The document presents a project focused on developing a microcontroller-based system for detecting machine overheating and smoke using sensors, which sends alerts through a GSM module. It emphasizes the importance of monitoring industrial machinery temperatures and how the system integrates various components like temperature sensors, microcontrollers, and alarm mechanisms for safety. The project includes detailed design specifications, application scenarios, and a flowchart for better understanding and implementation.

1. 4
TABLE OF CONTENTS
TOPIC NAME PAGE NO.
Abstract 7
1.CHAPTER ONE 9
Introduction 9
1.1 Objective of the project 10
1.2 Background of the Project 10
1.3 Flowchart of the Project 13
1.4 Significance of the Project 14
1.5 Application of the project 14
2.CHAPTER TWO
Block Diagram of the Project 15
2.1 Schematic of the Project 16
2.2 Hardware Development and Construction 17
2.3 Component Used 18
Hardware Specification 18
Software Specification 18
2.4 Coding for the Project 19
3.CHAPTER THREE
Component Descriptions 32
3.0 Power Supply 32

2. 5
3.1 AT89C52 Microcontroller 33
3.2 Thermistor 35
3.3 LCD 44
3.4 LM7805 Voltage Regulator 46
3.5 Transformer 47
3.6 NAV7802 Kgi ADC 48
3.7 Motor 51
3.8 Resistors 52
3.9 Capacitors 52
3.10 GSM Module SIMCom SIM900A 53
3.11 Optocoupler LM324N 56
3.12 Buzzer 57
3.13 Keil Software 58
Costs 59
Limitations 60
4. CHAPTER FOUR 61
Conclusion 61
Future Scopes 63
Project Kit figure 65
References 66

3. 6
LIST OF FIGURES
Fig 1.1 Flow Chart of the Project…………………………….………..........13
Fig 2.1 Block Diagram of the Project ………………………………….…...15
Fig 2.2 Schematic of the Project.………….………………………...............16
Fig 2.2 Flow code of System Program………………………………………19
Fig 3.0 Power Supply………………………………………………………..32
Fig 3.1 AT89C52 …….….……………………….………............................33
Fig 3.2 Crystal Oscillator…….………………………………...…………...34
Fig 3.3 Typical Thermistor.……………………………….…………….…..36
Fig 3.4 Two Point Characteristics Graph.……………………….………….39
Fig 3.5 NTC Thermistor Characteristics Graph.…………………………...40
Fig 3.6 Potential divider Circuit.…………………….………………….….41
Fig 3.7 Potential divider in NTC……………………………………………42
Fig 3.8 LCD……….…………………………………………………..……44
Fig 3.9 LM 7805 Voltage Regulator………………………………………. .46
Fig 3.10 Transformer……………………………………………………….47
Fig 3.11 NAU7802………………………………………………………… 48
Fig 3.12 Block Diagram of NAU7802 ADC………………………………. 50
Fig 3.13 PMDC Motor…………………………………………………….. 51
Fig 3.14 Resistors …………………………………………………………..52
Fig 3.15 Capacitors…………………………………………………………52
Fig 3.16 SIM900A Functional diagram…………………………………….54
Fig 3.17 Top view of SIM900A pin diagram……………………………….54
Fig 3.18 SIM900A pinout diagram………………………………………….55
Fig 3.19 Optocoupler………………………………………………………..56
Fig 3.20 Buzzer……………………………………………………………..57
Fig 4.1 System performances under different situations……………………62

4. 7
MACHINE OVERHEAT AND SMOKE DETECTION WITH GSM
MODULE
ABSTRACT
Malfunction or failure of mechanical, electrical and electro-mechanical equipment, for example equipment
used in manufacturing operations, is often preceded by an increase in the operating temperature of at least some portion
of the equipment. A temperature-sensitive, active material-containing actuator is pre-selected to operate at a pre-
determined temperature indicative of impending equipment failure and placed in thermal contact with the equipment.
If the equipment achieves the pre-selected temperature the actuator signals this by displaying a flag or providing some
other passive visual indication. In this work a review of existing fire-detector types has been carried out along with
the development of a low cost, portable, and reliable microcontroller based automated fire alarm system for remotely
alerting any fire incidents in household or industrial premises. The aim of the system designed is to alert the distant
property-owner efficiently and quickly by sending short message (SMS) via GSM network. A Linear integrated
temperature sensor detects temperature beyond preset value whereas semiconductor type sensor detects presence of
smoke or gas from fire hazards. The sensor units are connected via common data line to ATMega AVR
microcontroller. A SIM900A GSM kit based network module, capable of operating in standard GSM bands, has been
used to send alert messages. The system is implemented on bread board and tested under different experimental
conditions to evaluate its performances.
The purpose of this device is to provide a new machine overheat and smoke indicator apparatus which has
many of the advantages of the overheat indicators, smoke indicators and some added novel features. It comprises a
temperature sensor situated within an engine of a machine which is adapted to transmit an output voltage directly
proportional to the temperature within the engine of the vehicle user control over the temperature is provided using a
potentiometer. Its first terminal is connected to a constant voltage source and second terminal connected to ground. It
has a third terminal where the potentiometer is adapted to supply a user selected, adjustable voltage. There is also an
operational amplifier having a positive terminal input connected to the output of the temperature sensor and a negative
terminal input connected to the third terminal of the potentiometer which provides an activation signal at the output

5. 8
according to the voltage at the positive terminal and the voltage at the negative terminal (functions as a comparator).
a test switch is coupled between the constant voltage source and a resistor which is then grounded. Thus, the switch
can transmit an activation signal on its closing. There is an OR gate having the first input connected to the output of
the operational amplifier and the second input connected between the test switch and the resistor. It transmits the
signal if either or both the inputs are active. A non-retriggerable monostable multivibrator is provided having an input
connected to the output of the OR gate. On receiving the activation signal from the OR gate, the multivibrator transmits
the signal to the output. a play back mechanism is connected between a buzzer and the multivibrator which can recite
a verbal warning via the speaker only during the receipt of the activation signal. System uses smoke sensor system
that keeps measuring and report it through LCD display, Buzzer. The sensor interacts with microcontroller which
process this data and transmit it over LCD display. By help of this model that uses GSM module, buzzer and display
unit will allow to monitor heat level in different areas, and if system detects heat for that area is above allowed level
then the value of temperature will have displayed at display unit section, information will be sent to the responsible
authorities, for that area to inform the buzzer will go off. Again, Optocoupler kit will check for the smoke if any such
phenomena occurring then it will send a message to control unit to show the output as “fire detected” and also send
the message to the authorized person via GSM communication.

6. 9
CHAPTER ONE
INTRODUCTION
Machine Overheat and Smoke detection with GSM project is used to detect the temperature of the devices
which are overheated. This project is very useful in the industries or factories which have many big machines where
the action must have taken place when the machines are overheated. In this system we use the digital sensor of
temperature which is used to detect the temperature and after detecting the temperature it sends the signals towards
the microcontrollers which are attached in this project. The microcontrollers which are attached in this computer on
the data and then transfer the temperature reading and then this reading is displayed onto the screen. The display
screen consists of the seven segments which are used to display the three numbers on the LED screen. This system
consists of the different push buttons. These buttons are used to set the temperature whether it set high or it set low.
When we set the buttons, it allows the user to do increment or do decrement in the temperature of the whole system.
In this project we can use the 12 volts of transformer which is used to supply the power to the system. In this system
we can set the specific temperature of the machine. If the temperature exceeds the given value which is given to it, the
temperature sensor sends signals towards the microcontrollers and then microcontrollers shows message, or we use
the buzzer in this system which produces the beep sound on exceeding the specific value of temperature which is given
to the system.
This proposed system is used to detect temperature of devices that are overheated. This project is very beneficial
especially in places like factories or industries consisting of big machines where it is very necessary to take some
action in case the machine is overheated. The system uses a digital temperature sensor to detect temperature and pass
on the data to the microcontroller. The 8051 microcontroller processes data and sends the temperature to be displayed
on LCD screen. The display consists of 7 segment display unit to display up to 3 numbers. It consists of 4 push buttons
for setting the high and low temperatures. Pressing set button allows user to increment and decrement the temperature
of the system. The system uses 12V transformer to supply power to the system. We can set a limit to the temperature
and in case if the system exceeds the temperature limit, an alarm rings to indicate that the system has exceeded the set
temperature.

7. 10
As we can make this project as the final year project. So, I will describe the apparatus which are required in this
project. In the project of machine overheat detection alert we use microcontrollers, seven segment displays, crystals,
resistors, LED, temperature sensors, voltage regulator, diodes, push buttons are used in it whereas transformer which
supplies the 12 volts also used in it. As microcontrollers are used in this project so we should use the software for this
project. In it we use programming language of MC. We also use software in this project that is Keil software. As in
this project microcontrollers are also used in it. There are many capabilities of that microcontrollers. They have internal
RAM and ROM. Input and output parts with programmable pins. There are timers and counters in it. These
microcontrollers are capable of serial transfer of data and serial communication of data. We can give the 5 volts to the
microcontrollers. Buzzer is also used in this project. Buzzer is used to produce the beep sound which can inform to us
about the temperature. This project is very useful. It has many advantages in the industries and on many other places.
1.1 OBJECTIVE OF THE PROJECT
The objective of this work is to design a device such as is used, for example, in manufacturing operations, each
fitted-device serving to give notice of overheating of the machine to which it is attached or thermally connected
the release of the visible overheat sign can be further used to initiate an audible warning signal, and can also
initiate a signal for preserving a record of the overheating event.
1.2 BACKGROUND OF THE PROJECT
Modern manufacturing operations and other operating devices use many types of equipment that are subjected to
loads that cause heating in portions of the machine or unit. Sometimes the heating occurs in electrically powered
equipment, such as electric motors, welding transformers, and welding guns. The heating may also occur in
equipment such as gear boxes and machining equipment that experience frictional loading. Often the equipment
is used in circumstances that make maximum use of its design capabilities and may result in substantial heat
generation within a heavily loaded, manufacturing unit. Further, the equipment may be expected to operate with
minimal operator attention or oversight.

8. 11
Thus, there is a need for inexpensive and low energy-consuming devices that may be adapted to function
autonomously as a temperature monitor, providing an overheat signal or over-temperature signal, for the
environment of many different machines used in manufacturing or other operations. There is a need for such
devices to fit, non-obtrusively, on or in thermal contact with the equipment, or within the equipment, and to give
a visible warning signal if, or when, some portion of the equipment reaches a temperature that indicates that it is
overheating, which is likely to be harmful to its continued operation.
This invention provides devices that are adapted for placement on (or in thermal contact with) a surface of an
operating unit of equipment, machine, or the like, for raising a visible, tabular, warning flag when the operating
machine unit is experiencing overheating. The up-standing warning flag is sized and located to inform nearby
operating personnel that the operating unit is in danger of being damaged by its overheated condition.
Each such in-situ, overheating-detection device is shaped, or otherwise adapted, to be placed on a selected surface
of the equipment, often a surface that is visible to someone near the equipment as it is being operated. The selected
surface region of the equipment unit will serve as a useful sensing location if the unit experiences an overheating
condition of operation. During operation of the equipment, heat will be transferred from the selected surface of
the unit into a special material portion of the in-situ device. The special material is sometimes referred to in this
specification as an “active” material or as a “smart” material. The material is characterized as active or smart
because it is composed or adapted to experience a physical transformation when it is heated to a temperature
range indicative of overheating in the equipment on which it is placed or in intimate thermal contact. This
transformation of the active material is used to raise (or otherwise re-position) the tabular flag member to a
position in which it is visible, or may otherwise give its notice of machine overheating.
As will be more fully described in this specification, examples of suitable active materials include linear shapes
of shape memory alloy compositions, sheets or other suitable shapes of shape memory polymers or other polymer
compositions, and certain confined volumes or bodies of organic paraffin materials. As stated, the active material
is selected, composed, or otherwise adapted to experience a useful physical transformation when it is heated by
its contacting equipment unit to a temperature, or narrow temperature range, indicative of overheating within the
machine that it serves. Often such a temperature may be in the range of about 70° C. to about 100° C. and higher.
The active material will lie inactive, in suitable close heat transfer relationship with the equipment surface, during

9. 12
normal temperature operation of the equipment. But when the active material is heated to a temperature, indicative
of overheating of the equipment, the active material will transform in its composition and shape to serve as an
actuator of a warning flag, stored on the subject in-situ device. The actuated flag or tab will be moved (sometimes
simply rotated) to a position away from the surface of the overheated equipment to give appropriate notice of the
sudden and potentially damaging, over-temperature condition of the equipment unit.
In many embodiments of the invention, an in-situ device will comprise an over-temperature, alarm-giving, tabular
flag and a suitable body of active material for sensing an over-temperature condition of a unit of manufacturing
equipment. The flag tab is suitably formed of metal, polymer, wood, or other solid material and may often have
a generally flat rectangular shape. It may be brightly colored or coated to more-readily present its alarm-giving
message. The flag member is usually stored in a concealed position near the surface of the equipment that the in-
situ warning device is serving. In many embodiments of the invention, the flag is held in its stored condition
against the force of a coiled spring, capable, upon a release, of quickly rotating the flag about one of its ends into
its over-temperature, notice-giving position. The flag may be brightly colored to be readily visible, and to give
prompt notice to a worker near the over-heated machine, so that it may be shut down or its work-load reduced. In
some embodiments of the invention, the movement of the flag to its notice-giving position may also be used to
initiate an audible signal, or a more widely visible bright-light signal, of the over-temperature condition of the
manufacturing unit. In other embodiments, the relocated flag may also close a circuit to initiate an electronic
signal to a computer or other device for recording the over-temperature event or for a computer-initiated change
in the loading or operation of the equipment unit or associated equipment.
It will be appreciated that the respective components of the in-situ over-temperature device may be contained
within a suitable housing for maintaining the working relationship of the active material, spring(s), flag tab(s),
and other components of the subject device. The overall shape of the device is managed to enable it to fit the
active material in suitable heat transfer contact with a surface of the equipment to be protected or in a position
nearby the equipment in a suitable heat transfer relationship with the equipment. The device may also be
constructed for re-setting of the flag-member to its stored position after the device has cooled from an overheat
condition.

10. 13
1.3 FLOWCHART OF PROJECT
Flow chart of the project will easily help us to understand what happens in this with the
required functional blocks.
Fig1.1: Flowchart of the project

11. 14
1.4 SIGNIFICANCE OF THE PROJECT
This device that is adapted for placement on (or in thermal contact with) a surface of an operating unit of
equipment, machine, or the like, for raising a visible, tabular, warning flag when the operating machine unit
is experiencing overheating. The up-standing warning flag is sized and located to inform nearby operating
personnel that the operating unit is in danger of being damaged by its overheated condition. Advantages of
Microcontroller based Overheat detector using Temperature sensor with Buzzer indication. This project is
easy to use.
1.5 APPLICATIONS OF THE PROJECT
Applications of Microcontroller based Overheat detector using Temperature and Smoke sensor with GSM is
that this project can be used in Industries, Companies and Home to monitor and stop High temperature condition
resulting in loss of revenue and lives.
Firefighting robot controlled using RF transmitter and RF receiver is a simple example electronics project,
practical application of heat detector. The circuit consists of heat detector (thermistor) that is connected
microcontroller of the receiver block which is interfaced with robotic vehicle. Under normal room temperature,
heat detector will not give any signal to the microcontroller and thus pump remains off. If once heat detector
detects any considerable change, then it sends signal to the microcontroller. Microcontroller sends a signal to the
pump through a relay to activate it and extinguish the fire (if any). Detector can be used in real time embedded
systems based project firefighting robotic vehicle and temperature controller project.

12. 15
CHAPTER TWO
2. BLOCK DIAGRAM OF OVERHEAT DETECTION CIRCUIT
Block diagram of any project contains all essential components present in the actual system. This
system contains various components such as temperature sensor, smoke sensor, push buttons to set
threshold temperature, LCD, buzzer, motor and GSM module.
Fig2.1: Block Diagram of Project
Temp. sensor
from machines
smoke detector
LCD
MOTOR
BUZZER
set up point switch
GSM module
SIM900A

13. 16
2.1 SCHEMATIC CAPTURE OF THE PROJECT
A schematic, or schematic diagram, is a representation of the elements of a system using abstract,
graphic symbols rather than realistic pictures. A schematic usually omits all details that are not relevant to
the information the schematic is intended to convey, and may add unrealistic elements that aid
comprehension.
Fig2.2: Schematic of Project

14. 17
2.2 Hardware Development and Construction
This is the practical implementation phase of the project of the simulated version of project.
At first the suitable programs are developed and then the programs are simulated by using Proteus software to check
whether the programs were valid or not. Validation and correction of the simulation is necessary. Then the programs
are loaded into the 89C52 microcontroller by using AVR software. Then the circuit board is made along with the
microcontroller. The circuit is checked by using LED lights whether it works perfectly or not. After accomplishing
the hardware, it is associated with the temperature sensor. As it is a demo project and replicate the alternator by giving
power to the system from a direct source. Now temperature sensor is connected to the engine from the circuit board.
Then the system is given operating temperature of the engine and overheating alarm and signal when the engine
temperature exceeds the set temperature limit.

15. 18
2.3 COMPONENTS USED AND CODE:
HARDWARE SPECIFICATIONS:
 POWER SUPPLY
 AT89C52
 MOTOR (PMDC)
 PIEZO BUZZER
 SMPS (12V)
 NAU7802 (ADC)
 LM7805 (Voltage Regulator)
 LCD 16*2
 TIP122 (Darlington transistor) NPN
 POTENTIOMETER
 LM35 (Heat Sensor)
 LED
 CRYSTAL OSCILLATOR (11.092Mhz)
 Optocoupler
 GSM module 900A
 Electrolytic and Ceramic Capacitors
 RESISTORS (1Kilo ohm)
 Connecting Wire
 Board for mechanical support
SOFTWARE SPECIFICATIONS:
 Keil compiler
 Proteus v8.2 for Schematics

16. 19
2.4 CODING:
Programming of microcontroller is done in such a way that first input components is interfaced
such as inputs from ADC and the digital input of optocoupler and produces text on LCD as output message.
Thus, interfacing of LCD is done at the same time other output components such as motor and buzzer are
interfaced to output pins of the program for the microcontroller is generally written in C or assembly
language, finally the compiler generates a hex file which contains the machine language instructions like
zeros and ones that understandable by the microcontrollers. For Communication GSM module is
programmed in simplex way to send signal only.
Fig 2.3: Flow code of the system program.

17. 20
;====================================================================
; Main.asm file generated by New Project wizard
;
; Created: Sat Jan 30, 2018
; Processor: AT89C52
; Compiler: ASEM-51 (Proteus)
;====================================================================
org 0100h
Start:
; Write your code here
lcd equ p2
en bit p2.3
sda bit p1.0
scl bit p1.1
drdy bit p3.3
del1 equ 43h
del2 equ 44h
del3 equ 45h
save equ 46h
delays equ 47h
count equ 48h
;eras the ram
mov r0,#30h
aa:
mov @r0,#00
inc r0
cjne r0,#0ffh,aa
mov r0,#00
acall mdely
;in write operation r3=memory address and r4= data
;///////////////////////////
mov 70h,#11h
mov 71h,#24h
mov 72h,#14h
mov 73h,#9
mov 74h,#8
mov 75h,#3
mov 76h,#7
mov 77h,#3
mov 78h,#5
mov 79h,#0
mov 7ah,#4
mov 7bh,#8
mov 7ch,#3
mov 7dh,#0bh
mov 7eh,#0ddh
acall lcdreset
acall resets
mov dptr,#karan
acall display
acall hdely

18. 21
setb p3.6
mov 7fh,#4
SETB P0.0
SETB P3.6
rew:
jnb p3.2,ntw
jnb p3.3,ntw1
jnb p3.4,ntw2
sjmp rew
ntw:
mov a,7fh
cjne a,#8,df
sjmp rew
df:
inc 7fh
mov a,#0c0h
acall cmd
mov a,7fh
add a,#30h
acall dat
acall delay
sjmp rew
ntw1:
mov a,7fh
cjne a,#4,df1
sjmp rew
df1:
dec 7fh
mov a,#0c0h
acall cmd
mov a,7fh
add a,#30h
acall dat
acall delay
sjmp rew
ntw2:
;////////////////////////////
mov r3,#00h
mov r4,#0afh
acall write
mov r4,#0aeh
acall write
mov r3,#01h
mov r4,#00101000b
acall write
mov r3,#15h
mov r4,#0b0h;0b0 or 30h
acall write
mov r3,#03h
mov r4,#80h
acall write
mov r3,#04h
mov r4,#00h
acall write
mov r3,#05h
mov r4,#0ffh

19. 22
acall write
acall zero
mov r3,#11h
mov r4,#0c0h
acall write
aa10:;main program @
setb scl
nop
aa1a:
jb sda,aa1a
clr sda
nop
clr scl
mov a,#55h
acall send
mov r0,#40h
aa11:
acall receve
acall swish
sjmp aa10;@
zero:
mov r5,#13h
acall reads
mov a,r6
mov r3,#04h
mov r4,a
acall write
mov r5,#14h
acall reads
mov a,r6
mov r3,#05h
mov r4,a
acall write
ret
swish:;data display rutine start
mov 32h,40h;higest
mov 31h,41h;high
mov 30h,42h;low
mov b,#9
mov r0,#34h
clrs:
mov @r0,#00
inc r0
djnz b,clrs
mov 34h,#1
mov r0,#33h
mov b,#4
b1:
mov a,@r0
cjne a,#0,b0
dec r0
djnz b,b1
b0:
mov a,#8
mul ab
mov 3eh,a

20. 23
cjne a,#0,b2
mov dptr,#nodata
acall display
acall hdely
acall resets
ret;this is a return
;/////////////////////
b3:
acall b4
b2:
acall b5
jnc b8
acall b9
b8:
djnz 3eh,b3
mov a,#80h
acall cmd
;///////////////////
mov a,3ch
mov 3fh,a
anl a,#11110000b
swap a
add a,#30h
acall dat
mov a,3fh
anl a,#00001111b
add a,#30h
acall dat
;///////////////////###########################################################################
#################################################
mov a,3bh
mov 3fh,a
anl a,#11110000b
swap a
cjne a,7fh,shar1
clr p0.0
clr p3.6
ajmp jdam
shar1:
setb p0.0
setb p3.6
add a,#30h
acall dat
mov a,3fh
anl a,#00001111b
add a,#30h
acall dat
mov a,#'.'
acall dat
;///////////////////
mov a,3ah
mov 3fh,a
anl a,#11110000b
swap a
add a,#30h
acall dat

21. 24
mov a,3fh
anl a,#00001111b
add a,#30h
acall dat
sjmp karan1
;///////////////////
mov a,39h
mov 3fh,a
anl a,#11110000b
swap a
add a,#30h
acall dat
mov a,3fh
anl a,#00001111b
add a,#30h
acall dat
karan1:
;///////////////////
acall mdely
ret;this is a return
b4:
mov r0,#34h
mov b,#4
clr c
bc:
mov a,@r0
addc a,@r0
da a
mov @r0,a
inc r0
djnz b,bc
ret
;////////////////////
b5:
mov r0,#33h
mov b,#4
b6:
clr c
b7:
mov a,@r0
rrc a
mov @r0,a
dec r0
djnz b,b7
ret
;///////////////////
b9:
mov r0,#39h
mov b,#4
mov r1,#34h
clr c
ba:
mov a,@r0
addc a,@r1
da a
mov @r0,a

22. 25
inc r0
inc r1
djnz b,ba
mov a,3ch
addc a,#0
mov 3ch,a
ret;data display rutine stop
;in conv acc contain data
write:;write in eeprom////////////////////////////////////////////
acall start1
mov a,#54h
acall send
mov a,r3;memory address
acall send
mov a,r4;data
acall send
acall stop
acall mdely
ret
start1:;start condition//////////////////////////////////////////////
setb sda
acall ldely
setb scl
acall ldely
clr sda
acall ldely
clr scl
ret
stop:;stop condition//////////////////////////////////////
clr sda
acall ldely
setb scl
acall ldely
setb sda
acall ldely
clr scl
ret
send:;sending the data put data in the eeprom////////////////////////
mov count,#08
clr scl
a7:
rlc a
mov sda,c
setb scl
nop
clr scl
nop
djnz count,a7
clr sda
nop
setb scl
nop
clr scl
ret
receve:;receve the data from eeprom counter load in r0/////////////////////////
mov count,#08

23. 26
setb sda
a9:
mov c,sda
setb scl
nop
clr scl
nop
rlc a
djnz count,a9
mov @r0,a
clr a
inc r0
cjne r0,#43h,receve
clr sda
nop
setb scl
nop
setb sda
ret
reads:;reads rendomly in eeprom////////////////////////////////////
acall start1
mov a,#54h
acall send
mov a,r5;memory address
acall send
acall start1
mov a,#55h
acall send
mov count,#08
setb sda
aa9s:
mov c,sda
setb scl
acall ldely
clr scl
acall ldely
rlc a
djnz count,aa9s
setb sda
acall ldely
setb scl
acall ldely
clr scl
mov r6,a;result in the r6
ret
;i2c program stop
;//////////////////////////////$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
jdam:
mov tmod,#20h
mov th1,#-3
mov scon,#50h
setb tr1
mov dptr,#mycom1
acall rep1
mov dptr,#mycom2

24. 27
acall rep1
mov dptr,#mycom7
acall rep1
mov dptr,#mycom8
acall rep1
mov dptr,#mycom9
acall rep1
acall resets
acall hdely
mov a,#0c0h
acall cmd
mov r0,#73h
mov 48h,#11
mov 86h,#00
acall system
ajmp aa
system:;/////////////////////////////////////////////////////////////////////////////
mov tmod,#20h
mov th1,#-3
mov scon,#50h
setb tr1
;transmitting data
mov dptr,#mycom1
acall rep1
mov dptr,#mycom2
acall rep1
mov dptr,#mycom7
acall rep1
mov dptr,#mycom8
acall rep1
acall delay
mov dptr,#mycom11
mov 48H,#9
rep55:
clr a
MOVC A,@A+DPTR
mov sbuf,a
hear45:
jnb ti,hear45
clr ti
inc dptr
djnz 48h,rep55
acall hdely
mov r0,#73h
rep331:
clr c
mov a,@r0
add a,#30h
mov sbuf,a
hear25:
jnb ti,hear25
clr ti
inc r0
cjne r0,#7dh,rep331
mov sbuf,#'"'
hear46:

25. 28
jnb ti,hear46
clr ti
acall hdely
mov sbuf,#0Dh
hear47:
jnb ti,hear47
clr ti
acall hdely
cjne a,#7,gvp;ALL NORMAL
mov dptr,#mycom15
gvp:
cjne a,#6,gvp1;HIGH TEMP
mov dptr,#mycom10
gvp1:
cjne a,#11110010b,gvp2;OVER VOLTAGE
mov dptr,#mycom13
gvp2:
cjne a,#11110100b,gvp3;LOW OIL LEVEL
mov dptr,#mycom12
gvp3:
cjne a,#11111000b,gvp4;OVER LOAD
mov dptr,#mycom14
gvp4:
jnb p3.5,asdf
mov dptr,#mycom15
sjmp asdf1
asdf:
mov dptr,#mycom10
asdf1:
acall rep1
clr ri
acall delay
acall delay
ret
rep1:;////////////////////////////////////////////////////////////////////////////////
setb p3.0
setb p3.1
clr a
MOVC A,@A+DPTR
mov sbuf,a
clr ti
hear:
jnb ti,hear
clr ti
jz next
inc dptr
sjmp rep1
next:
mov 49h,#60h
mov 4ah,#68h
acall receve1
ret
;///////////////////////////////////////////////////////////////////////////////////////
receve1:
mov r1,49h

26. 29
coun:
clr ri
jnb ri,$
mov a,sbuf
clr ri
mov @r1,a
inc r1
mov a,r1
cjne a,4ah,coun
;display data
mov a,#01h
acall cmd
mov a,#80h
acall cmd
mov r1,49h
did:
mov a,@r1
acall dat
inc r1
mov a,r1
cjne a,4ah,did
acall hdely
ret;//////////////////////////////////////////////////////////////////////////////////
delay0:
mov del1,#100
rep: djnz del1,rep
ret
lcdreset:
mov lcd, #0FFH
mov delays,#20
acall delayms
mov lcd, #38H
mov lcd, #30H
mov delays,#15
acall delayms
mov lcd, #38H
mov lcd, #30H
mov delays,#5
acall delayms
mov lcd, #38H
mov lcd, #30H
mov delays,#5
acall delayms
mov lcd, #28H
mov lcd, #20H
mov delays,#5
acall delayms
ret
delayms:
mov del1,#232
djnz del1,$
djnz delays,delayms
ret
resets:
mov dptr,#mycom
a11:

27. 30
clr a
MOVC A,@A+DPTR
jz senddat0
acall cmd
inc dptr
sjmp a11
senddat0:
ret
display:
a2:
clr a
movc a,@a+dptr
jz senddat1
acall dat
inc dptr
sjmp a2
senddat1:
ret
cmd:
mov save,a
anl a,#0f0h
setb acc.3
mov lcd,a
acall mdely
clr en
mov a,save
swap a
anl a,#0f0h
setb acc.3
mov lcd,a
acall mdely
clr en
ret
dat:
mov save,a
anl a,#0f0h
add a,#0ch
mov lcd,a
acall mdely
clr en
mov a,save
swap a
anl a,#0f0h
add a,#0ch
mov lcd,a
acall mdely
clr en
ret
ldely:;low delay rutine
mov del1,#05
a6:
djnz del1,a6
ret
mdely:;medium delay rutine
mov del1,#10
hear2:

28. 31
mov del2,#10
hear1:
mov del3,#20
hear0:
djnz del3,hear0
djnz del2,hear1
djnz del1,hear2
ret
hdely:;high delay rutine
mov del1,#10
dd1:
mov del2,#255
dd2:
mov del3,#255
dd3:
djnz del3,dd3
djnz del2,dd2
djnz del1,dd1
ret
delay:
mov r1,#6
cc0:
mov r2,#150
cc1:
mov r3,#255
cc2:
djnz r3,cc2
djnz r2,cc1
djnz r1,cc0
ret
mycom: db 28h,01h,0ch,06h,80h,0
karan: db 'fast adc',0
nodata: db 'no data1',0
data1: db 'R3= R4= ',0
data2: db 'R5= ',0
mycom1: db 'AT',0DH,0
mycom2: db 'AT+CSQ',0DH,0
mycom3: db 'DEVICE IN ACTION',0
mycom6: db 'AT+CMGR='
mycom7: db 'AT+CREG?',0DH,0
mycom8: db 'AT+CMGF=1',0DH,0
mycom9: db 'AT+CMGD=1,4',0DH,00
mycom10: db 'FIRE FIRE',1AH,0
mycom12: db 'LOW OIL LEVEL',1AH,0
mycom13: db 'OVER VOLTAGE',1AH,0
mycom14: db 'FIRE FIRE',1AH,0
mycom15: db 'MACHINE OVER HEATED',1AH,0
mycom11: db 'AT+CMGS="'
Loop:
jmp Loop
;====================================================================
END

29. 32
CHAPTER THREE
Descriptions of the Components
3.0 POWER SUPPLY
Power supply is a supply of electrical power. A device or system that supplies electrical or other types of
energy to an output load or group of loads is called a power supply unit or PSU. The term is most commonly applied
to electrical energy supplies, less often to mechanical ones, and rarely to others.
A 12 Volt Li-Ion Rechargeable battery ensures uninterrupted power supply to the entire system. A LM7805
voltage regulator regulates the voltage at 5 V to power up the microcontroller and sensor units. The battery is charged
by AC power, under the control of a charger controller. Battery charge level is monitored by applying a reference
voltage to an ADC channel of the MCU. A voltage divider and a Zener diode are used to keep the reference voltage
level between 0 - 5 V. A pair of green and red LEDs indicates the charging and battery low status of the system
respectively. If the battery voltage is less than 10.5 v, the red LED flashes. So, the battery would have to be charged,
flashing the green LED.
Fig 3.0 Power Supply

30. 33
3.1 AT89C52 MICROCONTROLLER
The AT89C52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of in-system
programmable Flash memory. The device is manufactured using Atmel’s high-density nonvolatile memory
technology and is compatible with the industry-standard 80C51 instruction set and pinout.
The AT89C52 provides the following standard features: 8K bytes of Flash, 256 bytes of
RAM, 32 I/O lines, Watchdog timer, two data pointers, three 16-bit timer/counters, a six-vector two-level
interrupt architecture, a full duplex serial port, on-chip oscillator, and clock circuitry.
Fig 3.1:AT89C52
PORT 0:
Port 0 is an 8-bit open-drain bi-directional I/O port. 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.

31. 34
PORT 1:
Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. 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.
PORT 2:
Port 2 is a 8-bit bi-directional I/O port with internal pull-ups. 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 During
accesses to external data memory that uses (IIL) because of the internal pull-ups.
PORT 3:
Port 3 is an 8-bit bi-directional I/O port with internal pull-ups. 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)
because of the pull-ups.
Fig 3.2: Crystal Oscillator (12MHz)

32. 35
3.2 THERMISTOR
The Thermistor is a special type of variable resistive element that changes its physical resistance when
exposed to changes in temperature.
The Thermistor is a solid-state temperature sensing device that acts a bit like an electrical resistor
but is temperature sensitive. Thermistors can be used to produce an analogue output voltage with variations
in ambient temperature and as such can be referred to as a transducer. This is because it creates a change in
its electrical properties due to a physical change in heat.
A thermistor is basically a two-terminal solid state thermally sensitive transducer made from
sensitive semiconductor based metal oxides with metallized or sintered connecting leads onto a ceramic disc
or bead. This allows it to change its resistive value in proportion to small changes in temperature. In other
words, as its temperature changes, so too does its resistance and as such its name, “Thermistor” is a
combination of the words THERM-ally sensitive res-ISTOR.
While the change in resistance due to heat is generally undesirable in standard resistors, this effect can be put
to good use in many temperature detection circuits. Thus, being non-linear variable-resistance devices,
thermistors are commonly used as temperature sensors having many applications to measure the temperature
of both liquids and ambient air.
Also, being a solid-state device made from highly sensitive metal oxides, they operate at the molecular level
with the outermost (valence) electrons becoming more active and producing a negative temperature
coefficient, or less active producing a positive temperature coefficient as the temperature of the thermistor is
increased. This means that they can have very good reproducible resistance verses temperature characteristics
allowing them to operate up to temperatures of about 200o
C.

33. 36
Fig: 3.3 Typical Thermistor
While the primarily used of thermistors are as resistive temperature sensors, being resistive devices belonging
the resistor family, they can also be used in series with a component or device to control the current flowing through
them. In other words, they can also be used as current-limiting devices.
Thermistors are available in a range of types, materials and sizes depending on the response time and
operating temperature. Also, hermetically sealed thermistors eliminate errors in resistance readings due to moisture
penetration while offering high operating temperatures and a compact size. The three most common types are: Bead
thermistors, Disk thermistors, and Glass encapsulated thermistors.
These heat-dependent resistors can operate in one of two ways, either increasing or decreasing their resistive
value with changes in temperature. Then there are two types of thermistors available: negative temperature coefficient
(NTC) of resistance and positive temperature coefficient (PTC) of resistance.
Negative Temperature Coefficient Thermistor
Negative temperature coefficient of resistance thermistors, or NTC thermistors for short, reduce or
decrease their resistive value as the operating temperature around them increases. Generally, NTC thermistors
are the most commonly used type of temperature sensors as they can be used in virtually any type of
equipment where temperature plays a role.
NTC temperature thermistors have a negative electrical resistance versus temperature (R/T)
relationship. The relatively large negative response of an NTC thermistor means that even small changes in
temperature can cause significant changes in its electrical resistance. This makes them ideal for accurate
temperature measurement and control.

34. 37
We said previously that a thermistor is an electronic component whose resistance is highly
dependent on temperature so if we send a constant current through the thermistor and then measure the
voltage drop across it, we can thus determine its resistance and temperature.
NTC thermistors reduce in resistance with an increase in temperature and are available in a variety
of base resistances and curves. They are usually characterized by their base resistance at room temperature,
that is 25o
C, (77o
F) as this provides a convenient reference point. So for example, 2k2Ω at 25o
C, 10kΩ at
25o
C or 47kΩ at 25o
C, etc.
Another important characteristic is the “B” value. The B value is a material constant which is
determined by the ceramic material from which it is made and describes the gradient of the resistive (R/T)
curve over a particular temperature range between two temperature points. Each thermistor material will have
a different material constant and therefore a different resistance versus temperature curve.
Then the B value will define the thermistors resistive value at the first temperature or base point,
(which is usually 25o
C), called T1, and the thermistors resistive value at a second temperature point, for
example 100o
C, called T2. Therefore the B value will define the thermistors material constant between the
range of T1 and T2. That is BT1/T2or B25/100 with typical NTC thermistor B values given anywhere between
about 3000 and about 5000.
Note however, that both the temperature points of T1 and T2 are calculated in the temperature units of Kelvin
where 00
C = 273.15 Kelvin. Thus a value of 25o
C is equal to 25o
+ 273.15 = 298.15K, and 100o
C is equal to
100o
+ 273.15 = 373.15K, etc.
So by knowing the B value of a particular thermistor (obtained from manufacturers datasheet), it is
possible to produce a table of temperature versus resistance to construct a suitable graph using the following
normalized equation:
Thermistor Equation

35. 38
 Where:
o T1 is the first temperature point in K4elvin
o T2 is the second temperature point in Kelvin
o R1 is the thermistors resistance at temperature T1 in Ohms
o R2 is the thermistors resistance at temperature T2 in Ohms
Thermistor Example No1
A 10kΩ NTC thermistor has a B value of 3455 between the temperature range of 25 to 100o
C. Calculate its
resistive value at 25o
C and at 100o
C.
Data given: B = 3455, R1 = 10kΩ at 25o
. In order to convert the temperature scale from degrees Celsius, o
C
to degrees Kelvin add the mathematical constant 273.15
The value of R1 is already given as its 10kΩ base resistance, thus the value of R2 at 100o
C is calculated as:

36. 39
Giving the following two-point characteristics graph of:
Fig:3.4 two-point characteristics graph
Note that in this simple example, only two points were found, but generally thermistors change their
resistance exponentially with changes in temperature, so their characteristic curve is nonlinear, therefore the
more temperature points are calculated the more accurate will be the curve.
Temperatur
e
(o
C)
10 20 25 30 40 50 60 70 80 90
10
0
11
0
12
0
Resistance
(Ω)
1847
6
1218
5
1000
0
826
0
574
0
408
0
296
0
218
8
164
5
125
7
97
3
76
5
60
8
and these points can be plotted as shown to give a more accurate characteristics curve for the 10kΩ NTC Thermistor
which has a B-value of 3455.

37. 40
Fig:3.5 NTC Thermistor Characteristics Curve
Notice that it has a negative temperature coefficient (NTC), that is its resistance decreases with increasing
temperatures.
Using a Thermistor to Measure Temperature.
So how can we use a thermistor to measure temperature. Hopefully by now we know that a thermistor is a
resistive device and therefore according to Ohms law, if we pass a current through it, a voltage drop will be
produced across it. As a thermistor is an active type of a sensor, that is, it requires an excitation signal for its
operation, any changes in its resistance as a result of changes in temperature can be converted into a voltage
change.

38. 41
Fig:3.6 Potential divider circuit
The simplest way of doing this is to use the thermistor as part of a potential divider circuit as shown. A
constant voltage is applied across the resistor and thermistor series circuit with the output voltage measured
across the thermistor.
If for example we use a 10kΩ thermistor with a series resistor of 10kΩ, then the output voltage at the base
temperature of 25o
C will be half the supply voltage.
When the resistance of the thermistor changes due to changes in temperature, the fraction of the supply
voltage across the thermistor also changes producing an output voltage that is proportional to the fraction of
the total series resistance between the output terminals.
Thus, the potential divider circuit is an example of a simple resistance to voltage converter where the
resistance of the thermistor is controlled by temperature with the output voltage produced being proportional
to the temperature. So, the hotter the thermistor gets, the lower the voltage.
If we reversed the positions of the series resistor, RS and the thermistor, RTH, then the output voltage will
change in the opposite direction, that is the hotter the thermistor gets, the higher the output voltage.

39. 42
Fig 3.7: Potential division in NTC
We can use NTC thermistors as part of a basic temperature sensing configuration using a bridge circuit as
shown. The relationship between resistors R1 and R2 sets the reference voltage, VREF to the value required.
For example, if both R1and R2 are of the same resistive value, the reference voltage will be equal to half of
the supply voltage. That is Vs/2.
As the temperature and therefore the resistance of the thermistor changes, the voltage at VTH also changes
either higher or lower than that at VREF producing a positive or negative output signal to the connected
amplifier.
The amplifier circuit used for this basic temperature sensing bridge circuit could act as a differential amplifier
for high sensitivity and amplification, or a simple Schmitt-trigger circuit for ON-OFF switching.
The problem with passing a current through a thermistor in this way, is that thermistors experience what is
called self-heating effects, that is the I2
.R power dissipation could be high enough to create more heat than
can be dissipated by the thermistor affecting its resistive value producing false results.
Thus, it is possible that if the current through the thermistor is too high it would result in increased power
dissipation and as the temperature increases, its resistance decreases causing more current to flow, which
increases the temperature further resulting in what is known as Thermal Runaway. In other words, we want
the thermistor to be hot due to the external temperature being measured and not by itself heating up.

40. 43
Then the value for the series resistor, RS above should be chosen to provide a reasonably wide response over
the range of temperatures for which the thermistor is likely to be used while at the same time limiting the
current to a safe value at the highest temperature.
One way of improving on this and having a more accurate conversion of resistance against temperature (R/T)
is by driving the thermistor with a constant current source. The change in resistance can be measured by
using a small and measured direct current, or DC, passed through the thermistor in order to measure the
voltage drop produced.

41. 44
3.3 LCD
LCD (liquid crystal display) screen is an electronic display module and find a wide range of applications. A
16 * 2 LCD display is very basic module and is very commonly used in various device and circuits. These
modules are preferred over seven segments and other multi segment LEDs. The reasons being: LCDs are
economical; easily programmable; have no limitation of displaying special & even custom characters,
animations.
A 16*2 LCD means it can display 16 characters per line and there are 2 such lines. In this LCD each character
is displayed in 5*7-pixel matrix. This LCD has two registers, namely, Command and Data. The command
register stores the command instructions given to the LCD.
FIG 3.8: LCD

42. 45
VSS, VDD and VEE
Pin 1 (VSS) is a ground pin and it is certainly needed that this pin should be grounded for LCD to work properly.
VEE and VDD are given +5 volts normally. However, VEE may have a potentiometer voltage divider network to
get the contrast adjusted. But VDD is always at +5V.
RS, R/W and E
These three pins are numbered 4, 5 and 6 as shown above. RS is used to make the selection between data and
command register. For RS=0, command registers selected and for RS=1 data register is selected. R/W gives you the
choice between writing and reading. If set (R/W=1) reading is enabled. R/W=0 when writing.
Enable pins is used by the LCD to latch information presented to its data pins. When data is supplied to data pins, a
high to low pulse must be applied to this pin in-order for the LCD to latch in the data present at the data pins. It may
be noted here that the pulse must be of minimum 450ns wide.
D0-D7
The 8-bit data pins, D0-D7, are used to send information to the LCD or read the contents of LCD's internal register.
The following paragraph is taken and included from "Muhammad Ali Mazidi", "To display letters and numbers, we
send ASCII code for the letters A-Z, a-z and numbers 0-9 while making RS=1. We also use RS=0 to check the busy
flag bit to see if the LCD is ready to receive information. The busy flag is D-7 and can be read when R/W=1 and
RS=0, as follows: if R/W=1, RS=0. When D7=1 (busy flag=1), the LCD is busy taking care of internal operations
and will not accept any new information. When D7=0, the LCD is ready to receive new information. It is
recommended to check the busy flag before writing any data to LCD"/

43. 46
3.4 LM7805 VOLTAGE REGULATOR
Voltage source in a circuit may have fluctuations resulting in not giving fixed voltage outputs. Voltage
regulator IC maintains the output voltage at a constant value.7805 IC, a voltage regulator integrated
circuit(IC) is a member of 78xx series of fixed linear voltage regulator ICs used to maintain such fluctuations.
The xx in 78xx indicates the fixed output voltage it provides.7805 IC provides +5 volts regulated power
supply with provisions to add sink as well.
Fig: 3.9 LM7805 VOLTAGE REGULATOR

44. 47
3.5 TRANSFORMER
The principle parts of a transformer and their functions are:
1. The core, which makes a path for the magnetic flux.
2. The primary coil, which receives energy from the ac sources
3. The secondary coil, which receives energy from the primary coil and delivers to load.
4. The enclosure, which protects the transformer from dirt. 5. The composition of a transformer core depends
on voltage, current, and frequency. Commonly used core materials are air, iron, and steel. Each of these
materials is suitable for certain applications. Generally, air-core transformers are used when the voltage
source has a high frequency (above 20 kHz). Iron-core transformers are usually used when the source
frequency is low (below 20 kHz).
6. A soft-iron-core transformer is very useful where the transformer must be physically small, yet efficient.
The iron-core transformer provides better power transfer than does the air-core transformer. A transformer
whose core is constructed of laminated sheets of steel dissipates heat readily.
Fig: 3.10 TRANSFORMER

45. 48
3.6 NAU7802 KGI ADC
1.0 GENERAL DESCRIPTION
The Nuvoton NAU7802 is a precision low-power 24-bit analog-to-digital converter (ADC), with an onboard low-
noise programmable gain amplifier (PGA), onboard RC or Crystal oscillator, and a precision 24-bit sigma-delta
(Ó-Ä) analog to digital converter (ADC). The NAU7802 device is capable of up to 23-bit ENOB (Effective
Number of Bits) performance. This device provides a complete front-end solution for bridge/sensor measurement
such as in weigh scales, strain gauges, and many other high resolution, low sample rate applications.
The many built-in features enable high performance applications with very low external parts count. Additionally,
both operating current and standby current are very low, and many power management features are included.
These enable powering only those elements of the chip that are needed, and, to operate at greatly reduced power
if the full 23-bit ENOB performance is not required.
The Programmable Gain Amplifier (PGA) provides selectable gains from 1 to 128. The A/D conversion is
performed with a Sigma-Delta modulator and programmable FIR filter that provides a simultaneous 50Hz and
60Hz notch filter to effectively improve interference immunity. Also, this device provides a standard 2-wire
interface compatible with I2C protocol for simple and straightforward connection to and interoperation with a
wide range of possible host processors.
Fig: 3.11 NAU 7802

46. 49
2. FEATURES
 Supply power: 2.7V~5.5V
 On-chip VDDA regulator for internal analog circuit or external load cell

Programmable VDDA: Off, 2.4V to 4.5V with eight options Minimum 10mA output drive capability
at 3.0V output voltage

Note: DVDD must be 0.3Vdc greater than desired VDDA output voltage
 23 bits effective precision analog-to-digital converter
 Simultaneous 50Hz and 60Hz rejection (reaching －90dB）
 RMS Noise:

50nV in 10 SPS data output rate and PGA gain = 128

150nV in 80 SPS data output rate and PGA gain = 128
 Programmable PGA gains from 1 to 128
 Programmable ADC data output rates
 External differential reference voltage ranges from 0.1V to 5V
 System clock: External crystal oscillator or on-chip RC oscillator (4.9152Mhz)
 On-chip calibration
 On-chip power-on reset circuit
 On-chip temperature sensor
 Low Power Consumption and Programmable Power Management Options

< 1uA standby current
 External 4.9152MHz Crystal oscillator

Internal 4.9152MHz RC oscillator (power-on default system clock)

External 4.9152MHz Crystal oscillator
 MCU control interface: 2-wire interface compatible with I2C protocol
 Operating Temperature: -40~85C

47. 50
 Packages:

SOP-16 (150mil) / PDIP-16
3. APPLICATIONS
 Weigh scales
 Strain Gauge
 Industrial process control
 Liquid/gas flow control
 Pressure sensors
 Voltage monitors
Fig: 3.12 BLOCK DIAGRAM OF NAU7802 ADC

48. 51
3.7 MOTOR
Fig: 3.13 PMDC Motor
The speed of a DC motor is directly proportional to the supply voltage, so if we reduce the supply voltage
from 12 Volts to 6 Volts, the motor will run at half the speed. How can this be achieved when the battery is
fixed at 12 Volts. The speed controller works by varying the average voltage sent to the motor. It could do
this by simply adjusting the voltage sent to the motor, but this is quite inefficient to do. A better way is to
switch the motor’s supply on and off very quickly. If the switching is fast enough, the motor doesn’t notice
it, it only notices the average effect.

49. 52
3.8 RESISTORS
A resistor is a two-terminal electronic component designed to oppose an electric current by producing a
voltage drop between its terminals in proportion to the current, that is, in accordance with Ohm's law:
V = IR
Fig: 3.14 Resistors
3.9 CAPACITORS
A capacitor or condenser is a passive electronic component consisting of a pair of conductors separated by a
dielectric. When a voltage potential difference exists between the conductors, an electric field is present in
the dielectric.
Fig: 3.15 Capacitors.

50. 53
3.10 GSM MODULE SIMCom SIM900A
SIM900A is a dual-band GSM/GPRS engine that works on frequencies EGSM 900MHz and DCS 1800MHz.
SIM900A features GPRS multi-slot class 10/ class 8 (optional) and supports the GPRS coding schemes CS-1, CS-2,
CS-3 and CS-4.
With a tiny configuration of 24mm x 24mm x 3mm, SIM900A can meet almost all the space requirements in our
applications such as M2M, smart phone, PDA and other mobile devices. The SIM900A is integrated with the TCP/IP
protocol; extended TCP/IP AT commands are developed for customers to use the TCP/IP protocol easily, which is
very useful for those data transfer applications.
GSM (Global System for Mobile communication) is a digital mobile telephony system that is widely used in Europe
and other parts of the world. GSM uses a variation of time division multiple access (TDMA) and is the most widely
used of the three digital wireless telephony technologies (TDMA, GSM, and CDMA). GSM digitizes and compresses
data, then sends it down a channel with two other streams of user data, each in its own time slot. It operates at either
the 900 MHz or 1800 MHz frequency band.
SIM900A Functional Diagram
The following figure shows a functional diagram of the SIM900A and illustrates the mainly functional part:
The GSM baseband engine
Flash and SRAM
The GSM radio frequency part
the antenna interface

51. 54
Fig 3.16 SIM900A functional diagram
Fig 3.17 Top view of SIM900A EVB

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PIN Assignment of SIM900A
Fig3.18SIM900A pin out diagram (Top View)
List of AT commands used in the system.
Commands Description
AT Status
AT + CREG? Network registration
AT + CIMI Request international mobile subscriber identity
AT + CPBF Find phonebook entries
AT + CMGF Select SMS message format
AT + CMGS Send SMS message

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3.11 OPTOCOUPLER LM324N
The LM324-N series consists of four independent, high-gain, internally frequency compensated operational amplifiers
designed to operate from a single power supply over a wide range of voltages. Operation from split-power supplies is
also possible and the low-power supply current drain is independent of the magnitude of the power supply voltage.
Fig 3.19 Optocoupler J Package 14-Pin CDIP Top View

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3.12 BUZZER
Buzzer is used to produce sound as an alert if it receives signal from the microcontroller. Clocks,
travel watches, keyboards, toys, various alarms of automobile equipment.
Fig 3.20: Buzzer
Features:
i. These high reliability electromagnetic buzzers are applicable to automobile equipment.
ii. Compact, pin terminal type electromagnetic buzzer with 2048Hz output.
iii. Pin type terminal construction enables direct mounting onto printed circuit boards.

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3.13 KEIL Software Descriptions
Keil compiler is software used where the machine language code is written and compiled. After
compilation, the machine source code is converted into hex code which is to be dumped into the
microcontroller for further processing. Keil compiler also supports C language code. Keil compiler is
software used where the machine language code is written and compiled. After compilation, the machine
source code is converted into hex code which is to be dumped into the microcontroller for further processing.
Keil compiler also supports C language code.
STEPS TO WRITE AN ASSEMBLY LANGUAGE PROGRAM IN KEIL AND HOW TO COMPILE IT:
1. Install the Keil Software in the PC in any of the drives.
2. After installation, an icon will be created with the name “Keil uVision3”. Just drag this icon onto the desktop so
that it becomes easy whenever you try to write programs in Keil.
3. Double click on this icon to start the Keil compiler.
4. A page opens with different options in it showing the project workspace at the leftmost corner side, output
window in the bottom and an ash colored space for the program to be written.
5. Now to start using the Keil, click on the option “project”.
6. A small window opens showing the options like new project, import project, open project etc. Click on “New
project”.
7. A small window with the title bar “Create new project” opens. The window asks the user to give the project name
with which it should be created and the destination location.
8. The project can be created in any of the drives available. You can create a new folder and destination location; a
window opens where a list of vendors will be displayed.

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COSTS:
COMPONENTS PRICE (in Rs.)
MICROCONTROLLER AT89C52 45.00
SMPS ADAPTER 75.00
MOTOR PMDC 100.00
BUZZER 50.00
CRYSTAL OSCILLATOR 10.00
CAPACITORS 10.00
RESISTORS 10.00
ADC NAU7802 150.00
REGULATOR IC 10.00
HEAT SENSOR 100.00
POTENTIOMETER 5.00
DIODES 5.00
LED & PUSH BUTTONS 20.00
TIP122 TRANSISTOR 50.00
LCD 200.00
BREAD BOARD 75.00
CARDBOARD 80.00
GSM MODULE SIM900A 1200.00
OPTOCOUPLER KIT 100.00

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CONNECTING WIRES 40.00
ADHESIVE 50.00
OPTOCOUPLER KIT 50.00
Total 2435.00
LIMITATIONS
 Overheat detectors may not go off or give early warning in as many as 35% of all fires.
 An alarm system is not a substitute for insurance.
 It may not function properly unless they are maintained and tested regularly.
 Nonlinearity, limited support for temperature range, current source needed, fragile, self-heating etc. may be
some limitations.
 The disadvantage of smoke detectors is that they are usually more expensive to install, when compared to
thermal sensors, and are more resistant to inadvertent alarms. However, when properly selected and designed,
they can be highly reliable with a very low probability of false alarm.

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CHAPTER FOUR
CONCLUSIONS
The automatic signal and alarming system to avoid engine overheating has been successfully designed and
developed. Compared to other conventional methods, this system shows excellent performance with its
reliable digital technology and it is cheaper and durable. The automatic overheat alarm and signal system is
a promising system in terms of engine temperature response in the sensor, micro-controller and LCD. Thus,
the automatic signal and alarming system for overheating is a big boon as concerned with the automobile
engine, aviation engine, generator, power plant, nuclear power plant and industrial applications. It increases
engine-life and saves economical expenses. Based on the survey result, it is seen that the signal and alarming
system has a rising demand and it is a good asset from the electronics perspective.
Smoke detectors are great because they save lives. You should place a smoke detector at least 6 to
12 inches away from a wall. Smoke detectors should always be in a house or an apartment. There are different
shapes of smoke detectors, but the ones that are a circle shape are those that are in most homes. There are
also smoke detectors shaped as noses, to smell for smoke. There should be at least 2 or 3 smoke detectors in
your home. You should install a smoke detector on every floor of a house. Always have a smoke detector in
your home for your own safety. If the smoke detector gets used more then it will reduce the quality of the
smoke detector and the alarm will not go off as fast. From the results we got we concluded that the smoke
detector does take longer to detect smoke the more it is used.
The Overheat and Smoke detector alarm system using GSM communication has been designed and
developed for making our life easier and secured. We use 5V from board and use 12V DC power supply for
GSM shield. We use the GSM module for receiving signal from supply. Finally, we have designed and
developed the whole control system and tested using Smoke detector. We fix all the problems encountered
during the design and testing of the system. Finally, we successfully achieved our goals. In this study, the
application of microcontroller with improved algorithm of extended specifications has increased the use of
GSM shield and improves the controlling the smoke. So, our Smoke detector alarm system using GSM
communication is suitable.

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The performance of the project met the original technical problem, which was to build a circuit that would
sound an alarm when the heat in the machine reach a hazardous temperature. Also, the project was well
under the overall project cost projected, making the project a good product since the application was
successfully demonstrated and the circuit price was reasonable.
Fig 4.1: System performances under different situations.

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FUTURE SCOPES
The features and functions discussed will bring new value to the service and to industry owners. Benefits to
the overheat detection service relate to the provision of real time information that enhances operational
effectiveness and safety. Benefits to the owner involve enhanced reliability and reduced costs of maintaining
safety systems. The industry fire alarm system is the best candidate for the performance of these functions
since they have the needed infrastructure, reliability, and survivability needed to accomplish the objectives.
The studies can be used in future to identify the main volatiles that are responsible for causing the sensor
response variations. Using this knowledge gained from the analysis and studies one can customize the sensor
array towards these main volatiles. In this way one can identify a volatile pattern, which correlates with a
better odor discrimination outcome with a lower cost detection risk. This development is very beneficial in
biomedical applications in detecting different kinds of diseases because if it can correlate key volatiles to the
volatile shift observed in various data records used in medical test. In this way one can precede the approach
in the work having applications of low sensors in pathological diagnosis. Because it has been found in various
literature that the electronic nose is able to distinguish between control blood and ―uremic‖ blood. In
addition, the gas sensor series is not only able of discriminating perform after-dialysis blood however also it
can follow the unpredictable shift happening during a single hemodialysis session. The e-nose can be used
for equally dial sate side and blood-side monitoring of hemodialysis. In this way the work has marvelous
scope in social welfare and minimizing expenses in costly pathological test in diagnosis of diseases.
Algorithm wise one can also consider a classifier algorithm that can have some adaptive feature
which can help the algorithm to adjust the sensor heating voltage at a temperature level where we can get a
minimum error and highest discrimination level. For this purpose, many adaptive equalization algorithms
like LMS and RLS are already present and they can easily use to update the sensor response. Along with the
adaptive equalization scheme there are also neural network and fuzzy based classifier present and can be used
in classifying the response. But for this purpose, it will have to collect a large amount of data base to train
these classification algorithms. One can also work on different types of odor like samples used in detecting
fruit ripeness, in quality control of other pharmaceutical product using the same algorithm.

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The designed fire alarm system is simple, but it has wide area of application in household and industrial
safety, especially in developing countries. Using this system, quick and reliable alert response is possible to
initiate preventive measures to avert danger of fire hazards and minimize losses of life and property. This is
a cost-effective fire alarm system which performs reliably to ensure safety from fire, and can be installed in
houses, industries, offices, ware-houses etc. very easily. It can be used to detect burnable gas like methane,
LPG etc. as well. The designed systems have coverage up to 100 square meter area by using a category-6
cable as data line. Large industrial or residential area can be monitored through the proposed system installing
multiple modules, each for one floor or unit. The system can be further developed with added features like
web server interconnect, fire area tracking and fire extinguisher interfacing etc.
This project gives us an opportunity to do a big project in future. The applications stated above are some
demo applications that are possible with its future development. Initially for the limitation of time and
required fund we were able to develop just a Smoke detector alarm system. The system will also work using
GSM communication. It will more efficient by using 16x2 LCD display. So, we have a big work scope in
this sector. We hope that, we will be able to complete all the features needed for its ultimate applications.
The features which can be developed in the future are as
 We can monitor more parameters like LPG gas leakage.
 We can implement GPS modem to send co-ordinates of location where the fault is detected.
 It can also be implemented in hospitals or medical institutes to provide better precaution alerts.

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MACHINE OVERHEAT AND SMOKE DETECTION WITH GSM
Fig 4.2: Project top view

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