can be automatically loaded and the cursor placed on the line

containing the error. Fix the error and move to the next error (if any). Once all errors

have been fixed reassemble the code.

After successfully assembling the source code use the simulator to step through

the program. Check the registers, flags, ports and memory locations change as the

program progresses. The flow of program can be viewed and can be verified whether it

operates as intended. If it does not, then return to the editor, reassemble and go back to

the simulator. The 8051 Integrated Development Environment (IDE) is a Windows 95

based application. It operates with the same look and feel of other Windows based

application.

43


APPENDIX – D: THE PCB DESIGN

The overall circuitry laid on a bread board was too bulky, which led us to design a ‘printed circuit board’. The design of the circuit to be printed was done on the software called, Express PCB.

The ExpressPCB window

44


The PCB designs of the Transmitter, Receiver and the Motor Drive circuit are given below:

Transmitter

Receiver

45


Motor Drive Circuitry

46

Project Report RENJIT

Documents

information signal

data signal

signal properties

carrier signal

modulated signal

transmitter module

analog rf signal

kakkanad chapter