VIVEKANAND EDUCATION SOCIETY’S POLYTECHNIC

CHEMBUR, MUMBAI- 400071

PROJECT REPORT

ON

MICROCONTROLLER BASED ULTRASONIC DISTANCE METER

SUBMITTED BY

RAHUL DIVE

SANA DONGARE

MAHESH JADHAV

PRIYANKA KADAM.

UNDER THE GUIDANCE OF

MRS. ALKA PRAYAGKAR

IN PARTIAL FULFILLMENT OF THE REQUIREMENT OF THE DIPLOMA

IN

INDUSTRIAL ELECTRONICS

MAHARASHTRA STATE BOARD OF TECHNICAL EDUCATION

ACADEMIC YEAR 2012- 2013

1

VIVEKANAND EDUCATION SOCIETY’S

POLYTECHNIC

SINDHI SOCIETY, CHEMBUR, MUMBAI- 400071

CERTIFICATE

This is to certify that Mr ______________________________________________

Has satisfactorily carried out project work entitled “

“In partial fulfilment of the diploma in INDUSTRIAL ELECTRONICS of Maharashtra State Board of Technical Education Academic Year 2012- 2013

Principal Head of Department

Project Guide Examiner

2

ACKNOWLEDGEMENT

It is indeed a matter of great pleasure and proud privilege to be able to

present this project on “MICROCONTROLLER BASED ULTRASONIC

DISTANCE METER “.

The completion of the project work is a millstone in student’s life and its

execution is inevitable in the hands of guide . We are highly indebted the

project guides Mrs. Alka Prayagkar for his invaluable guidance and

appreciation.

We would like to tender our sincere thanks to all the staff members for

their co-operation. We would also like to express our deep regards and

gratitude to the principal Prof.V.B.Joshi .

Really it is highly impossible to repay the debt of all the people who have

directly or indirectly helped us for performing the project.

3

PREFACE

We take an opportunity to present this project report on

“MICROCONTROLLER BASED ULTRASONIC DISTANCEMETER”

and put before readers some useful information regarding our project.

We have made sincere attempts and taken every care to present this matter

in precise and compact form , the language being as simple as possible .

We are sure that the information contained in this volume would certainly

prove useful for better insight in the scope and dimension of this project in

its true perspective .

The task of completion of the project though being difficult was made quite

simple, interesting and successful due to involvement and dedication of

our group members .

ABSTRACT

4

The microcontroller based Ultrasonic distance meter or Ultrasonic proximity meter is a

non contact and non loading displacement measuring device. This device can be used to

even large displacement with pin point accuracy.

The heart of this distance meter is the microcontroller AT89C2051. This system

potentially has very large applications not only in various industries, the luxury

automobile sector but also in the armed force where accuracy and durability is of primary

importance.

5

TABLE OF CONTENTS

Abstract

List of figures

1: Introduction

2: Ultrasonic Principles

3: Basic Block Diagram

4: Circuit Diagram & Description

5: PCB Layout

6: Various Components involved in the circuit

7: Flow chart

8: Assembly Language Program

9: Applications of ultrasonic distance meter

10: Conclusion and future scope

11: Reference

6

CHAPTER-1

INTRODUCTION

There are several ways to measure distance. Ultrasonic distance meter is one such non

contact method, it measures distance without any mechanical coupling with the object

and is hence non loading as well.

The heart of the circuit is the microcontroller AT89C2051. The microcontroller based

Ultrasonic distance meter consists of 6 major components other than the microcontroller

itself, the 40Khz ultrasonic transmitter, 40Khz Ultrasonic receiver , CD4049 Fairchild

Hex inverting buffer, LM324 Low power quad operational-amplifier, ULN2003 current

buffer and four LTS542 common anode seven segment display.

The microcontroller is used to generate 40 kHz sound pulses. These sound pulses are

used to excite the ultrasonic transmitter thereby transmitting these waves, and expect an

echo from the object whose distance is to be measured.

These waves travels to the object in the air and is reflected back when they fall on the

object, this echo signal is picked up by another ultrasonic transducer unit, the Receiver,

also a 40Khz pre-tuned unit. These signals received are weak, they are further amplified

several times in the receiver circuit before being read by the micro controller and

microcontroller finds the time taken in microseconds for the to-and-fro travel of the

sound waves. Using the velocity of 333 m/sec, the speed of sound at 25 degree Celsius

ambient temperature, the micro controller does the calculations and finally displays the

distance of the object from the device on the four seven segment display.

7

ULTRASONIC PRINCIPLES

Ultrasonic is the study and application of high-frequency sound waves, usually in excess

of 20 KHz (20,000 cycles per second). Ultrasonic generators use piezo-electric 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 2.5 MHz

Modern ultrasonic generators can produce frequencies as high as several gigahertz

( several billion cycles per second) by transforming alternating electric currents into

mechanical oscillations, and scientists have produced ultrasound with frequencies up to

about 10Ghz. There maybe an upper limit to the frequency of usable ultrasound, but it is

not yet known.

Higher frequencies have shorter wavelengths, which allow them to reflect from objects

more readily and to provide better information about those objects. However extremely

high frequencies are difficult to generate and measure. Detection and measurement of

ultrasonic waves is accomplished mainly through the use of piezoelectric receivers or by

optical means. The latter is possible because ultrasonic waves are rendered visible by the

diffraction of light.

Ultrasound is far above the human auditory range, which is only about 20Hz to 18 KHz.

However, some mammals can hear well above this. For example, bats and whales use a

phenomenon called echo location for easy navigation that can reach frequencies in excess

of 100 KHz.

With an ultrasonic transducer, the waves propagate out from the transducer face with a

circular wave front, these waves travel through the medium until they encounter any

obstacles in its path, owing to their shorter wavelength, they are readily reflected back by

these obstacles , these reflected waves are picked up by the receiver circuit, these signals

are amplified several times . Weak echoes also occur due to the signals being received

8

directly through the side lobes. These maybe ignored as the real information regarding

the proximity and nature of the obstacle.

9

CHAPTER-2

BLOCK DIAGRAM

10

BLOCK DIAGRAM DISCRIPTION

11

CHAPTER-3

3.1 CIRCUIT DIAGRAM

12

3.2 CIRCUIT DESCRIPTION

The figure shows the circuit of the micro-controller based ultrasonic distance meter. The

40Khz pulse bursts from the microcontroller are amplified by transistor T5. Inverting

buffer CD4049 drives the ultrasonic sensor used as the transmitter. Three inverters

(N1,N2,N3) are connected in parallel to increase the transmitted power. This inverted

output is fed to another set of three inverters (N4,N5,N6). Outputs of both sets of parallel

inverters are applied as a push-pull drive to the ultrasonic transmitter.

The positive going pulse is applied to one of the terminals of the ultrasonic sensor and the

same pulse after 180-degree phase shift is applied to another terminal. Thus the

transmitted power is increased for increased range.

The echo signal received by the receiver sensor after reflection is very weak. It is

amplified by quad operational amplifier LM324. The first stage (A1) is a buffer with

unity gain. The received signal is directly fed to the to the non-inverting input (pin3) of

A1 and coupled to the second stage by a 3.3nF capacitor. The second stage of the

inverting amplifier uses a 2-mega-ohm resistor for feedback. The third stage is a

precision rectifier amplifier with a gain of 10.

The rectifier functions, unlike a simple diode, even for a signal voltage of less than 0.6V.

The output is filtered to accept 40Khz frequencies and fed to pin12 of microcontroller

AT89C2051, which is an analog comparator. Pin13 is the other pin of the comparator

used for level adjustment using preset VR1.

The ultrasonic transducer outputs a beam of sound waves, which has more energy on the

main lobe and less energy (60dB below the main lobe) on the side lobes. Even this low

side-lobe signals are picked up by the ultrasonic receiver unit. So the transmitter and

receiver units are spaced 5cm apart.

pins P1.7 through P1.2 connected to input pins 1 through 7 of IC2(IC ULN2003)

respectively. These pins are pulled up with a 10-kilo-ohm resistor network. They drive all

the segments of the 7-segment display with the help of the and port-3 pin P3.7 are

13

Microcontroller AT89C2051 is at the heart of the circuit. Port-1 inverting buffer (ULN

2003).

Port-3 pins P3.0 through P3.3 of the microcontroller are connected to the base of

transistor T1 through T4 to provide the supply to the four 7-segment displays. Pin P3.0 of

microcontroller IC1 goes low to drive transistor T1 into saturation, which provides

supply to the common-anode pin of the first 7-segment display. Similarly, Transistor T2

through T4 provides anode currents to other three 7-segment displays.

Microcontroller IC1 provides the segment data and display-enable signal simultaneously

in time-division multiplexed mode for displaying a particular number on the 7-segment

display unit.

Segment data and display enable pulse for the display are refreshed every 5ms. Thus the

display appears to be continuous, even though the individual LEDs used in it light up one

by one.

Using switch S1 you can manually reset the microcontroller. While the power-on reset

signal for the microcontroller is derived from the combination of capacitor C4 and

resistor R8. A 12Mhz crystal is used to generate the basic clock frequency for the

microcontroller. Resistor R16 connected to pin 5 of 7-segment 2 enables the decimal

point.

The comparator is inbuilt in the microcontroller. The echo signal will make port-3 pin

P3.6 low when it goes above the level set on pin13. This status is sensed by the

microcontroller as programmed.

When port-3 pin P3.6 goes high, we know that the signal has arrived; the timer is read

and the 16-bit number is divided by twice the velocity of sound and then converted into

decimal format as a 4-digit number.

14

3.3 POWER SUPPLY CIRCUIT

The 230V AC main is stepped down by the transformer to deliver the secondary

power of 15V-0-15V, 500mA. The transformer output is rectified by a full wave rectifier

comprising of four diodes (IN4001),filtered by a capacitors C8 and C9and then regulated

by ICs 7815(IC5), 7915(IC6),7805(IC7). Regulators 7815, 7915 and 7805 provide +15V,

-15V and +5V regulated supply respectively. The capacitors C10, C11, C12 bypasses the

ripples present in the regulated supply.

15

3.4 COMPONENT LIST

SEMICONDUCTORS:

1. IC1 - AT89C2051 microcontroller2. IC2 - ULN2003 current buffer3. IC3 - CD4049 hex inverting buffer4. IC4 - LM324 quad operational amplifier5. IC5 - 7815, 15V regulator6. IC6 - 7915, -15V regulator7. IC7 - 7805, 5V regulator8. T1-T4 - BC557 pnp transistor9. T5 - 2N2222 npn transistor10. D1, D2 - 1N4148 switching diode11. D3-D6 - 1N4007 rectifier diode12. DIS1-DIS4 - LTS 542 common-anode seven segment display

RESISTORS (all ¼-watt, ±5% carbon):

1. R1,R2-2-mega-ohm

2. R1, R2 - 2-mega-ohm

3. R3 - 82-kilo-ohm4. R4, R7-R10 - 10-kilo-ohm5. R5 - 33-kilo-ohm6. R6 - 100-kilo-ohm7. R11 - 1-kilo-ohm8. R12-R15 - 1.2-kilo-ohm9. R16 - 220-ohm10. RNW1 - 10-kilo-ohm resistor network11. VR1 - 1-kilo-ohm preset

CAPACITORS:

1. C8, C9 - 1000μF, 50V electrolytic

2. C1, C2 - 3.3nF ceramic disk3. C7, C10-C12 - 0.1μF ceramic disk4. C3 - 2.2nF ceramic disk5. C4 - 10μF, 16V electrolytic6. C5, C6 - 22pF ceramic disk

16

MISCLLANEOUS:

1. X1- 230V AC primary to secondary transformer2. XTAL - 12MHz crystal3. S1 - Push-to-on switch4. S2 - On/off switch5. TX1 - 40kHz ultrasonic transmitter6. RX1 - 40kHz ultrasonic receiver

17

CHAPTER-4

COMPONENT DISCRIPTION

4.1 SEMICONDUCTORS

4.1.1 AT89C2051 MICROCONTROLLER:

Fig.4.1.1: AT89C2051 Microcontroller

The AT89C2051 is a low-voltage, high-performance CMOS 8-bit microcomputer with

2K Bytes of Flash programmable and erasable read only memory (PEROM). The device

is manufactured using Atmel’s high density nonvolatile memory technology and is

compatible with the industry standard MCS-51™ instruction set. By combining a

versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C2051 is a powerful

microcomputer which provides a highly flexible and cost effective solution to many

embedded control applications.

18

Features :

1. Compatible with MCS-51 Products

2. 2K Bytes of Reprogrammable Flash Memory

3. 2.7 to 6V Operating Range

4. Fully Static Operation: 0 Hz to 24 MHz

5. Two-level Program Memory Lock

6. 128 x 8-bit Internal RAM

7. 15 Programmable I/O Lines

8. Two 16-bit Timer/Counters

9. Six Interrupt Sources

10. Programmable Serial UART Channel

11. Direct LED Drive Outputs

12. On-chip Analog Comparator

13. Low-power Idle and Power-down Modes

14. 20-pin DIP

Pin Diagram – AT89C2051 :

Fig 4.1.2:Pin Diagram – AT89C2051

19

Pin Description :

Pin Number Description

1RESET – Reset

2P3.0 – Port 3 – RXD

3P3.1 – Port 3 – TXD

4XTAL2 – Crystal

5 XTAL1 – Crystal

6P3.2 – Port 3 – INT0

7P3.3 – Port 3 – INT1

8P3.4 – Port 3 – TO

9P3.5 – Port 3 – T1

10GND – Ground

11 P3.7 – Port 3

12P1.0 – Port 1 – AIN0

13 P1.1 – Port 1 – A1N1

20

14P1.2 – Port 1

15P1.3 – Port 1

16P1.4 – Port 1

17P1.5 – Port 1

18P1.6 – Port 1

19 P1.7 – Port 1

20Vcc – Positive Power Supply

Fig.4.1.3 Pin description

4.2 IC7 – 7805 5V regulator:

7805 is a voltage regulator integrated circuit. It is a member of 78xx series of

fixed linear voltage regulator Ics. The voltage source in a circuit may have

fluctuations and would not give the fixed voltage output. The voltage regulator IC

maintains the output voltage at a constant value. The xx in 78xx indicates the

fixed output voltage it is designed to provide. 7805 provides +5V regulated power

supply. Capacitors of suitable values can be connected at input and output pins

depending upon the respective voltage levels.

 

21

Pin Diagram: 

Figure 4.2.1: Pin Diagram of IC 7805

Pin Description: 

Pin No Function Name

1 . Input voltage (5V-18V) Input

2 . Ground (0V) Ground

3 . Regulated output; 5V (4.8V-5.2V) Output

Table 4.2.2: Pin Description of IC 7805

22

The 7805 voltage regulators employ built-in current limiting, thermal shutdown,

and safe-operating area protection which makes them virtually immune to damage

from output overloads. 7805 is a three-terminal positive voltage regulator.

With adequate heatsinking, it can deliver in excess of 0.5A output current.

Typical applications would include local (on-card) regulators which can eliminate

the noise and degraded performance associated with single-point regulation.

7805 regulator comes from the 78xx family of self-contained fixed linear voltage

regulator integrated circuits. The 78xx family is a very popular choice for many

electronic circuits which require a regulated power supply, due to their ease of use

and relative cheapness. When specifying individual Ics within this family, the xx

is replaced with a two-digit number, which indicates the output voltage the

particular device is designed to provide (for example, the 7805 voltage regulator

has a 5 volt output, while the 7812 produces 12 volts).

The 78xx line are positive voltage regulators, meaning that they are designed to

produce a voltage that is positive relative to a common ground. There is a related

line of 79xx devices which are complementary negative voltage regulators. 78xx

and 79xx Ics can be used in combination to provide both positive and negative

supply voltages in the same circuit, if necessary.

7805 Ics have three terminals and are most commonly found in the TO220 form

factor, although smaller surface-mount and larger TO3 packages are also

available from some manufacturers. These devices typically support an input

voltage which can be anywhere from a couple of volts over the intended output

voltage, up to a maximum of 35 or 40 volts, and can typically provide up to

around 1 or 1.5 amps of current (though smaller or larger packages may have a

lower or higher current rating).

The 7805 series has several key advantages over many other voltage regulator

circuits which have resulted in its popularity:

23

7805 series Ics do not require any additional components to provide a constant,

regulated source of power, making them easy to use, as well as economical, and

also efficient uses of circuit board real estate. By contrast, most other voltage

regulators require several additional components to set the output voltage level, or

to assist in the regulation process. Some other designs (such as a switching power

supply) can require not only a large number of components but also substantial

engineering expertise to implement correctly as well.

7805 series Ics have built-in protection against a circuit drawing too much power.

They also have protection against overheating and short-circuits, making them

quite robust in most applications. In some cases, the current-limiting features of

the 7805 devices can provide protection not only for the 7805 itself, but also for

other parts of the circuit it is used in, preventing other components from being

damaged as well.

7805 Voltage Regulator Pinout :

Figure 4.2.3: 7805 Voltage Regulator Pin out

24

7805 Regulator Circuit:

Figure 4.2.4: 7805 Regulator Circuit

4.3 CD4049 HEX INVERTING BUFFER:

The CD4049 hex buffer is a monolithic complementary MOS (CMOS) integrated circuit,

manufactured by Fairchild semiconductor, constructed with N channel enhancement

mode transistors. This device feature logic level conversion using only one supply

voltage (VDD). The input signal high level (VIH) can exceed the VDD supply voltage

when the devices are used for logic level conversions. The device is intended for use as

hex buffers, CMOS to DTL/ TTL converters, or as CMOS current drivers, and at VDD =

5.0V, they can drive directly two DTL/TTL loads over the full operating temperature

range.

25

4.4 LM324 QUAD OPERATIONAL AMPLIFIER:

The LM124 series consists of four independent, high gain, internal frequency

compensated operational amplifiers which designed specifically to operate a single power

supply over a wide range of voltages. Operation from split power supplies is also possible

and the low power supply current is independent of the of the power supply voltage.

Application areas include transducer amplifiers,DC gain blocks and all the conventional

op amp circuits which now can be more easily implemented in single power supply

systems. For example, the LM124 series can be directly operated off of the standard 5V

power supply voltage which is used in digital systems and will easily provide the required

interface electronics without requiring the additional ± 15V power supplies.

4.5 ULN2003 CURRENT BUFFER:

Ideally suited for interfacing between low-level logic circuitry and multiple peripheral

power loads, the Series ULN20xxA/L high-voltage, high-current Darlington arrays

feature continuous load current ratings to 500 mA for each of the seven drivers. At an

appropriate duty cycle depending on ambient temperature and number of drivers turned

ON simultaneously, typical power loads totaling over 230 W (350 mA x 7, 95 V) can be

controlled.

Typical loads include relays, solenoids, stepping motors, magnetic print hammers,

multiplexed LED and incandescent displays, and heaters. All devices feature open-

collector outputs with integral clamp diodes.

26

4.6 D1 - 1N4007 rectifier diode

Fig4.6.1 :1N4007 Diode

The 1N4007 has a blocking voltage of 1000V and is typically supplied in an axial-leaded

DO-41 package. The 1N4007 is a 1 Amp (1A) general purpose rectifier diode commonly

used in power applications.

Currently the 1N4007 is sourced from manufacturers such as Comchip

Technology Corporation, DAICO Industries Inc., Diodes Incorporated, EIC

Semiconductor, Fairchild Semiconductor, Micro Commercial Components

(MCC), Microsemi Corporation, NTE Electronics, ON Semiconductor, SPC

Technology, and Vishay Semiconductors.

Related parts, primarily varying in blocking voltage include: 1N4001, 1N4002,

1N4003, 1N4004, 1N4005 and 1N4006.

27

1N4007 Features :

1. Current Rating: 1A

2. Blocking Voltage: 1000V

3. Packages: DO-41 (Axial Leaded), DO-20 (Axial Leaded)

1N4007 Applications :

1. General Purpose

2. AC Adaptors

3. Household Appliances

1N4007 Circuit Diagram :

Figure 4.9: 1N4007 Circuit Diagram

28

4.2 CAPACITORS

4.2.1 C8,C9 - 1000μF, 50V electrolytic

Figure 4.11 : 1000μF, 50V electrolytic capacitor

Specifications of 1000μF, 50V electrolytic capacitor

Category Capacitors

Family Aluminum

Series FC

Capacitance 1000µF

Voltage Rating 25V

Tolerance ±20%

29

Lifetime @ Temp. 5000 Hrs @ 105°C

Operating Temperature -55°C ~ 105°C

Features General Purpose

Ripple Current 1.655A

ESR (Equivalent Series Resistance) -

Impedance 38 mOhm

Mounting Type Through Hole

Package / Case Radial, Can

Size / Dimension 0.492" Dia (12.50mm)

Height - Seated (Max) 0.787" (20.00mm)

Lead Spacing 0.197" (5.00mm)

Surface Mount Land Size -

Packaging Bulk

Catalog Page 1689 (US2011 Interactive)

1689 (US2011 PDF)

Other Names EEUFC1E102

P10278

4.2.2 C7,C10-C12 - 0.1μF ceramic

30

Fig 4.2.1: C3 – 0.1Μf ceramic

Specifications Of C3 – 0.1Μf ceramic

CAPACITOR CERAMIC 0.1UF, 50V, Y5V, RAD

Capacitance

Capacitance Tolerance

Voltage Rating

Capacitor Mounting

Capacitor Terminals

Lead Spacing

RoHS Compliant

0.1µF

± 20%

50V

Through Hole

Radial Leaded

2.54mm

Yes

4.3 MISCELLANEOUS

31

4.3.1 S2 - SPST ‘on’/‘off’ switch:

Specifications:

1. Supply Power: +5v @ 100mA / -5V @ 60Ma

2. Logic Input High (2.5~5V, 1mA max) : On

3. Logic Input Low (0~0.6V, 3mA max) : Off

Electronics

specification

and

abbreviation

Expansion

of

abbreviatio

n

British

mains

wiring

name

America

n

electrica

l

wiring

name

Description Symbol

SPST

Single

pole, single

throw

One-

way

Two-

way

A simple on-off

switch: The two

terminals are either

connected together or

disconnected from

each other. An

example is a light

switch.

CHAPTER-5

32

SOFTWARE DEVELOPMENT

5.1 SOFTWARE

5.2 MICROCONTROLLER PROGRAMMING

33

ORG 0H

AJMP 30H

ORG 0BH ;TIMER 0 INTERRUPT VECTOR

; AJMP TIMER0ISR ;Timer 0 Interrupt

service routine address

ORG 30H

MOV SP,#60H ;set stack pointer

MOV P3,#0FFH ;set all port 3 bits high

to enable inputs also

MOV P1,#03 ;set port 1 to all zeros expect bits 0,1

MOV TMOD,#01100001B ;TIMER 1 - MODE 2

COUNTER,TIMR-0 TO MODE 1

BEG: MOV TH0,#0H ;TIMER REG.0 IS SET TO

0, GIVES 64ms

MOV TL0,#0 ; timer low reg. is also so

;TOTAL CYCLE TIME IS 64.6ms ,350m/s

gives 0.35mx65=22.5m

; up and down 10 metres say! .35 m/ms,

.35 mm/us, 1mm per 3 micros

; up and down .35/2 mm/us = 1/6 mm/us

; VELOCITY OF SOUND IN AIR IS 350 M/S

; AFTER 100 TIMES, WE HAVE TO STOP

TRANSMITTING FOR A TIME OF ABOUT .1 S;

SO WE STOP FOR THIS AMOUNT OF TIME

and expect an echo.

34

mov r2,#25 ; 25 pulses 26 us =.53 ms

(343m/s*.5ms=17cm)

pulse: setb p3.4 ;generates 40KHz

mov r1,#5

djnz r1,$

clr p3.4

mov r1,#5

djnz r1,$ ;wait for 13 us

djnz r2, pulse ;20pulses

setb tr0 ;start timer

mov r2,#10

djnz r2,$ ;wait 20 us

check_echo:

jnb p3.6,checktimeout

MOV 40h,TL0 ; read timer count

MOV 41h,TH0

mov r0,40h

mov r1,41h

mov r3,#0

mov r2,#6

call UDIV16 ;divide by 6

mov 40h,r0

mov 41h,r1

mov 50h,#25

disp: call disp1 ; show the value on

35

LED

djnz 50h,disp ; so many times for a

visible time limit

jmp beg

checktimeout: mov a,th0

cjne a,#0c0h,check_echo ;upto 4 metres

jmp beg

;subroutine UDIV16

;16 bit/16bit unsigned divide

;input r1,r0 =dividend X

;input r3,r2 =divisor Y

;output r1,r0 =quottient q of x/y

;output r3,r2 = remainder

; alters acc,r4-47,flags,dptr

UDIV16: mov r7,#0 ;clear partial remainder

mov r6,#0 ;

mov B,#16 ;set loop count

div_loop: clr C ;clear carry flag

mov a,r0 ; shift the highest bit of

dividend into

rlc a

mov r0,a

mov a,r1

rlc a

mov r1,a

36

mov a,r6 ;... the lowest bit of partial

remainder

rlc a

mov r6,a

mov a,r7

rlc a

mov r7,a

mov a,r6

clr C

subb a,r2

mov dpl,a

mov a,r7

subb a,r3

mov dph,a

cpl C

jnc div_1 ;update partial reaminder

if borrow

mov r7,dph

mov r6,dpl ; update parital reminder

div_1: mov a,r4

rlc a

mov r4,a

mov a,r5

rlc a

mov r5,a

37

djnz B,div_loop

mov a,r5

mov r1,a ; put qt. in r0,r1

mov a,r4

mov r0,a

mov a,r7 ;get rem. saved before the

mov r3,a ;last subtraction.

mov a,r6

mov r2,a

ret

;16 Bit Hex to BCD Conversion for 8051

Microcontroller

; This routine is for 16 bit Hex to BCD

conversion;

;Accepts a 16 bit binary number in

R1,R2 and returns 5 digit BCD in

;R7,R6,R5,R4,R3(upto 64K )

Hex2BCD: ;r1=high byte ;r7 most significant

digit

;R2 = LSByte

MOV R3,#00D

MOV R4,#00D

MOV R5,#00D

MOV R6,#00D

MOV R7,#00D

38

MOV B,#10D

MOV A,R2

DIV AB

MOV R3,B ;

MOV B,#10 ; R7,R6,R5,R4,R3

DIV AB

MOV R4,B

MOV R5,A

CJNE R1,#0H,HIGH_BYTE ; CHECK FOR HIGH

BYTE

SJMP ENDD

HIGH_BYTE: MOV A,#6

ADD A,R3

MOV B,#10

DIV AB

MOV R3,B

ADD A,#5

ADD A,R4

MOV B,#10

DIV AB

MOV R4,B

ADD A,#2

ADD A,R5

MOV B,#10

DIV AB

39

MOV R5,B

CJNE R6,#00D,ADD_IT

SJMP CONTINUE

ADD_IT: ADD A,R6

CONTINUE: MOV R6,A

DJNZ R1,HIGH_BYTE

MOV B, #10D

MOV A,R6

DIV AB

MOV R6,B

MOV R7,A

ENDD: ret

DISP1:

REFRESH: ; content of 18 to 1B memory

locations are output on LEDs

; only numbers 0 to 9 and A to F are

valid data in these locations

mov r1,41h

mov r2,40h

CALL HEX2BCD

MOV 18H,r3 ; least significant digit

MOV 19H,r4 ; next significant digit

MOV 1AH,r5

MOV 1BH,R6 ; most significant digit

(max:9999)

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refresh1: MOV R0,#1bh ; 1b,1a,19,18,

holds values for 4 digits

MOV R4,#8 ; pin p3.3_ 0 made low one by

one starts wth 18

mov r7,#2 ; decimal pt.on 3rd digit

from left (2 nd fromright)

PQ2: CALL SEGDISP

deC R0

mov a,r4

rrc a

mov r4,a

jnc pQ2

PV3:

RET

SEGDISP:

mov dptr,#ledcode

MOV A,@R0

ANL A,#0FH

MOVC A,@A+dptr

segcode:

MOV R5,A

ORL A,#03H ; WE WANT TO USE PORT 1 BITS

0 AND 1 FOR INPUT ANLOG

; so retain them high

S3: MOV P1,A ; SEGMENT_PORT

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MOV A,R5 ;we use p3.7 for the segment

‘a’ of display

RRC A ;so get that bit D0into carry

; cpl c

; mov p3.5,c ; dec pt is D0 bit that is

wired to p3.5

rrc a

mov p3.7,c ;segment ‘a;

S1: MOV A,R4 ; get digit code from r4

00001000

cpl a ;11110111

rrc a ;11111011-1

mov p3.0,c ; output to drive transsitors

for digit lighting

rrc a ;11111101-1

mov p3.1,c

rrc a ;11111110-1

mov p3.2,c

rrc a ;1111111-0 yes low makes leftmost

digit show msdigit

mov p3.3,c

S5:

S4: ACALL DELAY1 ; let it burn

for some time

MOV A,#0ffH ; extinguish

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the digit after that time

MOV P3,A ; to prevent shadow

s6: RET

ledcode:

DB 7EH,0CH,0B6H,9EH,0CCH,0DAH,0FAH

DB 0EH,0FEH,0CEH,0EEH,0F8H,72H,0BCH,0

F6H,0E2H

;these are code for

the numbers 0 to 9 and A to F

DELAY1: MOV R1,#0ffH

N: NOP

DJNZ R1,N

RET

END

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FLOWCHART

44

CHAPTER-6

PCB LAYOUT

6.1 Etching Process

PCB is printed circuit board which is of insulating base with layer of thin copper-foil

.

The etching process was carried out in this manner :

The PCB is cleaned with the thinner , so that the dust on the PCB is

removed and we get a shiny surface .

Then we inserted our PCB in the DIPCOAT that is negative photoresistive

material and expose the PCB for 5 to 10 seconds so that the negative

photoresistive material should dry .

Fig.6.1: Dipcoat

Then the photoresistive material ( liquid ) should be made hard on the PCB

for which the PCB is kept in the oven ( protocure ) for four minutes .

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After the liquid is made hard on the PCB it is kept in the PCB exposure

for two minutes. .In the PCB exposure the circuit is kept with its layout .

The ultraviolet rays are passed through the PCB.

Fig.6.2 : PCB Exposure

Then we have to expose our PCB to the nail polish remover solution which

is also called as developer liquid .As a result of this an impression of

tracks is formed on the PCB .

Put the PCB in a oven ( protocure ) to make the impression hard . The PCB

is kept in oven for four minutes .

After removing the PCB from the oven , the tracks on the PCB will be

developed .After this the PCB is dipped into the PROTO- ETCH for five

minutes . The solution used in the PROTO-ETCH is ferric chloride , due this

the tracks now are fully developed on the PCB .

Then the PCB is washed in water by hand and cleaned by the cloth .Thus

the etching process is completed to mount the components on the PCB we

need to drill the PCB according to the layout . we did the drilling in our

IPR lab under the guidance of the lab incharge.

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6.2 Component Layout

6.2.1 Positive Layout :

6.2.2 Negative Layout :

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6.2.3 Component Placement :

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6.3 Soldering

For soldering of any joints first the terminal to be soldered are cleaned to

remove oxide film or dirt on it. If required flux is applied on the points to be

soldered.

Now the joint to be soldered is heated with the help of soldering iron heat

applied should be such that when solder wire is touched to joint , it must melt

quickly.

The joint and the soldering iron is held such that molten solder should flow

smoothly over the joint .

When joint is completely covered with molten solder , the soldering iron is

removed .

The joint is allowed to cool, without any movement .

The bright shining solder indicates good soldering .

In case of dry solder joint, a air gap remains in between the solder

material and the joint. it means that soldering is improper .this is removed

and soldering is done.

Thus in this way all the components are soldered on PCB .

49

CHAPTER - 7

CALCULATIONS AND TESTING

7.1 Calculations

50

7.2 Testing

We need following Equipment’s for testing the Circuit-

Oscilloscope

An oscilloscope (also known as a scope, CRO, DSO or, an O-scope) is a type of electronic

test instrument that allows observation of constantly varying signal voltages.

Oscilloscopes are commonly used to observe the exact wave shape of an electrical

signal. In addition to the amplitude of the signal, an oscilloscope can show distortion,

the time between two events (such as pulse width, period, or rise time) and relative

timing of two related signals.

Digital Multi Meter (DMM)

Figure 7.3 : Digital Multi Meter

A multimeter is also known as a VOM (Volt-Ohm meter), is

an electronic measuring instrument that combines several measurement functions

in one unit. A typical multimeter may include features such as the ability to

measure voltage , current and resistance.

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52

CHAPTER-8

APPLICATIONS OF THE ULTRASONIC

DISTANCEMETER:

a) Ultrasonic distance meters are being increasingly used in various industries to measure

critical parameters like fluid height, thickness of materials…etc with very high accuracy.

b) Various luxury cars are equipped with state-of-the-art ultrasonic distance meters as

part of its parking assist system.

c) A technology pretty similar to this, Patented by Mercedes and Co. is being used in

their next generation luxury cars in what they call the ACCIDENT PREVENTION

SYSTEM.

d) Ultrasonic distance meters can be potentially used in rifles and war planes for target

assessment by the armed force. It is already a part of several military surveillance

equipments.

e) The same hardware system, with slight change in the microcontroller program can be

made to detect moving objects and find their range and speed, which maybe used in

speed guns to measure the speed of vehicles.

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CONCLUSION AND FUTURE SCOPE:

The unit can successfully used to measure distance with a very high degree of accuracy.

The range of this ultrasonic distance meter can be increased further than 2.5m by using a

higher pulse excitation voltage or a better transducer.

The same unit can be made to detect movement of objects such as cars racing on the

street and find their range and speed.

It can also be used with suitable additional software as a burglar alarm unit for homes and

office.

54

REFERENCES

Books:

1. Principles of Electronics by V.K.Meheta.

2. Electronic Instrumentation by H.S. Kalsi.

3. 8051 Microcontroller and Embedded System by Mazidi and Mazidi.

4. A textbook of Applied Electronics by R.S.Sedha.

Websites:

1. www.geocities.com

2. www.yahoo.com

3. http://olimp.infomir.kiev.ua/docs/PDF/AT89C2051

4. http://www.efy.com

5. www.8051projects.net

6. www.wikipedia.com

7. www.electronicsforu.com

8. www.ieee.org

9. www.crazyengineers.com

10. www.electronics4everyday.com

Software Used :

1. Eagle Software - For PCB

2. ASEM-51.exe - Assembler

3. Keil – Execution.

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