capstone project 2 final

7/28/2019 Capstone Project 2 Final

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CHAPTER 1

INTRODUCTION

The techniques of distance measurement using ultrasonic in air include continuous wave and

pulse echo technique. In the pulse echo method, a burst of pulses is sent through the

transmission medium and is reflected by an object kept at specified distance. The time taken

for the pulse to propagate from transmitter to receiver is proportional to the distance of

object. For contact less measurement of distance, the device has to rely on the target to reflect

the pulse back to itself. The target needs to have a proper orientation that is it needs to be

perpendicular to the direction of propagation of the pulses. The amplitude of the received

signal gets significantly attenuated and is a function of nature of the medium and the distance

between the transmitter and target. The pulse echo or time-of-flight method of range

measurement is subject to high levels of signal attenuation when used in an air medium, thus

limiting its distance range. A simple ultrasonic range finder using 8051 microcontroller is

presented in this article. This ultrasonic rangefinder can measure distances up to 2.5 meters

at an accuracy of 1 centi meter. AT89s51 microcontroller and the ultrasonic transducer

module HC-SR04 forms the basis of this circuit. The ultrasonic module sends a signal to the

object, then picks up its echo and outputs a wave form whose time period is proportional to

the distance. The microcontroller accepts this signal, performs necessary processing anddisplays the corresponding distance on the 3 digit seven segment display. This circuit finds a

lot of application in projects like automotive parking sensors, obstacle warning systems,

terrain monitoring robots, industrial distance measurements etc.

The means for the measurement of distance of the target and for different other applications

Ultrasonic distance sensors are used to detect the presence of flaw by measuring the distance.

They do so by evaluating the echo of a transmitted pulse with concern to its travel time. Time

dependent control of sensitivity is used to compensate the distance dependency of the echo

amplitude, while different reflection properties are compensated by an automatic gain

control, which holds the average echo amplitude constant. Echo amplitude therefore has very

little influence on the accuracy of the distance measurement provided the signal to noise ratio

is not very low. By considering whether the echo has been received within a time window,

i.e. a time interval, which can be preset by the user, the distance range is given in which the

sensor responds to the presence of an object. Using this technique, interference can be

suppressed and relevant objects are monitored more reliably.


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CHAPTER 2

OBJECTIVE OF THE PROJECT

The object of this work is to replace the old traditional range detector, used in several

applications. In present work the object position is measured electronically by using seven

segment displays by replacing the heavy and bulky circuits with the compact circuits using

intelligent Microcontroller. The bulky pressing switch is replaced by the small and one touch

tactile switch. It saves electric consumption, saves the no. of man power, through seven

segment display and one microcontroller as well as ultrasonic receiver & transmitter sensors.

CHAPTER 3

ULTRASONIC DISTANCE METER

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 25C ambient

temperature and shows it on a 7-segment display. Using it, you can measure distance up to

2.5 meters. For this particular application, the required components are AT89C2051microcontroller, two 40kHz ultrasonic transducers (one each for transmitter and receiver),

current buffer ULN2003, operational amplifier iM324I inverter Ca4M4VI four T-segment

displays I five transistors and some discreet components. The ultrasonic transmitter- receiver

pair is shown in Ultrasonic generators use piezoelectric materials such as zinc or lead

zirconium tartrates or quartz crystal.. The velocity of sound in the air is around 330 m/s at

0C and varies with temperature.

In this project, you excite the ultrasonic transmitter unit with a 40kHz pulse burst and

expect an echo from the object whose distance you want to measure. Fig. 2 shows the

transmitted burst, which lasts for a period of approximately 0.5 ms. It travels to the

object in the air and the echo signal is picked up by another ultrasonic transducer unit

(receiver), also a 40 kHz pre-tuned unit. The received signal, which is very weak is amplified

several times in the receiver circuit and appears somewhat as shown in Fig. 2 when seen on a

CRO. Of course, the signal gets weaker if the target is farther than 2.5 and will need a higher

pulse excitation voltage or a better transducer. Here the microcontroller is used to generate 40

kHz sound pulses. It reads when the echo arrives; it finds the time taken in microseconds for


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to-and-fro travel of sound waves. Using velocity of 333 m/s, it does the calculations and

shows on the four 7-segment displays the distance in centimeters and millimeters (three digits

for centimeters and one for millimeters).

3.1. BLOCK DIAGRAM OF ULTRASONIC DISTANCE METER

Figure 1 : Block Diagram of Ultrasonic Distance meter


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CHAPTER 4

THEORY OF OPERATION

The Ping sensor detects objects by emitting a short ultrasonic burst and then "listening" for

the echo. Under control of a host microcontroller (trigger pulse), the sensor emits a short 40

kHz (ultrasonic) burst. This burst travels through the air at about 1130 feet per second, hits an

object and then bounces back to the sensor. The PING sensor provides an output pulse to the

host that will terminate when the echo is detected, hence the width of this pulse corresponds

to the distance to the target.

Figure 2: Transmitting and Receiving Waves

4.1. ULTRASONIC WAVES

Sound waves with frequency range from 20 Hz to 20 KHz are responsive to the human ear.Vibrations above this frequency are termed as ultrasonic. Ultrasonic signals are affected by

the properties of the medium. Thus while passing through a particular medium these signals

get attenuated. The attenuation of ultrasonic signal is taken as the means for the measurement

of distance of the target and for different other applications Ultrasonic distance sensors are

used to detect the presence of flaw by measuring the distance. They do so by evaluating the

echo of a transmitted pulse with concern to its travel time. Time dependent control of

sensitivity is used to compensate the distance dependency of the echo amplitude, while

different reflection properties are compensated by an automatic gain control, which holds the


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average echo amplitude constant. Echo amplitude therefore has very little influence on the

accuracy of the distance measurement provided the signal to noise ratio is not very low. By

considering whether the echo has been received within a time window, i.e. a time interval,

which can be preset by the user, the distance range is given in which the sensor responds to

the presence of an object. Using this technique, interference can be suppressed and relevant

objects are monitored more reliably.

A variety of ultrasonic presence sensors with different operation frequencies are designed for

different distance range and different resolution. Such sensors are employed in the

automation of industrial processes as well as in traffic control systems, for example to

monitor, whether car parking places are occupied. Ultrasonic distance meters are used for the

measurement of the filling level in containers or the height of material on conveyor belts.

Ultrasonic waves are generally used two types which are given as :-

4.1.1LONGITUDINAL WAVES

Longitudinal waves exist when the motion of the particle and the medium is parallel to the

direction of propagation of the waves. These types of waves are referred as L waves. Since

these can travel in solid, liquid and gases. These waves can be easily detected.

4.1.2TRANSVERSE WAVES

In this case particles of the medium vibrate at right angle to the direction of propagation of

the waves. These are also called shear waves.

4.2. ULTRASONIC DISTANCE SENSORS

Ultrasonic sonar sensors actively transmit acoustic waves and receive them later. This is done

by ultrasonic transducers, which transform an electrical signal into an ultrasonic wave and

vice versa. The ultrasound signal carries the information about the variables to be measured.

The task for the ultrasonic sensors is not merely to detect ultrasound, as intelligent sensors

they have to extract the information carried by the ultrasonic signals efficiently and with high

accuracy. To achieve this performance, the signals are processed, demodulated and evaluated

by dedicated hardware. Algorithms based on models for the ultrasonic signal propagation and


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the interaction between the physical or chemical variables of interest are employed

(munich,1994).

Furthermore, techniques of a sensor specific signal evaluation are being applied. Ultrasonic

sensors can be embedded into a control system that accesses additional sensors, combines

information of the different sensors, handles the bus protocols and initiates actions.

Figure 3: Ultrasonic Transducer (Transmitter and Receiver)

CHAPTER 5

CIRCUIT DESCRIPTION

Figure 4 shows the circuit of the microcontroller based distance meter. The 40kHz pulsebursts from the microcontroller are amplified by transistor T5. Inverting buffer CD4049

drives the ultrasonic sensor used as the transmitter. Three inverters (N1, N2 and N3) are

connectedin parallelto increase thetransmitted power.This inverted outputis fed to another

set of threeinverters (N4, N5and N6). Outputsof both sets of parallelinverters areapplied as

a push pulldrive to theultrasonic transmitter.

The positive goingpulse is applied to one of the terminals of theultrasonic sensorand the

same pulseafter 180-degreephase shift is applied to another terminal. Thus the transmitter

poweris increased for increasingthe range.If you want toincrease the rangeup to 5 meters,

use a ferrite-core step-up pulse transformer, which steps-up the transmitter output to 60V

(peak-to-peak).The echo signal received by thereceiver sensor after reflection is veryweak.

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 non-inverting input (pin 3) of A1 and

coupled to the second stage by a 3.3nF (small-value) capacitor. If you use the ubiquitous

0.01F capacitor for coupling, there will be 2-mega-ohm resistor for feedback. The third

stage is a precision rectifier amplifier with a gain of 10.


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Figure 4: Circuit Diagram of Ultrasonic Distance meter


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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 (60 dB below the main lobe) on the side lobes as shown in Fig. 4. Even

this low side-lobe signal is directly picked up by the receiver unit. So you have to space the

transmitter and receiver units about 5 cm apart. The two units are fixed by cello tape on to a

cardboard, with the analogue circuit at one end. Microcontroller AT89C2051 is at the heart of

the circuit. Port-1 pins P1.7 through P1.2, and port-3 pin P3.7 are connected to input pins

through 1 to 7of IC2 (IC ULN2003), respectively. These pins are pulled up with a 10-kilo-

ohm resistor network RNW1. They drive all the segments of the 7-segment display with the

help of inverting buffer IC2. Port-3 pins P3.0 through P3.3 of the microcontroller are

connected to the base of transistors T1 through T4 to provide the supply to displays DIS1

through DIS4, respectively. Pin P3.0 of microcontroller IC1 goes low to drive transistor T1

into saturation, which provides supply to the common- anode pin (either pin 3 or 8) of

display DIS1. Similarly, transistors T2 through T4 provide anode currents to the 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 5 ms. 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 capacitorC4 and resistor R8. A 12MHz crystal is used to generate the basic clock frequency for the

microcontroller. Resistor R16 connected to pin 5 of DIS2 enables the decimal point. The

comparator is inbuilt in microcontroller AT89C2051. The echo signal will make port-3 pin

3.6 low when it goes above the level of voltage set on pin 13. This status is sensed by the

microcontroller as programmed. When port-3 pin P3.6 goes high, we know that the echo

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.

5.1 POWER SUPPLY

Figure shows the circuit of the power supply. The 230V AC mains is stepped down by

transformer X1 to deliver the secondary output of 15V-0-15V, 500 mA. The transformer

output is rectified by a full-wave bridge rectifier comprising diodes D3 through D6, filtered

by capacitors C8 and C9 and then regulated by ICs 7815 (IC5), 7915 (IC6)and 7805 (IC7).

Regulators 7815, 7915 and 7805 provide +15V, -15V and+5V regulated supply,


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respectively. Capacitors C10 through C12 bypass the ripples present in the regulated power

supply.

Figure 5: Power Supply Circuit Diagram

5.2 CONSTRUCTION AND TESTING

An actual-size, single-side PCB for the microcontroller-based distance meter is shown in Fig.

6 and its component layout in Fig. 7. Assemble the PCB and put the programmed

microcontroller into the socket. After switching on the power supply and microcontroller

automatically getting reset upon power-on, pin 8 will pulse at 40kHz bursts. This can be

seen using an oscilloscope. Give this signal to channel 1 of the oscilloscope. Adjust the time

base to 2 ms per division and set it to trigger mode instead of normal mode. Adjust the

potentiometer on the oscilloscope labeled level such that the trace starts with the burst and

appears steady as shown. Connect the transmitter and receiver ultrasonic units either by a

twisted pair of wire or by a shielded cable to the board. Give the received signal to channel 2

of the oscilloscope. Then, place an A4-size plastic sheet in front of the ultrasonic transducers

and observe the echo signal. It will appear as shown. The two transducers can be fixed to a

thick cardboard with two wires leading to the circuittwo 40cm long shielded cables will do.

The laser pointer is fixed such that it is axial to the transducers. Channel 2 is connected to pin

12, which is the positive non-inverting terminal of AT89C2051s comparator. The negative


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inverting terminal (pin 13) is connected to a preset reference. Adjust the preset such that the

voltage is 0.1V-0.2V at pin 13. This will enable detection of weak echoes also. When the

echo signal goes above the level of reference voltage set on pin 13, it will make P3.6 low; the

arrival of echo is sensed by the program using jnb p3.6 (jump not bit) instruction. Software

The software is \ written in Assembly language and assembled using 8051 cross-assembler. It

is well commented and easy to understand. The pulse train for 0.5 ms is started by making

pin 8 high and low alternately for 12.5 microseconds so that the pulse frequency is 40 kHz.

After 25 such pulses have passed, a waiting time is given to avoid direct echoes for about 20

s. Then the signal is awaited, while the timer runs counting time in microseconds. When the

echo arrives, port-3 pin P3.6 goes high, the timer reads and the 16-bit number is divided by

twice the velocity and converted into decimal format as a 4-digit number. If the echo does not

arrive even after 48 milliseconds, the waiting loop is broken and the pulse train sequence is

started once again. If the echo comes within this time, it is displayed for half a second before

proceeding to another measurement. Thus, the display appears continuous and flicker-free.

Other uses Simply by changing this program, the same unit can be made to detect moving

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 or offices.

Figure 6: Transmitted and Received Pulses


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CHAPTER 6

SOFTWARE USED FOR PROGRAMMING

The software is written in Assembly language and assembled using 8051 cross-assembler. It

is well commented and easy to understand. The pulse train for 0.5 ms is started by making

pin 8 high and low alternately for 12.5 microseconds so that the pulse frequency is 40 kHz.

After 25 such pulses have passed, a waiting time is given to avoid direct echoes for about 20

s. Then the signal is awaited, while the timer runs counting time in microseconds. When the

echo arrives, port-3 pin P3.6 goes high, the timer reads and the 16-bit number is divided by

twice the velocity and converted into decimal format as a 4-digit number. If the echo does not

arrive even after 48 milliseconds, the waiting loop is broken and the pulse train sequence is

started once again. If the echo comes within this time, it is displayed for half a second before

proceeding to another measurement. Thus, the display appears continuous and flicker-free.

KEIL U-VISION 3.0

Keil Software is used provide you with software development tools for 8051 based

microcontrollers. With the Keil tools, you can generate embedded applications for virtually

every 8051 derivative. The supported microcontrollers are listed in the microvision. Keil

development tools for the 8051 microcontroller family support every level of developer from

the professional applications engineer to the student just learning about embedded software

development. The industry-standard Keil C Compilers, Macro Assemblers, Debuggers, Real-

time Kernels, and Single-board Computers support ALL 8051-compatible derivatives and

help you get your projects completed on schedule. Vision is an IDE (Integrated

Development Environment) that helps you write, compile, and debug embedded programs. It

encapsulates the following components:

Multiple Monitor - flexible window management system. System Viewer - display device peripheral register information. Debug Views - create and save multiple debug window layouts. Multi-Project Workspace - simplify working with numerous projects. Source and Disassembly Linking - the Disassembly Window and Source Windows

are fully synchronized making program debugging and cursor navigation easier.

Memory Window Freeze - store the current Memory Window view allowing easycomparison of memory contents at different points in time.


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CHAPTER 7

APPENDICES

7.1. APPENDIXA

7.1.1. SEMICONDUCTORS:

S.No. NOTATTION COMPONENT

1. IC1 AT89C2051 microcontroller

2. IC2 ULN2003 current buffer

3. IC3 CD4049 hex inverting buffer

4. IC4 LM324 quad operational amplifier

5. IC5 7815, 15V regulator

6. IC6 7915, -15V regulator

7. IC7 7805, 5V regulator

8. T1,T4 BC557 pnp transistor

9. T5 2N2222 npn transistor

10. D1, D2 1N4148 switching diode

11. D3-D6 1N4007 rectifier diode

12. DIS1-DIS4- LTS 542 common-anode, 7-segment display

Table 1: Semiconductor Components

7.1.2. RESISTORS (all -watt, 5% carbon):

S.No. Notation Rating

1. R1, R2 2-mega-ohm

2. R3 82-kilo-ohm

3. R4, R7-R10 10-kilo-ohm

4. R5 33-kilo-ohm

5. R6 100-kilo-ohm

6. R11 1-kilo-ohm

7. R16 220-ohm

8. RNW1 10-kilo-ohm resistor network

9. VR1 1-kilo-ohm preset

Table 2: Resistors


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7.1.3. CAPACITORS

S.No. Notation Rating

1. C1, C2 3.3nF ceramic disk

2. C7, C10-C12 0.1F ceramic disk

3. C3 2.2nF ceramic disk

4. C4 10F, 16V electrolytic

5. C5, C6 22pF ceramic disk

6. C8, C9 1000F, 50V electrolytic

Table 3: Capacitors

7.1.4. MISCELLANEOUS

S.No. Notation Compnent

1. X1 230V AC primary to

15V-0-15V, 500mA secondary transformer

2. XTAL 12MHz crystal

3. S1 Push-to-on switch

4. S2 On/off switch

5. TX1 40kHz ultrasonic transmitter

6. RX1 40kHz ultrasonic receiver

Table 4: Miscellaneous

7.1.5. RESISTANCE

The electrical resistance of a circuit component or device is defined as the ratio of the voltage

applied to the electric current which flows through it
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If the resistance is constant over a considerable range of voltage, then Ohm's law, I = V/R,

can be used to predict the behavior of the material. Although the definition above involves

DC current and voltage, the same definition holds for the AC application of resistors.

Whether or not a material obeys Ohm's law, its resistance can be described in terms of its

bulk resistivity. The resistivity, and thus the resistance, is temperature dependent. Oversizable ranges of temperature, this temperature dependence can be predicted from a

temperature coefficient of resistance.

7.1.6. RESISTIVITY AND CONDUCTIVITY

The electrical resistance of a wire would be expected to be greater for a longer wire, less for a

wire of larger cross sectional area, and would be expected to depend upon the material out of

which the wire is made. Experimentally, the dependence upon these properties is a

straightforward one for a wide range of conditions, and the resistance of a wire can be

expressed as

The factor in the resistance which takes into account the nature of the material is the

resistivity. Although it is temperature dependent, it can be used at a given temperature to

calculate the resistance of a wire of given geometry.

The inverse of resistivity is called conductivity. There are contexts where the use of

conductivity is more convenient.

Electrical conductivity = = 1/

7.1.7. RESISTOR COMBINATIONS

The combination rules for any number ofresistors in series or parallel can be derived with the

use ofOhm's Law, the voltage law, and the current law.
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7.1.8. RESISTIVITY CALCULATION

The electrical resistance of a wire would be expected to be greater for a longer wire, less for a

wire of larger cross sectional area, and would be expected to depend upon the material out of

which the wire is made (resistivity). Experimentally, the dependence upon these properties is

a straightforward one for a wide range of conditions, and the resistance of a wire can be

expressed as

Resistance = resistivity x length/area

7.2. APPENDIX-B

7.2.1. CAPACITOR

A capacitor consists of two electrodes or plates, each of which stores an opposite charge.

These two plates are conductive and are separated by an insulatorordielectric. The charge is

stored at the surface of the plates, at the boundary with the dielectric. Because each plate

stores an equal but opposite charge, the totalcharge in the capacitor is always zero.
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Figure 7: Capacitor charge formation

When electric charge accumulates on the plates, an electric field is created in the region

between the plates that is proportional to the amount of accumulated charge. This electric

field creates a potential difference V= Edbetween the plates of this simple parallel-plate

capacitor.

Figure 8: Capacitor Charge formation 2

The electrons in the molecules move or rotate the molecule toward the positively charged left

plate. This process creates an opposing electric field that partially annuls the field created by

the plates. (The air gap is shown for clarity; in a real capacitor, the dielectric is in direct

contact with the plates.)

Capacitance

The capacitor's capacitance (C) is a measure of the amount ofcharge (Q) stored on each plate

for a given potential difference orvoltage (V) which appears between the plates:
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In SI units, a capacitor has a capacitance of one farad when one coulomb of charge causes a

potential difference of one volt across the plates. Since the farad is a very large unit, values of

capacitors are usually expressed in microfarads (F), nanofarads (nF) or picofarads (pF).

The capacitance is proportional to the surface area of the conducting plate and inversely

proportional to the distance between the plates. It is also proportional to thepermittivity ofthe dielectric (that is, non-conducting) substance that separates the plates.

Stored energy

As opposite charges accumulate on the plates of a capacitor due to the separation of charge, a

voltage develops across the capacitor owing to the electric field of these charges. Ever

increasing work must be done against this ever increasing electric field as more charge is

separated. The energy (measured in joules, in SI) stored in a capacitor is equal to the amount

of work required to establish the voltage across the capacitor, and therefore the electric field.

The energy stored is given by:

where V is the voltage across the capacitor.

7.2.2. IN ELECTRIC CIRCUITS

Circuits with DC sources

Electrons cannot directly pass across the dielectric from one plate of the capacitor to the

other. When there is a current through a capacitor, electrons accumulate on one plate and

electrons are removed from the other plate. This process is commonly called 'charging' the

capacitor even though the capacitor is at all times electrically neutral. In fact, the currentthrough the capacitor results in the separation rather than the accumulation of electric charge.

This separation of charge causes an electric field to develop between the plates of the

capacitor giving rise to voltage across the plates. This voltage V is directly proportional to the

amount of charge separated Q. But Q is just the time integral of the current I through the

capacitor. This is expressed mathematically as:
http://en.wikipedia.org/wiki/SIhttp://en.wikipedia.org/wiki/Faradhttp://en.wikipedia.org/wiki/Coulombhttp://en.wikipedia.org/wiki/Volthttp://en.wikipedia.org/wiki/Permittivityhttp://en.wikipedia.org/wiki/Dielectrichttp://en.wikipedia.org/wiki/Electrical_conductionhttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Joulehttp://en.wikipedia.org/wiki/SIhttp://en.wikipedia.org/wiki/SIhttp://en.wikipedia.org/wiki/Joulehttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Electrical_conductionhttp://en.wikipedia.org/wiki/Dielectrichttp://en.wikipedia.org/wiki/Permittivityhttp://en.wikipedia.org/wiki/Volthttp://en.wikipedia.org/wiki/Coulombhttp://en.wikipedia.org/wiki/Faradhttp://en.wikipedia.org/wiki/SI


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Where I is the current flowing in the conventional direction, measured in amperes dV/dt is

the time derivative of voltage, measured in volts / second. C is the capacitance in farads .For

circuits with a constant (DC) voltage source, the voltage across the capacitor cannot exceed

the voltage of the source. Thus, an equilibrium is reached where the voltage across the

capacitor is constant and the current through the capacitor is zero. For this reason, it is

commonly said that capacitors block DC current.

Series or parallel arrangements

Capacitors in aparallel configuration each have the same potential difference (voltage). To

find their total equivalent capacitance (Ceq):

The current through capacitors in series stays the same, but the voltage across each capacitor

can be different. The sum of the potential differences (voltage) is equal to the total voltage.

To find their total capacitance:

One possible reason to connect capacitors in series is to increase the overall voltage rating. In

practice, a very large resistor might be connected across each capacitor to divide the total

voltage appropriately for the individual ratings.

Capacitor/inductor duality

In mathematical terms, the ideal capacitor can be considered as an inverse of the ideal

inductor, because the voltage-current equations of the two devices can be transformed into

one another by exchanging the voltage and current terms. Just as two or more inductors can

be magnetically coupled to make a transformer, two or more charged conductors can be

electrostatically coupled to make a capacitor. The mutual capacitance of two conductors is

defined as the current that flows in one when the voltage across the other changes by unitvoltage in unit time.
http://en.wikipedia.org/wiki/Amperehttp://en.wikipedia.org/wiki/Derivativehttp://en.wikipedia.org/wiki/Volthttp://en.wikipedia.org/wiki/Secondhttp://en.wikipedia.org/wiki/Series_and_parallel_circuitshttp://en.wikipedia.org/wiki/Series_and_parallel_circuitshttp://en.wikipedia.org/wiki/Inductorhttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Transformerhttp://en.wikipedia.org/wiki/Inductorhttp://en.wikipedia.org/wiki/Series_and_parallel_circuitshttp://en.wikipedia.org/wiki/Image:Capacitorsparallel.pnghttp://en.wikipedia.org/wiki/Series_and_parallel_circuitshttp://en.wikipedia.org/wiki/Secondhttp://en.wikipedia.org/wiki/Volthttp://en.wikipedia.org/wiki/Derivativehttp://en.wikipedia.org/wiki/Ampere


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Capacitor symbols

7.3.APPENDIX-C

7.3.1. DATASHEET -IC 89C2051

7.3.1.1 FEATURES

Compatible with MCS-51 Products 2 Kbytes of Reprogrammable Flash Memory Endurance: 1,000 Write/Erase Cycles 2.7 V to 6 V Operating Range Fully Static Operation: 0 Hz to 24 MHz Two-Level Program Memory Lock 128 x 8-Bit Internal RAM 15 Programmable I/O Lines Two 16-Bit Timer/Counters Six Interrupt Sources Programmable Serial UART Channel Direct LED Drive Outputs On-Chip Analog Comparator Low Power Idle and Power Down Modes


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7.3.1.2. DESCRIPTION

The AT89C2051 is a low-voltage, high-performance CMOS 8-bit microcomputer with 2

Kbytes of Flash programmable and erasable read only memory (PEROM). The device is

manufactured using Atmels high density nonvolatile memory technology and is compatible

with the industry standard MCS-51 instruction set and pinout. 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.

The AT89C2051 provides the following standard features: 2 Kbytes of Flash, 128 bytes of

RAM, 15 I/O lines, two 16-bit timer/counters, a five vector two-level interrupt architecture, a

full duplex serial port, a precision analog comparator, on-chip oscillator and clock circuitry.

In addition, the AT89C2051 is designed with static logic for operation down to zero

frequency and supports two software selectable power saving modes.

The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port and

interrupt system to continue functioning. The Power Down Mode saves the RAM contents

but freezes the oscillator disabling all other chip functions until the next hardware reset.

7.3.1.3. PIN CONFIGURATION

Figure 9: IC 89C2051 Pinout Diagram


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7.3.1.4. BLOCK DIAGRAM

Figure 10: IC 89C2051 Block Diagram


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7.3.1.5. PIN DESCRIPTION

VCC

Supply voltage.

GND

Ground.

PORT 1

Port 1 is an 8-bit bidirectional I/O port. Port pins P1.2 to P1.7 provide internal pullups. P1.0

and P1.1 require external pullups. P1.0 and P1.1 also serve as the positive input (AIN0) and

the negative input (AIN1), respectively, of the on-chip precision analog comparator. The Port

1 output buffers can sink 20 mA and can drive LED displays directly. When 1s are written to

Port 1 pins, they can be used as inputs. When pins P1.2 to P1.7 are used as inputs and are

externally pulled low, they will source current (IIL) because of the internal pullups. Port 1

also receives code data during Flash programming and program verification.

PORT 3

Port 3 pins P3.0 to P3.5, P3.7 are seven bidirectional I/O pins with internal pullups. P3.6 is

hard-wired as an input to the output of the on-chip comparator and is not accessible as a

general purpose I/O pin. The Port 3 output buffers can sink 20 mA. When 1s are written to

Port 3 pins they are pulled high by the internal pullups and can be used as inputs. As inputs,

Port 3 pins that are externally being pulled low will source current (IIL) because of the

pullups.

Table 5: Port 3 Functions


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RST

Reset input. All I/O pins are reset to 1s as soon as RST goes Hig h. Holding the RST pin high

for two machine cycles while the oscillator is running resets the device. Each machine cycle

takes 12 oscillator or clock cycles.

XTAL1

Input to the inverting oscillator amplifier and input to the internal clock operating circuit.

XTAL2

Output from the inverting oscillator amplifier.

7.3.1.6. OSCILLATOR CHARACTERISTICS

XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier which

can be configured for use as an on-chip oscillator, as shown in Figure 1. Either a quartz

crystal or ceramic resonator may be used. To drive the device from an external clock source,

XTAL2 should be left unconnected while XTAL1 is driven as shown in Figure 2. There areno requirements on the duty cycle of the external clock signal, since the input to the internal

clocking circuitry is through a divide by- two flip-flops, but minimum and maximum voltage

high and low time specifications must be observed. Notes: C1, C2 = 30 pF, 10 pF for

Crystals= 40 pF, 10 pF for Ceramic Resonators

(a) (b)

Figure11: (a) Oscillator Connections, (b) External Clock Drive Configuration


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7.3.1.7. PROGRAM MEMORY LOCK BITS

On the chip are two lock bits which can be left unprogrammed (U) or can be programmed (P)

to obtain the additional features listed in the table:

Table 6: Program Memory Lock Bits

7.3.1.8. IDLE MODE

In idle mode, the CPU puts itself to sleep while all the on-chip peripherals remain active. The

mode is invoked by software. The content of the on-chip RAM and all the special functions

registers remain unchanged during this mode. The idle mode can be terminated by anyenabled interrupt or by a hardware reset. P1.0 and P1.1 should be set to 0 if no external pull

ups are used, or set to 1 if external pullups are used. It should be noted that when idle is

terminated by a hardware reset, the device normally resumes program execution, from where

it left off, up to two machine cycles before the internal reset algorithm takes control. On-chip

hardware inhibits access to internal RAM in this event, but access to the port pins is not

inhibited. To eliminate the possibility of an unexpected write to a port pin when Idle is

terminated by reset, the instruction following the one that invokes Idle should not be one that

writes to a port pin or to external memory.

7.3.1.9. POWER DOWN MODE

In the power down mode the oscillator is stopped, and the instruction that invokes power

down is the last instruction executed. The on-chip RAM and Special Function Registers

retain their values until the power down mode is terminated. The only exit from power down

is a hardware reset. Reset redefines the SFRs but does not change the on-chip RAM. The


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reset should not be activated before VCC is restored to its normal operating level and must be

held active long enough to allow the oscillator to restart and stabilize. P1.0 and P1.1 should

be set to 0 if no external pullups are used, or set to 1 if external pullups are used.

7.3.1.10. PROGRAMMING THE FLASH

The AT89C2051 is shipped with the 2 Kbytes of on-chip PEROM code memory array in the

erased state (i.e., contents = FFH) and ready to be programmed. The code memory array is

programmed one byte at a time. Once the array isprogrammed, to re-program any non-blank

byte, the entire memory array needs to be erased electrically.

7.3.1.11. INTERNAL ADDRESS COUNTER

The AT89C2051 contains an internal PEROM address counter which is always reset to 000H

on the rising edge of RST and is advanced by applying a positive going pulse to pin XTAL1.

7.3.1.12. PROGRAMMING ALGORITHM:

To program the AT89C2051, the following sequence is recommended.

1. Power-up sequence: Apply power between VCC and GND pins Set RST and XTAL1 to

GND With all other pins floating, wait for greater than 10 milliseconds

2. Set pin RST to H Set pin P3.2 to H

3. Apply the appropriate combination of H or L logic levels to pins P3.3, P3.4, P3.5, P3.7

to select one of the programming operations shown in the PEROM Programming Modes

table. To Program and Verify the Array:

4. Apply data for Code byte at location 000H to P1.0 to P1.7.

6. Pulse P3.2 once to program a byte in the PEROM array or the lock bits. The byte-write

cycle is self-timed and typically takes 1.2 ms.

7. To verify the programmed data, lower RST from 12V to logic H level and set pins P3.3

to P3.7 to the appropriate levels. Output data can be read at the port P1 pins.

8. To program a byte at the next address location, pulse XTAL1 pin once to advance the

internal address counter. Apply new data to the port P1 pins.

9. Repeat steps 5 through 8, changing data and advancing the address counter for the entire 2

Kbytes array or until the end of the object file is reached.

10. Power-off sequence: set XTAL1 to L set RST to L Float all other I/O pins Turn Vcc

power off.


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7.3.1.13. DATA POLLING

The AT89C2051 features Data Polling to indicate the end of a write cycle. During a write

cycle, an attempted read of the last byte written will result in the complement of the written

data on P1.7. Once the write cycle has been completed, true data is valid on all outputs, and

the next cycle may begin. Data Polling may begin any time after a write cycle has been

initiated.

7.3.1.14. READY/BUSY

The Progress of byte programming can also be monitored by the RDY/BSY output signal.

Pin P3.1 is pulled low after P3.2 goes High during programming to indicate BUSY. P3.1 is

pulled High again when programming is done to indicate READY.

7.3.1.15. PROGRAM VERIFY

If lock bits LB1 and LB2 have not been programmed code data can be read back via the data

lines for verification:

1. Reset the internal address counter to 000H by bringing RST from L to H.

2. Apply the appropriate control signals for Read Code data and read the output data at theport P1 pins.

3. Pulse pin XTAL1 once to advance the internal address counter.

4. Read the next code data byte at the port P1 pins.

5. Repeat steps 3 and 4 until the entire array is read.

The lock bits cannot be verified directly. Verification of the lock bits is achieved by

observing that their features are enabled.

7.3.1.16. CHIP ERASE

The entire PEROM array (2 Kbytes) and the two Lock Bits are erased electrically by using

the proper combination of control signals and by holding P3.2 low for 10 ms. The code array

is written with all "1"s in the Chip Erase operatio and must be executed before any non-blank

memory byte can be re-programmed.


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7.3.1.17. READING THE SIGNATURE BYTES

The signature bytes are read by the same procedure as a normal verification of locations

000H, 001H, and 002H, except that P3.5 and P3.7 must be pulled to a logic low. The values

returned are as follows.(000H) = 1EH indicates manufactured by Atmel (001H) = 21H

indicates 89C2051

7.3.1.18. PROGRAMMING INTERFACE

Every code byte in the Flash array can be written and the entire array can be erased by using

the appropriate combination of control signals. The write operation cycle is self-timed and

once initiated, will automatically time itself to completion.All major programming vendors

offer worldwide support for theAtmel microcontroller series.

7.3.1.19. FLASH PROGRAMMING MODES

Table 7: Flash Programming Modes


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(a) (b)

Figure 12: (a) Programming the Flash Memory (b)Verifying the Flash Memory

Table 8:Flash Programing and Verification


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7.3.1.20. FLASH PROGRAMMING AND VERIFICATION WAVEFORMS

Figure 13: Flash Programming and Verification Waveforms

7.3.1.21. ABSOLUTE MAXIMUM POWER RATING

Table 9: Absolute Maximum Power Rating


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7.3.1.22. DC CHARACTERSTICS

Table 9: DC Characterstics


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7.3.1.23. EXTERNAL CLOCK DRIVE WAVEFORM

Figure 14: External Clock Drive Waveform

7.3.1.24. EXTERNAL CLOCK DRIVE

Table 10: External Clock Drive


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CHAPTER 8

CONCLUSION

The objective of this project is to design and implement an Ultrasonic Obstruction Detection

and Distance Measurement device. As described in this report a system is developed that can

detect objects and calculate the distance of the tracked object. With respect to the

requirements for an ultrasonic range finder the following can be concluded.

(a) The system is able to detect objects within the sensing range.(b) The system can calculate the distance of the obstruction with

a. sufficient accuracy.b. This device has the capability to interact with other peripheral ifc. used as a secondary device.d. This can also communicate with PC through its serial port.e. This offers a low cost and efficient solution for non contact typef. distance measurements.

The Range Finder has numerous applications. It can be used for automatic guided vehicles,

positioning of robots as well as measuring generic distances, liquid levels in tanks, and the

depth of snow banks. The device can serve as a motion detector in production lines. The

ultrasonic detection range relates with size, figure, material and position of the object. The

bigger the reflector is, the better the reflectance is, and the stronger the reflection signal is.

The ultrasonic distance measurement is an untouchable detection mode. Compared with else

detection modes, it does not get much influenced by ray, temperature and colour etc, and it

has the great capability to adapt to various circumstances and ambient conditions. A restricted

target angle (it requires a near perpendicular surface) and large beam, which can create poorresolution, seem to be the Range Finders only limitations. Also there is a blind area and

distance limitation in ultrasonic distance measurement. Despite these drawbacks, we find the

devices main features to be extremely useful.


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CHAPTER 9

APPLICATIONS

Applications of ultrasonic can be divided into two categories.

1. Ultrasonics in industry

2. Ultrasonics in medicine

Both are big fields in themselves. The concentration would be more on the former one.

In industry ultrasonic is employed for :-

(a)Low power applications where in the ultrasonic energy explores a body of materialand is thereby modified.

(b)High power application where in the ultrasonics energy modifies the body of materialto which it is applied.

Some of the important low power applications are :-

1) Flow detection,

2) Thickness gauging,

3) Measurement of various physical properties of materials.

4) Extent of corrosion

5) Estimation of grain sizes in polycrystalline materials.

6) Measurement of pressure, concentration temperature, viscosity and flow rates.

7) leak detection

8) Variable delay lines for computer applications and imaging,

9) Liquid level control


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CHAPTER 10

BIBLOGRAPHY

1. Electronics for you - September 1998.

2. www.electronicsforu.com.

3. www.atmel.com/atmel/acrobat/doc0368.pdf.

4. Kenneth J. Ayala, The 8051 Microcontroller Architecture, Programming & Applications,

West Publishing Company, College & School Division, 1996.

5. Muhammad Ali Mazidi, Janice Gillispie Mazidi, The 8051 Microcontroller & Embedded

Systems, Pearson Education.

6. David A. Bell, Electronic Devices and Circuits, Oxford University Press, 2008.

7. Sensors & Transducers Journal, Vol. 95, Issue 8, August 2008, pp.49-57

8. Alan Andrews, ABCs ofUltrasonic, Arthur Barker Limited, London, 1961.
http://www.atmel.com/atmel/acrobat/doc0368.pdfhttp://www.atmel.com/atmel/acrobat/doc0368.pdf


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BIODATA

SUDEEP PARMARF inal year student (8th semester)

Department of Electronics & communication

Lovely Professional University

Phagwara, (Punjab).

Contact: +918126258452 , [email protected]

NANDAM MANOHAR

F inal year student (8th semester)



Phagwara, (Punjab).


BIKASH KUMAR SINGH

F inal year student (8th semester)



Phagwara, (Punjab).


capstone project 2 final

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