ABSTRACT

ABSTRACT

Audiometry is the technique to identify and quantitatively

determine the degree of hearing loss of a person by measuring his or her

hearing sensitivity, so that suitable medical treatment or one of the

appropriate hearing aids and assistive devices can be prescribed. In

audiological investigations, the hearing sensitivity is tested for pure tones,

speech or other sound stimuli. The result, when plotted graphically, is called

an audiogram. The electronic instrument used for measuring the hearing

threshold level is called an audiometer. Using it, the test tones of different

frequencies and levels are generated and presented to the patient and hearing

thresholds are determined on the basis of patient’s response. The auditory

system and its disorders are described. Audiometric test is discussed.

TABLE OF CONTENTS

CHAPTER NO. TITLE PAGE NO.

ABSTRACT v

LIST OF TABLE ix

LIST OF FIGURES x

1. INTRODUCTION 1

1.1 ABOUT THE PROJECT 1

1.2 ORGANIZATION PROFILE 3

2. PHYSIOLOGY OF THE AUDITORY SYSTEM 4

2.1 CAUSES FOR HEARING LOSS

6

3. HEARING TESTS 8

3.1 PURE TONE AIR CONDUCTION

THRESHOLD TESTING 9

3.2 REPRESENTATION OF SOUND 10

3.3 AUDIOGRAM 10

4. BLOCK DIAGRAM OF THE AUDIOMETER 14

4.1 BLOCK DIAGRAM DESCRIPTION 15

5. HARDWARE 16

5.1 POWER SUPPLY 16

5.1.1 Linear Mode Power Supply 16

5.2 FUNCTION GENERATOR 19

5.2.1 Circuit Description 22

5.2.1.1 Setting Up 23

5.2.2 IC 8038 Description 23

5.2.2.1 Features 23

5.3 PRE AMPLIFIER 25

5.3.1 Circuit Description 26

5.3.2 IC LM324 Description 27

5.3.2.1 Features 27

5.3.2.2 Unique Characteristics 28

5.3.2.3 Advantages 28

5.4 POWER AMPLIFIER 29

5.4.1 Circuit Description 30

5.4.2 IC LM386 Description 31

5.4.2.1 Features 31

5.5 ATTENUATOR CONTROL 32

5.6 HEADPHONE 34

5.7 CLAMPER CIRCUIT 35

5.7.1 Positive Clamper 35

5.8 ADC 37

5.8.1 Successive Approximation ADC 38

5.8.1.1 Operation 39

5.8.2 Connection Diagram of ADC0804 42

5.8.3 IC ADC0804 Description 43

5.8.3.1 Features 43

6. SOFTWARE 44

6.1 INTRODUCTION TO EMBEDDED SYSTEM 44

6.2 IC 89C51 MICROCONTROLLER 45

6.2.1 Features 46

6.2.2 Description 46

7. LIQUID CRYSTAL DISPLAY 48

8. CONCLUSION 49

9. APPENDICIES 50

9.1 APPENDIX 1 50

9.2 APPENDIX 2 51

9.3 APPENDIX 3 59

10. REFERENCES 82

LIST OF TABLES

NO. TITLE PAGE NO.

1. Relation between Hearing Thresholds and

Degree of Hearing Loss (for adults) 13

2. Relation between Regulator Names and its

Output Voltages 18

3. Details of IC 89C51 45

LIST OF FIGURES

NO. TITLE PAGE NO.

1. The organ of hearing 5

2. Audiogram of normal ears and impaired ears 11

3. Block diagram of

Embedded Microcontroller based Audiometry 14

4. Basic building block of Linear Mode Power Supply 17

5. Power Supply 18

6. Function Generator 21

7. Pre Amplifier Stage 26

8. Power Amplifier 30

9. Band Pass Filter 32

10. Frequency Response – Band Pass Filter 33

11. Clamper Circuit 35

12. Clamping a Waveform 36

13. Block diagram of

Successive Approximation A/D converter 38

14. Illustration of conversion process 41

15. Connection Diagram of ADC0804 42

INTRODUCTION

1. INTRODUCTION

1.1. ABOUT THE PROJECT

There could be various disorders in the various parts of the ear.

Audiological investigations help us to diagnose the nature of deafness and

localize the site of disorder. The method by which patient's hearing

sensitivity can be determined is termed as audiometry. It helps in assessing

the nature, degree, and probable cause of the hearing impairment. In this

technique, auditory stimuli with varying intensity levels are presented to the

person who responds to these stimuli. The minimum intensity level of these

stimuli to which consistent responses are obtained is taken as the threshold

of hearing. Depending on this threshold, the patient’s hearing sensitivity can

be estimated by obtaining an audiogram. An audiogram is a plot of threshold

intensity versus frequency. Then the best-suited medical treatment or

hearing aid or other assistive devices can be prescribed. There are different

audiometric procedures depending on the stimuli used.

An audiometer is an instrument, which is used for carrying out

these audiometric tests. The device would be portable, easy to use and can

be used by a single person. This makes it ideal for demonstration purposes.

The functionality offered by the audiometer consists of

automatic frequency and loudness selection that’s done during a typical test

procedure. The user is only required to raise his or her hand when he or she

hears a sound. This makes the product easy to use and user friendly. Once a

test is complete, the results are displayed in the form of an audiogram that

can be used to assess a person’s hearing ability. The basic functionality of

the product was used to break it down to simple electronic components that

could be designed to work together to create the complete system.

A summary of the detailed technical specifications is given below:

Test frequencies: 250Hz, 500Hz, 1000Hz, 2000Hz, 4000Hz

and 8000Hz

Intensity: -20dB HL to 200dB HL

Input: Pure tone

A vital necessity of obtaining the most accurate results from the

audiometer is achieved by performing the test in a location with little or no

background noise. The type of environment is not easily possible in today’s

rooms plagued with noise from electronic devices such as an air conditioner,

fridge and a computer. To add more value to the product and making its

results more reliable, the test must be conducted in a sound proof room. This

reduces the background noise heard by the human ear. This feature makes

the product more desirable, hence enhancing the overall system.  

This report deals with the detailed electronic circuit diagrams

and the practical application of the audiometer.

 

1.1. ORGANAIZATION PROFILE

Electronic Engineering Corporation is a leading Indian

Manufacturer of a wide range of bio-medical electronic instruments and

scientific pumps. 

With over a decade of experience and service to the scientific

and medical profession, EEC's products are acknowledged for excellent

performance and long-term reliability.  

These medical and scientific instruments are used by reputed

medical professionals and scientists in many clinics, hospitals government

organizations, defense establishments, educational institutions and research

laboratories. Rigid quality control and utmost care is exercised in the

selection of materials that go into each instrument. All products are futurist

in design and specially built to withstand rigorous use. Common features of

these instruments are latest technology, high reliability components,

compact design and simple operation.  

The Registered Office and Factory details are as follows:- 

Address

Electronic Engineering Corporation, 

   T-4, Dr.Vikram Sarabai Instronic Estate, 

Chennai – 600 041, Tamilnadu, India.

   Telephone Numbers : 091 - 044 - 4925853 

                                    091 - 044 - 4481680   

    Fax : 091 - 044 - 4925853 

   E-Mail : eecindia@vsnl.com 

Website : www.eec-india.com

PHYSIOLOGY OF THE

AUDITORY SYSTEM

2. PHYSIOLOGY OF AUDITORY SYSTEM

Fig.1. The organ of hearing

The ear consists of three basic parts - the outer ear, the middle

ear, and the inner ear. Each part of the ear serves a specific purpose in the

task of detecting and interpreting sound. The outer ear serves to collect and

channel sound to the middle ear. The middle ear serves to transform the

energy of a sound wave into the internal vibrations of the bone structure of

the middle ear and ultimately transform these vibrations into a compression

wave in the inner ear. The inner ear serves to transform the energy of a

compression wave within the inner ear fluid into nerve impulses which can

be transmitted to the brain.

Generally, the lowest sound level that people of excellent

hearing can discern has an acoustic sound power about 10-12 W, 0 dB

The loudest sound generally encountered is that of a jet aircraft

with a sound power of 105 W, 170 dB.

2.1. CAUSES FOR HEARING LOSS

Each section of the ear has diseases specific to it and specific

tests (investigations) are there to identify disorders in each portion. The

common cause of disorder in the external auditory meatus is collection of

either wax or fungal debris or foreign body in it. To diagnose this no

investigation is required and your doctor can see it directly and clean it with

instruments. This deafness due to blockage of the external ear is usually very

slight.

The middle ear comprises of the eardrum, the ossicles, and the

air space within the cavity of the middle ear. The common diseases affecting

this portion are perforation in the ear drum, a stiffness or damage to the

chain of small bones in the ear, and collection of fluid in the middle ear

space (called middle ear effusion). A perforation can usually be diagnosed

just by visualizing the ear-drum; however the other middle ear disorders

require special investigations for confirmation.

The disease of the inner ear, i.e. the cochlea is difficult to treat.

Disorders of the inner ear not only causes a deafness called sensorineural

(perceptive) deafness but also may case a peculiar sensation of buzzing

sounds in the ear called tinnitus. Deafness due to disorders of the inner ear is

commonly refractory to medical and surgical methods and usually hearing

aids are the only option. Deafness may also occur due to diseases of the

nerve carrying the sensation from the cochlea to the brain. Deafness due to

disorder of the nerve is called retrocochlear deafness and deafness due to

disorders of the nerves which carry the sensation of hearing still higher up to

auditory cortex are called central deafness.

The common symptoms of disorders in the auditory system are

difficulty in hearing normal conversation from a distance of 8 feet or a

whisper from a distance of 3 feet, can hear people talk but have difficulty in

understanding what they say i.e. spoken word appear jumbled up, hear

comparatively less in one ear, require to raise the volume of which is

uncomfortable to other people, hear whistling/buzzing sounds in the ear or in

the head when actually such sounds are not there, have a sensation of

blockage/heaviness in one or both ears.

HEARING TESTS

3. HEARING TESTS

Hearing test helps to detect hearing loss, identify how severe it

is, and determine what is causing it. It also measures the ability of sound to

reach the brain. Sounds are actually vibrations of different frequencies and

intensities in the air around us; air in the ear canals and bones in the ears and

skull helps these vibrations to travel from the ear to the brain, where we

"hear" them. By measuring our ability to hear sounds that reach the inner ear

through the ear canal (air-conducted sounds) and sounds transmitted through

bones (bone-conducted sounds), hearing tests helps us to determine what

kind of hearing loss we have.

Most hearing tests require a response to a series of tones or

words. These tests include:

Whispered speech testing, which is a simple screening test that

assesses our ability to hear whispered speech across a short distance.

Pure tone audiometry, which measures our ability to hear sounds that

reach the inner ear through the ear canal (air conduction). By using

vibrations, this test can also measure hearing through bone (bone

conduction).

Tuning fork testing, this assesses how well the sound moves through

our ear.

Speech reception and word recognition testing, which measure our

ability to hear and understand speech.

An ear examination may be done:

As part of a routine physical examination.

To screen infants and children for hearing loss.

To determine the cause of symptoms such as earache, a feeling of

pressure or fullness in the ear, or hearing loss.

To detect excess wax or a foreign object in the ear canal.

To detect the location of an ear infection. The infection may involve

only the external ear canal (otitis externa) or the middle ear behind the

eardrum (otitis media or otitis media with effusion).

To monitor the effectiveness of treatment for an ear problem.

3.1. PURE TONE AIR CONDUCTION THRESHOLD TESTING

To assess sensitivity, a series of 0.5 s bursts of single-frequency

stimuli are presented to the subject through calibrated earphones worn on the

head. The subject is requested to respond (by hand raising or button pushing)

each time a beep is heard, even if it is faint. Pure tone testing is performed

separately for each ear and for frequencies from 250 to 8000 Hz. The

audiometer attenuator is adjusted until the person responds correctly to 50%

of the test beeps presented. The smallest increment step on the attenuator is

usually 5 dB. The threshold (50% correct responses) is recorded on the

audiogram using a (red) “o” for the right ear and a (blue) “x” for the left ear.

The test signal passes through the outer ear, the middle ear, and the inner ear

and is further processed by the central auditory system. Any hearing loss

measured may be due to pathology of one or more parts of the ear.

3.2. REPRESENTATION OF SOUND

Sound is described in terms of frequency and intensity.

Frequency, or pitch (whether a sound is low or high), is measured in

vibrations per second, or hertz (Hz). The frequencies of normal

conversations in a quiet place are 500 to 2,000 Hz.

Intensity, or loudness, is measured in decibels (dB). The intensities of

some common sounds are 15 to 25 dB for a whisper, 40 to 60 dB for

background noise in the home or office, 100 to 120 dB for loud music,

and 140 to 180 dB for a jet aero plane.

3.3. AUDIOGRAM

An audiogram is a plot of threshold intensity versus frequency.

The intensity scale in HL increases downwards, and hence the audiogram

resembles like an attenuation response, a lower point on the audiogram

indicating higher loss. A typical audiogram (dB HL vs. frequency graph)

comparing normal and impaired hearing is shown in Fig.2. The dip or notch

at 4 kHz as shown, or at 6 kHz, is a symptom of noise-induced hearing loss.

Fig.2. Audiogram of normal ears and impaired ears

Most thresholds are approximately 0 dB HL for a normal ear.

Points below 0 dB HL on the scale denote louder threshold levels, whereas

those above, expressed in negative decibels with respect to the zero level,

are less intense levels which, because of individual hearing differences,

some people may normally hear. Four separate curves can be obtained - right

ear air conduction (AC), right ear bone conduction (BC), left ear AC, and

left ear BC. This comprises the audiogram.

The symbols used on most audiograms are

x - Left air conduction

o - Right air conduction

In normal individuals, a small discrepancy is often seen

between air and bone conduction thresholds, the "AC-BC gap". At any given

frequency the threshold for AC is somewhat lower than BC (i.e., a stronger

signal is needed for BC).

The following table relates hearing thresholds (how loud a

sound of certain frequency must be for a person to hear it) to the degree of

hearing loss for adults.

Table.1. Relation between Hearing Thresholds and Degree of Hearing Loss (for

adults)

Hearing

Thresholds (in

decibels, dB)

Degree of

hearing lossAbility to hear speech

0-25dB None No significant difficulty

26-40dB MildDifficulty with faint or distant

speech

41-55dB ModerateDifficulty with conversational

speech

56-70dBModerate to

severe

Speech must be loud; difficulty

with group conversation

71-90dB Severe

Difficulty with loud speech;

understands only shouted or

amplified speech

91+ dB Profound May not understand amplified

speech

BLOCK DIAGRAM

OF THE AUDIOMETER

4. BLOCK DIAGRAM

Fig.3. Block diagram of Embedded Microcontroller based Audiometry

4.1. BLOCK DIAGRAM DESCRIPTION

The block diagram for audiometer consists of

FUNCTIONGENERATOR

PRE AMPLIFIER

POWERAMPLIFIER

ATTENUATORCONTROL

CLAMPERCIRCUIT

HEADPHONE ON PATIENT

PATIENTRESPONSE

LCD DISPLAY-20dB HL TO 200dB HL

MICRO CONTROLLER89C51

OPERATORSWITCH

A / D CONVERTER

Function Generator

Pre Amplifier

Power Amplifier

Attenuator Control

Head Phone

Clamper Circuit

A/D Converter

Microcontroller-89C51

Liquid Crystal Display

The signals generated by the function generator are given to the

pre-amplifier. The square wave is amplified and is given to the clamper

circuit which in turn converts the square wave to positive going pulses. The

pulses are given to the A/D Converter. In the meantime, the sine wave is

amplified by the pre-amplifier and the output is given to power amplifier.

The output of power amplifier is given to the attenuator control. The

attenuator control allows only a certain band of frequencies to the Head

Phone (which should be placed on the patient) and to A/D Converter. The

output of ADC is given to the Microcontroller and finally the output is

displayed with the help of Liquid Crystal Display.

HARDWARE

5. HARDWARE

5.1. POWER SUPPLY

All electronic circuits need dc power supply either from battery

or power back units. It may not be economical and convenient to depend

upon battery power supply. Hence, many electronic equipment contain

circuits which convert the ac supply into dc voltage at the required level.

The unit containing these circuits is called the Linear Mode Power Supply

(LPS). In the absence of ac main supply the dc supply from battery can be

converted into required ac voltage which may be used by computer and

other electronic systems for their operation. Also, in certain applications dc

to dc conversion is required. Such a power supply unit that converts dc into

ac or dc is called Switched Mode Power Supply (SMPS).

1. Linear Mode Power Supply: ac/dc power supply convertor

2. Switched Mode Power Suppy:

a) dc/dc power supply convertor

b) dc/ac power supply convertor

5.1.1. Linear Mode Power Supply

An ac/dc power supply converts ac mains (230V, 50Hz) into

required dc voltages (and is found in all mains operable system). The basic

building blocks of the linear power supply are shown in figure.

Fig.4. Basic building block of Linear Mode Power Supply

A transformer supplies ac voltage at the required level. This

bidirectional ac voltage is converted into an unidirectional pulsating dc using

a rectifier. The unwanted ripple contents of this pulsating dc are removed by

a filter to get dc voltage. The output of the filter is fed to a regulator which

gives a steady dc output independent of load variations and input supply

fluctuations.

N1N2

N3

1N4007

10

u

10

u

10

u

10

u

10

u

10

u

10

u

10

u

7809 7805

7909

230 VAC

5 V9 V

-9 V

Fig.5. Power Supply

This circuit can give

Table.2. Relation between regulator names and its output voltages

Name Voltage

LM7809 + 9 volts

LM7905 - 5 volts

LM7909 - 9 volts

5.2. FUNCTION GENERATOR

A function generator is an instrument that generates signals for

use in electronic test situations.

A function generator generates signals.  We may also find that another

common name for the instrument is signal generator.

The signals produced by a function generator can have many

waveshapes.  We may find

o Sinusoidal signals

o Square wave signals

o Triangle signals

o Ramp signals

o Pulses

o Noise signals

o User-defined signals

The frequency of the signals can be controlled.

The amplitude of the signals can be controlled.

Not all of the signals above are found on every function

generator, and there are more specialized functions that can be performed. 

In general, a generator that produces the first three signals may be called a

signal generator, and with more functions the generator may be called a

function generator.

        There are three basic controls on a function generator.  They are:

A control to set frequency.

A control to set wave shape (sinusoid, triangle, square).

A control to set amplitude.

The function generator can be used to do the following adjustments:

To set the frequency to a value by using a pot.

To set the amplitude to a value by using another pot.

To change the wave shape with the help of a rotary switch.

Fig.6. Function Generator

5.2.1. Circuit Description

Built around a single 8038 waveform generator IC, this circuit

produces sine, square or triangle waves from 20Hz to 200 kHz in four

switched ranges. There are both high and low level outputs, which may be

adjusted with the level control.

All of the waveform generation is produced by IC8038. This

versatile IC even has a sweep input, but is not used in this circuit. The IC

contains an internal square wave oscillator, the frequency of which is

controlled by timing capacitors C1 - C4 and the 10k potentiometer. The

tolerance of the capacitors should be 10% or better for stability. The square

wave is differentiated to produce a triangular wave, which in turn is shaped

to produce a sine wave. All this is done internally, with a minimum of

external components. The purity of the sine wave is adjusted by the two

100k preset resistors.

The wave shape switch is a single pole 3 way rotary switch, the

wiper arm selects the wave shape and is connected to a 10k potentiometer,

which controls the amplitude of all waveforms. LM324 op-amp wired as a

standard direct-coupled non-inverting buffer, providing isolation between

the waveform generator, and also increasing output current.

The 2.2k and 47 ohm resistors form the output attenuator. At

the high output, the maximum amplitude is about 8V peak-peak with the

square wave. The maximum for the triangle and sine waves is around 6V

and 4V respectively. The low amplitude controls are useful for testing

amplifiers, as amplitudes of 20mV and 50mV are easily achievable.

5.2.1.1. Setting Up

The two 100k preset resistors adjust the purity of the sine wave.

If adjusted correctly, then the distortion amounts to less than 1%.

5.2.2. IC 8038 Description

The IC8038 waveform generator is a monolithic integrated

circuit capable of producing high accuracy sine, square, triangular, sawtooth

and pulse waveforms with a minimum of external components. The

frequency (or repetition rate) can be selected externally from 0.001Hz to

more than 300 kHz using either resistors or capacitors, and frequency

modulation and sweeping can be accomplished with an external voltage. The

IC8038 is fabricated with advanced monolithic technology, using Schottky

barrier diodes and thin film resistors, and the output is stable over a wide

range of temperature and supply variations. These devices may be interfaced

with phase locked loop circuitry to reduce temperature drift to less than

250ppm/o C.

5.2.2.1. Features

Low Frequency Drift with Temperature

- 250ppm/o C

Low Distortion

- 1% (Sine Wave Output)

High Linearity

- 0.1% (Triangle Wave Output)

Wide Frequency Range

- 0.001Hz to 300 kHz

Variable Duty Cycle

- 2% to 98%

High Level Outputs

- TTL to 28V

Easy to Use

- Just a handful of external components required.

Simultaneous Sine, Square, and Triangle wave outputs.

5.3. PRE AMPLIFIER

A two port device which accepts an input signal and produces

an output signal proportional to the input is called as an amplifier. The

proportionality constant between input and output is called as gain of the

amplifier.

An amplifier which amplifies the input without producing any

phase shift between input and output is called non-inverting amplifier. The

input is applied to the non-inverting input terminal of the op-amp. The op-

amp always amplifies the difference input voltage Vd. This difference

voltage is the difference between the voltages Vin and Vf where Vf is the

feedback voltage. The feedback voltage opposes the input voltage that is; it

is 180° out of phase with respect to the input. This indicates that the

feedback is negative.

When the input signal and part of the output signal are in phase,

the feedback is called positive feedback. Use of positive feedback results in

oscillations and hence not used in amplifiers. (Oscillator is an amplifier,

which uses a positive feedback and without any external input signal

generates an output waveform at a desired frequency).

Fig.7. Pre Amplifier

5.3.1. Circuit Description

Two stages are used to avoid oscillations and non-ideal

operation amplifier characteristics when very high gain (10000-1000000

times) configurations. Both amplifier stages are built using an LM324.

The input signal to the preamplifier is in the order of 0.5mV.

The two op-amps of a LM324 integrated circuit chip are employed to

amplify the signals from the function generator. The first amplifier stage

provides a gain of about 20. The second stage, which is identical to the first

stage, provides a subsequent gain of 20 to give a total amplification of about

400.

100k

10u

22k

200n

22

k

100k

10u

22k

200n

22

k

10

n

200n-

+ +

LM324/NS -

+ +

LM324/NS

FromBuffer

To PowerAmplifier

Capacitor C1 is the coupling capacitor for the first amplification

stage and C4 for the second amplification stage. The resistors R1 and R4 are

the compensating resistors and have a value of 22 kW. R2 = Ri = 22kW,

which is the input resistance of first stage and Ri = R5 = 22kW is the input

resistance of the second stage. Capacitors C2 and C5 are of 1 nF value and

are the feedback capacitances of first and second stages respectively. These

capacitances serve to improve the stability of the circuit and the low

frequency response.

5.3.2. IC LM324 Description

The LM324 series consists of four independent, high gain;

internally frequency compensated operational amplifiers which were

designed specifically to operate from a single power supply over a wide

range of voltages. Operation from split power supplies is also possible and

the low power supply current drain is independent of the magnitude of the

power supply voltage.

5.3.2.1. Features

Internally frequency compensated for unity gain

Large DC voltage gain 100 dB

Wide bandwidth (unity gain) 1 MHz (temperature compensated)

Wide power supply range: Single supply 3V to 32V or dual supplies

±1.5V to ±16V

Very low supply current drain (700 µA) - essentially independent of

supply voltage

Low input biasing current 45 nA (temperature compensated)

Low input offset voltage 2 mV and offset current: 5 nA

Input common-mode voltage range includes ground

Differential input voltage range equal to the power supply voltage

Large output voltage swing 0V to V+ -1.5V

5.3.2.2. Unique Characteristics

In the linear mode the input common-mode voltage range includes

ground and the output voltage can also swing to ground, even though

operated from only a single power supply voltage

The unity gain cross frequency is temperature compensated

The input bias current is also temperature compensated

5.3.2.3. Advantages

Eliminates need for dual supplies

Four internally compensated op amps in a single package

Allows directly sensing near GND and VOUT also goes to GND

Compatible with all forms of logic

Power drain suitable for battery operation

5.4. POWER AMPLIFIER

In general, an amplifier receives an input signal from some

transducer or other input source and provides a large amplified signal to

some output device or another amplifier stage. The small signal amplifiers

are basically voltage amplifiers, the voltage and current signal levels are

small in such amplifiers. The output current capability of such amplifier is

limited. The amount of power handling capacity and power efficiency are of

little concern for the small signal amplifiers.

The power amplifier is basically used to amplify an audio

signal faithfully. The loads to such amplifiers are generally loud speakers,

headphones and servomotors. Such loads require large current and sufficient

power, typically few watts to tens of watts. Such power amplifiers develop

and feed the sufficient power to the loads like speakers, motors and

headphones by handling the large signals hence these are also called as large

signal amplifiers or power amplifiers .The low output impedance is another

requirement and such loads which is to be satisfied by the power amplifiers.

Thus the main features of a large signal amplifier or a power amplifier

are,

The large amount of power to be delivered to the load.

The power efficiency.

The impedance matching to the output device.

Fig.8. Power Amplifier

5.4.1. Circuit Description

The simplest and most basic application of LM386 is an audio

amplifier. The IC can be used in inverting as well as non-inverting

configuration. When used in the non-inverting mode the inverting terminal

can be either shorted to ground, left open or returned to ground through

resistor or capacitor. Similarly, when it is used in the inverting

configuration, the non-inverting terminal may be either shorted to ground or

returned to ground through resistor or capacitor. In both the configurations,

the supply voltage must be decoupled by connecting a capacitor between the

terminal 6 and ground.

5.4.2. IC LM386 Description

The LM386 is a power amplifier designed for use in low

voltage consumer applications. The gain is internally set to 20 to keep

external part count low, but the addition of an external resistor and capacitor

between pins 1 and 8 will increase the gain to any value from 20 to 200. The

inputs are ground referenced while the output automatically biases to one-

half the supply voltage. The quiescent power drain is only 24 milliwatts

when operating from a 6 volt supply, making the LM386 ideal for battery

operation.

5.4.2.1. Features

Battery operation

Minimum external parts

Wide supply voltage range: 4V–12V or 5V–18V

Low quiescent current drain: 4mA

Voltage gains from 20 to 200

Ground referenced input

Self-centering output quiescent voltage

Low distortion: 0.2% (AV = 20, VS = 6V, RL = 8W, PO =125mW, f

= 1kHz)

Available in 8 pin MSOP package

5.5. ATTENUATOR CONTROL

The attenuator control acts as a band pass filter. A band pass

filter is basically a frequency selector. It allows one particular band of

frequencies to pass. Thus, the pass band is between the two cut-off

frequencies fH and fL where fH>fL. Any frequency outside this band gets

attenuated.

-

+ +

!OPAMP

470k

10n 10n

10n

68

k

InputOutput

Fig.9. Band Pass Filter

The frequency response of band pass filter is shown in the

figure.

Fig.10. Frequency Response - Band Pass Filter

5.6. HEADPHONE

The operator should place the person to be tested at ease

concerning the test. The operator should explain the purpose of the test and

what kind of sound or sounds will be heard. An unvarying and uniform

explanation to the person being tested will provide test results that are

consistently high in reliability. An explanation for pure tone or baseline

audiometry might be expressed as follows: "I am going to place these

headphones on your ears. You will hear a whistle or beeping sound that may

be loud or soft. Whenever you hear or think you hear one of these sounds,

raise your hand (or press the response switch button) and lower your hand

(or release the button) when you do not."

5.7. CLAMPER CIRCUIT

Clamper is a circuit that "clamps" a signal to a different dc

level. The different types of clampers are positive negative and biased

clampers. A clamping network must have a capacitor, a diode and a resistive

element. The magnitude R and C must be chosen such that the time constant

RC is large enough to ensure that the voltage across the capacitor does not

discharge significantly during the interval the diode is non- conducting.

10u 1k

D1

1N

400

7

10kInput Output

Fig.11. Clamper Circuit

5.7.1. Positive Clamper:

The circuit for a positive clamper is shown in the figure. During

the negative half cycle of the input signal, the diode conducts and acts like a

short circuit. The output voltage Vo = 0V. The capacitor is charged to the

peak value of input voltage Vm. and it behaves like a battery. During the

positive half of the input signal, the diode does not conduct and acts as an

open circuit. Hence the output voltage Vo = Vm + Vm. This gives a

positively clamped voltage.

Fig.12. Clamping a waveform

5.8. ADC

Most of the information carrying signals such as voltage,

current, charge, temperature, pressure and time are available in the analog

form. However, for processing, transmission and storage purposes, it is often

more convenient to express such signals in the digital form. When expressed

in the digital form, they provide better accuracy and reduce noise.

Moreover, the development in the microcontroller technology

has made it compulsory to process data in the digital form. Since digital

systems such as microcontroller use a binary system of 1’s and 0’s, we have

to convert signal from analog to digital form. The circuit that performs this

conversion is called an analog to digital (A/D) converter.

Analog to digital converter are classified into two general

groups based on the conversion techniques. One technique involves

comparing a given analog signal with the internally generated reference

voltages. This group includes successive approximation, flash, delta

modulated (DM), adaptive delta modulated and flash type converters.

Another technique involves changing an analog signal into time or

frequency and comparing these new parameters against known values. This

group includes integrator converters and voltage-to-frequency converters.

5.8.1. Successive Approximation ADC

In this technique, the basic idea is to adjust the DAC’s input

code such that its output is within +1/2 LSB of the analog input Vi to be A/D

converted. The code that achieves this represents the desired ADC output.

The successive approximation method uses very efficient code

searching strategy called binary search. It completes searching process for n-

bit conversion in just n clock periods.

Fig.13. Block diagram of successive approximation A/D converter

Fig.13 shows the block diagram of successive approximation

A/D converter. It consists of a DAC, a comparator, and a successive

approximation register (SAR).

The external clock input sets the internal timing parameters.

The control signal start of conversion (SOC) initiates an A/D conversion

process and end of conversion signal is activated when the conversion is

completed.

5.8.1.1. Operation

The searching code process in successive approximation

method is similar to weighing an unknown material with a balance scale and

a set of standard weights. Let us assume that we have 1kg, 2kg and 4kg

weights (SAR) plus a balance scale (comparator and DAC). Now we will see

the successive approximation analogy for 3-bit ADC.

Refer Fig.13 and Fig.14. The analog voltage Vin is applied at

one input of comparator. On receiving start of conversion signal (SOC),

successive approximation register sets 3-bit binary code 1002 (b2 = 1) as an

input of DAC. This is similar process of placing the unknown weight on one

platform of the balance and 4kg weight on the other. The DAC converts the

digital word 100 and applies it equivalent analog output at the second input

of the comparator. The comparator then compares two voltages just like

comparing unknown weight with 4kg weight with the help of balance scale.

If the input voltage is greater than the analog output of DAC, successive

approximation register keeps b2 = 1 and makes b1 = 1 (addition of 2kg

weight to have total 6kg weight) otherwise it resets b2 = 0 and makes b1 = 1

(replacing 2kg weight). The same process is repeated for b1 and b0. The

status of b0, b1 and b2 bits gives the digital equivalent of the analog input.

Fig.14 illustrates the process we have just discussed.

The dark line in the Fig.14 shows setting and resetting actions

of bits for input voltage 5.2V, on the basis of compression. It can be seen

from the Fig.14 that one clock pulse is required for the successive

approximation register to compare each bit. However an additional clock

pulse is usually required to reset the register prior to performing a

conversion.

Fig.14. Illustration of conversion process

The time for one analog to digital conversion must depend on

both the clock’s period T and number of bits n. It is given as,

Tc = T (n+1)

Where Tc = conversion time

T = clock period

n = number of bits

5.8.2. Connection Diagram of ADC0804

Fig.15. Connection Diagram of ADC0804

5.8.3. IC ADC0804 Description

The ADC0804 is a CMOS 8-Bit, successive approximation A/D

converters which use a modified potentiometric ladder and are designed to

operate with the 8080A control bus via three-state outputs. These converters

appear to the processor as memory locations or I/O ports, and hence no

interfacing logic is required. The differential analog voltage input has good

common- mode-rejection and permits offsetting the analog zero-input

voltage value. In addition, the voltage reference input can be adjusted to

allow encoding any smaller analog voltage span to the full 8 bits of

resolution.

5.8.3.1. Features

80C48 and 80C80/85 Bus Compatible - No Interfacing Logic

Required

Conversion Time <100µs

Easy Interface to Most Microprocessors

Will Operate in a “Stand Alone” Mode

Differential Analog Voltage Inputs

Works with Band gap Voltage References

TTL Compatible Inputs and Outputs

On-Chip Clock Generator

Analog Voltage Input Range (Single + 5V Supply) 0V to 5V

No Zero-Adjust Required

80C48 and 80C80/85 Bus Compatible - No Interfacing Logic

Required.

SOFTWARE

6. SOFTWARE

6.1. INTRODUCTION TO EMBEDDED SYSTEM

In the literature discussing microprocessors, we often see the

term embedded system. Microprocessors and microcontrollers are widely

used in embedded system products. An embedded product uses a

microprocessor or microcontroller to do one and task only. A printer is an

example of embedded system since the processor inside it performs one task

only ; namely, getting the data and printing it. Contrast this with a Pentium-

based PC (or any x86 IBM-compatible PC). A Pc can be used for any

number of applications such as word processor, print server, bank teller

terminal, video game player, network server, or Internet terminal. Software

for a variety of applications can be loaded and run. Of course the reason a

PC can perform myriad tasks is that it has RAM and an operating system

that loads the application software into RAM and lets the CPU run it. In

embedded system, there is only one application software that is typically

built in ROM.

6.2. IC 89C51 MICROCONTROLLER

The popular 8051 has on-chip ROM in the form of flash

memory. This is ideal for fast development since flash memory can be

erased in seconds compared to twenty minutes or more needed for the 8751.

For this reason the AT89C51 is used in the place of 8751 to eliminate the

waiting time needed to erase the chip and thereby speed up development

time. To use the AT89C51 to develop the microcontroller based system

requires a ROM burner that supports flash memory; however, a ROM eraser

is not needed. Notice that in flash memory we must erase the entire contents

of ROM in order to program it again. This erasing of flash is done by the

PROM burner itself and this why a separate eraser is not needed. To

eliminate the need for a PROM burner we can use AT89C51 that can be

programmed via the serial COM port of an IBM PC.

Table.3. Details of IC 89C51

ROM 4k

RAM 128

I/O Pins 32

Timer 2

Interrupt 6

Vcc 5V

Packaging 40

In AT89C51-xxPC the C before 51 indicates CMOS, which

has low power consumption, xx indicates xx MHZ, P is for plastic DIP

package and C is for commercial purpose. Often, the AT89C51-12PC is

ideal for many student projects.

6.2.1. Features

Compatible with MCS-51 TM Products

4 Kbytes of In-System Reprogrammable Flash Memory

Endurance: 1,000 Write/Erase Cycles

Fully Static Operation: 0 Hz to 24 MHz

Three-Level Program Memory Lock

128 x 8-Bit Internal RAM

32 Programmable I/O Lines

Two 16-Bit Timer/Counters

Six Interrupt Sources

Programmable Serial Channel

Low Power Idle and Power Down Modes

6.2.2. Description

The AT89C51 is a low-power, high-performance CMOS 8-bit

Microcomputer with 4 Kbytes 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-51TM instruction set and pinout. The on-chip Flash allows

the program memory to be reprogrammed in-system or by a conventional

nonvolatile memory programmer. By combining a versatile 8-bit CPU with

Flash on a monolithic chip, the Atmel AT89C51 is a powerful

microcomputer which provides a highly flexible and cost effective solution

to many embedded control applications.

The AT89C51 provides the following standard features: 4

Kbytes of Flash, 128 bytes of RAM, 32 I/O lines, two 16-bit timer/counters,

five vector two-level interrupt architecture, a full duplex serial port, on-chip

oscillator and clock circuitry. In addition, the AT89C51 is designed with

static logic for operation down to zero frequency and supports two software

selectable power saving modes

LIQUID CRYSTAL DISPLAY

7. LIQUID CRYSTAL DISPLAY

The supper twist back-lit Liquid Crystal Display (LCD) serves

as a visual communication link between the audiometer and its operator.

LCD’s do not generate light but they scatter light. LCD’s

consume very less power and they have good contrast ratio.

It is also called an electroluminescent display. The LCD

consists of a thin layer of normally transparent LC material between two

electrodes. When an electric field is applied, the material becomes turbulent,

reflecting and scattering ambient light. It provides excellent brightness under

high ambient light conditions and requires only 50W of power per

segment. This power is much lower as compared to that for the LED. But the

life expectancy is not as high as that of the LED. The required crystal

displays are used in watches, pocket calculators, pocket televisions and

portable instrument displays.

CONCLUSION

8. CONCLUSION

Thus the Embedded Microcontroller Based Audiometer is used

to determine the sensitivity of the human ear. Accurate assessment of the

hearing loss can be done using this device.

The conventional audiometer is analog in nature. In this project

the embedded micro-controller concepts are implemented to make

audiometry more versatile, cost effective and simpler in design.

In future, we can enhance the system by having additional

graphic features, data storage and signal processing advantage of a PC based

system, with the added benefit of economy and portability.

APPENDICIES

9. APPENDICIES

9.1 APPENDIX 1

SPECIFICATIONS

GENERAL

Power - 230v AC

Display - LCD; 16 characters x 2 lines

Presentation - Pure tone

Repetition Rate - Pseudo-random intervals

Standard Accessories - TDH-39 headset, patient response

button, user's guide

Optional Accessories - Carrying case, noise excluding

headphone enclosures, sound

room cords

AUDIOMETER

Frequencies - 250*, 1K*, 500, 1K, 2K, 3K, 4K, 6K,

8K Hz

Hearing Levels - 0-90 dB HL except 250 & 8K Hz to

70 dB HL

9.2 APPENDIX 2

IC DETAILS

REGULATOR IC’s

IC7809

1. Unregulated voltage in

2. Ground

3. Regulated voltage out

IC7909

1. Ground

2. Unregulated voltage in

3. Regulated voltage out

IC7805

1. Unregulated voltage in

2. Ground

3. Regulated voltage out

LM324

IC8038

LM386

ADC0804

IC 89C51

9.3 APPENDIX 3

CODING

ORG 0H

CLR A

MOV 80H,A ;Clear port 0

MOV 90H,A ;Clear port 1

MOV 0A0H,A ;clr p2

MOV 0B0H,A;clr p3

MOV R0,A

CL: CLR A

MOV @R0,A

INC R0

CJNE R0,#7EH,CL

CLR 94H

MOV 1FH,#2AH

MOV A,#3CH;

ACALL COM

MOV A,#0EH;curser blink command

ACALL COM

MOV A,#06H;curser on

ACALL COM

MOV A,#1

ACALL COM

ACALL DE

ACALL DE

MOV DPTR,#330H

ACALL BARATI

ACALL DEE

ACALL DEE

ACALL DEE

ACALL DEE

MOV A,#1

ACALL COM

ACALL DEE

ACALL DEE

MOV DPTR,#340H

ACALL BARATI

ACALL DEE

ACALL DEE

ACALL DEE

ACALL DEE

MOV A,#1

ACALL COM

ACALL DEE

ACALL DEE

MOV DPTR,#350H

ACALL BARATI

ACALL DEE

ACALL DEE

ACALL DEE

ACALL DEE

MOV A,#1

ACALL COM

ACALL DEE

ACALL DEE

MOV DPTR,#360H

ACALL BARATI

ACALL DEE

ACALL DEE

ACALL DEE

ACALL DEE

MOV A,#1

ACALL COM

ACALL DEE

ACALL DEE

MOV DPTR,#370H

ACALL BARATI

ACALL DEE

ACALL DEE

ACALL DEE

ACALL DEE

MOV A,#1

ACALL COM

ACALL DEE

ACALL DEE

MOV DPTR,#380H

ACALL BARATI

ACALL DEE

ACALL DEE

ACALL DEE

ACALL DEE

MOV A,#1

ACALL COM

ACALL DEE

ACALL DEE

MOV DPTR,#390H

ACALL BARATI

ACALL DEE

ACALL DEE

ACALL DEE

ACALL DEE

MOV A,#1

ACALL COM

ACALL DEE

ACALL DEE

MOV DPTR,#300H

ACALL BARATI

MOV DPTR,#310H

ACALL RANI

SENI:CLR A

CLR 95H

MOV 1AH,#28H

MOV 1BH,#50H

MOV 89H,#10H;TMOD

MOV 8BH,A

MOV 8DH,A

MOV 22H,#40H

MOV 23H,#42H

MOV 24H,#0FH

MOV 1DH,A

BB: JNB 90H,DD4

ACALL DEE

ACALL DEE

AJMP D4

DD4: JNB 93H,BBB

ACALL ARU

BBB: JB 94H,BB

CLR A

MOV R4,A

MOV R5,A

MOV R6,A

MOV R7,A

L1: JNB 94H,L1

SETB 8EH;TR1

L2: JB 94H,L2

KK: JNB 94H,KK

CLR 8EH;TR1

MOV 1AH,8BH;TL1

MOV 1BH,8DH;TH1

MOV 20H,1BH

;MOV A,1AH

;ADDC A,1AH

;JNC L3

;INC 1BH

;L3:MOV 1AH,A

MOV A,20H

;ADDC A,1BH

;JNC L4

;INC 21H

L4: MOV 1BH,A

L5: MOV A,22H

SUBB A,1AH

INC A

MOV 22H,A

MOV A,23H

SUBB A,1BH

MOV 23H,A

MOV A,24H

SUBB A,21H

MOV 24H,A

JNC LL5

SJMP SENI1

LL5: INC R4

CJNE R4,#10,L5

INC R5

MOV R4,#0

CJNE R5,#10,L5

INC R6

MOV R5,#0

CJNE R6,#10,L5

INC R7

MOV R6,#0

CJNE R7,#10,L5

INC 1DH

MOV R7,#0

SJMP L5

SENI1:ACALL DISPLAY

D12: ;CJNE R5,#0,XX

;CJNE R6,#0,XX

;SJMP XX1

;XX: ACALL DEE

XX1: CLR 97H ;interrupts to adc

ACALL DEE

SETB 97H

MOV A,0A0H

;CPL A

MOV 19H,A

ACALL CAL

;MOV DPTR,#200H

;MOVC A,@A+DPTR

ACALL CAA

;MOV 19H,A

;ACALL CA ;split the full number to display

;ACALL D

ACALL DISPLAY1

; MOV A,12H ;threshold which is in 12h moved to accumulator

; SUBB A,R4 ;port value is available in r4 subtracted with acc

; JNC G4

; SETB 96H ;buzzer & led

;G4: ACALL DEE

; ACALL DEE

; CLR 96H

; JNB 95H,G5; peakhold switch

;SE2: ACALL DEE

; JNB 93H,SE1 ;saving switch

; ACALL DEE

; ACALL DEE

; SJMP SE3

;SE1: JB 95H,SE2

; ACALL DEE

; ACALL DEE

; SJMP D12

;SE3: MOV R0,1AH

; MOV @R0,19H

; INC 1AH

; MOV R0,1BH

; MOV A,R7

; MOV 0F0H,R6

; MUL AB

; MOV @R0,A

; INC 1BH

; INC R0

; MOV A,R5

; MOV 0F0H,R4

; MUL AB

; MOV @R0,A

;INC 1AH

; CLR 0B4H

; CLR 0B0H

; ACALL DEE

; ACALL DEE

; SETB 0B4H

; SETB 0B0H

; MOV 1AH,R0

; SJMP SE2

RE: AJMP SENI

;HH:JNB 90H,HH

D4: ;MOV 1EH,#2AH

;CLR 0B1H;SECOND MODE INDICATION

;SETB 0B2H

MOV DPTR,#320H

ACALL BARATI

MOV R0,#2AH

MOV A,@R0

MOV 1DH,A

INC R0

MOV A,@R0

MOV R7,A

INC R0

MOV A,@R0

MOV R6,A

INC R0

MOV A,@R0

MOV R5,A

INC R0

MOV A,@R0

MOV R4,A

ACALL DISPLAY

INC R0

MOV 28H,R0

MOV A,@R0

ACALL CAL

ACALL DISPLAY1

G6: JNB 91H,G7

MOV R0,28H

INC R0

MOV A,@R0

MOV 1DH,A

INC R0

MOV A,@R0

MOV R7,A

INC R0

MOV A,@R0

MOV R6,A

INC R0

MOV A,@R0

MOV R5,A

INC R0

MOV A,@R0

MOV R4,A

ACALL DISPLAY

INC R0

MOV 28H,R0

MOV A,@R0

ACALL CAL

ACALL DISPLAY1

MOV R0,28H

ACALL DEE

ACALL DEE

G7: JNB 92H,G8

MOV R0,28H

DEC R0

MOV A,@R0

MOV 1DH,A

DEC R0

MOV A,@R0

MOV R7,A

DEC R0

MOV A,@R0

MOV R6,A

DEC R0

MOV A,@R0

MOV R5,A

DEC R0

MOV A,@R0

MOV R4,A

ACALL DISPLAY

DEC R0

MOV 28H,R0

MOV A,@R0

ACALL CAL

ACALL DISPLAY1

ACALL DEE

ACALL DEE

MOV R0,28H

G8: JNB 90H,G6

ACALL DEE

ACALL DEE

MOV R0,#0

MOV DPTR,#300H

ACALL BARATI

AJMP SENI

ARU: MOV R0,1FH;#2AH

MOV @R0,1DH

INC R0

INC 1FH

MOV @R0,07H

INC R0

INC 1FH

MOV @R0,06H

INC R0

INC 1FH

MOV @R0,05H

INC R0

INC 1FH

MOV @R0,04H

INC R0

INC 1FH

MOV @R0,19H

INC R0

INC 1FH

SETB 95H

ACALL DEE

ACALL DEE

ACALL DEE

CLR 95H

RET

BARATI:MOV A,#80H

ACALL COM

B1: CLR A

MOVC A,@A+DPTR

CJNE A,#2DH,C1

RET

C1: ACALL DAT

INC DPTR

SJMP B1

F2: MOV 15H,#240

RANI: MOV A,#0C0H

ACALL COM

BB1: CLR A

MOVC A,@A+DPTR

CJNE A,#2DH,CB1

RET

CB1: ACALL DAT

INC DPTR

SJMP BB1

CAL: MOV 1CH,#0

MOV R1,#0

MOV R2,#0

MOV R3,#0

CJNE A,#0,GF1

SJMP DC

GF1: INC 1CH

INC R1

INC R1

CJNE R1,#10,GF

INC R2

MOV R1,#0

CJNE R2,#10,GF

INC R3

MOV R2,#0

GF: MOV R0,1CH

CJNE A,1CH,GF1

DC: RET

CAA: MOV A,R3

MOV 0F0H,#100

MUL AB

MOV 1EH,A

MOV A,R2

MOV 0F0H,#10

MUL AB

ADDC A,R1

ADDC A,1EH

RET

ADDD:MOV 0F0H,#100

DIV AB

MOV R3,A

MOV A,0F0H

MOV 0F0H,#10

DIV AB

MOV R2,A

MOV R1,0F0H

RET

DISPLAY:MOV A,#8AH

ACALL COM

MOV A,1DH

ADD A,#30H

ACALL DAT

MOV A,R7

ADD A,#30H

ACALL DAT

MOV A,R6

ADD A,#30H

ACALL DAT

MOV A,R5

ADD A,#30H

ACALL DAT

MOV A,R4

ADD A,#30H

ACALL DAT

RET

DISPLAY1: MOV A,#0C6H

ACALL COM

MOV A,R3

ADD A,#30H

ACALL DAT

MOV A,R2

ADD A,#30H

ACALL DAT

MOV A,R1

ADD A,#30H

ACALL DAT

;MOV A,R4

;ADD A,#30H

;ACALL DAT

RET

DAT: MOV 80H,A

SETB 0B7H

CLR 0B5H

SETB 0B6H

CLR 0B6H

ACALL DE

RET

COM:MOV 80H,A

CLR 0B7H

CLR 0B5H

SETB 0B6H

CLR 0B6H

ACALL DE

RET

DE: MOV 17H,#250

KK1: DJNZ 17H,KK1

RET

DEE: MOV 18H,#250

GG1: ACALL DE

ACALL DE

DJNZ 18H,GG1

RET

ORG 300H

DB "FREQUENCY: -"

ORG 310H

DB "POWER: -"

ORG 320H

DB "SAVED FRE: -"

ORG 330H

DB " EMBEDDED -"

ORG 340H

DB " AUDIOMETRY -"

ORG 350H

DB " DONE BY -"

ORG 360H

DB "D.AMBUJAM -"

ORG 370H

DB " V.RANJINI -"

ORG 380H

DB " K.MUTHARASI -"

ORG 390H

DB " S.LAKSHMI -"

END

Instruction Set

Alphabetical List of Instructions

ACALL: Absolute Call

ADD, ADDC: Add Accumulator (With Carry)

AJMP: Absolute Jump

ANL: Bitwise AND

CJNE: Compare and Jump if Not Equal

CLR: Clear Register

CPL: Complement Register

DA: Decimal Adjust

DEC: Decrement Register

DIV: Divide Accumulator by B

DJNZ: Decrement Register and Jump if Not Zero

INC: Increment Register

JB: Jump if Bit Set

JBC: Jump if Bit Set and Clear Bit

JC: Jump if Carry Set

JMP: Jump to Address

JNB: Jump if Bit Not Set

JNC: Jump if Carry Not Set

JNZ: Jump if Accumulator Not Zero

JZ: Jump if Accumulator Zero

LCALL: Long Call

LJMP: Long Jump

MOV: Move Memory

MOVC: Move Code Memory

MOVX: Move Extended Memory

MUL: Multiply Accumulator by B

NOP: No Operation

ORL: Bitwise OR

POP: Pop Value From Stack

PUSH: Push Value Onto Stack

RET: Return From Subroutine

RETI: Return From Interrupt

RL: Rotate Accumulator Left

RLC: Rotate Accumulator Left Through Carry

RR: Rotate Accumulator Right

RRC: Rotate Accumulator Right Through Carry

SETB: Set Bit

SJMP: Short Jump

SUBB: Subtract From Accumulator With Borrow

SWAP: Swap Accumulator Nibbles

XCH: Exchange Bytes

XCHD: Exchange Digits

XRL: Bitwise Exclusive OR

Undefined: Undefined Instruction

REFERENCES

9. REFERENCES

Books

1. G.K. Mithal and Ravi Mittal (2000) ‘Electronic Devices and Circuits’, pp. 726, 758.

2. Muhammad Ali Mazadi and Janice Gillispie Mazadi (2002) ‘The 8051 Microcontroller and Embedded System’

3. D.Roy Choudhury and Shail B. Jain (2004) ‘Linear Integrated Circuits’, pp. 44-93, 380-402

Websites

1. www.electronics-lab.com2. www.earinfo.com

3. www.ee.mut.ac.th/datasheet /

4. www.circuitcellar.com