N414 Documentation Data.docx

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PLEASE NOTE: THE MATTER
PRODUCED BELOW IS
REFERENCE MATERIAL ONLY
FOR PREPARING THE PROJECT
REPORT. IT IS NOT THE
COMPLETE PROJECT REPORT.

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A PROJECT REPORT ON
IOT Early Flood Detection & Avoidance
Submitted in partial fulfillment of the requirements
For the award of the degree
BACHELOR OF ENGINEERING
IN
____________________________________ ENGINEERING
SUBMITTED BY
-------------------- (--------------)
--------------------- (---------------)
--------------------- (---------------)
DEPARTMENT OF _______________________ ENGINEERING
__________COLLEGE OF ENGINEERING
AFFILIATED TO ___________ UNIVERSITY

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ACKNOWLEDGEMENT
The satisfaction and euphoria that accompany the successful completion of any
task would be incomplete without the mentioning of the people whose constant
guidance and encouragement made it possible. We take pleasure in presenting
before you, our project, which is result of studied blend of both research and
knowledge.
We express our earnest gratitude to our internal guide, Assistant Professor
______________, Department of ECE, our project guide, for his constant support,
encouragement and guidance. We are grateful for his cooperation and his valuable
suggestions.
Finally, we express our gratitude to all other members who are involved either
directly or indirectly for the completion of this project.

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DECLARATION
We, the undersigned, declare that the project entitled ‘IOT Early Flood
Detection & Avoidance’, being submitted in partial fulfillment for the award
of Bachelor of Engineering Degree in Electronics and Communication
Engineering, affiliated to _________ University, is the work carried out by us.
__________ _________ _________
__________ _________ _________

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ABSTRACT
Flooding is usually broughton by an increased quantity of water in a water
system, like a lake, river overflowing. On occasion a dam fractures, abruptly
releasing a massivequantity of water. The outcome is that a number of the water
travels into soil, and ‘flooding’ the region. Rivers are involving river banks, in a
station.
Aside fromlack of products and houseand office property, streets infrastructure
flood water consists of bacteria and sewageflow of wastesites and chemical
spillage which leads to a variety of diseases afterwards.
Flood predictions need information like:
The speed of change in river stage on a realtime basis, which may help indicate
the seriousness and immediacy of this threat.
Understanding of the formof stormgenerating the moisture, such as length,
intensity and a real extent, which is valuable for discovering potential seriousness
of the flood.
In this systemwemake use of a Arduino Uno interfaced with 4 different sensors,
named as Ultrasonic sensor for measuring water levels , float sensor detect full
water, Flow sensor for knowing speed of water and humidity sensor. These
combination of sensor areused to predict flood and alert respectiveauthorities
with help of IOTand sound instant alarm in nearby villages to instantly transmit
information about possible floods. Thesesensors provideinformation over the
IOTusing Wifi module. On detection of conditions of flooding the systempredicts
the amountof time it would take to flood in a particular area and alerts the
villages/areas that could be affected by it. The systemalso calculates the time it
would take for flood to reach them and provides a time to people so that they can
evacuate accordingly.

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2. INTRODUCTION TO EMBEDDED SYSTEMS
What is embedded system?
An Embedded System is a combination of computer hardware and software, and perhaps
additional mechanical or other parts, designed to perform a specific function. An embedded
system is a microcontroller-based, software driven, reliable, real-time control system,
autonomous, or human or network interactive, operating on diverse physical variables and in
diverse environments and sold into a competitive and cost conscious market.
An embedded system is not a computer system that is used primarily for processing, not a
software system on PC or UNIX, not a traditional business or scientific application. High-end
embedded & lower end embedded systems. High-end embedded system - Generally 32, 64 Bit
Controllers used with OS. Examples Personal Digital Assistant and Mobile phones etc
.Lower end embedded systems - Generally 8,16 Bit Controllers used with an minimal operating
systems and hardware layout designed for the specific purpose.
SYSTEM DESIGN CALLS:

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Figure 3(a): Embedded system design calls
EMBEDDED SYSTEMDESIGN CYCLE
Figure 3(b) “V Diagram”
CharacteristicsofEmbedded System

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• An embedded system is any computer system hidden inside a product other than a
computer.
• They will encounter a number of difficulties when writing embedded system software in
addition to those we encounter when we write applications.
– Throughput – Our system may need to handle a lot of data in a short period of
time.
– Response–Our system may need to react to events quickly.
– Testability–Setting up equipment to test embedded software can be difficult.
– Debugability–Without a screen or a keyboard, finding out what the software is
doing wrong (other than not working) is a troublesome problem.
– Reliability – embedded systems must be able to handle any situation without
human intervention.
– Memory space – Memory is limited on embedded systems, and you must make
the software and the data fit into whatever memory exists.
– Program installation – you will need special tools to get your software into
embedded systems.
– Power consumption – Portable systems must run on battery power, and the
software in these systems must conserve power.
– Processor hogs – computing that requires large amounts of CPU time can
complicate the response problem.
– Cost – Reducing the cost of the hardware is a concern in many embedded system
projects; software often operates on hardware that is barely adequate for the job.
• Embedded systems have a microprocessor/ microcontroller and a memory. Some have a
serial port or a network connection. They usually do not have keyboards, screens or disk
drives.
APPLICATIONS
1) Military and aerospace embedded software applications
2) Communication Applications
3) Industrial automation and process control software

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4) Mastering the complexity of applications.
5) Reduction of product design time.
6) Real time processing of ever increasing amounts of data.
7) Intelligent, autonomous sensors.
CLASSIFICATION
 Real Time Systems.
 RTS is one which has to respond to events within a specified deadline.
 A right answer after the dead line is a wrong answer.
RTS CLASSIFICATION
 Hard Real Time Systems
 Soft Real Time System
HARD REAL TIME SYSTEM
 "Hard" real-time systems have very narrow response time.
 Example: Nuclear power system, Cardiac pacemaker.
SOFT REAL TIME SYSTEM
 "Soft" real-time systems have reduced constrains on "lateness" but still must operate very
quickly and repeatable.
 Example: Railway reservation system – takes a few extra seconds the data remains valid.

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4. HARDWARE REQUIREMENT
HARDWARE COMPONENTS:
 Arduino UNO
 Ultrasonic sensor
 Float sensor
 Humidity Sensor
 Flow sensor
 LCD 20x4
 Wifi module
 Resistors
 Capacitors
 Diodes

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BATTERY
An electrical battery is a combination of one or more electrochemical cells, used to convert
stored chemical energy into electrical energy. The battery has become a common power source
for many household and industrial applications.
Batteries may be used once and discarded, or recharged for years as in standby power
applications. Miniature cells are used to power devices such as hearing aids and wristwatches;
larger batteries provide standby power for telephone exchanges or computer data centers.
WORKING OF BATTERY:
A battery is a device that converts chemical energy directly to electrical energy. It
consists of a number of voltaic cells; each voltaic cell consists of two half cells connected in
series by a conductive electrolyte containing anions and cat ions. One half-cell includes
electrolyte and the electrode to which anions (negatively-charged ions) migrate, i.e. the anode or
negative electrode; the other half-cell includes electrolyte and the electrode to which cat ions
(positively-charged ions) migrate, i.e. the cathode or positive electrode. In the red ox reaction
that powers the battery, reduction (addition of electrons) occurs to cat ions at the cathode, while
oxidation (removal of electrons) occurs to anions at the anode. The electrodes do not touch each
other but are electrically connected by the electrolyte. Many cells use two half-cells with
different electrolytes. In that case each half-cell is enclosed in a container, and a separator that is
porous to ions but not the bulk of the electrolytes prevents mixing.
Each half cell has an electromotive force (or emf), determined by its ability to drive
electric current from the interior to the exterior of the cell. The net emf of the cell is the
difference between the emfs of its half-cells. Therefore, if the electrodes have emfs and, in other
words, the net emf is the difference between the reduction potentials of the half-reactions.

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The electrical driving force or across the terminals of a cell is known as the terminal
voltage (difference) and is measured in volts. The terminal voltage of a cell that is neither
charging nor discharging is called the open-circuit voltage and equals the emf of the cell.
Because of internal resistance, the terminal voltage of a cell that is discharging is smaller in
magnitude than the open-circuit voltage and the terminal voltage of a cell that is charging
exceeds the open-circuit voltage. An ideal cell has negligible internal resistance, so it would
maintain a constant terminal voltage of until exhausted, then dropping to zero. If such a cell
maintained 1.5 volts and stored a charge of one Coulomb then on complete discharge it would
perform 1.5 Joule of work. In actual cells, the internal resistance increases under discharge, and
the open circuit voltage also decreases under discharge. If the voltage and resistance are plotted
against time, the resulting graphs typically are a curve; the shape of the curve varies according to
the chemistry and internal arrangement employed.
An electrical battery is one or more electrochemical cells that convert stored chemical energy
into electrical energy. Since the invention of the first battery (or "voltaic pile") in 1800 by
Alessandro Volta, batteries have become a common power source for many household and
industrial applications. According to a 2005 estimate, the worldwide battery industry generates
US$48 billion in sales each year, with 6% annual growth. There are two types of batteries:
primary batteries (disposable batteries), which are designed to be used once and discarded, and
secondary batteries (rechargeable batteries), which are designed to be recharged and used
multiple times. Miniature cells are used to power devices such as hearing aids and wristwatches;
larger batteries provide standby power for telephone exchanges or computer data centers.
Principle of operation
A battery is a device that converts chemical energy directly to electrical energy. It consists of a
number of voltaic cells; each voltaic cell consists of two half cells connected in series by a
conductive electrolyte containing anions and cations. One half-cell includes electrolyte and the
electrode to which anions (negatively charged ions) migrate, i.e., the anode or negative electrode;
the other half-cell includes electrolyte and the electrode to which cations (positively charged
ions) migrate, i.e., the cathode or positive electrode. In the redox reaction that powers the battery,
cations are reduced (electrons are added) at the cathode, while anions are oxidized (electrons are

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removed) at the anode. The electrodes do not touch each other but are electrically connected by
the electrolyte. Some cells use two half-cells with different electrolytes. A separator between half
cells allows ions to flow, but prevents mixing of the electrolytes.
Each half cell has an electromotive force (or emf), determined by its ability to drive electric
current from the interior to the exterior of the cell. The net emf of the cell is the difference
between the emfs of its half-cells, as first recognized by Volta. Therefore, if the electrodes have
emfs and , then the net emf is ; in other words, the net emf is the difference
between the reduction potentials of the half-reactions. The electrical driving force or
across the terminals of a cell is known as the terminal voltage (difference) and is measured in
volts. The terminal voltage of a cell that is neither charging nor discharging is called the open-
circuit voltage and equals the emf of the cell. Because of internal resistance, the terminal voltage
of a cell that is discharging is smaller in magnitude than the open-circuit voltage and the terminal
voltage of a cell that is charging exceeds the open-circuit voltage. An ideal cell has negligible
internal resistance, so it would maintain a constant terminal voltage of until exhausted, then
dropping to zero. If such a cell maintained 1.5 volts and stored a charge of one coulomb then on
complete discharge it would perform 1.5 joule of work. In actual cells, the internal resistance
increases under discharge, and the open circuit voltage also decreases under discharge. If the
voltage and resistance are plotted against time, the resulting graphs typically are a curve; the
shape of the curve varies according to the chemistry and internal arrangement employed.
As stated above, the voltage developed across a cell's terminals depends on the energy release of
the chemical reactions of its electrodes and electrolyte. Alkaline and carbon-zinc cells have
different chemistries but approximately the same emf of 1.5 volts; likewise NiCd and NiMH
cells have different chemistries, but approximately the same emf of 1.2 volts. On the other hand
the high electrochemical potential changes in the reactions of lithium compounds give lithium
cells emfs of 3 volts or more.

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Lead-acid
Tried, tested, and trusted, lead-acid batteries have been with us since the middle of
the 19th century. With an overall rating of 12 volts, they have six separate cells,
each producing 2 volts. Crudely reduced to its basic components, each cell has a
"spongy" lead metal electrode (negative), a lead dioxide electrode (positive), and a
sulfuric acid electrolyte. As the battery discharges, both electrodes become coated
with lead sulfate and the sulfuric acid is largely converted into water, while
electrons flow out around the external circuit to provide power.
Lead-acid batteries made it possible to start cars without the help of a dangerous
and dirty hand crank. Normally, you never have to recharge them—because your
car does that automatically. The battery discharges (gives up a little of its energy)
to help the car's gasoline engine start up, and recharges (gets energy back again)
when the engine begins generating electrical energy through a device called an
alternator. As for disadvantages, lead-acid batteries are relatively big, surprisingly
heavy (try lifting one!), expensive, and can't be fully charged and discharged too
many times. Another problem is their use of toxic lead metal, which can cause
environmental problems when they're dumped in landfills.
Nickel-cadmium
Nickel-cadmium (NiCd, pronounced "nicad") are widely used as replacements for
disposable 1.5-volt batteries in things like toys, flashlights, and power tools.
They're relatively cheap, can be charged and discharged hundreds of times, and,
properly treated, will last about a decade.
Although very dependable, it's often said that NiCd batteries need to be discharged
fully before you charge them up or the amount of charge they will store (and their
effective lifespan) can be greatly reduced. Opinions vary on whether this is true
and, if so, why it happens, but as a rule of thumb, regularly discharging batteries
completely and then recharging them is a good practice. Another problem with
NiCd batteries is the toxic cadmium metal they contain. If they are buried in a
landfill, instead of properly recycled, the cadmium can escapeinto the soil and
could potentially pollute watercourses nearby.

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Nickel-metal-hydride (NiMH)
Nickel metal hydride batteries work in a similar way, but suffer less from the so-
called "memory effect." They became a popular alternative to NiCd batteries in the
1990s, partly because of environmental concerns about cadmium. NiMH batteries
work more effectively in gadgets like cellphones, which are often "topped-up" with
a quick recharge instead of a complete discharge and recharge (which is more
typical with something like power tools).
Lithium-ion
Lithium-ion batteries are the fastest-growing type of rechargeables; there are
probably lithium-ion batteries in your cellphone, MP3 player, and laptop computer.
What's so good about lithium? It's a lightweight metal that easily forms ions, so it's
excellent for making batteries. The latest lithium-ion batteries can store about
twice as much energy as traditional NiCd rechargeables, work at higher voltages,
and are more environmentally friendly, but don'tlast as long. Even so, they can be
charged and discharged hundreds of times and typically last several years, so
they're great for everyday use in electronic gadgets that aren't meant to last that
long.
How do they work? When you plug a cellphone or laptop into the power supply,
the lithium-ion battery inside starts buzzing with chemical activity. The battery's
job is to store as much electricity as possible, as fast as possible. It does this
through a chemical reaction that shunts lithium ions (lithium atoms that have lost
an electron to become positively charged) from one part of the battery to another.
When you unplug the power and use your laptop or phone, the battery switches
into reverse: the ions move the oppositeway and the battery gradually loses its
charge. Read more in our main article on how lithium-ion batteries work.

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4.2 VOLTAGE REGULATOR 7805
Features
• Output Current up to 1A.
• Output Voltages of 5, 6, 8, 9, 10, 12, 15, 18, 24V.
• Thermal Overload Protection.
• Short Circuit Protection.
• Output Transistor Safe Operating Area Protection.
Description
The LM78XX/LM78XXA series of three-terminal positive regulators are available in the
TO-220/D-PAK package and with several fixed output voltages, making them useful in a Wide
range of applications. Each type employs internal current limiting, thermal shutdown and safe
operating area protection, making it essentially indestructible. If adequate heat sinking is
provided, they can deliver over 1A output Current. Although designed primarily as fixed voltage
regulators, these devices can be used with external components to obtain adjustable voltages and
currents.
Internal Block Diagram

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FIG 4.2(a): BLOCK DIAGRAM OF VOLTAGE REGULATOR
Absolute Maximum Ratings
TABLE 4.2(b): RATINGS OF THE VOLTAGE REGULATOR

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4.3 RECTIFIER
A rectifier is an electrical device that converts alternating current (AC), which
periodically reverses direction, to direct current (DC), current that flows in only one direction, a
process known as rectification. Rectifiers have many uses including as components of power
supplies and as detectors of radio signals. Rectifiers may be made of solid state diodes, vacuum
tube diodes, mercury arc valves, and other components. The output from the transformer is fed to
the rectifier. It converts A.C. into pulsating D.C. The rectifier may be a half wave or a full wave
rectifier. In this project, a bridge rectifier is used because of its merits like good stability and full
wave rectification. In positive half cycle only two diodes( 1 set of parallel diodes) will conduct,
in negative half cycle remaining two diodes will conduct and they will conduct only in forward
bias only.
4.4 FILTER
Capacitive filter is used in this project. It removes the ripples from the output of rectifier
and smoothens the D.C. Output received from this filter is constant until the mains voltage and

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load is maintained constant. However, if either of the two is varied, D.C. voltage received at this
point changes. Therefore a regulator is applied at the output stage.
The simple capacitor filter is the most basic type of power supply filter. The use of this
filter is very limited. It is sometimes used on extremely high-voltage, low-current power supplies
for cathode-ray and similar electron tubes that require very little load current from the supply.
This filter is also used in circuits where the power-supply ripple frequency is not critical and can
be relatively high.below figure can show how the capacitor chages and discharges.

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Atmega 328
ATmega328 is an eightbitMicrocontroller. Itcanhandle the data sizedof upto eight bits. It isan AVR
basedminiaturizedscale controller.Itsbuilt ininteriormemoryisaround32KB.It worksextendingfrom
3.3V to 5V. It has a capacity to store the informationnotwithstandingwhenthe electrical supplyis
expelledfromitsbiasingterminals.Itsbrillianthighlightsincorporate the costeffectiveness,low power
dispersal,programminglockforsecuritypurposes,genuine clockcounterwith isolatedoscillator.It's
ordinarilyutilizedasa part of EmbeddedSystemsapplications.
The computeron one hand isintendedtoplayoutall the universallyuseful errandsonasolitary
machine like youcanutilize acomputertorun a product to perform estimationsoryoucan utilize a
computerto store some mediarecordor to getto webthroughthe program, while the microcontrollers
are intendedtoperformjustthe particularundertakings,fore.g.,turningthe ACoff naturallywhen
room temperature dropstoa specificcharacterizedconfineandagainturningitON whentemperature
transcendsas far as possible.
There are numberof mainstreamgroupsof microcontrollerswhichare utilizedasapart of various
applicationsaccordingtotheircapacityandattainabilitytoplayoutthe covetederrand,mostnormal of
these are 8051, AVRand PICmicrocontrollers.Inthiswe willpresentyouwithAVRgroupof
microcontroller.
There are numberof well knowngroupsof microcontrollerswhichare utilizedasa part of various
applicationsaccordingtotheircapacityandachievabilitytoplayoutthe covetedundertaking,most
normal of these are 8051, AVRand PIC microcontrollers.Inthiswe will presentyouwithAVRgroupof
microcontrollers.

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The presentmicrocontrollersare verydifferentfromwhatitwere inthe underlyingstage,andthe
quantityof producersare considerablymore incheckthanitwas 10 yearsor twoprior.At current
portionof the real producersare Microchip(production:PICmicrocontrollers),Atmel(distribution:AVR
microcontrollers),Hitachi,Phillips,Maxim, NXP,Intel andsoforth.OurintrestisuponATmega32. It has
a place withAtmel'sAVRarrangementsmall scale controllerfamily.How aboutwe see the highlights.
Features include:
 High Performance, Low Power Design
 8-Bit Microcontroller Atmel® AVR® advanced RISC architecture
o 131 Instructions most of which are executed in a single clock cycle
o Up to 20 MIPS throughput at 20 MHz
o 32 x 8 working registers
o 2 cycle multiplier
 Memory Includes
o 32KB of of programmable FLASH
o 1KB of EEPROM
o 2KB SRAM
o 10,000 Write and Erase Cycles for Flash and 100,000 for EEPROM
o Data retention for 20 years at 85°C and 100 years at 25°C
o Optional boot loader with lock bits
 In System Programming (ISP) by via boot loader
 True Read-While-Write operation
o Programming lock available for software security
 Features Include
o 2 x 8-bit Timers/Counters each with independent prescaler and compare modes
o A single 16-bit Timer/Counter with an idependent prescaler, compare and capture
modes
o Real time counter with independent oscillator
o 10 bit, 6 channel analog to digital Converter
o 6 pulse width modulation channels
o Internal temperature sensor
o Serial USART (Programmable)
o Master/Slave SPI Serial Interface - (Philips I2C compatible)
o Programmable watchdog timer with independent internaloscillator
o Internal analog comparator
o Interrupt and wake up on pin change
 AdditionalFeatures Features

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o Internal calibrated oscillator
o Power on reset and programmable brown out detection
o External and internal interrupts
o 6 sleep modes including idle, ADC noise reduction, power save, power down,
standby, and extended standby
 I/O and Package
o 23 programmable I/O lines
o 28 pin PDIP package
 Operating voltage:
o 1.8 - 5.5V
 Operating temperature range:
o 40°C to 85°C
 Speed Grades:
o 0-4 MHz at 1.8-5.5V
o 0-10 MHz at 2.7-5.5V
o 0-20 MHz at 4.5-5.5V
 Low power consumption mode at 1.8V, 1 MHz and 25°C:
o Active Mode: 0.3 mA
o Power-down Mode: 0.1 μA
o Power-save Mode: 0.8 μA (Including 32 kHz RTC)
Flash: 32 KBytes
EEPROM: 1 KBytes
SRAM: 2 KBytes
Max I/O Pins: 23
Frequency Max: 20 MHz
VCC: 1.8-5.5
10-bit A/D Channels: 6
Analog Comparator: Yes
16-bit Timers: 1
8-bit Timer: 2
Brown Out Detector: Yes
Ext Interrupts: 2
Hardware Multiplier: Yes
Interrupts: 26
ISP: Yes
On Chip Oscillator: Yes

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PWM Channels: 6
RTC: Yes
Self Program Memory: Yes
SPI: 1
TWI: Yes
UART: 1
Watchdog: Yes
Pacakage: Lead Free PDIP 28
Pin Diagram
Pin configuration
Pin
No.
Pin name Description Secondary Function
1 PC6 (RESET)
Pin6 of
PORTC
Pin by default is used as RESET pin. PC6 can only be
used as I/O pin when RSTDISBL Fuse is programmed.

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2 PD0 (RXD)
Pin0 of
PORTD
RXD (Data Input Pin for USART)
USART Serial Communication Interface
[Can be used for programming]
3 PD1 (TXD)
Pin1 of
PORTD
TXD (Data Output Pin for USART)
USART Serial Communication Interface
[Can be used for programming]
INT2( External Interrupt 2 Input)
4 PD2 (INT0)
Pin2 of
PORTD
External Interrupt source 0
5
PD3
(INT1/OC2B)
Pin3 of
PORTD
External Interrupt source1
OC2B(PWM - Timer/Counter2 Output Compare
Match B Output)
6 PD4 (XCK/T0)
Pin4 of
PORTD
T0( Timer0 External Counter Input)
XCK ( USART External Clock I/O)
7 VCC Connected to positive voltage
8 GND Connected to ground

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9
PB6
(XTAL1/TOSC1)
Pin6 of
PORTB
XTAL1 (Chip Clock Oscillator pin 1 or External clock
input)
TOSC1 (Timer Oscillator pin 1)
10
PB7
(XTAL2/TOSC2)
Pin7 of
PORTB
XTAL2 (Chip Clock Oscillator pin 2)
TOSC2 (Timer Oscillator pin 2)
11
PD5
(T1/OC0B)
Pin5 of
PORTD
T1(Timer1 External Counter Input)
OC0B(PWM - Timer/Counter0 Output Compare
Match B Output)
12
PD6
(AIN0/OC0A)
Pin6 of
PORTD
AIN0(Analog Comparator Positive I/P)
OC0A(PWM - Timer/Counter0 Output Compare
Match A Output)
13 PD7 (AIN1)
Pin7 of
PORTD
AIN1(Analog Comparator Negative I/P)
14
PB0
(ICP1/CLKO)
Pin0 of
PORTB
ICP1(Timer/Counter1 Input Capture Pin)
CLKO (Divided System Clock. The divided system
clock can be output on the PB0 pin)

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15 PB1 (OC1A)
Pin1 of
PORTB
OC1A (Timer/Counter1 Output Compare Match A
Output)
16 PB2 (SS/OC1B)
Pin2 of
PORTB
SS (SPI Slave Select Input). This pin is low when
controller acts as slave.
[Serial Peripheral Interface (SPI) for programming]
OC1B (Timer/Counter1 Output Compare Match B
Output)
17
PB3
(MOSI/OC2A)
Pin3 of
PORTB
MOSI (Master Output Slave Input). When controller
acts as slave, the data is received by this pin. [Serial
Peripheral Interface (SPI) for programming]
OC2 (Timer/Counter2 Output Compare Match
Output)
18 PB4 (MISO)
Pin4 of
PORTB
MISO (Master Input Slave Output). When controller
acts as slave, the data is sent to master by this
controller through this pin.
19 PB5 (SCK)
Pin5 of
PORTB
SCK (SPI Bus Serial Clock). This is the clock shared
between this controller and other system for
accurate data transfer.
20 AVCC Power for Internal ADC Converter

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21 AREF Analog Reference Pin for ADC
22 GND GROUND
23 PC0 (ADC0)
Pin0 of
PORTC
ADC0 (ADC Input Channel 0)
24 PC1 (ADC1)
Pin1 of
PORTC
25 PC2 (ADC2)
Pin2 of
PORTC
26 PC3 (ADC3)
Pin3 of
PORTC
27
PC4
(ADC4/SDA)
Pin4 of
PORTC
SDA (Two-wire Serial Bus Data Input/output Line)
28 PC5 (ADC5/SCL)
Pin5 of
PORTC
SCL (Two-wire Serial Bus Clock Line)

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Applications
There are hundreds of applications for ATMEGA328P:
 Used in ARDUINO UNO, ARDUINO NANO and ARDUINO MICRO boards.
 Industrial control systems.
 SMPS and Power Regulation systems.
 Digital data processing.
 Analog signal measuring and manipulations.
 Embedded systems like coffee machine, vending machine.
 Motor control systems.
 Display units.
 Peripheral Interface system.
LED
Light Emitting Diodes (LED) have recently become available that are white and bright,
so bright that they seriously compete with incandescent lamps in lighting applications. They are
still pretty expensive as compared to a GOW lamp but draw much less current and project a
fairly well focused beam.
The diode in the photo came with a neat little reflector that tends to sharpen the beam a
little but doesn't seem to add much to the overall intensity.
When run within their ratings, they are more reliable than lamps as well. Red LEDs are
now being used in automotive and truck tail lights and in red traffic signal lights. You will be
able to detect them because they look like an array of point sources and they go on and off
instantly as compared to conventional incandescent lamps.

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LEDs are monochromatic (one color) devices. The color is determined by the band gap of
the semiconductor used to make them. Red, green, yellow and blue LEDs are fairly common.
White light contains all colors and cannot be directly created by a single LED. The most
common form of "white" LED really isn't white. It is a Gallium Nitride blue LED coated with a
phosphor that, when excited by the blue LED light, emits a broad range spectrum that in addition
to the blue emission, makes a fairly white light.
There is a claim that these white LED's have a limited life. After 1000 hours or so of
operation, they tend to yellow and dim to some extent. Running the LEDs at more than their
rated current will certainly accelerate this process.
There are two primary ways of producing high intensity white-light using LED’S. One is
to use individual LED’S that emit three primary colours—red, green, and blue—and then mix all
the colours to form white light. The other is to use a phosphor material to convert
monochromatic light from a blue or UV LED to broad-spectrum white light, much in the same
way a fluorescent light bulb works. Due to metamerism, it is possible to have quite different
spectra that appear white.
LEDs are semiconductor devices. Like transistors, and other diodes, LEDs are made out
of silicon. What makes an LED give off light are the small amounts of chemical impurities that
are added to the silicon, such as gallium, arsenide, indium, and nitride.

35
When current passes through the LED, it emits photons as a byproduct. Normal light
bulbs produce light by heating a metal filament until it is white hot. LEDs produce photons
directly and not via heat, they are far more efficient than incandescent bulbs.
Fig 3.1(a): circuit symbol
Not long ago LEDs were only bright enough to be used as indicators on dashboards or
electronic equipment. But recent advances have made LEDs bright enough to rival traditional
lighting technologies. Modern LEDs can replace incandescent bulbs in almost any application.
Types of LED’S
LEDs are produced in an array of shapes and sizes. The 5 mm cylindrical package is the most
common, estimated at 80% of world production. The color of the plastic lens is often the same as the
actual color of light emitted, but not always. For instance, purple plastic is often used for infrared
LEDs, and most blue devices have clear housings. There are also LEDs in extremely tiny packages,
such as those found on blinkers and on cell phone keypads. The main types of LEDs are miniature,
high power devices and custom designs such as alphanumeric or multi-color.
Fig 3.1(b) Different types of LED’S

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Servo motors have been around for a long time and are utilized in many applications. They are small in size but
pack a big punch and are very energy-efficient. These features allow them to be used to operate remote-controlled or
radio-controlled toy cars, robots and airplanes. Servo motors are also used in industrial applications, robotics, in-
line manufacturing, pharmaceutics and food services.But how do the little guys work?
The servo circuitry is built right inside the motor unit and has a positionable shaft, which usually is fitted with
a gear (as shown below). The motor is controlled with an electric signal which determines the amount of movement
of the shaft.
What's inside the servo?
Hitec HS-322HD Standard Heavy Duty Servo
To fully understand howthe servo works, you need to take a look under the hood.Inside there is a pretty simple set-
up: a small DC motor,potentiometer, and a control circuit. The motor is attached by gears to the control wheel. As
the motor rotates,the potentiometer's resistance changes,so the control circuit can precisely regulate how much
movement there is and in which direction.
When the shaft of the motor is at the desired position, power supplied to the motor is stopped.If not, the motor is
turned in the appropriate direction. The desired position is sent via electrical pulses through the signal wire. The
motor's speed is proportional to the difference between its actual position and desired position. So if the motor is
near the desired position,it will turn slowly, otherwise it will turn fast. This is called proportional control. This
means the motor will only run as hard as necessary to accomplish the task at hand,a very efficient little guy.
How is the servo controlled?
The guts of a servo motor (L) and an assembled servo (R)
Servos are controlled by sending an electrical pulse of variable width, or pulse width modulation (PWM), through
the control wire. There is a minimum pulse, a maximum pulse, and a repetition rate. A servo motor can usually only
turn 90 degrees in either direction for a total of 180 degree movement. The motor's neutral position is defined as the
position where the servo has the same amount of potential rotation in the both the clockwise or counter-clockwise

37
direction. The PWM sent to the motor determines position of the shaft, and based on the duration of the pulse sent
via the control wire; the rotor will turn to the desired position.The servo motor expects to see a pulse every 20
milliseconds (ms) and the length of the pulse will determine how far the motor turns.For example, a 1.5ms pulse
will make the motor turn to the 90-degree position. Shorter than 1.5ms moves it to 0 degrees,and any longer than
1.5ms will turn the servo to 180 degrees.
Variable Pulse width control servo
position
When these servos are commanded to move, they will move to the position and hold that position.If an external
force pushes against the servo while the servo is holding a position,the servo will resist from moving out of that
position. The maximum amount of force the servo can exert is called the torque rating of the servo.Servos will not
hold their position forever though; the position pulse must be repeated to instruct the servo to stay in position.
Types of Servo Motors
There are two types of servo motors - AC and DC. AC servo can handle higher current surges and tend to be used in
industrial machinery.DC servos are not designed for high current surges and are usually better suited for smaller
applications. Generally speaking, DC motors are less expensive than their AC counterparts.These are also servo
motors that have been built specifically for continuous rotation,making it an easy way to get your robot movin g.
They feature two ball bearings on the output shaft for reduced friction and easy access to the rest-point
adjustment potentiometer.
Servo Motor Applications
Servos are used in radio-controlled airplanes to position control surfaces like elevators, rudders, walking a robot, or
operating grippers. Servo motors are small, have built-in control circuitry and have good power for their size.
In food services and pharmaceuticals, the tools are designed to be used in harsher environments, where the potential
for corrosion is high due to being washed at high pressures and temperatures repeatedly to maintain strict hygiene
standards. Servos are also used in in-line manufacturing, where high repetition yet precise work is necessary.

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Of course, you don't have to know how a servo works to use one, but as with most electronics, the more you
understand, the more doors open for expanded projects and projects' capabilities. Whether you're a hobbyist
building robots, an engineer designing industrial systems, or just constantly curious, where will servo motors take
you?
4.9 PUSH BUTTONS
Fig 4.9(a): Push Buttons
A push-button (also spelled pushbutton) or simply button is a simple switch mechanism
for controlling some aspect of a machine or a process. Buttons are typically made out of hard
material, usually plastic or metal. The surface is usually flat or shaped to accommodate the
human finger or hand, so as to be easily depressed or pushed. Buttons are most often biased
switches, though even many un-biased buttons (due to their physical nature) require a spring to
return to their un-pushed state. Different people use different terms for the "pushing" of the
button, such as press, depress, mash, and punch.

39
Uses:
In industrial and commercial applications push buttons can be linked together by a
mechanical linkage so that the act of pushing one button causes the other button to be released.
In this way, a stop button can "force" a start button to be released. This method of linkage is used
in simple manual operations in which the machine or process have no electrical circuits for
control.
Pushbuttons are often color-coded to associate them with their function so that the
operator will not push the wrong button in error. Commonly used colors are red for stopping the
machine or process and green for starting the machine or process.
Red pushbuttons can also have large heads (mushroom shaped) for easy operation and to
facilitate the stopping of a machine. These pushbuttons are called emergency stop buttons and
are mandated by the electrical code in many jurisdictions for increased safety. This large
mushroom shape can also be found in buttons for use with operators who need to wear gloves for
their work and could not actuate a regular flush-mounted push button. As an aid for operators
and users in industrial or commercial applications, a pilot light is commonly added to draw the
attention of the user and to provide feedback if the button is pushed. Typically this light is
included into the center of the pushbutton and a lens replaces the pushbutton hard center disk.
The source of the energy to illuminate the light is not directly tied to the contacts on the
back of the pushbutton but to the action the pushbutton controls. In this way a start button when
pushed will cause the process or machine operation to be started and a secondary contact
designed into the operation or process will close to turn on the pilot light and signify the action
of pushing the button caused the resultant process or action to start.
In popular culture, the phrase "the button" refers to a (usually fictional) button that a
military or government leader could press to launch nuclear weapons.

40
Push to ON button:
Fig. 4.9(b): push on button
Initially the two contacts of the button are open. When the button is pressed they become
connected. This makes the switching operation using the push button.
4.10 BC547
The BC547 transistor is an NPN Epitaxial Silicon Transistor. The BC547 transistor is a general-
purpose transistor in small plastic packages. It is used in general-purpose switching and
amplification BC847/BC547 series 45 V, 100 mA NPN general-purpose transistors.
BC 547 TRANSISTOR PINOUTS
The BC547 transistor is an NPN bipolar transistor, in which the letters "N" and "P" refer
to the majority charge carriers inside the different regions of the transistor. Most bipolar
transistors used today are NPN, because electron mobility is higher than hole mobility in
semiconductors, allowing greater currents and faster operation. NPN transistors consist of a layer

41
of P-doped semiconductor (the "base") between two N-doped layers. A small current entering the
base in common-emitter mode is amplified in the collector output. In other terms, an NPN
transistor is "on" when its base is pulled high relative to the emitter. The arrow in the NPN
transistor symbol is on the emitter leg and points in the direction of the conventional current flow
when the device is in forward active mode. One mnemonic device for identifying the symbol for
the NPN transistor is "not pointing in." An NPN transistor can be considered as two diodes with
a shared anode region. In typical operation, the emitter base junction is forward biased and the
base collector junction is reverse biased. In an NPN transistor, for example, when a positive
voltage is applied to the base emitter junction, the equilibrium between thermally generated
carriers and the repelling electric field of the depletion region becomes unbalanced, allowing
thermally excited electrons to inject into the base region. These electrons wander (or "diffuse")
through the base from the region of high concentration near the emitter towards the region of low
concentration near the collector. The electrons in the base are called minority carriers because
the base is doped p-type which would make holes the majority carrier in the base.
Whenever base is high, then current starts flowing through base and emitter and after that
only current will pass from collector to emitter. So that the LED which is connected to collector
will glow to indicate that transistor is ON.

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4.11 1N4007
Diodes are used to convert AC into DC these are used as half wave rectifier or full wave
rectifier. Three points must he kept in mind while using any type of diode.
1.Maximum forward current capacity
2.Maximum reverse voltage capacity
3.Maximum forward voltage capacity
Fig: 1N4007 diodes
The number and voltage capacity of some of the important diodes available in the market
are as follows:
 Diodes of number IN4001, IN4002, IN4003, IN4004, IN4005, IN4006 and IN4007 have
maximum reverse bias voltage capacity of 50V and maximum forward current capacity of 1
Amp.
 Diode of same capacities can be used in place of one another. Besides this diode of more
capacity can be used in place of diode of low capacity but diode of low capacity cannot be used
in place of diode of high capacity. For example, in place of IN4002; IN4001 or IN4007 can be
used but IN4001 or IN4002 cannot be used in place of IN4007.The diode BY125made by
company BEL is equivalent of diode from IN4001 to IN4003. BY 126 is equivalent to diodes
IN4004 to 4006 and BY 127 is equivalent to diode IN4007.

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Fig:PN Junction diode
PN JUNCTION OPERATION
Now that you are familiar with P- and N-type materials, how these materials are joined
together to form a diode, and the function of the diode, let us continue our discussion with the
operation of the PN junction. But before we can understand how the PN junction works, we must
first consider current flow in the materials that make up the junction and what happens initially
within the junction when these two materials are joined together.
Current Flow in the N-Type Material
Conduction in the N-type semiconductor, or crystal, is similar to conduction in a copper
wire. That is, with voltage applied across the material, electrons will move through the crystal
just as current would flow in a copper wire. This is shown in figure 1-15. The positive potential
of the battery will attract the free electrons in the crystal. These electrons will leave the crystal
and flow into the positive terminal of the battery. As an electron leaves the crystal, an electron from
the negative terminal of the battery will enter the crystal, thus completing the current path.

44
Therefore, the majority current carriers in the N-type material (electrons) are repelled by the
negative side of the battery and move through the crystal toward the positive side of the battery.
Current Flow in the P-Type Material
Current flow through the P-type material is illustrated. Conduction in the P material is by
positive holes, instead of negative electrons. A hole moves from the positive terminal of the P
material to the negative terminal. Electrons from the external circuit enter the negative terminal
of the material and fill holes in the vicinity of this terminal. At the positive terminal, electrons
are removed from the covalent bonds, thus creating new holes. This process continues as the
steady stream of holes (hole current) moves toward the negative terminal
4.12 RESISTORS
A resistor is a two-terminal electronic component designed to oppose an electric current by
producing a voltage drop between its terminals in proportion to the current, that is, in accordance
with Ohm's law:
V = IR
Resistors are used as part of electrical networks and electronic circuits. They are
extremely commonplace in most electronic equipment. Practical resistors can be made of various

45
compounds and films, as well as resistance wire (wire made of a high-resistivity alloy, such as
nickel/chrome).
The primary characteristics of resistors are their resistance and the power they can
dissipate. Other characteristics include temperature coefficient, noise, and inductance. Less well-
known is critical resistance, the value below which power dissipation limits the maximum
permitted current flow, and above which the limit is applied voltage. Critical resistance depends
upon the materials constituting the resistor as well as its physical dimensions; it's determined by
design.
Resistors can be integrated into hybrid and printed circuits, as well as integrated
circuits. Size, and position of leads (or terminals) are relevant to equipment designers; resistors
must be physically large enough not to overheat when dissipating their power.
A resistor is a two-terminal passive electronic component which implements electrical
resistance as a circuit element. When a voltage V is applied across the terminals of a resistor, a
current I will flow through the resistor in direct proportion to that voltage. The reciprocal of the
constant of proportionality is known as the resistance R, since, with a given voltage V, a larger
value of R further "resists" the flow of current I as given by Ohm's law:
Resistors are common elements of electrical networks and electronic circuits and are
ubiquitous in most electronic equipment. Practical resistors can be made of various compounds

46
and films, as well as resistance wire (wire made of a high-resistivity alloy, such as nickel-
chrome). Resistors are also implemented within integrated circuits, particularly analog devices,
and can also be integrated into hybrid and printed circuits.
The electrical functionality of a resistor is specified by its resistance: common
commercial resistors are manufactured over a range of more than 9 orders of magnitude. When
specifying that resistance in an electronic design, the required precision of the resistance may
require attention to the manufacturing tolerance of the chosen resistor, according to its specific
application. The temperature coefficient of the resistance may also be of concern in some
precision applications. Practical resistors are also specified as having a maximum power rating
which must exceed the anticipated power dissipation of that resistor in a particular circuit: this is
mainly of concern in power electronics applications. Resistors with higher power ratings are
physically larger and may require heat sinking. In a high voltage circuit, attention must
sometimes be paid to the rated maximum working voltage of the resistor.
The series inductance of a practical resistor causes its behaviour to depart from ohms law;
this specification can be important in some high-frequency applications for smaller values of
resistance. In a low-noise amplifier or pre-amp the noise characteristics of a resistor may be an
issue. The unwanted inductance, excess noise, and temperature coefficient are mainly dependent
on the technology used in manufacturing the resistor. They are not normally specified
individually for a particular family of resistors manufactured using a particular technology. A
family of discrete resistors is also characterized according to its form factor, that is, the size of
the device and position of its leads (or terminals) which is relevant in the practical manufacturing
of circuits using them.
Units
The ohm (symbol: Ω) is the SI unit of electrical resistance, named after Georg Simon
Ohm. An ohm is equivalent to a volt per ampere. Since resistors are specified and manufactured
over a very large range of values, the derived units of milliohm (1 mΩ = 10−3 Ω), kilohm (1 kΩ =
103 Ω), and megohm (1 MΩ = 106 Ω) are also in common usage.
The reciprocal of resistance R is called conductance G = 1/R and is measured in Siemens
(SI unit), sometimes referred to as a mho. Thus a Siemens is the reciprocal of an ohm: S = Ω − 1.

47
Although the concept of conductance is often used in circuit analysis, practical resistors are
always specified in terms of their resistance (ohms) rather than conductance.
Theory of operation
Ohm's law
The behaviour of an ideal resistor is dictated by the relationship specified in Ohm's law:
Ohm's law states that the voltage (V) across a resistor is proportional to the current (I) passing
through it, where the constant of proportionality is the resistance (R).
Equivalently, Ohm's law can be stated:
This formulation of Ohm's law states that, when a voltage (V) is present across a resistance (R), a
current (I) will flow through the resistance. This is directly used in practical computations. For
example, if a 300 ohm resistor is attached across the terminals of a 12 volt battery, then a current
of 12 / 300 = 0.04 amperes (or 40 mill amperes) will flow through that resistor.
Series and parallel resistors
In a series configuration, the current through all of the resistors is the same, but the
voltage across each resistor will be in proportion to its resistance. The potential difference
(voltage) seen across the network is the sum of those voltages, thus the total resistance can be
found as the sum of those resistances:
As a special case, the resistance of N resistors connected in series, each of the same resistance R,
is given by NR.

48
Resistors in a parallel configuration are each subject to the same potential difference (voltage),
however the currents through them add. The conductance of the resistors then add to determine
the conductance of the network. Thus the equivalent resistance (Req) of the network can be
computed:
The parallel equivalent resistance can be represented in equations by two vertical lines "||" (as in
geometry) as a simplified notation. For the case of two resistors in parallel, this can be calculated
using:
As a special case, the resistance of N resistors connected in parallel, each of the same resistance
R, is given by R/N.
A resistor network that is a combination of parallel and series connections can be broken up into
smaller parts that are either one or the other. For instance,

49
However, some complex networks of resistors cannot be resolved in this manner, requiring more
sophisticated circuit analysis. For instance, consider a cube, each edge of which has been
replaced by a resistor. What then is the resistance that would be measured between two opposite
vertices? In the case of 12 equivalent resistors, it can be shown that the corner-to-corner
resistance is 5⁄6 of the individual resistance. More generally, the Y-Δ transform, or matrix
methods can be used to solve such a problem. One practical application of these relationships is
that a non-standard value of resistance can generally be synthesized by connecting a number of
standard values in series and/or parallel. This can also be used to obtain a resistance with a
higher power rating than that of the individual resistors used. In the special case of N identical
resistors all connected in series or all connected in parallel, the power rating of the individual
resistors is thereby multiplied by N.
4.13 CAPACITORS

50
A capacitor or condenser is a passive electronic component consisting of a pair of
conductors separated by a dielectric. When a voltage potential difference exists between the
conductors, an electric field is present in the dielectric. This field stores energy and produces a
mechanical force between the plates. The effect is greatest between wide, flat, parallel, narrowly
separated conductors.
An ideal capacitor is characterized by a single constant value, capacitance, which is
measured in farads. This is the ratio of the electric charge on each conductor to the potential
difference between them. In practice, the dielectric between the plates passes a small amount of
leakage current. The conductors and leads introduce an equivalent series resistance and the
dielectric has an electric field strength limit resulting in a breakdown voltage.
The properties of capacitors in a circuit may determine the resonant frequency and
quality factor of a resonant circuit, power dissipation and operating frequency in a digital logic
circuit, energy capacity in a high-power system, and many other important aspects.
A capacitor (formerly known as condenser) is a device for storing electric charge. The
forms of practical capacitors vary widely, but all contain at least two conductors separated by a
non-conductor. Capacitors used as parts of electrical systems, for example, consist of metal foils
separated by a layer of insulating film.

51
Capacitors are widely used in electronic circuits for blocking direct current while
allowing alternating current to pass, in filter networks, for smoothing the output of power
supplies, in the resonant circuits that tune radios to particular frequencies and for many other
purposes.
A capacitor is a passive electronic component consisting of a pair of conductors separated
by a dielectric (insulator). When there is a potential difference (voltage) across the conductors, a
static electric field develops in the dielectric that stores energy and produces a mechanical force
between the conductors. An ideal capacitor is characterized by a single constant value,
capacitance, measured in farads. This is the ratio of the electric charge on each conductor to the
potential difference between them.
The capacitance is greatest when there is a narrow separation between large areas of
conductor, hence capacitor conductors are often called "plates", referring to an early means of
construction. In practice the dielectric between the plates passes a small amount of leakage
current and also has an electric field strength limit, resulting in a breakdown voltage, while the
conductors and leads introduce an undesired inductance and resistance.
Theory of operation
Capacitance
Charge separation in a parallel-plate capacitor causes an internal electric field. A dielectric
(orange) reduces the field and increases the capacitance.
A capacitor consists of two conductors separated by a non-conductive region. The non-
conductive region is called the dielectric or sometimes the dielectric medium. In simpler terms,
the dielectric is just an electrical insulator. Examples of dielectric mediums are glass, air, paper,

52
vacuum, and even a semiconductor depletion region chemically identical to the conductors. A
capacitor is assumed to be self-contained and isolated, with no net electric charge and no
influence from any external electric field. The conductors thus hold equal and opposite charges
on their facing surfaces, and the dielectric develops an electric field. In SI units, a capacitance of
one farad means that one coulomb of charge on each conductor causes a voltage of one volt
across the device.
The capacitor is a reasonably general model for electric fields within electric circuits. An
ideal capacitor is wholly characterized by a constant capacitance C, defined as the ratio of charge
±Q on each conductor to the voltage V between them:
Sometimes charge build-up affects the capacitor mechanically, causing its capacitance to
vary. In this case, capacitance is defined in terms of incremental changes:
Energy storage
Work must be done by an external influence to "move" charge between the conductors in a
capacitor. When the external influence is removed the charge separation persists in the electric
field and energy is stored to be released when the charge is allowed to return to its equilibrium
position. The work done in establishing the electric field, and hence the amount of energy stored,
is given by:
Current-voltage relation
The current i(t) through any component in an electric circuit is defined as the rate of flow
of a charge q(t) passing through it, but actual charges, electrons, cannot pass through the
dielectric layer of a capacitor, rather an electron accumulates on the negative plate for each one
that leaves the positive plate, resulting in an electron depletion and consequent positive charge
on one electrode that is equal and opposite to the accumulated negative charge on the other. Thus
the charge on the electrodes is equal to the integral of the current as well as proportional to the

53
voltage as discussed above. As with any anti-derivative, a constant of integration is added to
represent the initial voltage v (t0). This is the integral form of
the capacitor equation,
.
Taking the derivative of this, and multiplying by C, yields the derivative form,
.
The dual of the capacitor is the inductor, which stores energy
in the magnetic field rather than the electric field. Its current-
voltage relation is obtained by exchanging current and voltage
in the capacitor equations and replacing C with the inductance
L.

54
ULTRASONIC SENSOR MODULE
Here is a more easy use serial ultrasonic module. It will auto output the distance
information via serial port after power on, you don't need to do any trigger and calculated, just
need to read the serial pin and get the distance information.
Ultrasonic sensor provides a very low-cost and easy method of distance measurement.
This sensor is perfect for any number of applications that require you to perform measurements
between moving or stationary objects. Naturally, robotics applications are very popular but you'll
also find this product to be useful in security systems or as an infrared replacement if so desired.
You will definitely appreciate the activity status LED and the economic use of just one I/O pin.
The ultrasonic sensor measures distance using sonar; an ultrasonic (well above human
hearing) pulse is transmitted from the unit and distance-to-target is determined by measuring the
time required for the echo return. Output from the ultrasonic sensor is a variable-width pulse that
corresponds to the distance to the target.
Features:
 Provides precise, non-contact distance measurements within a 2 cm to 3 m range

55
 Simple pulse in/pulse out communication
 Burst indicator LED shows measurement in progress
 20 mA power consumption
 Narrow acceptance angle
 3-pin header makes it easy to connect using a servo extension cable, no soldering
required
Key Specifications:
 power supply :5V DC
 quiescent current : <15mA
 effectual angle: <15°
 ranging distance : 2cm – 350 cm
 resolution : 0.3 cm
 Output cycle : 50ms
 Baud Rate : 9600
Output frame format （4Bytes）
 1st Byte : 0xFF (Start bit, Fixed value)
 2nd Byte: H_Data (High 8 bit of the distance)
 3rd Byte: L_Date (Low 8 bit of the distance)
 4th Byte: Check Sum (0XFF+H_DATA+L_DATA=SUM, Check SUM is the low 8 bit of
the SUM)
Uses:
Ultrasonic sensors are used to detect the presence of targets and to measure the distance
to targets in many automated factories and process plants. Sensors with an on or off digital
output are available for detecting the presence of objects, and sensors with an analog output

56
which varies proportionally to the sensor to target separation distance are commercially
available.
Because ultrasonic sensors use sound rather than light for detection, they work in
applications where photoelectric sensors may not. Ultrasonic are a great solution for clear object
detection and for liquid level measurement, applications that photo electrics struggle with
because of target translucence. Target colour and/or reflectivity don't affect ultrasonic sensors
which can operate reliably in high-glare environments.
Other types of transducers are used in commercially available ultrasonic cleaning
devices. An ultrasonic transducer is affixed to a stainless steel pan which is filled with a solvent
(frequently water or isopropanol) and a square wave is applied to it, imparting vibrational energy
on the liquid.
TEMPERATURE AND HUMIDITY SENSOR
The DHT11 sensor comes in a single row 4-pin package and operates from 3.5 to 5.5V
power supply. It can measure temperature from 0-50 °C with an accuracy of ±2°C and
relative humidity ranging from 20-95% with an accuracy of ±5%. The sensor provides fully
calibrated digital outputs for the two measurements. It has got its own proprietary 1-wire
protocol, and therefore, the communication between the sensor and a microcontroller is not
possible through a direct interface with any of its peripherals. The protocol must be
implemented in the firmware of the MCU with precise timing required by the sensor.

57
DHT11 sensor comes in a single row 4-pin package
The following timing diagrams describe the data transfer protocol between a MCU and the
DHT11 sensor. The MCU initiates data transmission by issuing a “Start” signal. The MCU pin
must be configured as output for this purpose. The MCU first pulls the data line low for at
least 18 ms and then pulls it high for next 20-40 ?s before it releases it. Next, the sensor
responds to the MCU “Start” signal by pulling the line low for 80 ?s followed by a logic high
signal that also lasts for 80 ?s. Remember that the MCU pin must be configured to input
after finishing the “Start” signal. Once detecting the response signal from the sensor, the
MCU should be ready to receive data from the sensor. The sensor then sends 40 bits (5
bytes) of data continuously in the data line. Note that while transmitting bytes, the sensor
sends the most significant bit first.
"Start" and "Response" signals
The 40-bit data from the sensor has the following structure.

58
Data (40-bit) = Integer Byte of RH + Decimal Byte of RH + Integer Byte of Temp. + Decimal Byte
of Temp. + Checksum Byte
For DHT11 sensor, the decimal bytes of temperature and humidity measurements are
always zero. Therefore, the first and third bytes of received data actually give the numeric
values of the measured relative humidity (%) and temperature (°C). The last byte is the
checksum byte which is used to make sure that the data transfer has happened without
any error. If all the five bytes are transferred successfully then the checksum byte must be
equal to the last 8 bits of the sum of the first four bytes, i.e.,
Checksum = Last 8 bits of (Integer Byte of RH + Decimal Byte of RH + Integer Byte of Temp. +
Decimal Byte of Temp.)
Now lets talk about the most important thing, which is signalling for transmitting “0” and
“1”. In order to send a bit of data, the sensor first pulls the line low for 50 ?s. Then it raises
the line to high for 26-28 ?s if it has to send “0”, or for 70 ?s if the bit to be transmitted is
“1”. So it is the width of the positive pulse that carries information about 1 and 0.
Timing difference for transmitting "1s" and "0s"
Start, Response and Data signals in sequence
At the end of the last transmitted bit, the sensor pulls the data line low for 50 ?s and then
releases it. The DHT11 sensor requires an external pull-up resistor to be connected

59
between its Vcc and the data line so that under idle condition, the data line is always pulled
high. After finishing the data transmission and releasing the data line, the DHT11 sensor
goes to the low-power consumption mode until a new “Start” signal arrives from the MCU.
LIQUID CRYSTAL DISPLAY (LCD)
Description:
This is the example for the Parallel Port. This example doesn't use the Bi-directional
feature found on newer ports, thus it should work with most, if not all Parallel Ports. It however
doesn't show the use of the Status Port as an input for a 16 Character x 2 Line LCD Module to
the Parallel Port. These LCD Modules are very common these days, and are quite simple to work
with, as all the logic required running them is on board.
Pros:
 Very compact and light
 Low power consumption
 No geometric distortion
 Little or no flicker depending on backlight technology
 Not affected by screen burn-in
 No high voltage or other hazards present during repair/service
 Can be made in almost any size or shape
 No theoretical resolution limit
LCD Background:
Frequently, an 8051 program must interact with the outside world using input and output
devices that communicate directly with a human being. One of the most common devices
attached to an 8051 is an LCD display. Some of the most common LCDs connected to the 8051
are 16x2 and 20x2 displays. This means 16 characters per line by 2 lines and 20 characters per
line by 2 lines, respectively.

60
Fortunately, a very popular standard exists which allows us to communicate with the vast
majority of LCDs regardless of their manufacturer. The standard is referred to as HD44780U,
which refers to the controller chip which receives data from an external source (in this case, the
8051) and communicates directly with the LCD.
FIG 4.10: LCD
44780 LCD BACKGROUND
The 44780 standard requires 3 control lines as well as either 4 or 8 I/O lines for the data
bus. The user may select whether the LCD is to operate with a 4-bit data bus or an 8-bit data bus.
If a 4-bit data bus is used the LCD will require a total of 7 data lines (3 control lines plus the 4
lines for the data bus). If an 8-bit data bus is used the LCD will require a total of 11 data lines (3
control lines plus the 8 lines for the data bus).

61
The three control lines are referred to as EN, RS, and RW.
The EN line is called "Enable." This control line is used to tell the LCD that you are
sending it data. To send data to the LCD, your program should make sure this line is low (0) and
then set the other two control lines and/or put data on the data bus. When the other lines are
completely ready, bring EN high (1) and wait for the minimum amount of time required by the
LCD datasheet (this varies from LCD to LCD), and end by bringing it low (0) again.
The RS line is the "Register Select" line. When RS is low (0), the data is to be treated as a
command or special instruction (such as clear screen, position cursor, etc.). When RS is high (1),
the data being sent is text data which should be displayed on the screen. For example, to display
the letter "T" on the screen you would set RS high.
The RW line is the "Read/Write" control line. When RW is low (0), the information on
the data bus is being written to the LCD. When RW is high (1), the program is effectively
querying (or reading) the LCD. Only one instruction ("Get LCD status") is a read command. All
others are write commands--so RW will almost always be low .Finally, the data bus consists of 4
or 8 lines (depending on the mode of operation selected by the user). In the case of an 8-bit data
bus, the lines are referred to as DB0, DB1, DB2, DB3, DB4, DB5, DB6, and DB7.
How LCDs Work?
The principle behind the LCD’s is that when an electrical current is applied to the liquid crystal
molecule, the molecule tends to untwist. This causes the angle of light which is passing through
the molecule of the polarized glass and also cause a change in the angle of the top polarizing
filter. As a result a little light is allowed to pass the polarized glass through a particular area of

62
the LCD. Thus that particular area will become dark compared to other. The LCD works on the
principle of blocking light. While constructing the LCD’s, a reflected mirror is arranged at the
back. An electrode plane is made of indium-tin oxide which is kept on top and a polarized glass
with a polarizing film is also added on the bottom of the device. The complete region of the LCD
has to be enclosed by a common electrode and above it should be the liquid crystal matter.
Next comes to the second piece of glass with an electrode in the form of the rectangle on the
bottom and, on top, another polarizing film. It must be considered that both the pieces are kept at
right angles. When there is no current, the light passes through the front of the LCD it will be
reflected by the mirror and bounced back. As the electrode is connected to a battery the current
from it will cause the liquid crystals between the common-plane electrode and the electrode
shaped like a rectangle to untwist. Thus the light is blocked from passing through. That particular
rectangular area appears blank.
Advantages of an LCD’s:
o LCD’s consumes less amount of power compared to CRT and LED
o LCD’s are consist of some microwatts for display in comparison to some mill watts for LED’s
o LCDs are of low cost
o Provides excellent contrast
o LCD’s are thinner and lighter when compared to cathode ray tube and LED

63
5. SOFTWARE REQUIREMENTS
Software Requirement:
Arduino
Arduino is an open-source prototyping platform based on easy-to-use hardware and
software. Arduino boards are able to read inputs - light on a sensor, a finger on a button,
or a Twitter message - and turn it into an output - activating a motor, turning on an
LED, publishing something online. You can tell your board what to do by sending a
set of instructions to the microcontroller on the board. To do so you use the Arduino
programming language (based onWiring), and the Arduino Software (IDE), based
on Processing.
Over the years Arduino has been the brain of thousands of projects, from everyday
objects to complex scientific instruments. A worldwide community of makers -
students, hobbyists, artists, programmers, and professionals - has gathered around this

64
open-source platform, their contributions have added up to an incredible amount
of accessible knowledge that can be of great help to novices and experts alike.
Arduino was born at the Ivrea Interaction Design Institute as an easy tool for fast
prototyping, aimed at students without a background in electronics and programming.
As soon as it reached a wider community, the Arduino board started changing to adapt
to new needs and challenges, differentiating its offer from simple 8-bit boards to
products for IoT applications, wearable, 3D printing, and embedded environments. All
Arduino boards are completely open-source, empowering users to build them
independently and eventually adapt them to their particular needs. The software, too, is
open-source, and it is growing through the contributions of users worldwide.
Why Arduino?
Thanks to its simple and accessible user experience, Arduino has been used in
thousands of different projects and applications. The Arduino software is easy-to-use
for beginners, yet flexible enough for advanced users. It runs on Mac, Windows, and
Linux. Teachers and students use it to build low cost scientific instruments, to prove
chemistry and physics principles, or to get started with programming and robotics.
Designers and architects build interactive prototypes, musicians and artists use it for
installations and to experiment with new musical instruments. Makers, of course, use
it to build many of the projects exhibited at the Maker Faire, for example. Arduino is a
key tool to learn new things. Anyone - children, hobbyists, artists, programmers - can
start tinkering just following the step by step instructions of a kit, or sharing ideas
online with other members of the Arduino community.
There are many other microcontrollers and microcontroller platforms available for
physical computing. Parallax Basic Stamp, Netmedia's BX-24, Phidgets, MIT's

65
Handyboard, and many others offer similar functionality. All of these tools take the
messy details of microcontroller programming and wrap it up in an easy-to-use
package. Arduino also simplifies the process of working with microcontrollers, but it
offers some advantage for teachers, students, and interested amateurs over other
systems:
 Inexpensive - Arduino boards are relatively inexpensive compared to other
microcontroller platforms. The least expensive version of the Arduino module can be
assembled by hand, and even the pre-assembled Arduino modules cost less than $50
 Cross-platform - The Arduino Software (IDE) runs on Windows, Macintosh OSX,
and Linux operating systems. Most microcontroller systems are limited to Windows.
 Simple, clear programming environment - The Arduino Software (IDE) is easy-to-use
for beginners, yet flexible enough for advanced users to take advantage of as well. For
teachers, it's conveniently based on the Processing programming environment, so
students learning to program in that environment will be familiar with how the
Arduino IDE works.
 Open source and extensible software - The Arduino software is published as open
source tools, available for extension by experienced programmers. The language can
be expanded through C++ libraries, and people wanting to understand the technical
details can make the leap from Arduino to the AVR C programming language on
which it's based. Similarly, you can add AVR-C code directly into your Arduino
programs if you want to.
 Open source and extensible hardware - The plans of the Arduino boards are published
under a Creative Commons license, so experienced circuit designers can make their
own version of the module, extending it and improving it. Even relatively
inexperienced users can build the breadboard version of the module in order to
understand how it works and save money.
Arduino Uno
The most common version of Arduino is the Arduino Uno. This board is what
most people are talking about when they refer to an Arduino. In the next step,
there is a more complete rundown of its features.

66
Arduino NG, Diecimila, and the Duemilanove (Legacy Versions)
Legacy versions of the Arduino Uno product line consist of the NG, Diecimila,
and the Duemilanove. The important thing to note about legacy boards is that
they lack particular feature of the Arduino Uno. Some key differences:
 The Diecimila and NG use an ATMEGA168 chips (as opposed to the more
powerful ATMEGA328),
 Both the Diecimila and NG have a jumper next to the USB port and require
manual selection of either USB or battery power.
 The Arduino NG requires that you hold the rest button on the board for a few
seconds prior to uploading a program.
Arduino Mega 2560
The Mega is the second most commonly encountered version of the Arduino
family. The Arduino Mega is like the Arduino Uno's beefier older brother. It boasts
256 KB of memory (8 times more than the Uno). It also had 54 input and output
pins, 16 of which are analog pins, and 14 of which can do PWM. However, all of
the added functionality comes at the cost of a slightly larger circuit board. It may
make your project more powerful, but it will also make your project larger. Check
out the official Arduino Mega 2560 page for more details.
Arduino Mega ADK
This specialized version of the Arduino is basically an Arduino Mega that has
been specifically designed for interfacing with Android smartphones.
Arduino LilyPad
The LilyPad was designed for wearable and e-textile applications. It is intended
to be sewn to fabric and connected to other sewable components using
conductive thread. This board requires the use of a special FTDI-USB TTL serial
programming cable. For more information, the Arduino LilyPad page is a decent
starting point.

67
Some people think of the entire Arduino board as a microcontroller, but this is
inaccurate. The Arduino board actually is a specially designed circuit board for
programming and prototyping with Atmel microcontrollers.
The nice thing about the Arduino board is that it is relatively cheap, plugs straight
into a computer's USB port, and it is dead-simple to setup and use (compared to
other development boards).
Some of the key features of the Arduino Uno include:
 An open source design. The advantage of it being open source is that it has
a large community of people using and troubleshooting it. This makes it easy to
find someone to help you debug your projects.
 An easy USB interface . The chip on the board plugs straight into your USB
port and registers on your computer as a virtual serial port. This allows you to
interface with it as through it were a serial device. The benefit of this setup is
that serial communication is an extremely easy (and time-tested) protocol,
and USB makes connecting it to modern computers really convenient.
 Very convenient power management and built-in voltage regulation. You can
connect an external power source of up to 12v and it will regulate it to both 5v
and 3.3v. It also can be powered directly off of a USB port without any
external power.
 An easy-to-find, and dirt cheap, microcontroller "brain." The ATmega328 chip
retails for about $2.88 on Digikey. It has countless number of nice hardware
features like timers, PWM pins, external and internal interrupts, and multiple
sleep modes. Check out the official datasheetfor more details.
 A 16mhz clock. This makes it not the speediest microcontroller around, but
fast enough for most applications.
 32 KB of flash memory for storing your code.
 13 digital pins and 6 analog pins. These pins allow you to connect external
hardware to your Arduino. These pins are key for extending the computing
capability of the Arduino into the real world. Simply plug your devices and

68
sensors into the sockets that correspond to each of these pins and you are
good to go.
 An ICSP connector for bypassing the USB port and interfacing the Arduino
directly as a serial device. This port is necessary to re-bootload your chip if it
corrupts and can no longer talk to your computer.
 An on-board LED attached to digital pin 13 for fast an easy debugging of
code.
 And last, but not least, a button to reset the program on the chip.

70
9. CODING
#include <iotgecko.h>
#include <LiquidCrystal.h>
#include "DHT.h"
#define esp_baudrate9600
///////variables////////////////
String id = "tejas.chandegara3@gmail.com"; //iotgecko login id
String pass = "9583"; //iotgecko login password
String ssid = "iot"; // SSID/nameof your wifirouter or wifi hotspot
String pass_key = "project1234"; //Wifi password
bool notConected = true;
bool login = false;
constint no_of_senddata = 5;
constint no_of_getdata = 0;
String iot_data[no_of_senddata];
int motor_status[no_of_getdata];
int pump_status = 0;
unsigned long current_time ;
iotgecko gecko = iotgecko(esp_baudrate);
constint rs = 13, en = 12, d4 = 11, d5 = 10, d6 = 9, d7 = 8;
LiquidCrystallcd(rs, en, d4, d5, d6, d7);

71
#define trigPin A4
#define echoPin A5
#define DHTPIN4
#define Water_Level_Sensor 6
#define buzzer 5
int buttonState = 0; // variablefor reading the pushbutton status
long duration;
int distance;
#define DHTTYPEDHT11
DHTdht(DHTPIN, DHTTYPE);
volatile int flow_frequency; // Measures flow sensor pulses
unsigned int l_hour; // Calculated litres/hour
unsigned char flowsensor =2; // Sensor Input
unsigned long currentTime;
unsigned long cloopTime;
int humidity, temperature;
bool water_level;
void flow () // Interruptfunction
{
flow_frequency++;
}
void setup() {
lcd.begin (20, 4);
lcd.clear();
//lcd.setCursor(0,0);
lcd.print(" FLOOD DETECTION");
// lcd.clear();
lcd.setCursor(0, 1);
lcd.print(" SYSTEM");
// lcd.clear();
delay(2000);
lcd.clear();
lcd.print(F("Connecting Wifi"));
gecko.listen();

72
while (notConected)
{
if (gecko.GeckoConnect(ssid, pass_key)) //connectto wifi with given SSID and
password
{
while (!login)
{
if (gecko.GeckoVerify(id, pass))//login to iotgecko.com with given ID and
password
{
lcd.clear();
lcd.print(F("Connected"));
login = true;
notConected = false;
}
}
}
delay(1000);
lcd.clear();
// pinMode (Led, OUTPUT);
pinMode (trigPin, OUTPUT);
pinMode (echoPin, INPUT);
dht.begin();
pinMode(Water_Level_Sensor, INPUT);
// pinMode(LED_BUILTIN, OUTPUT);
pinMode(buzzer, OUTPUT);
pinMode(flowsensor, INPUT);
digitalWrite(flowsensor, HIGH); //OptionalInternalPull-Up
attachInterrupt(0, flow, RISING); //Setup Interrupt
sei(); // Enable interrupts
currentTime = millis();
cloopTime = currentTime;

73
Serial.begin (9600);
}
}
void loop()
{
loop1();
//delay(500);
loop2();
//delay(500);
loop3();
//delay(500);
loop4();
delay(2000);
//iot_data[0] =(String)2;
iot_data[0] =(String)temperature;
iot_data[1] = (String)humidity;
iot_data[2] = (String)distance;
iot_data[3] = (String)l_hour;
iot_data[4] = (String)water_level;
int iot_status = gecko.SendandGetGParams(iot_data,no_of_senddata,
motor_status , no_of_getdata);//send and get data on iotgecko.com
if(iot_status == VALID)
{
}
else
{
lcd.clear();
lcd.print(F("reconnecting"));
while(!gecko.GeckoReconnect())//reconnectto the iotgecko.com
{
//Serial.println(F("conncetion failed.....reconnecting"));
delay(2000);
}
lcd.clear();

74
lcd.print("Connected");
//Serial.println(F("connected succesfully"));
}
delay(3000);
}
/*else
{
lcd.clear();
lcd.setCursor(5,0);
lcd.print("FLOOD DETECTION");
lcd.clear();
lcd.setCursor(8,1);
lcd.print("SYSTEM");
}
}*/
void loop1()
{
digitalWrite (trigPin, LOW);
delayMicroseconds (2);
digitalWrite (trigPin, HIGH);
duration = pulseIn (echoPin, HIGH);
distance = duration / 58 ;
Serial.print ("Distance :");
Serial.print (distance);
Serial.println (" cm ");
delay (120);
// lcd.clear();
lcd.setCursor(0, 0); //Sets the location at which subsequenttext written to the
LCD will be displayed
lcd.print("Distance :"); // Prints string "Distance" on the LCD
lcd.print(distance); // Prints the distance value fromthe sensor

75
lcd.print(" cm ");
//lcd.clear();
delay (120);
}
void loop2()
{
delay(2000);
// Reading temperature or humidity takes about 250 milliseconds!
// Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
int h = dht.readHumidity();
// Read temperature as Celsius (the default)
int t = dht.readTemperature();
// Read temperature as Fahrenheit (isFahrenheit= true)
//float f = dht.readTemperature(true);
// Check if any reads failed and exit early (to try again).
if (isnan(h) || isnan(t)) {
Serial.println("Failed to read fromDHT sensor!");
return;
}
// Compute heat index in Fahrenheit(the default)
// float hif = dht.computeHeatIndex(f, h);
// Compute heat index in Celsius (isFahreheit= false)
//float hic = dht.computeHeatIndex(t, h, false);
Serial.println("Humidity: ");
Serial.print(h);
Serial.println(" %t");
Serial.print("Temperature: ");
Serial.println(t);
Serial.println(" *C ");
// lcd.clear();
humidity = h;

76
temperature = t;
lcd.print(" HUM:");
lcd.print(h);
lcd.print("%");
lcd.print(" Temp:");
lcd.print(t);
lcd.print("*C");
delay(120);
//Serial.print(f);
// Serial.print(" *Ft");
// Serial.print("Heatindex: ");
// Serial.print(hic);
// Serial.print(" *C ");
// Serial.print(hif);
// Serial.println(" *F");
}
void loop3()
{
buttonState = digitalRead(Water_Level_Sensor);
if (buttonState == LOW) {
Serial.println( "WATER LEVEL - LOW");
// digitalWrite(LED_BUILTIN, LOW); // turn the LED on (HIGH is the voltage
level)
digitalWrite(buzzer, LOW);
// lcd.clear();
lcd.setCursor(0,3);
lcd.print("Water Level: LOW");
water_level = 0;
delay(500);
}
else {
Serial.println( "WATER LEVEL - HIGH" );
//digitalWrite(LED_BUILTIN, HIGH); // turn the LED on (HIGH is the voltage
level)
digitalWrite(buzzer, HIGH);

77
// lcd.clear();
lcd.setCursor(0,3);
lcd.print("Water Level:HIGH");
water_level=1;
// lcd.print("Floa
delay(500);
}
}
void loop4()
{
// Every second, calculate and print litres/hour
if (currentTime>= (cloopTime + 1000))
{
cloopTime = currentTime; // Updates cloopTime
// Pulsefrequency (Hz) = 7.5Q, Q is flow rate in L/min.
l_hour = (flow_frequency * 60 / 7.5); // (Pulse frequency x 60 min) / 7.5Q =
flowratein L/hour
flow_frequency = 0; // Reset Counter
Serial.print(l_hour, DEC); // Print litres/hour
Serial.println(" L/hour");
lcd.setCursor(0,2);
lcd.print("Flow Level:");
lcd.print(l_hour, DEC);
lcd.print(" L/H ");
}
}#include <iotgecko.h>
#include <LiquidCrystal.h>
#include "DHT.h"
#define esp_baudrate9600
///////variables////////////////
String id = "tejas.chandegara3@gmail.com"; //iotgecko login id

78
String pass = "9583"; //iotgecko login password
String ssid = "iot"; // SSID/nameof your wifirouter or wifi hotspot
String pass_key = "project1234"; //Wifi password
bool notConected = true;
bool login = false;
constint no_of_senddata = 5;
constint no_of_getdata = 0;
String iot_data[no_of_senddata];
int motor_status[no_of_getdata];
int pump_status = 0;
unsigned long current_time ;
iotgecko gecko = iotgecko(esp_baudrate);
constint rs = 13, en = 12, d4 = 11, d5 = 10, d6 = 9, d7 = 8;
LiquidCrystallcd(rs, en, d4, d5, d6, d7);
#define trigPin A4
#define echoPin A5
#define DHTPIN4
#define Water_Level_Sensor 6
#define buzzer 5
int buttonState = 0; // variablefor reading the pushbutton status
long duration;
int distance;
#define DHTTYPEDHT11
DHTdht(DHTPIN, DHTTYPE);
volatile int flow_frequency; // Measures flow sensor pulses
unsigned int l_hour; // Calculated litres/hour
unsigned char flowsensor =2; // Sensor Input
unsigned long currentTime;

79
unsigned long cloopTime;
int humidity, temperature;
bool water_level;
void flow () // Interruptfunction
{
flow_frequency++;
}
void setup() {
lcd.begin (20, 4);
lcd.clear();
//lcd.setCursor(0,0);
lcd.print(" FLOOD DETECTION");
// lcd.clear();
lcd.print(" SYSTEM");
// lcd.clear();
delay(2000);
lcd.clear();
lcd.print(F("Connecting Wifi"));
gecko.listen();
while (notConected)
{
if (gecko.GeckoConnect(ssid, pass_key)) //connectto wifi with given SSID and
password
{
while (!login)
{
if (gecko.GeckoVerify(id, pass))//login to iotgecko.com with given ID and
password
{
lcd.clear();
lcd.print(F("Connected"));
login = true;
notConected = false;
}

80
}
}
delay(1000);
lcd.clear();
// pinMode (Led, OUTPUT);
pinMode (trigPin, OUTPUT);
pinMode (echoPin, INPUT);
dht.begin();
pinMode(Water_Level_Sensor, INPUT);
// pinMode(LED_BUILTIN, OUTPUT);
pinMode(buzzer, OUTPUT);
pinMode(flowsensor, INPUT);
digitalWrite(flowsensor, HIGH); //OptionalInternalPull-Up
attachInterrupt(0, flow, RISING); //Setup Interrupt
sei(); // Enable interrupts
cloopTime = currentTime;
Serial.begin (9600);
}
}
void loop()
{
loop1();
//delay(500);
loop2();
//delay(500);
loop3();
//delay(500);
loop4();
delay(2000);

81
//iot_data[0] =(String)2;
iot_data[0] =(String)temperature;
iot_data[1] = (String)humidity;
iot_data[2] = (String)distance;
iot_data[3] = (String)l_hour;
iot_data[4] = (String)water_level;
int iot_status = gecko.SendandGetGParams(iot_data,no_of_senddata,
motor_status , no_of_getdata);//send and get data on iotgecko.com
if(iot_status == VALID)
{
}
else
{
lcd.clear();
lcd.print(F("reconnecting"));
while(!gecko.GeckoReconnect())//reconnectto the iotgecko.com
{
//Serial.println(F("conncetion failed.....reconnecting"));
delay(2000);
}
lcd.clear();
lcd.print("Connected");
//Serial.println(F("connected succesfully"));
}
delay(3000);
}
/*else
{
lcd.clear();
lcd.setCursor(5,0);
lcd.print("FLOOD DETECTION");
lcd.clear();
lcd.setCursor(8,1);
lcd.print("SYSTEM");
}
}*/

82
void loop1()
{
digitalWrite (trigPin, HIGH);
duration = pulseIn (echoPin, HIGH);
distance = duration / 58 ;
Serial.print ("Distance :");
Serial.print (distance);
Serial.println (" cm ");
delay (120);
// lcd.clear();
lcd.setCursor(0, 0); //Sets the location at which subsequenttext written to the
LCD will be displayed
lcd.print("Distance :"); // Prints string "Distance" on the LCD
lcd.print(distance); // Prints the distance value fromthe sensor
lcd.print(" cm ");
//lcd.clear();
delay (120);
}
void loop2()
{
delay(2000);
// Reading temperature or humidity takes about 250 milliseconds!
// Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
int h = dht.readHumidity();
// Read temperature as Celsius (the default)
int t = dht.readTemperature();

83
// Read temperature as Fahrenheit (isFahrenheit= true)
//float f = dht.readTemperature(true);
// Check if any reads failed and exit early (to try again).
if (isnan(h) || isnan(t)) {
Serial.println("Failed to read fromDHT sensor!");
return;
}
// Compute heat index in Fahrenheit(the default)
// float hif = dht.computeHeatIndex(f, h);
// Compute heat index in Celsius (isFahreheit= false)
//float hic = dht.computeHeatIndex(t, h, false);
Serial.println("Humidity: ");
Serial.print(h);
Serial.println(" %t");
Serial.print("Temperature: ");
Serial.println(t);
Serial.println(" *C ");
// lcd.clear();
humidity = h;
temperature = t;
lcd.print(" HUM:");
lcd.print(h);
lcd.print("%");
lcd.print(" Temp:");
lcd.print(t);
lcd.print("*C");
delay(120);
//Serial.print(f);
// Serial.print(" *Ft");
// Serial.print("Heatindex: ");
// Serial.print(hic);
// Serial.print(" *C ");
// Serial.print(hif);

84
// Serial.println(" *F");
}
void loop3()
{
buttonState = digitalRead(Water_Level_Sensor);
if (buttonState == LOW) {
Serial.println( "WATER LEVEL - LOW");
// digitalWrite(LED_BUILTIN, LOW); // turn the LED on (HIGH is the voltage
level)
digitalWrite(buzzer, LOW);
// lcd.clear();
lcd.setCursor(0,3);
lcd.print("Water Level: LOW");
water_level = 0;
delay(500);
}
else {
Serial.println( "WATER LEVEL - HIGH" );
//digitalWrite(LED_BUILTIN, HIGH); // turn the LED on (HIGH is the voltage
level)
digitalWrite(buzzer, HIGH);
// lcd.clear();
lcd.setCursor(0,3);
lcd.print("Water Level:HIGH");
water_level=1;
// lcd.print("Floa
delay(500);
}
}
void loop4()
{
// Every second, calculate and print litres/hour
if (currentTime>= (cloopTime + 1000))
{

85
cloopTime = currentTime; // Updates cloopTime
// Pulsefrequency (Hz) = 7.5Q, Q is flow rate in L/min.
l_hour = (flow_frequency * 60 / 7.5); // (Pulse frequency x 60 min) / 7.5Q =
flowratein L/hour
flow_frequency = 0; // Reset Counter
Serial.print(l_hour, DEC); // Print litres/hour
Serial.println(" L/hour");
lcd.setCursor(0,2);
lcd.print("Flow Level:");
lcd.print(l_hour, DEC);
lcd.print(" L/H ");
}
}

86
Arduino IDE
Before you can start doing anything with the Arduino, you need to download and
install the Arduino IDE (integrated development environment). From this point on
we will be referring to the Arduino IDE as the Arduino Programmer.
The Arduino Programmer is based on the Processing IDE and uses a variation of
the C and C++ programming languages.

89
Before you can start doing anything in the Arduino programmer, you must set the
board-type and serial port.
To set the board, go to the following:
Tools --> Boards
Select the version of board that you are using. Since I have an Arduino Uno
plugged in, I obviously selected "Arduino Uno."
To set the serial port, go to the following:
Tools --> Serial Port

90
Select the serial port that looks like:
/dev/tty.usbmodem [random numbers]

93
Arduino programs are called sketches. The Arduino programmer comes with a
ton of example sketches preloaded. This is great because even if you have never
programmed anything in your life, you can load one of these sketches and get
the Arduino to do something.
To get the LED tied to digital pin 13 to blink on and off, let's load the blink
example.
The blink example can be found here:
Files --> Examples --> Basics --> Blink

94
The blink example basically sets pin D13 as an output and then blinks the
test LED on the Arduino board on and off every second.
Once the blink example is open, it can be installed onto the ATMEGA328
chip by pressing the upload button, which looks like an arrow pointing to
the right.
Notice that the surface mount status LED connected to pin 13 on the
Arduino will start to blink. You can change the rate of the blinking by
changing the length of the delay and pressing the upload button again.
Serial monitor

96
The serial monitor allows your computer to connect serially with the Arduino. This
is important because it takes data that your Arduino is receiving from sensors
and other devices and displays it in real-time on your computer. Having this
ability is invaluable to debug your code and understand what number values the
chip is actually receiving.
For instance, connect center sweep (middle pin) of a potentiometer to A0, and
the outer pins, respectively, to 5v and ground. Next upload the sketch shown
below:
File --> Examples --> 1.Basics --> AnalogReadSerial

97
Click the button to engage the serial monitor which looks like a magnifying
glass. You can now see the numbers being read by the analog pin in the
serial monitor. When you turn the knob the numbers will increase and
decrease.
The numbers will be between the range of 0 and 1023. The reason for this is
that the analog pin is converting a voltage between 0 and 5V to a discreet
number.
The Arduino has two different types of input pins, those being analog and digital.
To begin with, lets look at the digital input pins.
Digital input pins only have two possible states, which are on or off. These two on
and off states are also referred to as:
 HIGH or LOW
 1 or 0
 5V or 0V.
This input is commonly used to sense the presence of voltage when a switch is
opened or closed.
Digital inputs can also be used as the basis for countless digital communication
protocols. By creating a 5V (HIGH) pulse or 0V (LOW) pulse, you can create a
binary signal, the basis of all computing. This is useful for talking to digital
sensors like a PING ultrasonic sensor, or communicating with other devices.
For a simple example of a digital input in use, connect a switch from digital pin 2
to 5V, a 10K resistor** from digital pin 2 to ground, and run the following code:
File --> Examples --> 2.Digital --> Button

98
Analog in
Aside from the digital input pins, the Arduino also boasts a number of analog
input pins.
Analog input pins take an analog signal and perform a 10-bit analog-to-digital
(ADC) conversion to turn it into a number between 0 and 1023 (4.9mV steps).
This type of input is good for reading resistive sensors. These are basically
sensors which provide resistance to the circuit. They are also good for reading a
varying voltage signal between 0 and 5V. This is useful when interfacing with
various types of analog circuitry.

99
To write your own code, you will need to learn some basic programming
language syntax. In other words, you have to learn how to properly form the code
for the programmer to understand it. You can think of this kind of like
understanding grammar and punctuation. You can write an entire book without
proper grammar and punctuation, but no one will be abler to understand it, even
if it is in English.
Some important things to keep in mind when writing your own code:
 An Arduino program is called a sketch.
 All code in an Arduino sketch is processed from top to bottom.
 Arduino sketches are typically broken into five parts.

100
1. The sketch usually starts with a header that explains what the sketch is
doing, and who wrote it.
2. Next, it usually defines global variables. Often, this is where constant names
are given to the different Arduino pins.
3. After the initial variables are set, the Arduino begins the setup routine. In the
setup function, we set initial conditions of variables when necessary, and
run any preliminary code that we only want to run once. This is where serial
communication is initiated, which is required for running the serial monitor.
4. From the setup function, we go to the loop routine. This is the main routine
of the sketch. This is not only where your main code goes, but it will be
executed over and over, so long as the sketch continues to run.
5. Below the loop routine, there is often other functions listed. These functions
are user-defined and only activated when called in the setup and loop
routine. When these functions are called, the Arduino processes all of the
code in the function from top to bottom and then goes back to the next line
in the sketch where it left off when the function was called. Functions are
good because they allow you to run standard routines - over and over -
without having to write the same lines of code over and over. You can
simply call upon a function multiple times, and this will free up memory on
the chip because the function routine is only written once. It also makes
code easier to read. To learn how to form your own functions, check outthis
page.
 All of that said, the only two parts of the sketch which are mandatory are the
Setup and Loop routines.
 Code must be written in the Arduino Language, which is roughly based on C.
 Almost all statements written in the Arduino language must end with a ;
 Conditionals (such as if statements and for loops) do not need a ;
 Conditionals have their own rules and can be found under "Control
Structures" on the Arduino Language page
 Variables are storage compartments for numbers. You can pass values into
and out of variables. Variables must be defined (stated in the code) before
they can be used and need to have a data type associated with it. To learn
some of the basic data types, review the Language Page.

101
Okay! So let us say we want to write code that reads a photocell connected to pin
A0, and use the reading we get from the photocell to control the brightness of an
LED connected to pin D9.
First, we want to open the BareMinimum sketch, which can be found at:
File --> Examples --> 1.Basic --> BareMinimum
The BareMinimum Sketch should look like this:
<pre>void setup() {
// put your setup code here, to run once:
}
void loop() {
// put your main code here, to run repeatedly:
}
Next, lets put a header on the code, so other people know about what we are
making, why, and under what terms:
<pre>/*
LED Dimmer
by Genius Arduino Programmer
2012

102
Controls the brightness of an LED on pin D9
based on the reading of a photocell on pin A0
This code is in the Public Domain
*/
void setup() {
}
void loop() {
}
Once that is all squared away, let us define the pin names, and establish
variables:
<pre>/*
LED Dimmer
2012

103
*/
// name analog pin 0 a constant name
const int analogInPin = A0;
// name digital pin 9 a constant name
const int LEDPin = 9;
//variable for reading a photocell
int photocell;
void setup() {
}
void loop() {
}
Now that variables and pin names are set, let us write the actual code:
<pre>/*
LED Dimmer

104
2012
*/
int photocell;
void setup() {
//nothing here right now
}
void loop() {
//read the analog in pin and set the reading to the photocell variable
photocell = analogRead(analogInPin);
//control the LED pin using the value read by the photocell

105
analogWrite(LEDPin, photocell);
//pause the code for 1/10 second
//1 second = 1000
delay(100);
}
If we want to see what numbers the analog pin is actually reading from the
photocell, we will need to use the serial monitor. Let's activate the serial port and
output those numbers:
<pre>/*
LED Dimmer
2012
*/

106
int photocell;
void setup() {
Serial.begin(9600);
}
void loop() {
//read the analog in pin and set the reading to the photocell variable
photocell = analogRead(analogInPin);
//print the photocell value into the serial monitor
Serial.print("Photocell = " );
Serial.println(photocell);
//control the LED pin using the value read by the photocell
analogWrite(LEDPin, photocell);
//pause the code for 1/10 second
//1 second = 1000
delay(100);
}

107
10.HARDWARE TESTING
10.1 CONTINUITYTEST:
In electronics, a continuity test is the checking of an electric circuit to see if current flows
(that it is in fact a complete circuit). A continuity test is performed by placing a small voltage
(wired in series with an LED or noise-producing component such as a piezoelectric speaker)
across the chosen path. If electron flow is inhibited by broken conductors, damaged components,
or excessive resistance, the circuit is "open".
Devices that can be used to perform continuity tests include multi meters which measure
current and specialized continuity testers which are cheaper, more basic devices, generally with a
simple light bulb that lights up when current flows.
An important application is the continuity test of a bundle of wires so as to find the two ends
belonging to a particular one of these wires; there will be a negligible resistance between the
"right" ends, and only between the "right" ends.
This test is the performed just after the hardware soldering and configuration has been
completed. This test aims at finding any electrical open paths in the circuit after the soldering.
Many a times, the electrical continuity in the circuit is lost due to improper soldering, wrong and
rough handling of the PCB, improper usage of the soldering iron, component failures and
presence of bugs in the circuit diagram. We use a multi meter to perform this test. We keep the
multi meter in buzzer mode and connect the ground terminal of the multi meter to the ground.
We connect both the terminals across the path that needs to be checked. If there is continuation
then you will hear the beep sound.
10.2 POWER ON TEST:
This test is performed to check whether the voltage at different terminals is according to
the requirement or not. We take a multi meter and put it in voltage mode. Remember that this test
is performed without microcontroller. Firstly, we check the output of the transformer, whether
we get the required 12 v AC voltage.
Then we apply this voltage to the power supply circuit. Note that we do this test without
microcontroller because if there is any excessive voltage, this may lead to damaging the

108
controller. We check for the input to the voltage regulator i.e., are we getting an input of 12v and
an output of 5v. This 5v output is given to the microcontrollers’ 40th pin. Hence we check for the
voltage level at 40th pin. Similarly, we check for the other terminals for the required voltage. In
this way we can assure that the voltage at all the terminals is as per the requirement.
BIBLIOGRAPHY
TEXT BOOKS REFERED
1. ATMEGA 328 Data Sheets.
WEBSITES
 www.atmel.com
 www.beyondlogic.org
 www.wikipedia.org
 www.howstuffworks.com
 www.alldatasheets.com

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