This document summarizes a mini project report on an ultrasonic distance meter submitted for a Bachelor of Technology degree. It includes an introduction, history of distance measurement techniques, circuit diagram, implementation details of the ultrasonic distance meter using an ATmega8 microcontroller, ultrasonic sensor, LCD display and buzzer. It also includes the block diagram, sample output, advantages, source code, conclusion and outlook for future improvements. The project involves designing and developing an ultrasonic distance measurement system to measure distances up to 4 meters without contact.

1. A
Mini Project Report
on
“ULTRASONIC DISTANCE METER”
submitted in partial fulfillment of the
requirement for the award of degree of
BACHELOR OF TECHNOLOGY
in
ELECTRONICS AND COMMUNICATION ENGINEERING
submitted by
P.UTTEJ KUMAR 12M61A04A2
Under the Guidance of
Mr. Mohammad Hafizzudin M.Tech
Assistant Professor
DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING
SWARNA BHARATHI INSTITUTE OF SCIENCE & TECHNOLOGY, KHAMMAM
(Approved by AICTE, Govt. of A.P. & Affiliated to JNTUH, Hyderabad)
(2015-16)

2. Department of Electronics & Communication Engineering
Swarna Bharathi Institute of Science & Technology, Khammam
(Approved by AICTE, Govt. of A.P. & Affiliated to JNTUH, Hyderabad)
CERTIFICATE
This is to certify that the project report entitled “ULTRASONIC
DISTANCE METER” is a bonafide record of work carried out by
P.UTTEJ KUMAR 12M61A04A2
We hereby accord our approval of it as a project work carried out and
presented in a manner required for its acceptance in partial fulfillment for the
award of degree of BACHELOR OF TECHNOLOGY in ELECTRONICS AND
COMMUNICATION ENGINEERING of Jawaharlal Nehru Technological
University Hyderabad, Hyderabad during the academic year 2015-2016.
External Examiner
INTERNAL GUIDE
Mr. Mohammad Hafizzudin M.Tech,
Assistant Professor
PRINCIPAL
Prof. P. Krishna Murthy M.Tech., Ph.D,
HEAD OF THE DEPARTMENT
Mr.Gandham Srinivasa Rao M.Tech, MIEEE,
Associate Professor

3. ACKNOWLEDGEMENT
I take the opportunity to express my deep sense of gratitude to my Project guide,
Mr. Mohammad Hafizzudin, Assistant Professor, Department of ECE, Swarna Bharathi
Institute of Science & Technology, Khammam, for his excellent guidance, technical
information and support which helped me in successfully completing this project report.
I take the opportunity to express my heartfelt thanks to the Head of the
Department Mr. Gandham Srinivasa Rao, Associate Professor, Department of
Electronics & Communication Engineering, Swarna Bharathi Institute of Science &
Technology, Khammam, for his excellent guidance, technical information and support
which helped me in successfully completing this project.
I wish to express my profound thanks to Prof. P. Krishna Murthy, Principal,
Swarna Bharathi Institute of Science & Technology, Khammam, for providing necessary
facilities to make this project a success.
I thank all the members of Teaching and Non-Teaching Staff, Department of ECE,
and all those who have helped me directly or indirectly in completing my project
successfully.
UTTEJ KUMAR PALAVAI
12M61A04A2

4. DECLARATION
I declare that the project entitled “ULTRASONIC DISTANCE
METER” recorded in this report does not form part of any other
thesis on which a degree has been awarded earlier. I further declare
that this project report is based on my work carried out at the
“SWARNA BHARATHI INSTITUTE OF SCIENCE & TECHNOLOGY”,
Khammam during the B.Tech course.
DATE:
PLACE: Khammam
Reported by,
Mr.UTTEJ KUMAR PALAVAI
12M61A04A2

5. ABSTRACT
Ultrasonic Distance Meter working principle is based on ultrasonic waves.
As the human ear’s audible perception range is 20 Hz to 20 kHz, it is Insensitive
to ultrasonic waves, and hence the ultrasound waves can be used for applications
in industries/vehicles without hindering human activity. The distance can be
measured using pulse echo and phase measurement method. The signal is
transmitted by an ultrasonic transducer, reflected by an obstacle and received by
another transducer where the signal is detected. The time delay of the transmitted
and the received signal corresponds to the distance between the system and the
obstacle.
A common use of ultrasound is for range finding. Sonar works similarly to
radar. An ultrasonic pulse is generated in a particular direction. If there is an
object in the way of this pulse, the pulse is reflected back to the sender as an echo
and is detected. Measuring the difference in time between the pulse transmitted
and the echo received, it is possible to determine how far away the object is. Bats
use a variety of ultrasonic ranging (echolocation) to detect their prey.
The application area of the Ultrasonic Distance Meter is very wide in rescue
operations, spy robot, versatile use in autonomous technology, use in mining; it
has found essential use in light industry (e.g. Toy industry) agriculture, used in
car parking systems and all other engineering practices.

6. INDEX
CONTENTS PAGE NO
1. INTRODUCTION 1
2. HISTORY AND CIRCUIT DIAGRAM 3
2.1 History 4
2.2 Circuit Diagram 5
3. IMPLEMENTATION 6
3.1 Design Implementation 6
3.1.1 ATMEGA8 Microcontroller 6
3.1.2 Ultrasonic Sensor 17
3.1.3 Liquid Crystal Display 20
3.1.4 Buzzer 22
3.1.5 Voltage Regulator 23
3.2 Software Requirement 23
3.2.1 AVR STUDIO Overview 24
3.2.2 PROTUES Overview 24
3.2.3 PROGISP Overview 25
4. BLOCK DIAGRAM AND OUTPUT 26
4.1 Block Diagram 26
4.2 Sample Output 27

7. 5. ADVANTAGES 28
5.1 Advantages 28
5.2 Limitations 28
6. SOURCE CODE 29
7. CONCLUSION 32
8. BIBLIOGRAPHY 33
9. PROJECT OUTLOOK 34

8. LIST OF FIGURES
1.1 Electronic Distance Measurement 2
2.1 Measuring Using Scales 4
2.2 Traditional Measuring Devices 5
2.3 Circuit Diagram 5
3.1 Atmega8 Microcontroller 8
3.2 Pin Diagram of Atmega8 Microcontroller 11
3.3 Block Diagram of Atmega8 Microcontroller 12
3.4 AVR Status Register 13
3.5 AVR CPU General Purpose Working Registers 15
3.6 Ultrasonic Sensor 17
3.7 Measuring the Distance Using Ultrasonic Sensor 19
3.8 Timing Diagram of the Sensor 20
3.9 LCD Screen 21
3.10 Power Supply Connection to LCD 22
3.11 Buzzer 22
3.12 Pin Diagram of Voltage Regulator 23
4.1 Block Diagram 26
4.2 PCB Design Used For the Project 27

9. CHAPTER 1
1. INTRODUCTION
There are several ways to measure distance without contact. One way is to
use ultrasonic waves at 40 kHz for distance measurement. Ultrasonic transducers
measure the amount of time taken for a pulse of sound to travel to a particular
surface and return as the reflected echo. This circuit calculates the distance based
on the speed of sound at 25°C ambient temperature and shows it on a 7-segment
display. Using it, you can measure distance up to 4 meters.
Linear measurement is a problem that a lot of applications in the industrial
and consumer market segment have to contend with. Ultrasonic technology is one
of the solutions used by the industry. However, an optimized balance between cost
and features are a must for almost all target applications. The ultrasonic distance
measurer (UDM) is used mainly when a non-contact measurer is required.
A Distance meter is used to measure the distance between two objects.
Ultrasonic Distance Meter working principle is based on ultrasonic waves. As the
human ear’s audible perception range is 20 Hz to 20 kHz, it is insensitive to
ultrasonic waves, and hence the ultrasound waves can be used for applications in
industries/vehicles without hindering human activity. The distance can be
measured using pulse echo and phase measurement method. The signal is
transmitted by an ultrasonic transducer, reflected by an obstacle and received by
another transducer where the signal is detected. The time delay of the transmitted
and the received signal corresponds to the distance between the system and the
obstacle.
The speed which sound travels depends on the medium which it passes
through. In general, the speed of sound is proportional (the square root of the
ratio) to the stiffness of the medium and its density. This is a fundamental

10. property of the medium. Physical properties and the speed of sound change with
the conditions in the environment. The speed of sound in the air depends on the
temperature. In the air speed are approximately 345 m/s, in water 1500 m/s and
in a bar of steel 5000 m/s.
A common use of ultrasound is for range finding. This use is also called
sonar. Sonar works similarly to radar. An ultrasonic pulse is generated in a
particular direction. If there is an object in the way of this pulse, the pulse is
reflected back to the sender as an echo and is detected. Measuring the difference
in time between the pulse transmitted and the echo received, it is possible to
determine how far away the object is. Bats use a variety of ultrasonic ranging
(echolocation) to detect their prey.
Ultrasonic generators use piezoelectric materials such as zinc or lead
zirconium tartrates or quartz crystal. The material thickness decides the resonant
frequency when mounted and excited by electrodes attached on either side of it.
The medical scanners used for abdomen or heart ultrasound are designed at
2.5MHz. In this circuit, a 40 kHz transducer is used for measurement in the air
medium. The velocity of sound in the air is around 330 m/s at 0°C and varies with
temperature.
1.1 Electronic distance measurement
CHAPTER-2
2.1 HISTORY:
Compared with the direct measurement of distances by tapes, band and
chains, EDM have a short history. Its fast development is linked with the rapid

11. progress in electronics during this century. The availability of relatively cheap
instruments was only possible due to the rapid progress which has been made in
solid state electronics since the early 1970s.
The development of the first light wave EDM instrument is connected with
the name of the Swedish scientist E.Bergstrand. He designed the First Geodetic
meter (short form of GEOdetic distance METER) for the determination of the
velocity of light in 1943. The commercial instrument Geodimeter NASM-2 became
available in 1950, produced by a large Swedish manufacturer of chemicals, AGA.
With the early Geodimeters, longer distances could only be measured at night. The
latest long-range Geodimeters, models 600 and 8, are at present in wide use in
geodetic surveying throughout the world.
The first EDM instrument using radio waves was developed by T.L. Wadley
at the National Institute of Telecommunications Research of South Africa in 1954.
It became available under the name Tellurometer in 1957. Its range exceeded that
of the Geodimeter and it was therefore in much wider use until lasers were
introduced in EDM late in the 1960's.
The first prototypes of short range EDM instruments (incorporating
luminescence diodes) appeared in the mid 1960's (Tellurometer MA 100 in 1965;
Zeiss SM 11 in 1967). These instruments have been commercially released since
the late 1960's (Wi Id/Secret Distomat DI 10 in 1968; Tellurometer MA 100 in
1969; Zeiss SM 11 in 1970). Short range instruments with infrared (I R) light
sources are now increasingly used for all types of surveys; long range instruments
are used for the measurement of geodetic networks.
Two other groups also need be mentioned. The most precise EDM
instrument to date, the Mekometer, was built by K.D.Froome and R.H.Bradsell in
1961 at the National Physical Laboratory, Teddington (U.K.) and became
commercially available early in 1973. On short distances, accuracies of 0.2 mm
can be achieved.
The first electronic tachometer (sometimes termed "total station"), the Zeiss
(Oberkochen) Reg E1 to 14, became available in 1970 and featured electronic
readout not only of distance but also of the vertical and horizontal circles. The
second total station, the AGA Geodimeter 700 became available in 1971.

12. Electronic tachometers have a great future in large scale detail surveys, especially
if combined with electronic booking and computerized data processing and
plotting.
2.1 Measuring using scales
The traditional measuring devices are the tapes, scales, chains etc…
2.2 Traditional measuring devices
2.2 CIRCUIT DIAGRAM

13. The circuit diagram of the ULTRASONIC DISTANCE METER is shown below:
2.3 Circuit diagram
CHAPTER-3
3.1 DESIGN IMPLEMENTATION:
The hardware components used are:
 ATMEGA8 microcontroller
 Ultrasonic sensor (HCSR04)
 LCD module (LM016L)
 Buzzer
 Voltage Regulator (LM7805)
 Diodes (1N4007)
 Resistors
 Transistors

14.  Capacitors
 Switch
3.1.1 ATMEGA8 MICROCONTROLLER
Definition of a Microcontroller
Microcontroller, as the name suggests, are small controllers. They are like
single chip computers that are often embedded into other systems to function as
processing/controlling unit. For example, the remote control you are using
probably has microcontrollers inside that do decoding and other controlling
functions. They are also used in automobiles, washing machines, microwave
ovens, toys ... etc., where automation is needed.
The key features of microcontrollers include:
 High Integration of Functionality
 Microcontrollers sometimes are called single-chip computers because they
have on-chip memory and I/O circuitry and other circuitries that enable
them to function as small standalone computers without other supporting
circuitry.
 Field Programmability, Flexibility
 Microcontrollers often use EEPROM or EPROM as their storage device to
allow field programmability so they are flexible to use. Once the program is
tested to be correct then large quantities of microcontrollers can be
programmed to be used in embedded systems.
 Easy to Use
Assembly language is often used in microcontrollers and since they usually
follow RISC architecture, the instruction set is small. The development package
of microcontrollers often includes an assembler, a simulator, a programmer to
"burn" the chip and a demonstration board. Some packages include a high
level language compiler such as a C compiler and more sophisticated libraries.
Most microcontrollers will also combine other devices such as:
 A Timer module to allow the microcontroller to perform tasks for certain
time periods.

15.  A serial I/O port to allow data to flow between the microcontroller and other
devices such as a PC or another microcontroller.
 An ADC to allow the microcontroller to accept analogue input data for
processing.
ATMEGA8 microcontroller is used in this project:
The Atmel AVR core combines a rich instruction set with 32 general purpose
working registers. All the 32 registers are directly connected to the Arithmetic
Logic Unit (ALU), allowing two independent registers to be accessed in one single
instruction executed in one clock cycle. The resulting architecture is more code
efficient while achieving throughputs up to ten times faster than conventional
CISC microcontrollers.
3.1 Atmega8 Microcontroller
The ATmega8 provides the following features: 8 Kbytes of In-System
Programmable Flash with Read-While-Write capabilities, 512 bytes of EEPROM, 1
Kbyte of SRAM, 23 general purpose I/O lines, 32 general purpose working
registers, three flexible Timer/Counters with compare modes, internal and
external interrupts, a serial programmable USART, a byte oriented Two- wire
Serial Interface, a 6-channel ADC (eight channels in TQFP and QFN/MLF
packages) with 10-bit accuracy, a programmable Watchdog Timer with Internal
Oscillator, an SPI serial port, and five software selectable power saving modes.
The Idle mode stops the CPU while allowing the SRAM; Timer/Counters, SPI port,

16. and interrupt system to continue functioning. The Power- down mode saves the
register contents but freezes the Oscillator, disabling all other chip functions
until the next Interrupt or Hardware Reset. In Power-save mode, the
asynchronous timer continues to run, allowing the user to maintain a timer base
while the rest of the device is sleeping. The ADC Noise Reduction mode stops the
CPU and all I/O modules except asynchronous timer and ADC, to minimize
switching noise during ADC conversions. In Standby mode, the
crystal/resonator Oscillator is running while the rest of the device is sleeping.
This allows very fast start-up combined with low-power consumption. The device
is manufactured using Atmel’s high density non-volatile memory technology.
The Flash Program memory can be reprogrammed In-System through an SPI
serial interface, by a conventional non-volatile memory programmer, or by an On-
chip boot program running on the AVR core. The boot program can use any
interface to download the application program in the Application Flash memory.
Software in the Boot Flash Section will continue to run while the Application
Flash Section is updated, providing true Read-While-Write operation. By
combining an 8-bit RISC CPU with In-System Self-Programmable Flash on a
monolithic chip, the Atmel ATmega8 is a powerful microcontroller that provides a
highly-flexible and cost-effective solution to many embedded control applications.
The ATmega8 is supported with a full suite of program and system development
tools, including C compilers, macro assemblers, program debugger/simulators,
In-Circuit Emulators, and evaluation kits. The high-performance Atmel AVR ALU
operates in direct connection with all the 32 general purpose working registers.
Within a single clock cycle, arithmetic operations between general purpose
registers or between a register and an immediate are executed. The ALU
operations are divided into three main categories – arithmetic, logical, and bit-
functions. Some implementations of the architecture also provide a powerful
multiplier supporting both signed/unsigned multiplication and fractional format.
Key features
 High-performance, Low-power Atmel AVR 8-bit Microcontroller.
 Advanced RISC Architecture
 130 Powerful Instructions – Most Single-clock Cycle Execution
 32 × 8 General Purpose Working Registers

17.  Fully Static Operation Up to 16MIPS Throughput at 16MHz On-chip 2-cycle
Multiplier
 High Endurance Non-volatile Memory segments.
 8Kbytes of In-System Self-programmable Flash program memory
 512Bytes EEPROM, 1Kbyte Internal SRAM
 Write/Erase Cycles: 10,000 Flash/100,000 EEPROM.
 Data retention: 20 years at 85°C/100 years at 25°C.
 Optional Boot Code Section with Independent Lock Bits.
 In-System Programming by On-chip Boot Program True Read-While-Write
Operation
 Programming Lock for Software Security
 Peripheral Features, Two 8-bit Timer/Counters with Separate Presale, one
Compare Mode
 One 16-bit Timer/Counter with Separate Pre scalar, Compare Mode, and
Capture Mode
 Real Time Counter with Separate Oscillator
 Three PWM Channels
 8-channel ADC in TQFP and QFN/MLF package Eight Channels 10-bit
Accuracy.
 6-channel ADC in PDIP package Six Channels 10-bit Accuracy
 Byte-oriented Two-wire Serial Interface.
 Programmable Serial USART.
 Master/Slave SPI Serial Interface.
 Programmable Watchdog Timer with Separate On-chip Oscillator.
 On-chip Analog Comparator
 Power-on Reset and Programmable Brown-out Detection
 Internal Calibrated RC Oscillator
 External and Internal Interrupt Sources
 Five Sleep Modes: Idle, ADC Noise Reduction, Power-save, Power-down, and
Standby
 23 Programmable I/O Lines, 28-lead PDIP, 32-lead TQFP, and 32-pad
QFN/MLF.

18.  2.7V - 5.5V (ATmega8L),4.5V - 5.5V (ATmega8)
 Power Consumption at 4Mhz, 3V, 25°C
PIN DIAGRAM
The PIN diagram of the ATmega8 microcontroller is shown below:
3.2 Pin diagram of Atmega8 Microcontroller

19. BLOCK DIAGRAM
The block diagram of ATmega8 Microcontrller is shown below:

20. 3.3 BLOCK DIAGRAM of ATMEGA8 MICROCONTROLLER
The high-performance Atmel AVR ALU operates in direct connection with
all the 32 general purpose working registers. Within a single clock cycle,
arithmetic operations between general purpose registers or between a register
and an immediate are executed. The ALU operations are divided into three main
categories – arithmetic, logical, and bit-functions. Some implementations of the
architecture also provide a powerful multiplier supporting both
signed/unsigned multiplication and fractional format. For a detailed description,
The Status Register contains information about the result of the most
recently executed arithmetic instruction. This information can be used for
altering program flow in order to perform conditional operations. Note that the
Status Register is updated after all ALU operations,
Status Register
The Status Register is not automatically stored when entering an interrupt
routine and restored when returning from an interrupt. This must be handled by
software.
3.4 AVR status register
Global Interrupt Enable
The Global Interrupt Enable bit must be set for the interrupts to be enabled.
The individual interrupt enable control is then performed in separate control
registers. If the Global Interrupt Enable Register is cleared, none of the interrupts
are enabled independent of the individual interrupt enable settings. The I-bit is
cleared by hardware after an interrupt has occurred, and is set by the RETI
instruction to enable subsequent interrupts. The I-bit can also be set and cleared

21. by the application with the SEI and CLI instructions, as described in the
Instruction Set Reference.
Bit Copy Storage
The Bit Copy instructions BLD (Bit Load) and BST (Bit Store) use the T-bit
as source or destination for the operated bit. A bit from a register in the Register
File can be copied into T by the BST instruction, and a bit in T can be copied
into a bit in a register in the Register File by the BLD instruction.
Half Carry Flag
The Half Carry Flag H indicates a Half Carry in some arithmetic operations.
Half Carry is useful in BCD arithmetic.
Two’s Complement Overflow Flag
The Two’s Complement Overflow Flag V supports two’s complement
arithmetic’s.
Negative Flag
The Negative Flag N indicates a negative result in an arithmetic or logic
operation.
Zero Flag
The Zero Flag Z indicates a zero result in an arithmetic or logic operation.
Carry Flag
The Carry Flag C indicates a Carry in an arithmetic or logic operation.
General Purpose Register File
The Register File is optimized for the AVR Enhanced RISC instruction set.
In order to achieve the required performance and flexibility, the following
input/output schemes are supported by the Register File.

22. 3.5 AVR CPU General Purpose Working Registers
Most of the instructions operating on the Register File have direct access
to all registers, and most of them are single cycle instructions as shown in Figure,
each register is also assigned a Data memory address, mapping them directly
into the first 32 locations of the user Data Space. Although not being physically
implemented as SRAM locations, this memory organization provides great
flexibility in access of the registers, as the X-pointer, Y-pointer, and Z-pointer
Registers can be set to index any register in the file
MEMORY
This section describes the different memories in the Atmel AVR ATmega8.
The AVR architecture has two main memory spaces, the Data memory and the
Program Memory space. In addition, the ATmega8 features an EEPROM Memory
for data storage. All three memory spaces are linear and regular.
Most of the instructions operating on the Register File have direct access
to all registers, and most of them are single cycle instructions as shown in Figure,

23. each register is also assigned a Data memory address, mapping them directly
into the first 32 locations of the user Data Space. Although not being physically
implemented as SRAM locations, this memory organization provides great
flexibility in access of the registers, as the X-pointer, Y-pointer, and Z-pointer
Registers can be set to index any register in the file.
In-System Reprogrammable Flash memory
The ATmega8 contains 8Kbytes On-chip In-System Reprogrammable
Flash memory for pro- gram storage. Since all AVR instructions are 16-bits or
32-bits wide, the Flash is organized as 4K × 16 bits. For software security, the
Flash Program memory space is divided into two sections, Boot Program section
and Application Program section.
The Flash memory has an endurance of at least 10,000 write/erase cycles.
The ATmega8 Pro- gram Counter (PC) is 12 bits wide, thus addressing the 4K
Program memory locations. The operation of Boot Program section and
associated Boot Lock Bits for software protection are described in detail in
“Boot Loader Support – Read-While-Write Self-Programming”.
SRAM DATA MEMORY
The lower 1120 Data memory locations address the Register File, the I/O
Memory, and the internal data SRAM. The first 96 locations address the Register
File and I/O Memory, and the next 1024 locations address the internal data
SRAM.
The five different addressing modes for the Data memory cover Direct,
Indirect with Displacement, Indirect, Indirect with Pre-decrement, and Indirect
with Post-increment. In the Register File, registers R26 to R31 feature the
indirect addressing pointer registers.
3.1.2 ULTRASONIC SENSOR
Ultrasonic sensor ranging module HCSR04 provides 2cm-400cm non-
contact measurement function, the ranging accuracy can reach to 3mm.the
module includes ultrasonic transmitter, receiver and a control circuit.

24. The ultrasonic distance sensor provides precise, non-contact distance
measurements from about 0.8 to 120 inches. The ultrasonic sensor emits short
bursts of sound and listens for this sound to echo off of nearby objects. The
frequency of the sound is too high for humans to hear (it is ultrasonic). The
ultrasonic sensor measures the time of flight of the sound burst. A user then
computes the distance to an object using this time of flight and the speed of sound
(1,126 ft. /s).
This sensor uses ultrasonic sound to measure distance just like bats and
dolphins do. Ultrasonic sound has such a high pitch that humans cannot hear it.
This particular sensor sends out an ultrasonic sound that has a frequency of
about 40 kHz.
3.6 Ultrasonic sensor
The sensor has two main parts:
A transducer that creates an ultrasonic sound and another listens to its echo.
The basic work principle of work:
 Using I/O trigger for at least 10us high level.
 The module automatically sends eight 40 KHz and whether there is a pulse
signal back.
 If the signal back, through high level, time of high output I/O duration is
the time from sending ultrasonic to returning.
Test distance= (high level time * velocity of sound (340m/s)/2)

25. Sound travels at approximately 340 meters per second. This corresponds to about
29.412us (microseconds) per centimeter.
To measure the distance the sound has travelled we use the formula:
Distance = (Time x Speed of Sound) / 2.
The "2" is in the formula because the sound has to travel back and forth. First the
sound travels away from the sensor, and then it bounces off of a surface and
returns back.
The easy way to read the distance as centimeters is use the formula:
Centimeters = ((Microseconds / 2) / 29).
For example, if it takes 100us (microseconds) for the ultrasonic sound to bounce
back, then the distance is ((100 / 2) / 29) centimeters or about 1.7 centimeters.
3.7 Measuring the Distance Using Ultrasonic Sensor
Wire connecting direct as following
 5V Supply

26.  Trigger Pulse Input
 Echo Pulse Output
 0V Ground
Electric Parameters
 Working Voltage : DC 5 V
 Working Current : 15mA
 Working Frequency : 40Hz
 Max Range : 4m
 Min Range : 2cm
 Measuring Angle : 15 degree
 Trigger Input Signal : 10uS TTL pulse
 Echo output signal : input TTL lever signal & the range in proportion
 Dimension : 45*20*15mm
Timing diagram
The Timing diagram is shown below. You only need to supply a short 10uS
pulse to the trigger input to start the ranging, and then the module will send out
an 8 cycle burst of ultrasound at 40 kHz and raise its echo. The Echo is a distance
object that is pulse width and the range in proportion .You can calculate the range
through the time interval between sending trigger signal and receiving echo signal.
3.8 Timing diagram of the sensor

27. 3.1.3 LIQUID CRYSTAL DISPLAY
LCD stands for Liquid Crystal Display. LCD is finding wide spread use
replacing LEDs (seven segment LEDs or other multi segment LEDs) because of the
following reasons:
1. The declining prices of LCDs.
2. The ability to display numbers, characters and graphics. This is in contrast
to LEDs, which are limited to numbers and a few characters.
3. Incorporation of a refreshing controller into the LCD, thereby relieving the
CPU of the task of refreshing the LCD. In contrast, the LED must be
refreshed by the CPU to keep displaying the data.
4. Ease of programming for characters and graphics.
These components are “specialized” for being used with the microcontrollers,
which means that they cannot be activated by standard IC circuits. They are used
for writing different messages on a miniature LCD.
LM160L type liquid crystal display board is used here.
3.9 LCD screen
LCD screen

28. LCD screen consists of two lines with 16 characters each. Each character
consists of 5x7 dot matrix. Contrast on display depends on the power supply
voltage and whether messages are displayed in one or two lines. For that reason,
variable voltage 0-Vdd is applied on pin marked as Vee. Trimmer potentiometer is
usually used for that purpose the connections some versions of displays have built
in backlight (blue or green diodes). When used during operating, a resistor for
current limitation should be used (like with any LE diode).
3.10 Power supply connection to LCD
3.1.4 BUZZER
A buzzer or beeper is an audio signaling device, which may be mechanical,
electromechanical or piezoelectric. Typical uses of buzzers and beepers include
alarm devices, timers and confirmation of user input such as a mouse click or
keystroke.
3.11 Buzzer
Electromechanical
Early device were based on an electromechanical system identical to an
electric bell without the metal gong. Similarly a relay may be connected to

29. interrupt its own actuating current, causing the contacts to buzz. Often these
units were anchored to a wall or ceiling to use it as a sounding board. The word
“buzzer comes from the rasping noise that electromechanical buzzers made.
Mechanical
A joy buzzer is an example of a purely mechanical buzzer. They require a
driver.
Piezoelectric
A Piezoelectric element may be driven by an oscillating electronic circuit or
by other audio signal source, driven with a piezoelectric audio amplifier. Sounds
commonly used to indicate that a button has been pressed are a click, a ring or a
beep.
3.1.5 VOLTAGE REGULATOR
A Voltage regulator is designed to automatically maintain a constant voltage
level. A Voltage regulator may be a simple “feed-forward” design or may include
negative feedback control loops. It may use an electromechanical mechanism, or
electronic components. Depending upon the design, it may be used to regulate one
or more AC or DC voltages.

30. 3.12 Pin diagram of voltage regulator
3.2 Software Requirements:
 AVR Studio
 Proteus
 ProgISP
3.2.1 AVR STUDIO Overview
AVR stands for advanced virtual RISC.
AVR Studio, the popular Software, combines Project Management, Source
Code Editing, Program Debugging, and Flash Programming in a single, powerful
environment.
 Project Management, Device Setup, and Tool Configuration.
 Editor facilities for Creating, Modifying, and Correcting Programs.
 Target Debugging or CPU & Peripheral Simulation.
3.2.2 PROTEUS Overview
PROTEUS stands for PROcesses and Transactions Editable by Users.
Proteus is simulation software for various designs with microcontroller. It is
mainly popular because of availability of almost all microcontrollers in it. So it is a
handy tool to test programs and embedded design as for electronics hobbyist.
User can simulate his programming of microcontroller in Proteus simulation
software.
After simulating your circuit in Proteus software user can directly make PCB
design with it so it could be an all in one package for the clients.

31. 3.2.3 PROGISP Overview:
PROGISP stands for Project In System Programmer.
PROGISP is a way for, in system programming of micro controllers in
controlled way.
Its development credit goes to Chi Fang Technology Co., Ltd, which engages
in the design of embedded systems products, sharing and free software
developing.
PROGISP supports for nearly 110 CPUs with on board by default fuse bits
selection for every controller. It’s very friendly user interface with required
graphics.

32. Chapter-4
4.1 Block diagram:
4.1 Block Diagram
SENSOR
ATMEGA8
MICRO
CONTROLLER
POWER
SUPPLY
LCD
BUZZER

33. 4.2 Sample output
4.2 PCB design used for the project

34. Chapter-5
5.1 Advantages:
 Works very accurately.
 As it uses sound waves the operational speed is very high.
 It is when a non-contact measurer is required.
 Low cost.
5.2 Limitations:
 The range of the ultrasonic sensor is low (=4m).
 The power level of the signal is too low for long range measurement.

35. 6. Source code:
#define F_CPU 8000000UL // Set Clock frequency to 8 MHz
#include <avr/io.h>
#include <util/delay.h>
#include "lcd.h"
unsigned int ultra(unsigned char pin1,unsigned char pin2)
{
unsigned int value;
DDRB = (0<<PB0)|(1<<PB1); //echo low trigr high
PORTB &= 0x00 ;
TCCR1B = 0 ;// Timer counter register
TCNT1 &= 0;//Count value=0
PORTB= (1<<pin1); //echo high
_delay_ms(10);
PORTB = (0<<pin1); //echo LOW
while((PINB & pin2) == 0x00); //trigger 0
if((PINB & pin2) == pin2)
{

36. TCCR1B = 0x02;
}
while((PINB & pin2) == pin2);
value = TCNT1 ;
return(value);
}
int main(void)
{
int f1;
DDRC=0xff;
InitLCD(0);
_delay_ms(50);
LCDClear();
_delay_ms(50);
LCDWriteStringXY(0,0,"Welcome to UDM");
_delay_ms(50);
LCDWriteStringXY(0,1,"N.RAMYA ");
_delay_ms(5000);
LCDWriteStringXY(0,1,"P.HARSHA ");
_delay_ms(5000);
LCDWriteStringXY(0,1,"P.UTTEJ KUMAR ");
_delay_ms(5000);
LCDClear();
_delay_ms(50);

37. while(1)
{
LCDWriteStringXY(0,0,"Welcome to UDM");
_delay_ms(50);
f1=ultra(PB1,0x01); //taking distance(ultrasonic)
_delay_ms(100);
f1=f1/60;
LCDWriteStringXY(0,1,"Distance:");
_delay_ms(50);
LCDWriteIntXY(9,1,f1,4);
_delay_ms(50);
LCDWriteStringXY(14,1,"CM");
_delay_ms(50);
if(f1<10)
{
PORTC=0xff;
}
else
{
PORTC=0;
}
_delay_ms(200);
}
}

38. 7. CONCLUSION:
Ultrasonic distance measurement is a convenient method compared to
traditional one using measurement scales. This kind of measurement is
particularly applicable to inaccessible areas where traditional means cannot be
implemented such as high temperature, pressure zones etc.
The ultrasonic sensors have a great future scope as it is a non-contact
distance measurer. The application area of the Ultrasonic Distance Meter is very
wide in rescue operations, spy robot, versatile use in autonomous technology, use
in mining; it has found essential use in light industry (e.g. Toy industry)
agriculture, used in car parking systems and all other engineering practices.

39. 8. BIBILIOGRAPHY:
 www.google.co.in
 www.wikipedia.com
 www.atmel.com/images/atmel-2486-8-bit-avr-microcontroller-
atmega8_l_datasheet.pdf
 www.micropik.com/pdf/HCSR04.pdf
 www.seminarsonly.com

40. 9. PROJECT OUTLOCK