Automatic irrigation and flood controlling system by using GSM

i
A MAJOR PROJECT REPORT
On
AUTOMATIC IRRIGATION AND FLOOD CONTROLLING
SYSTEM BY USING GSM
Submitted
in partial fulfillment of the requirement
for the award of the degree of
BACHELOR OF TECHNOLOGY
IN
ELECTRONICS AND COMMUNICATION ENGINEERING
By
B.SANDEEP
(12C81A0410)
Under the esteemed guidance of
Ms. K.GAYATHRI M.Tech.,
Assistant Professor, Dept of ECE.
DEPTARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
Spurthi Educational Society’s
SREEKAVITHA ENGINEERING COLLEGE
(Approved by AICTE, New Delhi & Affiliated to JNTUH),
(Accredited by NBA)
Karepally-507 122, Khammam (Dist), T.S, INDIA.
E-mail: skec2001@gmail.com
2015-16

ii
Ph: 08745 – 246008, 09
08745 – 246017.
ESTD 2001
SPURTHI EDUCATIONAL SOCIETY’S
SREEKAVITHA ENGINEERING COLLEGE
(APPROVED BY AICTE, NEW DELHI AND AFFILIATED TO JNTU, HYDERABAD)
(Accredited by NBA)
KAREPALLY, KHAMMAM – 507 122.
DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING
BONAFIDE CERTIFICATE
This is to certify that the dissertation entitled “AUTOMATIC
IRRIGATION AND FLOOD CONTROLLING SYSTEM BY USING GSM” is being
submitted by B.SANDEEP (12C81A0410) in partial fulfillment of the requirement
for the award of the degree of Bachelor of Technology in ELECTRONICS AND
COMMUNICATION ENGINEERING, from Jawaharlal Nehru Technological
University, Hyderabad for the academic year 2015- 16.
Ms. K.Gayathri M.Tech., Mrs.D.Sailaja M.Tech,(Ph.D).,
Asst.Professor, Internal guide, Assoc. Professor
Dept.of ECE. Head of the Department,
Dept.of ECE.
Submitted for Viva Voce Examination held on.
External Examiner

iii
ACKNOWLEDGEMENT
I take this opportunity to thank all who have rendered their full support to my
project work.
I offer my sincere thanks to the internal guide Ms.K.Gayathri M.Tech,
Assist.Professor for her valuable suggestions and support
I thank and express my gratitude to Mrs. D.Sailaja M.Tech, (Ph.D.),and
Head of the department for providing with both time and amenities to make this
project a success with in schedule.
I express my special thanks to Sri Prof.P. Bala Gangadhar Rao, Dean of the
college for his valuable advice in this work.
I express my sincere gratitude to Principal, Vice-Principal of Sreekavitha
Engineering College, for providing excellent academic environment in the college.
I render my thanks to Mr. P.UshaKiran Kumar M.Tech, Chairman
SreeKavitha Engineering College, for his encouragement.
I am grateful to Mr. S.Chalama Reddy M.Sc, M.Ed Correspondent
SreeKavitha Engineering College, for facilitating all the required amenities.
I offer my sincere thanks to our Faculty members and Lab in-charges that have
helped me a lot.
I extend my thanks to all the people, who have helped me a lot directly or
indirectly in the completion of this project.
B.SANDEEP
(12C81A0410)

iv
Ph: 08745 – 246008,09
08745 – 246017.
ESTD 2001
SPURTHI EDUCATIONAL SOCIETY’S
SREEKAVITHAENGINEERINGCOLLEGE
(APPROVED BY AICTE, NEW DELHI AND AFFILIATED TO JNTU, HYDERABAD)
(Accredited by NBA)
KAREPALLY, KHAMMAM – 507 122.
DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING
DECLARATION
I am here by declare that the results embodied in this dissertation entitled
“AUTOMATIC IRRIGATION AND FLOOD CONTROLLING SYSTEM BY USING
GSM” is record of work done by us in the department of Electronics and
Communication Engineering from Jawaharlal Nehru Technological University,
Hyderabad.
The reported are based on the project work done entirely by me and not copied
from any other source. The results embodied in this dissertation have not been
submitted to any other University for the award of any degree or diploma.
DATE:
PLACE:
B.SANDEEP
(12C81A0410)

v
ABSTRACT
Irrigation has been the backbone of human civilization since man has started
agriculture. As the generation evolved, man developed many methods of irrigation to supply
water to the land. In the present scenario on conservation of water is of high importance. The
motivation for this project came from the countries where economy is based on agriculture
and the climatic conditions lead to lack of rains & scarcity of water. The farmers working in
the farm lands are solely dependent on the rains and bore wells for irrigation of the land.
Even if the farm land has a water-pump, manual intervention by farmers is required to turn
the pump on/off whenever needed. Present work is attempts to save the natural resources
available for human kind. By continuously monitoring the status of the soil, we can control
the flow of water and thereby reduce the wastage. By knowing the status of moisture and
temperature through GSM with the use of moisture and temperature sensors, water flow can
be controlled by just sending a message from our mobile.And automatically control the flood
in the field when sudden raining.
The aim of our project is to minimize this manual intervention by the farmer, which is
why we are using a micro-controller (AT89S52). The micro-controller based Automated
Irrigation system will serve the
following purposes:
1) As there is no un-planned usage of water, a lot of water is saved from being wasted.
2) The irrigation is d only when there is not enough moisture in the soil and the
microcontroller decides
when should the pump be turned on/off based on SMS from the farmers, saves a lot time for
the farmers. This also gives much needed rest to the farmers, as they don’t have to go and
turn the pump on/off manually.

vi
INDEX
ACKNOWLEDGEMENT iii
DECLARATION iv
ABSTRACT v
INDEX vi-vii
LIST OF TABLES viii
LIST OF FIGURES ix
LIST OF ABRIVATIONS x
CHAPTER 1: INTRODUCTION (01-03)
1.1 EMBEDDED SYSTEMS 01
1.2 OBJECTIVE OF THE PROJECT 03
CHAPTER 2: BLOCK DIAGRAM DESCRIPTION (04-05)
CHAPTER 3: DESCRIPTION OF HARDWARE COMPONENTS (06-56)
3.1 MICRO CONTROLLER 06
3.2 LM324 21
3.3 GSM MODEM 23
3.4 MAX-232 AND RS-232 29
3.5 GEAR MOTOR 39
3.6 RELAY 42
3.7 LIQUID CRYSTAL DISPLAY (LCD) 46
3.8 POWER SUPPLY 48
CHAPTER 4: CIRCUIT DIAGRAM AND OPERATION (57-58)
4.1 CIRCUIT DIAGRAM 57
4.2 CIRCUIT OPERATION 58
CHAPTER 5: SOFTWARE DEVOLOPEMENT (59-74)
5.1 INTRODUCTION 59
5.2 C51 COMPILER & A51 MACRO ASSEMBLER 60
5.3 µVISION 60
5.4 FLASH MAGIC 69
5.5 CODING 71

vii
CHAPTER 6: RESULTS (77-83)
CHAPTER 7: CONCLUSION 84
CHAPTER 8: FUTURE SCOPE 85
CHAPTER 9: REFERENCES 86

viii
LIST OF TABLES
S.NO TABLE NAME OF TABLE PAGE NO
1 TABLE 3.1 TECHNICAL SPECIFICATIONS OF GSM 25
2 TABLE 3.2 PIN DESCRIPTION OF SIM900A 29
3 TABLE 3.3 PIN DESCRIPTION OF MAX232 33
4 TABLE 3.4 MAX 232 PIN DETAILS 36
5 TABLE 3.5 LCD PIN DETAILS 47
6 TABLE 3.6 COMMANDS OF LCD 48
7 TABLE 3.6 SPECIFICATIONS OF IC7805 48

ix
LIST OF FIGURES
S.NO FIGURE NAME OF FIGURE PAGE NO
1 FIG 2.1 BLOCK DIAGRAM 4
2 FIG 3.1 FUNCTIONAL BLOCK DIAGRAM OF MICRO CONTROLLER 6
3 FIG 3.2 PIN DIAGRAM OF 89S52 MICRO CONTROLLER 4
4 FIG 3.3 OSCILLATOR AND TIMING CIRCUIT 15
5 FIG.3.4 PIN DIAGRAM OF LM-324 21
6 FIG.3.5 GSM MODEM 23
7 FIG.3.6 TRANSMITTER FOR THE VOICE SIGNAL 26
8 FIG.3.7 RECEIVER FOR THE VOICE SIGNAL 26
9 FIG.3.8 GSM SIM 900A 28
10 FIG.3.9 BLOCK DIAGRAM OF RS232 32
11 FIG.3.10 MAX 232 IC 33
12 FIG.3.11 MAX-232 CONNECTER DIAGRAM 35
13 FIG.3.12 RS-232 INTERFACE DIAGRAM 37
14 FIG.3.13 12V HIGH TORQUE DC GEAR MOTOR 39
15 FIG.3.14 LCD DISPLAY AND DATA R/W WAVEFORM 46
16 FIG 3.15 INTERFACING OF LED 48
17 FIG 3.16 BASIC BLOCK DIAGRAM OF A FIXED REGULATED
POWER SUPPLY 49
18 FIG3.17 CIRCUIT DIAGRAM OF POWER SUPPLY 56
19 FIG.4.1 CIRCUIT DIAGRAM 57
20 FIG.5.1 KEIL SOFTWARE- INTERNAL STAGES 59

x
LIST OF ABBREVIATIONS
TITLE EXPANSION
PDA PERSONAL DIGITAL ASSISTANTS
SMS SHORT MESSAGE SERVICE
RAM RANDOM ACCESS MEMORY
ROM READ ONLY MEMORY
GSM GLOBAL SYSTEM FOR MOBILES
CPU CENTRAL PROCESSING UNIT
CMOS COMPLEMENTARY METAL-OXIDE SEMI CONDUCTOR
ISP IN-SYSTEM PROGRAMMING
IAP IN-APPLICATION PROGRAMMABLE
TTL TRANSISTOR-TRANSISTOR LOGIC
ETSI EUROPEAN TELECOMMUNICATIONS STANDARDS INSTITUTE
CEPT CONFERENCE OF EUROPEAN POSTS AND TELEGRAPHS
GPRS GENERAL PACKET RADIO SERVICE
RS-232 RECOMMENDED STANDARD-232
UART UNIVERSAL ASYNCHRONOUS RECEIVER-TRANSMITTER
USART UNIVERSAL SYNCHRONOUS ASYNCHRONOUS RECEIVER
TRANSMITTER
PCB PRINTED CIRCUIT BOARD
LCD LIQUID CRYSTAL DISPLAY

AUTOMATIC IRRIGATION AND FLOOD CONTROLLING SYSTEM BY USING GSM
DEPT OF ECE, SREEKAVITHA ENGINEERING COLLEGE Page 1
CHAPTER-1
INTRODUCTION
1.1 EMBEDDED SYSTEMS :
An embedded system is a special-purpose system in which the computer is completely
encapsulated by or dedicated to the device or system it controls. Unlike a general-purpose
computer, such as a personal computer, an embedded system performs one or a few pre-defined
tasks, usually with very specific requirements. Since the system is dedicated to specific tasks,
design engineers can optimize it, reducing the size and cost of the product. Embedded systems
are often mass-produced, benefiting from economies of scale
Personal digital assistants (PDAs) or handheld computers are generally considered
embedded devices because of the nature of their hardware design, even though they are more
expandable in software terms. This line of definition continues to blur as devices expand.
Physically, embedded systems range from portable devices such as digital watches, MP3
players, large stationary installations like traffic lights, factory controllers, or the systems
controlling nuclear power plants.
In terms of complexity embedded systems can range from very simple with a single
microcontroller chip, to very complex with multiple units, peripherals and networks mounted
inside a large chassis or enclosure.
Fig 1.1 real-time system interacts with environment
EMBEDDED
SYSTEM
INPUTS
(Sensors)
OUTPUTS
(Actuators)

1.1.1EXAMPLES OF EMBEDDED SYSTEM
 Automatic teller machines (ATMs)
 Avionics, such as inertial guidance systems, flight control hardware/software and other
integrated systems in aircraft and missiles
 Cellular telephones and telephone switches
 engine controllers and antilock brake controllers for automobiles
 Home automation products, such as thermostats, air conditioners, sprinklers, and security
monitoring systems
 Handheld calculators
 Handheld computers
 Household appliances, including microwave ovens, washing machines, television sets, DVD
players and recorders
 Medical equipment
 Personal digital assistant
 Videogame consoles
 Computer peripherals such as routers and printers
 Industrial controllers for remote machine operation.
1.1.2 CHARACTERISTICS
Embedded systems are designed to do some specific task, rather than be a general-
purpose computer for multiple tasks. Some also have real-time performance constraints that must
be met, for reason such as safety and usability; others may have low or no performance
requirements, allowing the system hardware to be simplified to reduce costs.
An embedded system is not always a separate block - very often it is physically built-in to
the device it is controlling. The software written for embedded systems is often called firmware,
and is stored in read-only memory or Flash memory chips rather than a disk drive. It often runs
with limited computer hardware resources: small or no keyboard, screen, and little memory.

1.2 OBJECTIVE OF THE PROJECT
Actually this project is for our farmers. They work hard and hard not only everyday but
also every night in the field. Because in the day they do their field work and in the night our
farmers have to irrigate the field land at some intervals. So to wake up in the night from a sleep
and then go to field and irrigate the land is to typical for a farmer. There are many disadvantage
of this irrigation system that if a farmer started the irrigation system in the night and he forgot to
switch off the irrigation system again. In this condition the a lot of water goes to wastage and the
crops may get harm or sometimes he forget to switch on the irrigation system then again the
crops get dried due to lack of water. This depends on the type of crops. Lighter weight fruits
always follow slight water deficiency. Sometimes it is harmful to farmers by snakes and insects.
And due to sudden rainfalls the crops get damaged
So to rectify this problem I have brought this is electronic project (GSM Based
Automatic Irrigation System Using 8052 Micro-controller). The system works on SMS feature of
the mobile phone. No hard work need to be done by the farmer. He has to send a SMS to the
irrigation system to switched on as well as off the irrigation system. The irrigation system
switching status will be received to the farmer in his mobile as a SMS. The return sms will be
automatically sent by the irrigation system. This project works on two mode. It depends on the
farmer that what he choose to control the irrigation system. This project is developed based on
EMBEDDED and GSM Technology. When a field is in the dry condition, the sensing logic
senses the state of the field and intimates it to the microcontroller. It in response makes the motor
on. We can know the status of the field by sending a message to the GSM modem which is
placed at the field. Through our mobile we can switch on-off the motor by sending the respective
commands to the kit through the GSM modem. Thus the irrigation motor can be controlled
through our mobiles using GSM technology.
The project deals with When get sudden rainfalls level control of water in field for the
safety purpose the control of water level in field With help of microcontroller. the
microcontroller automatically on the motor when the field is full or reaches the MAX level and
the gate will be open automatically.

CHAPTER-2
BLOCK DIAGRAM DESCRIPTION
BLOCK DIAGRAM:
Fig 2.1 Block diagram
The block diagram and its brief description of the project work are explained in
block wise and this block diagram consists the following blocks.
1. Microcontroller(AT89S52)
2. GSM
3. LCD 16*2
POWER
SUPPLY
LM324
RELAY
WATER PUMP
MOTOR
MOISTURESENSOR
ATPLANTROOTS
LCD DISPLAY
AT
89S52
MOTOR
AS GATE
GSM

4. Power supply
5. LM324
6. Moisture sensor
7. Water pump motor
8. Gear Motor
9. Relay
2.2.1 MICROCONTROLLER SECTION
This section forms the control unit of the whole project. This section basically consists of
a Microcontroller with its associated circuitry like Crystal with capacitors, Reset circuitry, Pull
up resistors (if needed) and so on. The Microcontroller forms the heart of the project because it
controls the devices being interfaced and communicates with the devices according to the
program being written.
2.2.2 POWER SUPPLY SECTION
This section is meant for supplying Power to all the sections mentioned above.It basically
consists of a Transformer to step down the 230V ac to 24 V ac followed by diodes. Here diodes are used
to rectify the ac to dc. After rectification the obtained rippled dc is filtered using a capacitor Filter. A
positive voltage regulator is used to regulate the obtained dc voltage.

CHAPTER 3
DESCRIPTION OF HARDWARE COMPONENTS
3.1 MICRO CONTROLLER:
3.1.1 A BRIEF HISTORY OF 8051:
In 1981, Intel Corporation introduced an 8 bit microcontroller called 8051. This
microcontroller had 128 bytes of RAM, 4K bytes of chip ROM, two timers, one serial port, and
four ports all on a single chip. At the time it was also referred as ―A SYSTEM ON A CHIP‖.
Fig 3.1 Functional block diagram of micro controller

 8031 has 128 bytes of RAM, two timers and 6 interrupts.
 8051 has 4K ROM, 128 bytes of RAM, two timers and 6 interrupts.
 8052 has 8K ROM, 256 bytes of RAM, three timers and 8 interrupts.
Of the three microcontrollers, 8051 is the most preferable. Microcontroller supports both
serial and parallel communication.
In the concerned project 8052 microcontroller is used. Here microcontroller used is
AT89S52, which is manufactured by ATMEL laboratories.
The 8051 is the name of a big family of microcontrollers. The device which we are going
to use along this tutorial is the 'AT89S52' which is a typical 8051 microcontroller manufactured
by Atmel™. Note that this part doesn't aim to explain the functioning of the different
components of a 89S52 microcontroller, but rather to give you a general idea of the organization
of the chip and the available features, which shall be explained in detail along this tutorial.
This figures shows the main features and components that the designer can interact with.
You can notice that the 89S52 has 4 different ports, each one having 8 Input/output lines
providing a total of 32 I/O lines. Those ports can be used to output DATA and orders do other
devices, or to read the state of a sensor, or a switch. Most of the ports of the 89S52 have 'dual
function' meaning that they can be used for two different functions: the fist one is to perform
input/output operations and the second one is used to implement special features of the
microcontroller like counting external pulses, interrupting the execution of the program
according to external events, performing serial data transfer or connecting the chip to a computer
to update the software.
NECESSITY OF MICROCONTROLLERS:
Microprocessors brought the concept of programmable devices and made many
applications of intelligent equipment. Most applications, which do not need large amount of data
and program memory, tended to be costly.
The microprocessor system had to satisfy the data and program requirements so,
sufficient RAM and ROM are used to satisfy most applications .The peripheral control
equipment also had to be satisfied. Therefore, almost all-peripheral chips were used in the
design. Because of these additional peripherals cost will be comparatively high.

An example:
8085 chip needs:
An Address latch for separating address from multiplex address and data.32-KB RAM and
32-KB ROM to be able to satisfy most applications. As also Timer / Counter, Parallel
programmable port, Serial port, and Interrupt controller are needed for its efficient applications.
In comparison a typical Micro controller 8051 chip has all that the 8051 board has except a
reduced memory as follows.
4K bytes of ROM as compared to 32-KB, 128 Bytes of RAM as compared to 32-KB.
Bulky:
On comparing a board full of chips (Microprocessors) with one chip with all components
in it (Microcontroller).
Debugging:
Lots of Microprocessor circuitry and program to debug. In Micro controller there is no
Microprocessor circuitry to debug.
Slower Development time: As we have observed Microprocessors need a lot of debugging at
board level and at program level, where as, Micro controller do not have the excessive circuitry
and the built-in peripheral chips are easier to program for operation.
So peripheral devices like Timer/Counter, Parallel programmable port, Serial
Communication Port, Interrupt controller and so on, which were most often used were integrated
with the Microprocessor to present the Micro controller .RAM and ROM also were integrated in
the same chip. The ROM size was anything from 256 bytes to 32Kb or more. RAM was
optimized to minimum of 64 bytes to 256 bytes or more.
Microprocessor has following instructions to perform:
1. Reading instructions or data from program memory ROM.
2. Interpreting the instruction and executing it.

3. Microprocessor Program is a collection of instructions stored in a Nonvolatile memory.
4. Read Data from I/O device
5. Process the input read, as per the instructions read in program memory.
6. Read or write data to Data memory.
7. Write data to I/O device and output the result of processing to O/P device.
3.1.2 Introduction to AT89S52:
AT89S52:
The AT89S52 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 on-chip Flash allows the program memory to be reprogrammed
in-system or by a conventional nonvolatile memory pro-grammer. By combining a versatile 8-bit
CPU with in-system programmable Flash on a monolithic chip, the Atmel AT89S52 is a
powerful microcontroller, which provides a highly flexible and cost-effective solution to many,
embedded control applications.
The AT89S52 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.
In addition, the AT89S52 is designed with static logic for operation down to zero frequency and
supports two software selectable power saving modes. The Idle Mode stops the CPU while
allowing the RAM, timer/counters, serial port, and interrupt system to continue functioning. The
Power-down mode saves the RAM con-tents but freezes the oscillator, disabling all other chip
functions until the next interrupt or hardware reset.
The system requirements and control specifications clearly rule out the use of 16, 32 or 64
bit micro controllers or microprocessors. Systems using these may be earlier to implement due to
large number of internal features. They are also faster and more reliable but, the above

application is satisfactorily served by 8-bit micro controller. Using an inexpensive 8-bit
Microcontroller will doom the 32-bit product failure in any competitive market place. Coming to
the question of why to use 89S52 of all the 8-bit Microcontroller available in the market the main
answer would be because it has 8kB Flash and 256 bytes of data RAM32 I/O lines, three 16-bit
timer/counters, a Eight-vector two-level interrupt architecture, a full duplex serial port, on-chip
oscillator, and clock circuitry.
In addition, the AT89S52 is designed with static logic for operation down to zero
frequency and supports two software selectable power saving modes. The Idle Mode stops the
CPU while allowing the RAM, timer/counters, serial port, and interrupt system to continue
functioning. The Power Down Mode saves the RAM contents but freezes the oscillator, disabling
all other chip functions until the next hardware reset. The Flash program memory supports both
parallel programming and in Serial In-System Programming (ISP). The 89S52 is also In-
Application Programmable (IAP), allowing the Flash program memory to be reconfigured even
while the application is running.
By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89S52 is
a powerful microcomputer which provides a highly flexible and cost effective solution to many
embedded control applications.
FEATURES:
Compatible with MCS-51 Products
8K Bytes of In-System Reprogrammable Flash Memory
Fully Static Operation: 0 Hz to 33 MHz
Three-level Program Memory Lock
256 x 8-bit Internal RAM
32 Programmable I/O Lines
Three 16-bit Timer/Counters
Eight Interrupt Sources
Programmable Serial Channel
Low-power Idle and Power-down Modes
4.0V to 5.5V Operating Range

Full Duplex UART Serial Channel
Interrupt Recovery from Power-down Mode
Watchdog Timer
Dual Data Pointer
Power-off Flag
Fast Programming Time
Flexible ISP Programming (Byte and Page Mode)
3.1.3 PIN DIAGRAM:
Fig 3.2 Pin diagram of 89S52 micro controller

3.1.4 PIN DESCRIPTION:
The AT89S52 has 40 pins. In these 32 are I/O pins and 8 are special purpose pins. I/O
pins are classified into 4 ports and each port has 8 pins
Port 0:
Port 0 is an 8-bit open drain bidirectional 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 highimpedance
inputs.Port 0 can also be configured to be the multiplexed loworder address/data bus during
accesses to external program and data memory. In this mode, P0 has internal pullups. Port 0 also
receives the code bytes during Flash programming and outputs the code bytes during program
verification.
External pullups are required during program verification.
Port 1:
Port 1 is an 8-bit bidirectional I/O port with internal pullups. 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 pullups and can be used as inputs. As inputs,Port 1 pins that are externally being pulled
low will source current (IIL) because of the internal pullups. In addition, P1.0 and P1.1 can be
configured to be the timer/counter 2 external count input (P1.0/T2) and the timer/counter 2
trigger input (P1.1/T2EX), respectively, as shown in the following table. Port 1 also receives the
low-order address bytes during Flash programming and verification.
Port 2:
Port 2 is an 8-bit bidirectional I/O port with internal pullups.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 pullups and can be used as inputs. As inputs, Port 2 pins that are externally being
pulled low will source current (IIL) because of the internal pullups. Port 2 emits the high-order
address byte during fetches from external program memory and during accesses to external data
memory that use 16-bit addresses (MOVX @ DPTR). In this application, Port 2 uses strong
internal pull-ups when emitting 1s. During accesses to external data memory that use 8-bit
addresses (MOVX @ RI), Port 2 emits the contents of the P2 Special Function Register. Port 2
also receives the high-order address bits and some control signals during Flash programming and
verification.
Port 3:
Port 3 is an 8-bit bidirectional I/O port with internal pullups.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 pullups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled
low will source current (IIL) because of the pullups. Port 3 also serves the functions of various
special features of the AT89S52, as shown in the following table. Port 3 also receives some
control signals for Flash programming and verification.
VCC: Supply voltage.
GND: Ground.
RST:
Reset input. A high on this pin for two machine cycles while the oscillator is running
resets the device. This pin drives High for 96 oscillator periods after the Watchdog times out.
The DISRTO bit in SFR AUXR (address 8EH) can be used to disable this feature. In the default
state of bit DISRTO, the RESET HIGH out feature is enabled. ALE/PROG Address Latch Enable
(ALE) is an output pulse for latching the low byte of the address during accesses to external

memory. This pin is also the program pulse input (PROG) during Flash programming. In normal
operation, ALE is emitted at a constant rate of 1/6 the oscillator frequency and may be used for
external timing or clocking purposes. Note, however, that one ALE pulse is skipped during each
access to external data memory. If desired, ALE operation can be disabled by setting bit 0 of
SFR location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction.
Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the
microcontroller is in external execution mode.
PSEN:
Program Store Enable (PSEN) is the read strobe to external program memory. When the
AT89S52 is executing code from external program memory, PSEN is activated twice each
machine cycle, except that two PSEN activations are skipped during each access to external data
memory.
EA/VPP:
External Access Enable. EA must be strapped to GND in order to enable the device to
fetch code from external program memory locations starting at 0000H up to FFFFH. Note,
however, that if lock bit 1 is programmed, EA will be internally latched on reset. EA should be
strapped to VCC for internal program executions. This pin also receives the 12-volt
programming enable voltage
(VPP) during Flash programming.
XTAL1:
Input to the inverting oscillator amplifier and input to the internal clock operating circuit.
XTAL2:
Output from the inverting oscillator amplifier.
The 8052 Oscillator and Clock:
The heart of the 8051 circuitry that generates the clock pulses by which all the internal all
internal operations are synchronized. Pins XTAL1 And XTAL2 is provided for connecting a resonant
network to form an oscillator. Typically a quartz crystal and capacitors are employed. The crystal
frequency is the basic internal clock frequency of the microcontroller. The manufacturers make 8051
designs that run at specific minimum and maximum frequencies typically 1 to 16 MHz.

Fig3.3 Oscillator and timing circuit
MEMORIES:
Types of memory:
The 8052 have three general types of memory. They are on-chip memory, external Code
memory and external Ram. On-Chip memory refers to physically existing memory on the micro
controller itself. External code memory is the code memory that resides off chip. This is often in
the form of an external EPROM. External RAM is the Ram that resides off chip. This often is in
the form of standard static RAM or flash RAM.

a) Code memory:
Code memory is the memory that holds the actual 8052 programs that is to be run. This
memory is limited to 64K. Code memory may be found on-chip or off-chip. It is possible to have
8K of code memory on-chip and 60K off chip memory simultaneously. If only off-chip memory
is available then there can be 64K of off chip ROM. This is controlled by pin provided as EA
b) Internal RAM:
The 8052 have a bank of 256 bytes of internal RAM. The internal RAM is found on-chip.
So it is the fastest Ram available. And also it is most flexible in terms of reading and writing.
Internal Ram is volatile, so when 8051 is reset, this memory is cleared. 256 bytes of internal
memory are subdivided. The first 32 bytes are divided into 4 register banks. Each bank contains
8 registers. Internal RAM also contains 256 bits, which are addressed from 20h to 2Fh. These
bits are bit addressed i.e. each individual bit of a byte can be addressed by the user. They are
numbered 00h to FFh. The user may make use of these variables with commands such as SETB
and CLR.
Special Function registered memory:
Special function registers are the areas of memory that control specific functionality of
the 8052 micro controller.
a) Accumulator (0E0h):
As its name suggests, it is used to accumulate the results of large no of instructions. It can
hold 8 bit values.
b) B registers (0F0h):
The B register is very similar to accumulator. It may hold 8-bit value. The b register is
only used by MUL AB and DIV AB instructions. In MUL AB the higher byte of the product gets
stored in B register. In div AB the quotient gets stored in B with the remainder in A.

c) Stack pointer (81h):
The stack pointer holds 8-bit value. This is used to indicate where the
next value to be removed from the stack should be taken from. When a value is to be pushed
onto the stack, the 8052 first store the value of SP and then store the value at the resulting
memory location. When a value is to be popped from the stack, the 8052 returns the value from
the memory location indicated by SP and then decrements the value of SP.
d) Data pointer :
The SFRs DPL and DPH work together work together to represent a 16-bit value called
the data pointer. The data pointer is used in operations regarding external RAM and some
instructions code memory. It is a 16-bit SFR and also an addressable SFR.
e) Program counter:
The program counter is a 16 bit register, which contains the 2 byte address, which tells
the 8052 where the next instruction to execute to be found in memory. When the 8052 is
initialized PC starts at 0000h. And is incremented each time an instruction is executes. It is not
addressable SFR.
f) PCON (Power control, 87h):
The power control SFR is used to control the 8051’s power control modes. Certain
operation modes of the 8051 allow the 8051 to go into a type of ―sleep mode‖ which consumes
much lee power.
g) TCON (timer control, 88h):

The timer control SFR is used to configure and modify the way in which the 8051’s two
timers operate. This SFR controls whether each of the two timers is running or stopped and
contains a flag to indicate that each timer has overflowed. Additionally, some non-timer related
bits are located in TCON SFR. These bits are used to configure the way in which the external
interrupt flags are activated, which are set when an external interrupt occurs.
h) TMOD (Timer Mode, 89h):
The timer mode SFR is used to configure the mode of operation of each of the two
timers. Using this SFR your program may configure each timer to be a 16-bit timer, or 13 bit
timer, 8-bit auto reload timer, or two separate timers. Additionally you may configure the timers
to only count when an external pin is activated or to count ―events‖ that are indicated on an
external pin.
i) TO (Timer 0 low/high, address 8A/8C h):
These two SFRs taken together represent timer 0. Their exact behavior depends on how
the timer is configured in the TMOD SFR; however, these timers always count up. What is
configurable is how and when they increment in value.
j) T1 (Timer 1 Low/High, address 8B/ 8D h):

These two SFRs, taken together, represent timer 1. Their exact behavior depends on how
the timer is configured in the TMOD SFR; however, these timers always count up..
k) P0 (Port 0, address 90h, bit addressable):
This is port 0 latch. Each bit of this SFR corresponds to one of the pins on a micro
controller. Any data to be outputted to port 0 is first written on P0 register. For e.g., bit 0 of port
0 is pin P0.0, bit 7 is pin p0.7. Writing a value of 1 to a bit of this SFR will send a high level on
the corresponding I/O pin whereas a value of 0 will bring it to low level.
l) P1 (port 1, address 90h, bit addressable):
This is port latch1. Each bit of this SFR corresponds to one of the pins on a micro
0 is pin P1.0, bit 7 is pin P1.7. Writing a value of 1 to a bit of this SFR will send a high level on
the corresponding I/O pin whereas a value of 0 will bring it to low level
m) P2 (port 2, address 0A0h, bit addressable):
This is a port latch2. Each bit of this SFR corresponds to one of the pins on a micro
n) P3 (port 3, address B0h, bit addressable) :
This is a port latch3. Each bit of this SFR corresponds to one of the pins on a micro
o) IE (interrupt enable, 0A8h):
The Interrupt Enable SFR is used to enable and disable specific interrupts. The low 7 bits
of the SFR are used to enable/disable the specific interrupts, where the MSB bit is used to enable
or disable all the interrupts. Thus, if the high bit of IE is 0 all interrupts are disabled regardless of
whether an individual interrupt is enabled by setting a lower bit.

p) IP (Interrupt Priority, 0B8h):
The interrupt priority SFR is used to specify the relative priority of each interrupt. On
8051, an interrupt maybe either low or high priority. An interrupt may interrupt interrupts. For
e.g., if we configure all interrupts as low priority other than serial interrupt. The serial interrupt
always interrupts the system, even if another interrupt is currently executing. However, if a serial
interrupt is executing no other interrupt will be able to interrupt the serial interrupt routine since
the serial interrupt routine has the highest priority.
q) PSW (Program Status Word, 0D0h):
The program Status Word is used to store a number of important bits that are set and
cleared by 8052 instructions. The PSW SFR contains the carry flag, the auxiliary carry flag, the
parity flag and the overflow flag. Additionally, it also contains the register bank select flags,
which are used to select, which of the ―R‖ register banks currently in use.
r) SBUF (Serial Buffer, 99h):
SBUF is used to hold data in serial communication. It is physically two registers. One is
writing only and is used to hold data to be transmitted out of 8052 via TXD. The other is read
only and holds received data from external sources via RXD. Both mutually exclusive registers
use address 99h.
SERIAL DATA INPUT/OUTPUT
Onecost –effective way to communicate with other computers is to send and receive data bits
serially. The 89C51 has a serial data communication circuit but uses register SBUF to hold data. Register
SCON controls data communication and register PCON controls data rates and pins RXD (P3.0) and TXD

(P3.1) connect to the serial data network. SBUF is physically two registers. One is write only and used to
hold data to be transmitted out of the micro controller using TXD. The other is read only and hold-
receive data fromexternal sources using RXD.
INTERRUPTS
Interrupts may be generated by the internal chip operations or provided by external
sources. Five interrupts are provided in the 89C51.Internal operations timer flag0, timer flag1
and the serial port generate three of these automatically interrupt (R1 or T1). Two interrupts are
triggered by external signals provided by circuitry which are connected to pins INT0 and INT1.
3.2 LM324:
LM324 is a 14pin IC consisting of four independent operational amplifiers (op-amps)
compensated in a single package. Op-amps are high gain electronic voltage amplifier with
differential input and, usually, a single-ended output. The output voltage is many times higher
than the voltage difference between input terminals of an op-amp.
These op-amps are operated by a single power supply LM324 and need for a dual supply
is eliminated. They can be used as amplifiers, comparators, oscillators, rectifiers etc. The
conventional op-amp applications can be more easily implemented with LM324.
Fig 3.4: Pin diagram of LM-324

Application areas include transducer amplifiers, DC gain blocks and all the conventional op amp
circuits which now can be more easily implemented in single power supply systems. For example, the
LM124 series can be directly operated off of the standard +5V power supply voltage which is used in
digital systems and will easily provide the required interface electronics without requiring the additional
±15V power supplies.
Unique Characteristics:
In the linear mode the input common-mode voltage range includes ground and the output voltage
can also swing to ground, even though operated from only a single power supply voltage the unity gain
cross frequency is temperature compensated. The input bias current is also temperature compensated
Advantages
 Eliminates need for dual supplies four internally compensated op amps in a single package
 Allows directly sensing near GND and VOUT also goes to GND Compatible with all forms of
logic Power drain suitable for battery operation.
Features:
Internally frequency compensated for unity gain Large DC voltage gain 100 Db Wide and width
(unity gain) 1 MHz (temperature compensated) Wide power supply range:
Single supply 3V to 32V or dual supplies ±1.5V to ±16V Very low supply current drain (700 μA)—
essentially. Independent of supply voltage Low input biasing current 45 nA (temperature compensated)
Low input offset voltage 2 mV and offset current: 5 nA Input common-mode voltage range includes
ground Differential input voltage range equal to the power supply voltage
Large output voltage swing 0V to V+ − 1.5V.
SENSING LOGIC :
In this section we will discuss how the sensing action takes place in the project. In this we use
the simple principle of conduction between two wires through a medium. The logic consists of two
wires one with the 5V supply and the other one was the ground. When there is water in the field, a
medium is being established between the wires and the conduction will take place between the wires
and the voltage at the microcontroller will go low indicating the wet condition of the field. In this wet
condition the mpotor will be in off position.

If there is no water in the field, the re is no conduction between the wires and the voltage at
the microcontroller will go high indicating the dry condition of the field and the motor will be made on
position.
We can not only know the status of the field but also control the motor action from our home
itself by using the GSM technology. The following are the commands or messages to be passed to the
GSM modem from our user moblie for the above mentioned operations.
 To know the status of the field, GIFMOD
 To make the motor off postion, we use MTR OF
 To make the motor on.. MTR ON
3.3 GSM MODEM:
Definitions
The words, ―Mobile Station‖ (MS) or ―Mobile Equipment‖ (ME) are used for mobile
terminals Supporting GSM services.
A call from a GSM mobile station to the PSTN is called a ―mobile originated call‖
(MOC) or ―Outgoing call‖, and a call from a fixed network to a GSM mobile station is called a
―Mobile Terminated call‖ (MTC) or ―incoming call‖.
Fig 3.5: GSM modem

What is GSM?
GSM (Global System for Mobile communications) is an open, digital cellular technology
used for transmitting mobile voice and data services.
What does GSM offer?
GSM supports voice calls and data transfer speeds of up to 9.6 kbit/s, together with the
transmission of SMS (Short Message Service).
GSM operates in the 900MHz and 1.8GHz bands in Europe and the 1.9GHz and 850MHz
bands in the US. The 850MHz band is also used for GSM and 3G in Australia, Canada and many
South American countries. By having harmonised spectrum across most of the globe, GSM’s
international roaming capability allows users to access the same services when travelling abroad
as at home. This gives consumers seamless and same number connectivity in more than 218
countries.
Terrestrial GSM networks now cover more than 80% of the world’s population. GSM
satellite roaming has also extended service access to areas where terrestrial coverage is not
available
HISTORY
In 1980’s the analog cellular telephone systems were growing rapidly all throughout
Europe, France and Germany. Each country defined its own protocols and frequencies to work
on. For example UK used the Total Access Communication System (TACS), USA used the
AMPS technology and Germany used the C-netz technology. None of these systems were
interoperable and also they were analog in nature.
In 1982 the Conference of European Posts and Telegraphs (CEPT) formed a study group
called the GROUPE SPECIAL MOBILE (GSM) The main area this focused on was to get the
cellular system working throughout the world, and ISDN compatibility with the ability to
incorporate any future enhancements. In 1989 the GSM transferred the work to the European
Telecommunications Standards Institute (ETSI.) the ETS defined all the standards used in GSM.

Some of the technical specifications of GSM are listed below –
Multiple Access Method TDMA / FDMA
Uplink frequencies (MHz) 933-960 (basic GSM)
Downlink frequencies (MHz) 890-915 (basic GSM)
Duplexing FDD
Channel spacing, kHz 200
Modulation GMSK
Portable TX power, maximum / average (mW) 1000 / 125
Power control, handset and BSS Yes
Speech coding and rate (kbps) RPE-LTP / 13
Speech Channels per RF channel: 8
Channel rate (kbps) 270.833
Channel coding Rate 1/2 convolutional
Frame duration (ms) 4.615
Table 3.1: Technical specifications of GSM
GSM was originally defined for the 900 Mhz range but after some time even the 1800
Mhz range was used for cellular technology. The 1800 MHz range has its architecture and
specifications almost same to that of the 900 Mhz GSM technology but building the Mobile
exchanges is easier and the high frequency Synergy effects add to the advantages of the 1800
Mhz range.
3.3.2 ARCITECTURE AND BUILDIGN BLOCKS :
GSM is mainly built on 3 building blocks. (Ref Fig. 2)
 GSM Radio Network – This is concerned with the signaling of the system. Hand-overs
occur in the radio network. Each BTS is allocated a set of frequency channels.
 GSM Mobile switching Network – This network is concerned with the storage of data
required for routing and service provision.

 GSM Operation and Maintenance – The task carried out by it include Administration and
commercial operation , Security management, Network configuration, operation,
performance management and maintenance tasks.
3.3.3 SIGNALLING SCHEMES AND CIPHERING CODES USED :
GSM is digital but voice is inherently analog. So the analog signal has to be converted
and then transmitted. The coding scheme used by GSM is RPE-LTP (Rectangular pulse
Excitation – Long Term Prediction)
Fig.3.6 Transmitter for the voice signal
Fig.3.7 Receiver for the Voice signal
The voice signal is sampled at 8000 bits/sec and is quantized to get a 13 bit resolution
corresponding to a bit rate of 104 kbits/sec. This signal is given to a speech coder (codec) that
compresses this speech into a source-coded speech signal of 260 bit blocks at a bit rate of 13

kbit/sec. The codec achieves a compression ratio of 1:8. The coder also has a Voice activity
detector (VAD) and comfort noise synthesizer. The VAD decides whether the current speech
frame contains speech or pause, this is turn is used to decide whether to turn on or off the
transmitter under the control of the Discontinuous Transmission (DTX). This transmission takes
advantage of the fact that during a phone conversation both the parties rarely speak at the same
time. Thus the DTX helps in reducing the power consumption and prolonging battery life. The
missing speech frames are replaced by synthetic background noise generated by the comfort
noise synthesize in a Silence Descriptor (SID) frame. Suppose a loss off speech frame occurs due
to noisy transmission and it cannot be corrected by the channel coding protection mechanism
then the decoder flags such frames with a bad frame indicator (BFI) In such a case the speech
frame is discarded and using a technique called error concealment which calculates the next
frame based on the previous frame.
3.3.4 GSM Sim 900A:
GSM/GPRS Modem-RS232 is built with Dual Band GSM/GPRS engine- SIM900A,
works on frequencies 900/ 1800 MHz. The Modem is coming with RS232 interface, which
allows you connect PC as well as microcontroller with RS232 Chip(MAX232). The baud rate is
configurable from 9600-115200 through AT command. The GSM/GPRS Modem is having
internal TCP/IP stack to enable you to connect with internet via GPRS. It is suitable for SMS,
Voice as well as DATA transfer application in M2M interface. The onboard Regulated Power
supply allows you to connect wide range unregulated power supply . Using this modem, you can
make audio calls, SMS, Read SMS, attend the incoming calls and internet ect through simple AT
commands.

Fig 3.8: Diagram of SIM 900A
Features:
 Dual band GSM/GPRS 900/1800MHz.
 Configurable baud rate.
 SIM card holder.
 Built in network status LED.
 Inbuilt powerful TCP/IP protocol stack for internet data transfer over GPRS.
Applications:
 Access control devices.
 Supply chain management

Specifications:
Parameter Value
Operating voltage +12v DC
weight <140g
Pin Specification:
Pin Name Details
1 GND Power supply ground
2 tx transmitter
3 rx receiver
4 Line_r & Line_l Line input
5 Spk_p & spk_n Speaker positive & negative
6 Mic_p & mic_n Mic positive & negative
7 DTR Data terminal ready
8 CTS Clear to send
9 RTS Request to send
Table 3.2: Pin Description of SIM900A
Working:
Unlike mobile phones, a GSM modem doesn’t have a keypa interact with. It just accepts
certain commands through a serial interface and acknowledges for those. These commands are
called as AT commands. There are a list of AT commands to instruct the modem to perform its
functions. Every command starts with "AT". That’s why stands for attention.
In our simple project, the program waits for the mobile number to be entered through
the keyboard. When a ten digit mobile number is provided, the program instructs the modem to
send the text message using a sequence of AT commands
3.4 MAX 232 AND RS-232:
3.4.1 RS232 STANDARD:
RS denotes ―Recommended Standard‖ and refers to official standards of Electronics
Industries Association. RS-232 is the most known serial port used in transmitting the data in

communication and interface. Even though serial port is harder to program than the parallel port, this is
the most effective method in which the data transmission requires less that yields to the less cost. Serial
RS-232 communication works with voltages (-15V ... -3V for high [sic]) and +3V ... +15V for low [sic])
which are not compatible with normal computer logic voltages.
The maximum RS-232 signal levels are far too high for computer logic electronics, and the
negative RS-232 voltage for high cant be applicable at all by computer logic. Therefore, to receive serial
data from an RS-232 interface the voltage has to be reduced, and the low and high voltage level
inverted. In the other direction (sending data from some logic over RS-232) the low logic voltage has to
be bumped up‖, and a negative voltage has to be generated, too.
Independent channels are established for two-way (full-duplex) communications. The RS232
signals are represented by voltage levels with respect to a system common (power I logic ground). The
―idle‖ state (MARK) has the signal level negative with respect to common, and the ―active‖ state
(SPACE) has the signal level positive with respect to common. RS232 has numerous handshaking lines
(primarily used with modems), and also specifies a communications protocol.
The RS-232 interface presupposes a common ground between the DTE and DCE. This is a
reasonable assumption when a short cable connects the DTE to the DCE, but with longer lines and
connections between devices that may be on different electrical busses with different grounds, this may
not be true.
RS232 data is bi-polar.... +3 to +12 volts indicate an ―ON or 0-state (SPACE) condition’s while
A -3 to -12 volts indicates an ―OFF‖ 1-state (MARK) condition.... Modern computer equipment ignores
the negative level and accepts a zero voltage level as the ―OFF‖ state. In fact, the ―ON‖ state may be
achieved with lesser positive potential.
The output signal level usually swings between +12V and -12V. The ―dead area‖ between +3v
and -3v is designed to absorb line noise. In the various RS-232-like definitions this dead area may vary.
This can cause problems when using pin powered widgets - line drivers, converters, modems etc.
These types of units need enough voltage & current to power them self’s up. Typical URART (the RS-
232 I/O chip) allows up to 50ma per output pin - so if the device needs 70ma to run we would need to

use at least 2 pins for power. The number of output lines, the type of interface driver IC, and the state of
the output lines are important considerations.
The types of driver ICs used in serial ports can be divided into three general categories:
 Drivers which require plus (+) and minus (-) voltage power supplies such as the 1488 series of interface
integrated circuits. (Most desktop and tower PCs use this type of driver.)
 Low power drivers which require one +5 volt power supply. This type of driver has an internal charge
pump for voltage conversion. (Many industrial microprocessor controls use this type of driver.)
 Low voltage (3.3 v) and low power drivers which meet the EIA-562 Standard. (Used on notebooks and
laptops.)
Data is transmitted and received on pins 2 and 3 respectively. Data Set Ready (DSR) is an
indication from the Data Set (i.e., the modem or DSU/CSU) that it is on. Similarly, DTR indicates to the
Data Set that the DTE is on. Data Carrier Detect (DCD) indicates that a good carrier is being received
from the remote modem.
Pins 4 RTS (Request to Send - from the transmitting computer) and 5 CTS (Clear to Send - from
the Data set) are used to control. In most Asynchronous situations, RTS and CTS are constantly on
throughout the communication session. However where the DTE is connected to a multipoint line. RTS
is used to turn carrier on the modem on and off. On a multipoint line, it’s imperative that only one
station is transmitting at a time (because they share the return phone pair). When a station wants to
transmit, it raises RTS. The modem turns on carrier, typically waits a few milliseconds for carrier to
stabilize, and then raises CTS. The DTE transmits when it sees CTS up. When the station has finished
its transmission, it drops RTS and the modem drops CTS and carrier together.
Clock signals (pins 15, 17, & 24) are only used for synchro/.
nous communications. The modem or DSU extracts the clock from the data stream and provides a
steady clock signal to the DTE. The transmit and receive clock signals do not have to be the same, or
even at the same baud rate.

To allow compatibility among data communication equipment made by various Manufacturers,
an interfacing standard called RS232 was set by the Electronics and Industries Association in
1960.Today, RS232 is the most widely used serial I/O interfacing standard. RS232 standard is not TTL
compatible; therefore it requires a line driver such as MAX232chip to convert RS232 voltage levels to
TTL levels and vice versa. One advantage of the MAX 232 chip is that it uses +5V power source that
has same source voltage as that of 8052.
RS232 Logic Level Converter TTL Logic
Figure 3.9: Block Diagram of RS232
3.4.2 MAX 232:
The RS 232 is not compatible with micro controllers, so a line driver converts the RS 232's
signals to TTL voltage levels. It is a 16 pin DIP package.
The MAX232 is a dual driver/receiver that includes a capacitive voltage generator to supply
TIA/EIA-232-F voltage levels from a single 5-V supply. Each receiver converts TIA/EIA-232-F inputs
to 5-V TTL/CMOS levels. These receivers have a typical threshold of 1.3 V, a typical hysteresis of 0.5
V, and can accept ±30-V inputs. Each driver converts TTL/CMOS input levels into TIA/EIA-232-F
levels.
S
y
s
t
e
m
Max
232
89C
5
1

Figure 3.10: MAX 232 IC
Table 3.3: Pin Description of MAX232

Registers Used For Communication
SBUF Register
SBUF is an 8-bit register used solely for serial communication in the 8051. For byte of data to be
transferred via TxD line, it must be placed in SBUF register. SBUF also holds the byte of data when it is
received by the 8051’s RxD line.
The moment a byte is written into SBUF, it is framed with the start and stop bits and transferred
serially via TxD line. Similarly when bits r received serially via RxD, the 8051 defames it by
eliminating a byte out of the received, and then placing it in the SBUF.
RS-232 WAVEFORM
TTL/CMOS Serial Logic Waveform
The diagram above shows the expected waveform from the UART when using the
common 8N1 format. 8N1 signifies 8 Data bits, No Parity and 1 Stop Bit. The RS-232 line, when
idle is in the Mark State (Logic 1). A transmission starts with a start bit which is (Logic 0). Then
each bit is sent down the line, one at a time. The LSB (Least Significant Bit) is sent first. A Stop
Bit (Logic 1) is then appended to the signal to make up the transmission.
The data sent using this method, is said to be framed. That is the data is framed
between a Start and Stop Bit.
RS-232 Voltage levels
 +3 to +25 volts to signify a "Space" (Logic 0)
 -3 to -25 volts for a "Mark" (logic 1).
 Any voltage in between these regions (i.e. between +3 and -3 Volts) is undefined.
The data byte is always transmitted least-significant-bit first.

The bits are transmitted at specific time intervals determined by the baud rate of the
serial signal. This is the signal present on the RS-232 Port of your computer, shown below.
RS-232 Logic Waveform
3.4.3 PC INTERFACE SECTION:
Fig 3.11 MAX-232 Connecter diagram

The above shown connector known as 9-pin, D-type male connector is used for RS232
connections. The pin description is given in the following table.
Pin number Common
Name
RS232
name
Description Signal
direction
1 /CD CF Receivedline signal detector IN
2 RXD BB Received data IN
3 TXD BA Transmitted data OUT
4 /DTR CD Data terminal ready OUT
5 GND AB Signal ground --
6 /DSR CC Data set ready IN
7 /RTS CA Request to send OUT
8 /CTS CB Clear to send IN
9 -- CE Ring indicator IN
Table 3.4: MAX 232 pin details
We cannot simply connect our system to this terminal without providing proper hand
shaking signal. For communicating with RS-232 type equipment, the /RTS of the connector is
simply looped into the /CTS, so /CTS will automatically be asserted when /RTS is asserted
internally. Similarly the /DTR is looped into /DSR and /CD, so when PC asserts its /DTR output
the /DSR and /CD inputs are automatically be asserted. These connections do not provide for any
hardware hand shaking. They are necessary to get the PC and our system talk each other. The
connection diagram is shown below.

Fig 3.12 RS-232 Interface diagram
Serial communication:
When a processor communicates with the outside world, it provides data in byte sized
chunks. Computers transfer data in two ways: parallel and serial. In parallel data transfers, often
more lines are used to transfer data to a device and 8 bit data path is expensive. The serial
communication transfer uses only a single data line instead of the 8 bit data line of parallel
communication which makes the data transfer not only cheaper but also makes it possible for
two computers located in two different cities to communicate over telephone.
Serial data communication uses two methods, asynchronous and synchronous. The
synchronous method transfers data at a time while the asynchronous transfers a single byte at a
time. There are some special IC chips made by many manufacturers for data communications.
These chips are commonly referred to as UART (universal asynchronous receiver-transmitter)
and USART (universal synchronous asynchronous receiver transmitter). The AT89C51 chip has
a built in UART.
In asynchronous method, each character is placed between start and stop bits. This
is called framing. In data framing of asynchronous communications, the data, such as ASCII
characters, are packed in between a start and stop bit. We have a total of 10 bits for a character: 8
bits for the ASCII code and 1 bit each for the start and stop bits. The rate of serial data transfer
communication is stated in bps or it can be called as baud rate.

To allow the compatibility among data communication equipment made by various
manufacturers, and interfacing standard called RS232 was set by the Electronics industries
Association in 1960. Today RS232 is the most widely used I/O interfacing standard. This
standard is used in PCs and numerous types of equipment. However, since the standard was set
long before the advent of the TTL logic family, its input and output voltage levels are not TTL
compatible. In RS232, a 1 bit is represented by -3 to -25V, while a 0 bit is represented +3 to +25
V, making -3 to +3 undefined. For this reason, to connect any RS232 to a microcontroller system
we must use voltage converters such as MAX232 to connect the TTL logic levels to RS232
voltage levels and vice versa. MAX232 ICs are commonly referred to as line drivers.
The RS232 cables are generally referred to as DB-9 connector. In labeling, DB-9P
refers to the plug connector (male) and DB-9S is for the socket connector (female). The simplest
connection between a PC and microcontroller requires a minimum of three pin, TXD, RXD, and
ground. Many of the pins of the RS232 connector are used for handshaking signals. They are
bypassed since they are not supported by the UART chip.
IBM PC/ compatible computers based on x86(8086, 80286, 386, 486 and Pentium)
microprocessors normally have two COM ports. Both COM ports have RS232 type connectors.
Many PCs use one each of the DB-25 and DB-9 RS232 connectors. The COM ports are
designated as COM1 and COM2. We can connect the serial port to the COM 2 port of a PC for
serial communication experiments. We use a DB9 connector in our arrangement.

3.5 GEAR MOTOR:
What Is a Gear Motor?
Gear motors are complete motive force systems consisting of an electric motor
and a reduction gear train integrated into one easy-to-mount and -configure package. This greatly
reduces the complexity and cost of designing and constructing power tools, machines and
appliances calling for high torque at relatively low shaft speed or RPM. Gear motors allow the
use of economical low-horsepower motors to provide great motive force at low speed such as in
lifts, winches, medical tables, jacks and robotics. They can be large enough to lift a building or
small enough to drive a tiny clock.
.
Fig 3.13: 12V High Torque DC GEAR MOTOR

Operation Principle:
Most synchronous AC electric motors have output ranges of from 1,200 to 3,600 revolutions per
minute. They also have both normal speed and stall-speed torque specifications. The reduction
gear trains used in gear
motors are designed to reduce the output speed while increasing the torque. The increase in
torque is inversely proportional to the reduction in speed. Reduction gearing allows small electric
motors to move large driven loads, although more slowly than larger electric motors. Reduction
gears consist of a small gear driving a larger gear. There may be several sets of these reduction
gear sets in a reduction gear box.
Toothed wheel that transmits the turning movement of one shaft to another shaft.
Gear wheels may be used in pairs or in threes if both shafts are to turn in the same direction. The
gear ratio – the ratio of the number of teeth on the two wheels – determines the torque ratio, the
turning force on the output shaft compared with the turning force on the input shaft. The ratio of
the angular velocities of the shafts is the inverse of the gear ratio.
The common type of gear for parallel shafts is the spur gear, with straight teeth parallel to the
shaft axis. The helical gear has teeth cut along sections of a helix or corkscrew shape; the double
form of the helix gear is the most efficient for energy transfer. Bevel gears, with tapering teeth
set on the base of a cone, are used to connect intersecting shafts.

The toothed and interlocking wheels which make up a typical gear movement.
Gear ratio is calculated by dividing the number of teeth on the driver gear by the number of teeth
on the driven gear (gear ratio = driver/driven); the idler gears are ignored. Idler gears change the
direction of rotation but do not affect speed. A high driven to driver ratio (middle) is a speed-
reducing ratio.
Different gears are used to perform different engineering functions depending on the change in
direction of motion that is needed. Rack and pinion gears are the commonest gears and are used
in car steering mechanics.
Speed Reduction
 Sometimes the goal of using a gear motor is to reduce the rotating shaft speed of a motor
in the device being driven, such as in a small electric clock where the tiny synchronous
motor may be spinning at 1,200 rpm but is reduced to one rpm to drive the second hand,
and further reduced in the clock mechanism to drive the minute and hour hands. Here the
amount of driving force is irrelevant as long as it is sufficient to overcome the frictional
effects of the clock mechanism.
Torque Multiplication
 Another goal achievable with a gear motor is to use a small motor to generate a very
large force albeit at a low speed. These applications include the lifting mechanisms on
hospital beds, power recliners, and heavy machine lifts where the great force at low speed
is the goal.
Motor Varieties
 Most industrial gear motors are AC-powered, fixed-speed devices, although there are
fixed-gear-ratio, variable-speed motors that provide a greater degree of control. DC gear

motors are used primarily in automotive applications such as power winches on trucks,
windshield wiper motors and power seat or power window motors.
Many Applications
 What power can openers, garage door openers, stair lifts, rotisserie motors, timer cycle
knobs on washing machines, power drills, cake mixers and electromechanical clocks
have in common is that they all use various integrations of gear motors to derive a large
force from a relatively small electric motor at a manageable speed. In industry, gear
motor applications in jacks, cranes, lifts, clamping, robotics, conveyance and mixing are
too numerous to count.
3.6 RELAY:
3.6.1 Overview:
A relay is an electrically operated switch. Current flowing through the coil of the relay
creates a magnetic field which attracts a lever and changes the switch contacts. The coil current
can be ON or OFF so relays have two switch position and they are double throw (changeover)
switches.
Relays allow one circuit to switch a second circuit which can be completely separate
from the first. For example a low voltage battery circuit can use a relay to switch a 230V AC
mains circuit. There is no electrical connection inside the relay between the two circuits; the link
is magnetic and mechanical.
The coil of a relay passes a relatively large current, typically 30mA for a 12V relay, but it
can be as much as 100mA for relays designed to operate from lower voltages. Most ICs (chips)
can not provide this current and a transistor is usually used to amplify the small IC current to the
larger value required for the relay coil. The maximum output current for the popular 555 timer
IC is 200mA so these devices can supply relay coils directly without amplification.
Relays are usually SPDT or DPDT but they can have many more sets of switch contacts,
for example relay with 4 sets of changeover contacts are readily available. Most relays are

designed for PCB mounting but you can solder wires directly to the pins providing you take care
to avoid melting the plastic case of the relay.
The supplier's catalogue should show you the relay's connection. The coil will be obvious
and it may be connected either way round. Relay coils produce brief high voltage 'spikes' when
they are switched off and this can destroy transistors and ICs in the circuit. To prevent damage
you must connect a protection diode across the relay coil.
The relay’s switch connections are usually contains COM, NC and NO.
COM = Common, always connect to this; it is the moving part of the switch.
NC = Normally Closed, COM is connected to this when the relay coil is off.
NO = Normally Open, COM is connected to this when the relay coil is on.
Connect to COM and NO if you want the switched circuit to be on when the relay coil is on.
Connect to COM and NC if you want the switched circuit to be on when the relay coil is off.
Most relays are SPDT or DPDT which are often described as "single pole changeover" (SPCO)
Or "double pole changeover"(DPCO).
This is a Single Pole Double Throw relay. Current will flow between the movable contact
and one fixed contact when the coil is energized and between the movable contact and the
alternate fixed contact when the relay coil is energized. The most commonly used relay in car
audio, the Bosch relay, is a SPDT relay..

This relay is a Double Pole Double Throw relay. It operates like the SPDT relay but has
twice as many contacts. There are two completely isolated sets of contacts.
3.6.2 Relay Construction:
Relays are amazingly simple devices. There are four parts in every relay:
Electromagnet
Armature that can be attracted by the electromagnet
Spring
Set of electrical contacts
A relay consists of two separate and completely independent circuits. The first is at
the bottom and drives the electromagnet. In this circuit, a switch is controlling power to the
electromagnet. When the switch is on, the electromagnet is on, and it attracts the armature. The
armature is acting as a switch in the second circuit. When the electromagnet is energized, the
armature completes the second circuit and the light is on. When the electromagnet is not
energized, the spring pulls the armature away and the circuit is not complete. In that case, the
light is dark.
When you purchase relays, you generally have control over several variables:
 The voltage and current that is needed to activate the armature
 The maximum voltage and current that can run through the armature and the armature
contacts
 The number of armatures (generally one or two)

 The number of contacts for the armature (generally one or two -- the relay shown here
has two, one of which is unused)
 Whether the contact (if only one contact is provided) is normally open (NO) or normally
closed (NC)
3.6.3 Relay Applications:
In general, the point of a relay is to use a small amount of power in the electromagnet
coming, say, from a small dashboard switch or a low-power electronic circuit -- to move an
armature that is able to switch a much larger amount of power. For example, you might want the
electromagnet to energize using 5 volts and 50 milliamps (250 mill watts), while the armature
can support 120V AC at 2 amps (240 watts).
Relays are quite common in home appliances where there is an electronic control turning
on something like a motor or a light. They are also common in cars, where the 12V supply
voltage means that just about everything needs a large amount of current. In later model cars,
manufacturers have started combining relay panels into the fuse box to make maintenance easier.
In places where a large amount of power needs to be switched, relays are often cascaded.
In this case, a small relay switches the power needed to drive a much larger relay, and that
second relay switches the power to drive the load.
Relays can also be used to implement Boolean logic.
3.6.4 Advantages of Relay:
 Relays can switch AC and DC, transistors can only switch DC.
 Relays can switch high voltages, transistors cannot.
 Relays are a better choice for switching large currents (> 5A).
 Relays can switch many contacts at once.

3.7 LIQUID CRYSTAL DISPLAY (LCD):
To display interactive messages we are using LCD Module. We examine an intelligent
LCD display of two lines,16 characters per line that is interfaced to the controllers. The protocol
(handshaking) for the display is as shown. Whereas D0 to D7th bit is the Data lines, RS, RW and
EN pins are the control pins and remaining pins are +5V, -5V and GND to provide supply.
Where RS is the Register Select, RW is the Read Write and EN is the Enable pin.
The display contains two internal byte-wide registers, one for commands (RS=0) and the
second for characters to be displayed (RS=1). It also contains a user-programmed RAM area (the
character RAM) that can be programmed to generate any desired character that can be formed
using a dot matrix. To distinguish between these two data areas, the hex command byte 80 will
be used to signify that the display RAM address 00h will be chosen.Port1 is used to furnish the
command or data type, and ports 3.2 to3.4 furnish register select and read/write levels.
The display takes varying amounts of time to accomplish the functions as listed. LCD bit 7 is
monitored for logic high (busy) to ensure the display is overwritten.
Liquid Crystal Display also called as LCD is very helpful in providing user interface as well as
for debugging purpose. The most common type of LCD controller is HITACHI 44780 which
provides a simple interface between the controller & an LCD. These LCD's are very simple to
interface with the controller as well as are cost effective.
2x16 Line Alphanumeric LCD Display
Fig 3.14 (a)LCD Display (b) LCD Data R/W waveform

The most commonly used ALPHANUMERIC displays are 1x16 (Single Line & 16
characters), 2x16 (Double Line & 16 character per line) & 4x20 (four lines & Twenty characters
per line).
The LCD requires 3 control lines (RS, R/W & EN) & 8 (or 4) data lines. The number on data
lines depends on the mode of operation. If operated in 8-bit mode then 8 data lines + 3 control
lines i.e. total 11 lines are required. And if operated in 4-bit mode then 4 data lines + 3 control
lines i.e. 7 lines are required. How do we decide which mode to use? It’s simple if you have
sufficient data lines you can go for 8 bit mode & if there is a time constrain i.e. display should be
faster then we have to use 8-bit mode because basically 4-bit mode takes twice as more time as
compared to 8-bit mode.
Pin Symbol Function
1 Vss Ground
2 Vdd Supply Voltage
3 Vo Contrast Setting
4 RS Register Select
5 R/W Read/Write Select
6 En Chip Enable Signal
7-14 DB0-DB7 Data Lines
15 A/Vee Gnd for the backlight
16 K Vcc for backlight
Table 3.5 LCD pin details
When RS is low (0), the data is to be treated as a command. When RS is high (1), the
data being sent is considered as text data which should be displayed on the screen.
When R/W is low (0), the information on the data bus is being written to the LCD. When
RW is high (1), the program is effectively reading from the LCD. Most of the times there is no
need to read from the LCD so this line can directly be connected to Gnd thus saving one
controller line.
The ENABLE pin is used to latch the data present on the data pins. A HIGH - LOW signal is
required to latch the data. The LCD interprets and executes our command at the instant the EN
line is brought low. If you never bring EN low, your instruction will never be executed.

Fig 3.15: Interfacing of LED
COMMANDS USED IN LCD:
Table 3.6: Commands of LCD
3.8 POWER SUPPLY:
All digital circuits require regulated power supply. In this article we are going to learn
how to get a regulated positive supply from the mains supply.

Figure 3.16 Basic block diagram of a fixed regulated power supply
Figure 3.16 shows the basic block diagram of a fixed regulated power supply. Let us go through
each block.
Transformer:
A transformer consists of two coils also called as ―WINDINGS‖ namely Primary &
Secondary.
They are linked together through inductively coupled electrical conductors also called as
CORE. A changing current in the primary causes a change in the Magnetic Field in the core &
this in turn induces an alternating voltage in the secondary coil. If load is applied to the
secondary then an alternating current will flow through the load. If we consider an ideal

condition then all the energy from the primary circuit will be transferred to the secondary circuit
through the magnetic field.
So
The secondary voltage of the transformer depends on the number of turns in the Primary as well as in
the secondary.
Rectifier:
A rectifier is a device that converts an AC signal into DC signal. For rectification purpose
we use a diode, a diode is a device that allows current to pass only in one direction i.e. when the
anode of the diode is positive with respect to the cathode also called as forward biased condition
& blocks current in the reversed biased condition.
Rectifier can be classified as follows:
1) Half Wave rectifier:
This is the simplest type of rectifier as you can see in the diagram a half wave rectifier
consists of only one diode. When an AC signal is applied to it during the positive half cycle the

diode is forward biased & current flows through it. But during the negative half cycle diode is
reverse biased & no current flows through it. Since only one half of the input reaches the output,
it is very inefficient to be used in power supplies.
2) Full wave rectifier:
Half wave rectifier is quite simple but it is very inefficient, for greater efficiency we
would like to use both the half cycles of the AC signal. This can be achieved by using a center
tapped transformer i.e. we would have to double the size of secondary winding & provide
connection to the center. So during the positive half cycle diode D1 conducts & D2 is in reverse
biased condition. During the negative half cycle diode D2 conducts & D1 is reverse biased. Thus
we get both the half cycles across the load.
One of the disadvantages of Full Wave Rectifier design is the necessity of using a center
tapped transformer, thus increasing the size & cost of the circuit. This can be avoided by using
the Full Wave Bridge Rectifier.

3) Bridge Rectifier:
As the name suggests it converts the full wave i.e. both the positive & the negative half
cycle into DC thus it is much more efficient than Half Wave Rectifier & that too without using a
center tapped transformer thus much more cost effective than Full Wave Rectifier.
Full Bridge Wave Rectifier consists of four diodes namely D1, D2, D3 and D4. During
the positive half cycle diodes D1 & D4 conduct whereas in the negative half cycle diodes D2 &
D3 conduct thus the diodes keep switching the transformer connections so we get positive half
cycles in the output.

If we use a center tapped transformer for a bridge rectifier we can get both positive &
negative half cycles which can thus be used for generating fixed positive & fixed negative
voltages.
Filter capacitor:
Even though half wave & full wave rectifier give DC output, none of them provides a
constant output voltage. For this we require to smoothen the waveform received from the
rectifier. This can be done by using a capacitor at the output of the rectifier this capacitor is also
called as ―FILTER CAPACITOR‖ or ―SMOOTHING CAPACITOR‖ or ―RESERVOIR
CAPACITOR‖. Even after using this capacitor a small amount of ripple will remain.
We place the Filter Capacitor at the output of the rectifier the capacitor will charge to the peak voltage
during each half cycle then will discharge its stored energy slowly through the load while the rectified voltage
drops to zero, thus trying to keep the voltage as constant as possible.

If we go on increasing the value of the filter capacitor then the Ripple will decrease. But then the
costing will increase. The value of the Filter capacitor depends on the current consumed by the circuit, the
frequency of the waveform & the accepted ripple.
Where,
Vr= accepted ripple voltage.( should not be more than 10% of the voltage)
I= current consumed by the circuit in Amperes.
F= frequency of the waveform. A half wave rectifier has only one peak in one cycle so F=25hz
Where as a full wave rectifier has Two peaks in one cycle so F=100hz.
Voltage regulator :
A Voltage regulator is a device which converts varying input voltage into a constant
regulated output voltage. Voltage regulator can be of two types
1) Linear Voltage Regulator:
Also called as Resistive Voltage regulator because they dissipate the excessive voltage
resistively as heat.
2) Switching Regulators:
They regulate the output voltage by switching the Current ON/OFF very rapidly. Since their
output is either ON or OFF it dissipates very low power thus achieving higher efficiency as
compared to linear voltage regulators. But they are more complex & generate high noise due to
their switching action. For low level of output power switching regulators tend to be costly but
for higher output wattage they are much cheaper than linear regulators.
The most commonly available Linear Positive Voltage Regulators are the 78XX series where the
XX indicates the output voltage. And 79XX series is for Negative Voltage Regulators.

After filtering the rectifier output the signal is given to a voltage regulator. The maximum
input voltage that can be applied at the input is 35V.Normally there is a 2-3 Volts drop across the
regulator so the input voltage should be at least 2-3 Volts higher than the output voltage. If the
input voltage gets below the Vmin of the regulator due to the ripple voltage or due to any other
reason the voltage regulator will not be able to produce the correct regulated voltage.
IC 7805:
7805 is an integrated three-terminal positive fixed linear voltage regulator. It supports an
input voltage of 10 volts to 35 volts and output voltage of 5 volts. It has a current rating of 1 amp
although lower current models are available. Its output voltage is fixed at 5.0V. The 7805 also
has a built-in current limiter as a safety feature. 7805 is manufactured by many companies,
including National Semiconductors and Fairchild Semiconductors.
The 7805 will automatically reduce output current if it gets too hot.The last two digits
represent the voltage; for instance, the 7812 is a 12-volt regulator. The 78xx series of regulators
is designed to work in complement with the 79xx series of negative voltage regulators in systems
that provide both positive and negative regulated voltages, since the 78xx series can't regulate
negative voltages in such a system.
The 7805 & 78 is one of the most common and well-known of the 78xx series regulators,
as it's small component count and medium-power regulated 5V make it useful for powering TTL
devices.

Specifications of IC 7805:
Table 3.7. Specifications of IC7805
Circuit diagram:
Fig 3.17 Circuit Diagram of power supply
SPECIFICATIONS IC 7805
Vout 5V
Vein - Vout Difference 5V - 20V
Operation Ambient Temp 0 - 125°C
Output Imax 1A

CHAPTER 4
CIRCUIT DIAGRAM AND OPERATION
CIRCUIT DIAGRAM:
Fig 4.1 Circuit Diagram

OPERATION:
This project is developed based on EMBEDDED and GSM Technology. When a field is in the dry
condition, the sensing logic senses the state of the field and intimates it to the microcontroller. It in
response makes the motor on by sending message by GSM. We can know the status of the field by
sending a message by the GSM modem which is placed at the field. Through our mobile we can switch
on-off the motor by sending the respective commands to the kit through the GSM modem. Thus the
irrigation motor can be controlled through our mobiles using GSM technology, and automatically control
the flood in the field when sudden raining by open the gate by on the gate motor.
Algorithm:
Step1: Start the process.
Step2: Initialize Micro controller
Step3: Initialize Motors
Step4: Initialize GSM
Step5: Initialize LCD
Step6: Check the moisture levels
Step7: If Field is dry send sms to the registered number as ―Field is dry‖, If Field is wet send sms
to tothe registered number as ―Field is wet‖
Step8:Wait for response
Step9: Based on replay Motor will be ON/OFF
Step10: Monitor the sensors
Step11:If no water flow send sms as No water flow
Step12: Check the gate sensors
Step13:If water level increases gate motor will be ON and send sms
Step14: After the process completed it getting move to original state.
Step15: Stop the process.

CHAPTER 5
SOFTWARE DEVELOPMENT
5.1 INTRODUCTION:
In this chapter the software used and the language in which the program code is defined
is mentioned and the program code dumping tools are explained. The chapter also documents the
development of the program for the application. This program has been termed as ―Source code‖.
Figure 5.1 Keil Software- internal stages

Keil development tools for the 8051 Microcontroller Architecture support every level of
software developer from the professional applications
5.2 C51 COMPILER & A51 MACRO ASSEMBLER:
Source files are created by the µVision IDE and are passed to the C51 Compiler or A51
Macro Assembler. The compiler and assembler process source files and create replaceable object
files.
The Keil C51 Compiler is a full ANSI implementation of the C programming language
that supports all standard features of the C language. In addition, numerous features for direct
support of the 8051 architecture have been added.
5.3 µVISION:
What's New in µVision3?
µVision3 adds many new features to the Editor like Text Templates, Quick Function
Navigation, and Syntax Coloring with brace high lighting Configuration Wizard for dialog based
startup and debugger setup. µVision3 is fully compatible to µVision2 and can be used in parallel
with µVision2.
What is µVision3?
µVision3 is an IDE (Integrated Development Environment) that helps you write, compile,
and debug embedded programs. It encapsulates the following components:
 A project manager.
 A make facility.
 Tool configuration.
 Editor.
 A powerful debugger.

Starting µVision2 and Creating a Project:
1. Click on the Keil uVision Icon on Desktop
2. The following fig will appear
3. Click on the Project menu from the title bar
4. Then Click on New Project

5. Save the Project by typing suitable project name with no extension in u r own folder sited in
either C: or D:
6. Then Click on Save button above.
7. Select the component for u r project. i.e. Atmel……
8. Click on the + Symbol beside of Atmel

9. Select AT89C51 as shown below
10.Then Click on ―OK‖
11.The Following fig will appear

12.Then Click either YES or NO………mostly ―NO‖
13. Now your project is ready to USE
14. Now double click on the Target1, you would get another option ―Source group 1‖ as shown
in next page.
15. Click on the file option from menu bar and select ―new‖

16. The next screen will be as shown in next page, and just maximize it by double clicking on its
blue boarder.
17. Now start writing program in either in ―C‖ or ―ASM‖
18. For a program written in Assembly, then save it with extension ―. asm‖ and for ―C‖ based
program save it with extension ― .C‖

19. Now right click on Source group 1 and click on ―Add files to Group Source‖
20. Now you will get another window, on which by default ―C‖ files will appear.

21. Now select as per your file extension given while saving the file
22. Click only one time on option ―ADD‖
23. Now Press function key F7 to compile. Any error will appear if so happen.
24. If the file contains no error, then press Control+F5 simultaneously.
25. The new window is as follows

26. Then Click ―OK‖
27. Now Click on the Peripherals from menu bar, and check your required port as shown in fig
below
28. Drag the port a side and click in the program file.
29. Now keep Pressing function key ―F11‖ slowly and observe.
30. You are running your program successfully

5.4 FLASH MAGIC:
Features:
 Straightforward and intuitive user interface
 Five simple steps to erasing and programming a device and setting any
options desired
 Programs Intel Hex Files
 Automatic verifying after programming
 Fills unused flash to increase firmware security
 Ability to automatically program checksums. Using the supplied checksum
calculation routine your firmware can easily verify the integrity of a Flash
block, ensuring no unauthorized or corrupted code can ever be executed
 Program security bits
 Check which Flash blocks are blank or in use with the ability to easily erase
all blocks in use
 Read the device signature
 Read any section of Flash and save as an Intel Hex File
 Reprogram the Boot Vector and Status Byte with the help of confirmation
features that prevent accidentally programming incorrect values
 Displays the contents of Flash in ASCII and Hexadecimal formats
 Single-click access to the manual, Flash Magic home page and NXP
Microcontrollers home page
 Ability to use high-speed serial communications on devices that support it.
Flash Magic calculates the highest baud rate that both the device and your PC
can use and switches to that baud rate transparently
 Command Line interface allowing Flash Magic to be used in IDEs and Batch
Files
 Manual in PDF format
 supports half-duplex communications
 Verify Hex Files previously programmed
 Save and open settings

 Able to control the DTR and RTS RS232 signals when connected to RST and
/PSEN to place the device into Boot ROM and Execute modes automatically.
An example circuit diagram is included in the Manual. This is essential for
ISP with target hardware that is hard to access.
 This enables us to send commands to place the device in Boot ROM mode,
with support for command line interfaces. The installation includes an
example project for the Keil and Raisonance 8051 compilers that show how to
build support for this feature into applications.
 Able to play any Wave file when finished programming.
 built in automated version checker - helps ensure you always have the latest
version.
 Powerful, flexible Just In Time Code feature. Write your own JIT Modules to
generate last minute code for programming. Uses include:
 Serial number generation
 Copy protection and copy authorization
 Storing program date and time - manufacture date
 Storing program operator and location
 Lookup table generation
 Language tables or language selection
 Centralized record keeping
Obtaining latest firmware from the Corporate Web site or project intranet
Requirements:
Flash Magic works on any versions of Windows, except Windows 95. 10Mb of
disk space is required. As mentioned earlier, we are automating two different routines in
our project and hence we used the method of polling to continuously monitor those tasks
and act accordingly

5.5 CODING:
Source code:
#include<reg52.h>
#include<string.h>
#include "Headers.h"
#include "Lcd.C"
#include "Serial.C"
#include "GSM.C"
#include "app.C"
int main()
{
Buzzzz=0;
Motor=0;
Lcd_Init();
Init_UART0();
Init_UART0_Interrupt();
GSM_S900();
Project_Label();
while(1)
{
Check_Sensors();
//Check_Message();
}
}
void Project_Label(void)
{
Lcd_Clear;
Lcd_Data_Str(1,1,"GSM Based Monitr");
Lcd_Data_Str(2,1,"Flood Control ");
Delay(300);
Lcd_Clear;
}

Delay(unsigned int time)
{
unsigned int i,j;
for(i=0;i<time;i++)
for(j=0;j<1200;j++);
}
/******************************************/
bit LCD_Cmd=0,LCD_Data=1;
Lcd_Init();
Lcd_Data_Chr(bit RS ,unsigned char line,unsigned char position,unsigned char temp1) ;
Lcd_Data_Str(unsigned char line,unsigned char position,unsigned char *temp);
Lcd_Wr(unsigned char r);
Delay(unsigned int);
/***********************************************************************
Lcd_Data_(0-cmd:1-data,line no,position,char to disp on LCD);
******************************************************************************
***/
sfr LCD_DATA=0X90;//PORT 1
sbit RS=P2^6;
sbit EN=P2^7;
Lcd_Init()
{
unsigned char LCD_2_LINE=0x38;
unsigned char LCD_CLEAR=0X01;
unsigned char DISPLAY_ON=0X0E;
unsigned char LCD_CURSOR_OFF=0x0C;

Lcd_Data_Chr(0,0,0, LCD_2_LINE);
Lcd_Data_Chr(0,0,0, DISPLAY_ON);
Lcd_Data_Chr(0,0,0, LCD_CURSOR_OFF);
Lcd_Data_Chr(0,0,0, LCD_CLEAR);
}
Lcd_Data_Chr(bit RS ,unsigned char line,unsigned char position,unsigned char temp1)
{
if(RS==0)
{
LCD_DATA=temp1;
Lcd_Wr(LCD_Cmd);
}
if(RS==1)
{
if(line==1)
{
LCD_DATA=0x7f+position;
Lcd_Wr(LCD_Cmd);
}
if(line==2)
{
LCD_DATA=0xbf+position;
Lcd_Wr(LCD_Cmd);
}
LCD_DATA=temp1;
Lcd_Wr(LCD_Data);
}
}
Lcd_Data_Str(unsigned char line,unsigned char position,unsigned char *temp)
{

unsigned char p;
if(line==1)
{
p=0x7f+position;
Lcd_Data_Chr(0,0,0,p);
}
if(line==2)
{
p=0xbf+position;
Lcd_Data_Chr(0,0,0,p);
}
while(*temp!='0')
{
LCD_DATA=*temp;
Lcd_Wr(LCD_Data);
temp++;
}
}
Lcd_Wr(unsigned char r)
{
RS=r;
EN=1;
Delay(1);
EN=0;
}
Check_Sensors()
{
if(Level1==0&&Level2==0&&Level3==0)
{
Lcd_Data_Str(1,1,"Dam Level Full ");
Buzzzzz=1;
if(flag1==0)
{
flag1=1;

Sending_Message("GSM Based Dam Level Alert For Floods rn Alert...! Dam Water Level
Fullrn",Misscall_Data_Upload());
//Buzzzzz=0;
}
}
{
Lcd_Data_Str(1,1,"Dam Level Medium");
Buzzzzz=1;
flag1=0;
if(flag2==0)
{
flag2=1;
//Sending_Message("GSM Based Water Tank System rn Aler...! Water Level
Mediumrn",Misscall_Data_Upload());
//Buzzzzz=0;
}
}
{
Lcd_Data_Str(1,1,"Dam Level Low ");
Buzzzzz=1;
flag1=0;
if(flag4==0)
{
flag4=1;
Lowrn",Misscall_Data_Upload());
//Buzzzzz=0;
}
}
{
Lcd_Data_Str(1,1,"Tank Level Empty");
Buzzzzz=1;
flag1=0;
if(flag3==0)
{
flag1=0;
flag3=1;

flag2=0;
Emptyrn",Misscall_Data_Upload());
//Buzzzzz=0;
}
}
}
GSM_modem_init()
{
serialtx_str_intr("ATE0rn");
Delay(10);
serialtx_str_intr("ATrn");
Delay(10);
serialtx_str_intr("ATrn");
Delay(10);
serialtx_str_intr("AT+CNMI=1,1,0,0,0rn");
serialtx_chr_intr(0x0d);
Delay(10);
serialtx_str_intr("AT+CNMI=1,1,0,0,0rn");
serialtx_str_intr("AT+CMGF=1");
serialtx_str_intr("AT+CMGF=1");
Delay(10);
}
Misscal_Messg_Send()
{
serialtx_str("AT+CPBS="MC"rn");
while(serial_rx()!='O');
while(serial_rx()!='K');
serialtx_str("AT+CPBR=1rn");
while(serial_rx()!='1')
}

CHAPTER 6
RESULTS
Our overall system of Automatic irrigation and flood controlling system is shown below

Initially when we switch on the system, the system is initial condition & booting up as
shown below
Initially the LCD display shown as

In the LCD message display as
When we give a missed call to system, call automatically rejected and sends a SMS to
registered mobile number

The motor will be ON/OFF by the SMS from registered mobile number

The results is observesd as
If dam water level reaches maximum level gate motor will on
 This project is developed based on EMBEDDED and GSM Technology.
 When a field is in the dry condition, the sensing logic senses the state of the field and
intimates it to the microcontroller.

 It in response makes the motor on by sending message by GSM. We can know the status
of the field by sending a message by the GSM modem which is placed at the field.
 Through our mobile we can switch on-off the motor by sending the respective commands
to the kit through the GSM modem.
 Thus the irrigation motor can be controlled through our mobiles using GSM technology,
and automatically control the flood in the field when sudden raining by open the gate by
on the gate motor.
Advantages:
1. Easy to implement
2. Low cost
3. Eco-Friendly
4. Use the man-power more efficiently
Disadvantages:
1. Here the soil sensors can cover only certain distance.
Applications:
1. Agriculture applications
2. Industrial applications
RESULT:
The project ―AUTOMATIC IRRIGATION AND FLOOD CONTROLLING SYSTEM”
has been successfully designed and tested. Integrating features of all the hardware components
used have developed it.

CHAPTER 7
CONCLUSION
Since earlier days farmer is supposed to visit their agricultural land and check
the moisture content of soil manually. To avoid more human efforts this technology
can be used. It allows the user to monitor and maintain the moisture remotely
irrespective of time. It is really an effective and economic way to reduce human effort
and water wastage in agriculture land. Current techniques in agriculture have reduced
the ground-water level and availability of human resource. This Irrigation control
system using GSM can help farmer in many ways through the use of Humidity,
Automatic and Manual modes of operation.

CHAPTER 8
FUTURE SCOPE
Apart from agricultural fields, this system can be used in Cricket stadiums or Golf
stadiums and also in public gardens. The system has a huge demand and future scope too. It
allows a lot of development within it and leads to the standard and useful system which can be
used vary widely in agricultural field.

CHAPTER 9
REFERENCES
[1] Veena Divya K member IACSIT ,Ayush Akhouri, Chanda based Automated Irrigation
Control System using Drip Irrigation Methology International Journal of Scientific &
Engineering Research, Volume 4, Issue 5, May 2013 ISSN 2229-5518
[2] In R.Suresh, S.Gopinath, K.Govindaraju, T.Devika,on Control using Raingun Irrigation
System‖ Internat Vol. 3, Issue 2, February 2014
[3] Purnima, S.R.N. Reddy, PhD. Proposed a ―Designtomatic of Irrigation System
using GSM-Bluetooth ―(International Journal–888)Volume of C 47–No.12, June 2012 )
[4] Chandrika Chanda, Surbhi Agarwal Proposed scheme Systems‖ -(ISSN2459,Volume
22502,Issue10, October 2012)
[5] Irrigation, 5th Edition, Muhammad Irfan Khan Yousafzai, Claude H. Pair,
editor, published by the Irrigation Association, 1983
[6] Drip and Micro Irrigation Design and Management for Trees, Vines, and Field
Crops, 3rd Edition, by Charles M. Burt and Stuart W. Styles, published by the
Irrigation Training and Research Center, 2007
[7] http://en.wikipedia.org/wiki/Drip_irrigation
[8] http://en.wikipedia.org/wiki/Android_(operatingsystem)
[9] 8051 programming and applications – by K.J.Ayala
[10] Microprocessors and interfacing - by Douglas V.Hall
[11] https://www.sparkfun.com/datasheets/Components/LM7805.pdf
[12] http://www.atmel.com/images/doc1919.pdf
[13] http://www.ti.com/lit/ds/symlink/lm124-n.pdf
[14] http://forum.researchdesignlab.com/datasheet/SIM900A

Automatic irrigation and flood controlling system by using GSM

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