1

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY

HYDERABAD, A.P

A FINAL PROJECT REPORT

ON

“MYOELECTRIC CONTROLLED PROSTHETIC HAND”

In partial fulfillment for the degree of

BACHELOR OF TECHNOLOGY

IN

ELECRICAL AND ELECTRONIC ENGINEERING

BY

NARESH . V. 06M31A0230

BHASKAR. L. 06M31A0208

NISHITHA COLLEGE OF ENGINEERING AND

TECHNOLOGY

LEMOOR. (VI), KANDUKUR(MAN), R.R. (DIST)

2

ABSTRACT

Our mini project was inductance meter using 89c2051 microcontroller. As an

expansion and knowledge improvement we have opted for LCF meter as our

final year project. Which is not only challenging but also useful device. To

be different our choice was LCF meter (inductance , capacitance and

frequency meter), instead of LCR meter

3

1.0 Introduction

2.0 Block diagram

2.1 Block diagram explanation

2.2 Block diagram of frequency counter

3.0 Implementation

3.1 Microcontroller

3.2 Amplifier

3.3 LCD display

4.0 Schematic Diagram.

4.2 microcontroller sghematic diagram

4.1 Functional Description

4.3 Theory of operation

5.0 Results and discussion

6.0 Summary and conclusion

Future Scope

Annexure - 1

1. List of figures

2. List of tables

Annexure -2

1. Microcontroller code

2. Capacitence meter code

Bibilography

4

CHAPTER – 1

1. INTRODUCTION

Capacitance meter:

Capacitance meter can be very helpful in identifying old components where its mark has been

erased or became unreadable. Such instrument can be quite expensive, but fortunately we can

build it easily with much lower cost. The capacitance meter described here can measure any

capacitor between 1pF and 10uF. Here is the schematic diagram of the circuit:You can just use a

connector for the voltmeter, and the circuit becomes a capacitance meter adapter for your

general purpose voltmeter. Just plug the input of your voltmeter to this capacitance meter circuit

and now your voltmeter becomes capacitance meter.

You can use an analog voltmeter or digital voltmeter. If you use a digital voltmeter,

make sure your digital voltmeter is a dual/single slope type reading, since it has an inherent

averaging function. If your digital voltmeter is a fast sampling type, then you need to insert a

resitor-capacitor filter between this capacitance meter circuit and the voltmeter. A 1k resitor and

a 10uF electrolytic capacitor sould be enough for the filter. Analog voltmeter doesn‟t need any

filter since its mechanical inertia acts like a low-pass filter in nature. More information can be

found at

This simple controller based unit was designed to measure and display the values of inductors

and capacitors.As a by-product of the technique used.it can also display the frequency of an

external 0V/ +5V signal source The ranges are approximately:

Capacitance : 1pF to 6500uF

Inductance : 1uH to 10H

Frequency : 0.05Hz to 5MHz

Inductance meter:

The algorithm works with the device is as follows:

1. After the power, if the buttons SA1, SA2 are pressed, then the indicator will show "L" or "C",

5

thus hinting at what button must be overcome.

2. When squeezed the knob, the instrument calibration mode, as evidenced by the inscription

"WAIT", a couple of seconds, alternating on "OK". During this time, the relay, including a

reference capacitor in the general contour of the L1 and C1. The microcontroller reads the

frequency with condenser and without him, which then e yshem will be used to calculate the

exact values of L1 and C1. Measuring terminals at this time disconnected from the circuit and do

not affect the measurement.

3. By clicking on the appropriate radio button is selected or the measurement of capacitance or

inductance. Accordingly, the indicator displays "L =", or "C =". In the first case, the measured

capacitance connected in parallel with C1, the second - as measured inductance connected in

series L1. Microcontroller measures the frequency and computes the desired value. The limit of

measurement is set automatically, and after the indicated values of the dimension: "pF", "nF", "

uH "," mH ".

Frequency counter:

Digital frequency counter is being used for wide range of applications. Digital frequency counter

is extensively uses digital circuits and hence fairly good knowledge of digital circuits and of

digital integrated circuits is required to understand the operation of the frequency counter.

However application of micro controllers have greatly simplified hardware requirement for

frequency counter. The following figure shows the conventional frequency counter design.

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2. BLOCK DIAGRAM

89S52/

ATMEGA16

RCF

selection

switch

16X2 LCD DISPALY

Op-Amp

oscillator

Frequency

counter

Transformer

Power

supply

Regulator

Filter

7

Fig: Block Diagram inductor capacitor and frequency counter meter

2.1 Block diagram explanation:

Power supply:

The electrical power output is rated at 230v Ac. Which is not suitable for driving any

electronic devices, which operate at lower voltages 12V, 5V and 3V etc. hence 230V AC is

converted to 12V ac using step-down transformer. The o/p of the step down transformer is

rectified using bridge rectifier for max efficiency

Bridge Rectifier:

A bridge rectifier makes use of four diodes in a bridge arrangement to achieve full-wave

rectification. This is a widely used configuration, both with individual diodes wired as shown

and with single component bridges where the diode bridge is wired internally.

Fig 49: Bridge Recifier

Diodes 1N4007 are used as rectifiers. which are rated at 1Amp.

The output of rectifier is pulsating DC which is filtered using a filter capacitor to

smoothen out the ripples.

RC Filter

8

the diode bridge is wired internally. A bridge rectifier makes use of four diodes in a

bridge arrangement to achieve full-wave rectification. This is a widely used configuration, both

with individual diodes wired as shown and with single component bridges where

Fig 50: Current Flow in the Bridge Rectifier

Due to variations at the input the output may also vary hence we need a regulator maintain

constant output voltage and better line regulation and load regulation irrespective of variations at

the input.

The regulator used is 7805 which is a positive voltage regulator. The first two digits “78”

indicates fixed positive regulator and last two digits indicate output voltage in our case “05”

stands for 5V constant output.

Simple 5V power supply for digital circuits

Summary of circuit features and Brief description of operation:

1) Gives out well regulated +5V output, output current capability of 100 mA

2) Circuit protection: Built-in overheating protection shuts down output when regulator IC gets

too hot

3) Circuit complexity: Very simple and easy to build

4) Circuit performance: Very stable +5V output voltage, reliable operation

5) Availability of components: Easy to get, uses only very common basic components

6) Applications: Part of electronics devices, small laboratory power supply

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7) Power supply voltage: Unreglated DC 8-18V power supply

2.2 Block diagram of digital frequency meter & Explanation

The circuit is built around a member of the atmel family of microcontrollers. In this project we

hope to give some insight into the methodology of software design for microcontrollers, and in

particular an insight into programming the microcontroller. The challenge was to achieve a

solution with the minimum of hardware by moving the functionality into software. Basing the

circuit on a microcontroller, rather than opting for a more conventional electronic design, gives a

greater degree of flexibility. Software is more adaptable than hardware, it is much easier to

change a line or two in the source code than to add another track to a pcb.

A microcontroller is robust, simple to interface to the outside world, and relatively simple to

program.

Individual instructions are represented by mnemonics which are easier to remember than the

binary codes that the processor actually understands. A mnemonic gives an indication of what an

instruction does. For example the instruction reti returns from a subroutine. A software tool

called an assembler converts the mnemonics (source code) into binary (object code).

The microcontroller I/O pin is connected to an external probe for the meter via some circuitry to

condition the input signal. The port pin can trigger on a rising or a falling edge, in this design we

have conventionally selected triggering on rising edges. There is also a prescaler associated with

the timer which can prescale the input to the counter from 1:2 to 1:256.

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The desired accuracy of ± 1Hz rules out using an RC oscillator to drive the microcontroller. A

crystal or ceramic resonator must be used. The frequency meter must measure up to an 1Khz

input signal so the processor needs to be fast.

How does one measure the frequency of a signal ? Simply by counting the total number of

pulses over a fixed period of time, typically 1 second. This will always give a reading accurate to

± 1Hz. For high frequencies (above 10kHz) the meter can be made more responsive by timing

over a shorter period, say 1/8 s. This reduces the accuracy to ± 8Hz but because only 4

significant digits are displayed anyway that doesn‟t matter.

One of the design goals was to dispense with range switches or the equivalent. Consequently the

software must be adaptive to whatever input signal frequency it is fed with.The first problem to

be solved was how to display such a range of frequencies using just four digits (i.e. without

being able to display the units, whether Hz, kHz or MHz). The solution was to always display the

signal frequency in kHz with the position of the decimal point effectively indicating the units.

Table 1 gives the displayed readings for the range of frequencies. A more sophisticated (and

expensive) approach would be to use an alphanumeric LCD display which could display the

units as well as the digits.

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3.0 IMPLIMENTETION

The design is based upon the concept that osillators can be constructed from CMOS NAND

gates or inverters.and that their oscillation frequency depends on the valuesof inductance.

capacitance and resistance in their feedback paths. Using a suitable microconteroller. Such as

one from the PIC 16F62x or PIC 16F87x

families. software can read the frequency of an oscillator and calculate the value of the ot- her

components are known.In this design. A PIC16F628 is used and the results are output to an

alphanumeric liquid crystal display (I.c.d.). One technique for using an inductor in a CMOS

oscillator circuit is that shown in Fig.1.Here the oscillation frequency is determined by the

formula:

F = _______1_______

2 π √ ( L x C )

where:

F = frequency

C = C1 x C2

C1 + C2

L = inductance

π = 22/7

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Using this formula. If any two values are known. The third can be readily calculated For

instance . if C and F are known. Than L can be calculated using the formula:

L=(1†(2Πf)^2÷ C

Similarly using the capacitance –resistance oscillator configuration ,.the output Frequency can

be calculated for known values of R and C. several formulae exist for this calculation and the one

used in this application is:

F = ____1____

2x R x C

from which the value for C can be calculated if R and F are known:

C = 1___

Π x R x F

inductance measurment

Inductors are passive devices used in electronic circuits to store energy in the form of a

magnetic field. They are the compliment of capacitors, which store energy in the form of an

electric field. An ideal inductor is the equivalent of a short circuit (0 ohms) for direct currents

(DC), and presents an opposing force (reactance) to alternating currents (AC) that depends on the

frequency of the current. The reactance (opposition to current flow) of an inductor is

proportional to the frequency of the current flowing through it. Inductors are sometimes referred

to as "coils" because most inductors are physically constructed of coiled sections of wire.

The property of inductance that opposes current flow is exploited for the purpose of preventing

signals with a higher frequency component from passing while allowing signals of lower

frequency components to pass. This is why inductors are sometimes referred to as "chokes,"

since they effectively choke off higher frequencies. A common application of a choke is in a

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radio amplifier biasing circuit where the collector of a transistor needs to be supplied with a DC

voltage without allowing the RF (radio frequency) signal from conducting back into the DC

supply.

Most of the formulas for the inductance of a coil are valid for the current sheet

approximation, where the c urrent flows in an indefinitely thin surface around the coil

diameter. This is the same as assuming the coil wound with an indefinitely thin tape with

negligible separation between turns. If the separation between turns is not small, a correction

factor should be applied. Moreover, at high frequencies the current crowds towards the

inside of the coil so the effective radius where the current flows become smaller. Sometimes

it is suggested to use the internal radius of the coil instead of the wire mean radius in the

calculations, in order to compensate for this effect. However the difference between the low- and

high-frequency inductances is usually not large [1].

To compute accurately the inductance of any kind of coil (or also of more complicated

conductiong structures) one has to use an electromagnetic simulator.

Regarding current sheet inductance formulas for single-layer coils, one of the most widely

known is the one by Wheeler [2], which states (after converting to metric units):

L = (d2n

2) / (l + 0.45d)

where

„d‟ is the coil diameter in meters,

„n‟ the number of turns and

„l‟ the coil length in meters.

The above formula is accurate within 1 % for l>0.4d ; for shorter coils one can use the

well- known Nagaoka formula [3] (which has the inconvenience of requiring a list of

tabulated values for different diameter / length ratios) or other asymptotic approximations

[4].

Some useful formulas, applicable for any diameter to length ratio, are presented in [4]

and [5]; the following form implements the latter, for which the maximum relative error

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is stated to be less than 3 ppm.

The Q value is computed here using the formula of [6]; take the resulting value with

care, since the limits of validity are not clear to me.

INPUT DATA

Coil diameter, d : 0.33m

Coil length, l : 0.24m

Number of turns, n :55

Frequency, MHz : 0.137 mh

(used only for computing Q)

CALCULATED VALUES

Inductance value L :896 µH

Inductor Q : 575

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Frequency measurment

For cyclical processes , such as rotation, oscillations , or waves frequency is

defined as a number of cycles per unit time. In physics and engineering

disciplines , such as optics , acoustics , and radio , frequency is usually denoted by

a Latin letter f or by a Greek letter ν (nu).

In SI units , the unit of frequency is hertz (Hz), named after the German physicist

Heinrich Hertz. 1 Hz means that an event repeats once per second. A previous name

for this unit was cycles per second.A traditional unit of measure used with rotating

mechanical devices is revolutions per minute, abbreviated RPM. 60 RPM equals one

hertz.[1]

The period, usually denoted by T, is the length of time taken by one cycle, and is the

reciprocal of the frequency f:

The SI unit for period is the second.

M easurement

Calculating the frequency of a particular event is accomplished by counting the number

of times that event occurs within a specific time intervall, then dividing the count by the

length of the time interval. For example , if 71 events occur within 15 seconds, the

frequency is:

If the number of counts is not very large , it is more accurate to measure the time

interval for a predetermined number of occurrences, rather than the number of occurrences

within a specified time.[2]

The latter method introduces a random e rror into the count of

between zero and one count, so on average half a count. This is called gating error and

causes an average error in the calculated frequency of Δf = 1/(2 Tm), or a fractional error

of Δf / f = 1/(2 f Tm) where Tm is the timing interval and f is the measured frequency. This

error decreases with frequency, so it is a problem at low frequencies where the number of

counts N is small.

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An older method of measuring the frequency of rotating or vibrating objects is to use a

stroboscope. This is an intense repetitively flashing light (strobe light) whose frequency can be

adjusted with a calibrated timing circuit. The strobe light is pointed at the rotating object and the

frequency adjusted up and down. When the frequency of the strobe equals the frequency of the

rotating or vibrating object, the object completes one cycle of oscillation and returns to its

original position between the flashes of light, so when illuminated by the strobe the object

appears stationary. Then the frequency can be read from the calibrated readout on the

stroboscope.

schematic diagram of microcontroller:

Fig 1.1: Schematic of Micro controller interface

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Fig 1.2: Analog front end oscillator schematic

Fig 1.3: Frequency counter interface sc

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3.3 LIQUID CRYSTEL DISPLAY:

A liquid crystal display (LCD) is a thin, flat display device made up of any number of color

or monochrome pixels arrayed in front of a light source or reflector. It is often utilized in

battery-powered electronic devices because it uses very small amounts of electric power.

In recent years the LCD is finding widespread use replacing LED‟s (seven-segment

LED‟s or other multi segment LED‟s). This is due to the following reasons:

1. The declining prices of LCD‟s.

2. The ability to display numbers, characters, and graphics. This is in contrast to LED‟s, which

are limited to numbers and a few characters.

3. Incorporation of a refreshing controller into the LCD, thereby relieving the CPU of the task

of refreshing the LCD. In contrast, the LED must be refreshed by the CPU to keep displaying

the data.

4. Ease of programming for characters and graphics.

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Fig 3.3: A general purpose alphanumeric LCD, with two lines of 16 characters

An alphanumeric 2 line 16 character LCD display is used for user interface and

debugging purposes.

It can be operated in 8bit mode or 4bit mode. Since the processor resources are a

premium and we need to interface several devices we have implemented a multiplexed LC and

Keypad interface using least number of ports.

LCD displays are very versatile and require low power to operate.

Attractive backlight enhances the poor light visibility.

Fig 3.4 Schematic of LCD connector

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Schematic Diagram.

21

4.0 SCHEMATIC DIAGRAM

4.1 Schematic diagram of LCF meter:

Capacitance meter can be very helpful in identifying old components where its mark has been

erased or became unreadable. Such instrument can be quite expensive, but fortunately we can

build it easily with much lower cost. The capacitance meter described here can measure any

capacitor between 1pF and 10uF. Here is the schematic diagram of the circuit:

You can just use a connector for the voltmeter, and the circuit becomes a capacitance meter

adapter for your general purpose voltmeter. Just plug the input of your voltmeter to this

capacitance meter circuit and now your voltmeter becomes capacitance meter. You can use an

analog voltmeter or digital voltmeter. If you use a digital voltmeter, make sure your digital

voltmeter is a dual/single slope type reading, since it has an inherent averaging function. If your

digital voltmeter is a fast sampling type, then you need to insert a resitor-capacitor filter between

this capacitance meter circuit and the voltmeter. A 1k resitor and a 10uF electrolytic capacitor

sould be enough for the filter. Analog voltmeter doesn‟t need any filter since its mechanical

inertia acts like a low-pass filter in nature. More information can be found at

[Source: talkingelectronics.com]

22

Inductance meter:

The algorithm works with the device is as follows:

1. After the power, if the buttons SA1, SA2 are pressed, then the indicator will show "L" or "C",

thus hinting at what button must be overcome.

2. When squeezed the knob, the instrument calibration mode, as evidenced by the inscription

"WAIT", a couple of seconds, alternating on "OK". During this time, the relay, including a

reference capacitor in the general contour of the L1 and C1. The microcontroller reads the

frequency with condenser and without him, which then e yshem will be used to calculate the

exact values of L1 and C1. Measuring terminals at this time disconnected from the circuit and do

not affect the measurement.

3. By clicking on the appropriate radio button is selected or the measurement of capacitance or

inductance. Accordingly, the indicator displays "L =", or "C =". In the first case, the measured

capacitance connected in parallel with C1, the second - as measured inductance connected in

series L1. Microcontroller measures the frequency and computes the desired value. The limit of

measurement is set automatically, and after the indicated values of the dimension: "pF", "nF", "

uH "," mH ".

Frequency counter:

Digital frequency counter is being used for wide range of applications. Digital frequency counter

is extensively uses digital circuits and hence fairly good knowledge of digital circuits and of

digital integrated circuits is required to understand the operation of the frequency counter.

However application of micro controllers have greatly simplified hardware requirement for

frequency counter. The following figure shows the conventional frequency counter design.

23

4.2 THEORY OF OPERATION

The frequency counter has to count the number of cycles per second of an incoming signal.

Hence we need a device to count. In electronics circuits, counter ICs are available for counting.

These IC's can count the input pulses. The count is given as coded output from the IC (in binary

form or BCD form). The count must be converted into decimal digit to be understood by human

beings. More number of IC's can be cascaded to increase the number of digits. The number of

digits required for the counter to display the count value depends on the application and the

accuracy needed. In our design we use a single 4 bit BCD high-speed CMOS counter chips. One

chip is used for one digits and we use 7 similar ICs to get seven digit counter. Also we use

CMOS decoder IC to decode the BCD out put of the counter to drive 7 segment displays.

Since the counter can count only digital pulses, we need to convert the incoming signal wave to

digital pulse or we should obtain one pulse for every input wave. Hence we need a special circuit

to shape the input wave into a square wave of same frequency and amplitude confined to the

TTL signal levels. A signal conditioning section is needed for this purpose.

The input Signal-conditioning section consists of the following stages.

1. Amplifier or attenuation stage

2. TTL level converter stage

Besides the above initial stages, some times a few more additional stages such as input protection

stages, filter stages, etc are can be found in some designs. The input whose frequency is to

measured is given to the input stage consisting of the above and the out put of this stage is the

square pulses. Now the square pulses are given to the counter to count the number of pulses for a

fixed duration. If the duration is 1 seconds, then the counter displays a value that equals to the

number of cycles per second, now if we want to measure a frequency of say 20MHz, the counter

should display 20000000. this means the counter should have 8 digits to display. Now the

resolution of the counter ( minimum change of frequency that can be displayed ) is 1Hz. If we do

not require that much of resolution, we can reduce the number of digits. For example, if we are

counting the input cycles for a duration of 0.1 seconds, the display shows 2000000. Now if we

put a decimal points after two digits from the left of the display, the frequency can be read in

MHz, in both cases, the resolution for the later being 10Hz. The time for which the counter is

counting is called as gating time and if the gating is say 1 milli second, we get a display with

resolution of 1kHz. A frequency counter must always count the input frequency and display

frequency. This means there should be an arrangement to count the input for a fixed time, display

the reading. While displaying the reading, the counter should clear again to read input again.

Then only we get a continuous reading that displays the correct frequency at all times. A control

circuit is needed to achieve this. The function of the control circuit to generate the following

signals.

1. Clear the counter for refreshing

2. Provide a precision gating signal to allow the input pulses to the counter circuit

3. Latch the count value to decode and display

4. Repeat the above steps continuously to get a continuous reading

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The control circuit must operate with precision timing. This is achieved by deriving all timing

signals from a crystal oscillator or time base circuit. The accuracy of the counter solely depends

on the stability and accuracy of the time base circuit.

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

We present a design for a simple, low-cost digital frequency meter with the following features:

operating range from about 1hz to 15Hz to 8MHz (sufficiently high to make the meter

useful for troubleshooting digital circuits, microcontrollers etc.)

internal accuracy ± 1Hz

4 digits of displayed accuracy (enough accuracy for most situations)

adaptive (no range switch)

input conditioning amplifier sensitive to 50mV

input protection

crystal controlled (therefore no need for calibration)

powered by a single 9V alkaline battery

How does LC Meter Work?

To be able to determine the value of an unknown inductor / capacitor we can use the

frequency formula given below.

Note that there are three variables that we can work with; f, L and C (f represents a

frequency, L inductance and C capacitance). If we know the values of the two variables we

may calculate the value of the third variable.

Lets say we want to determine the value of an unknown inductor with X inductance. We plug

X inductance into the formula and we also use value of a known capacitor. Using this data we

can calculate the frequency. Once we know the frequency we can use the power of the

algebra and rewrite the above formula to solve for L (inductance). This time we will use the

calculated frequency and a value of a known capacitor to calculate the inductance.

25

Isn't this amazing? We just calculated the value of unknown inductor, and we may use the

same technique to solve for the unknown capacitance and even frequency.

Applying the Theory to LC Meter's Hardware

Now let's use the above theory and apply it to electronics. The LC Meter uses a popular

LM311 IC that that functions as a frequency generator and this is exactly what we need. If we

want to calculate the value of an unknown inductor we use a known Ccal 1000pF capacitor

and the value of an unknown inductor. LM311 will generate a frequency that we can measure

with a frequency meter. Once we have this information we can use the frequency formula to

calculate the inductance.

The same thing can be done for calculating the value of a unknown capacitor. This time we

don't know the value a capacitor so instead we use the value of a known inductor to calculate

the frequency. Once we have that information we apply the formula to determine the

capacitance.

All this sounds great, however if we want to determine the value of a lot of inductors /

capacitors then this may become a very time consuming process. Sure, we can write a

computer program to do all these calculations, but what if we don't have an access to a

computer or a frequency meter?

That's were PIC16F84A microchip comes handy. PIC16F84A is like a small computer that

can execute HEX programs that are written using an assembly language. PIC16F84A is a

very flexible microchip because it has PINs which can be configured as inputs and outputs.

Besides that, PIC16F84A IC requires very minimal number of external components like

4MHz crystal / resonator and few resistors depending on what project we are building. Before

we can use PIC16F84A microchip we have to program it with a HEX code which has to be

sent from the computer.

In the next step we use the frequency generated by LM311 IC and pass it on to PIC16F84A's

PIN 17. We designate this PIN as an input, as well as all other PINs that are directly

connected to switches and jumpers. User can use these inputs to tell the microchip to execute

specified set of instructions or perform calculations.

Once the microchip will calculate the unknown inductance or capacitance it will use PINs

that are designated as outputs and pass the results on to the 16 character LCD display.

26

LC-meter with the 89C2051

LC-meter is a device for measuring capacitance and inductance .it works based on the principle

of LC oscillator frequency measurement and subsequent calculations, which provides single-chip

microcomputer used in our project.

Here in after described measurement device is designed to jejbylo possible to construct as simple

as possible and with minimal financial náklady. Proto this article will not deal with excessive

detail, but focused on a simple description of the construction equipment. Software is also

explained in detail.

LC meter function

Measurement capabilities range from 0.01pF, the maximum capacity of the until-oscillating

oscillator (2 m M tested), only the bipolar capacity, means that do not measure electrolytes.

Measure inductance range from 1NH, the maximum-inductance is not known (about 100mH but

certainly even more).

Calibration

To ensure the accuracy of any need jedenkondenzátor, which has a capacity as closely as

possible 1005pF, or any other, precisely measured, the value entered in the program for

microcomputers (now there just 1005pF). Microcomputer after pressing the S2 values

všechostatních components calculated.

Display Range

Value calculations are performed in floating desetinnéčárce, the calculated value is displayed

with 14 bit precision. Desetinnáčárka is the third, second, or first digit from the right. It ranges

vyplývajítyto displayed:

Inductance Capacity

0.000 to 16.383 m H 0.00 to 163.83 pF

16.38 -163.83 m H 163.8 to 1638.3 pF

163.8 to 1638.3 m H 1.638 to 16.383 nF

1.638 to 16.383 mH 16.38 to 163.83 nF

16.38 to 163.83 mH 163.8 to 1638.3 nF

27

163.8 to 1638.3 mH 1.638 to 16.383 m F

1.638 to 16.383 H 16.38 to 163.83 m F

16.38 to 163.83 H 163.8 to 1638.3 m F

etc.. etc..

The range selection is of course old microprocessor control program.

Screen

To view the result is a smart LCD16x2 characters. The first line shows the resulting value of the

measured components, the second line is displayed the current frequency LC oscillator.

Example:

Cx = 1004.9 pF

302,052 Hz

Speed Measurement

Velocity measurement is a reasonable compromise between rychlostízobrazení and accuracy.

The principle of frequency measurement is čítánífrekvence the counter and the contents of the

counters are periodically read and reset. A compromise was set to 4 measurements per second,

it's frequency is measured with an accuracy of 4 Hz.

Description of involvement

The device is powered from a 9V battery (terminals X2), stabilization 5V small stabilization in

the housing TO92 (IC3). Microcomputer is reset zabezpečenelektrolytem C8 - 1 m F.

11.059MHz crystal is used, which, however, limits the maximum frekvencioscilátoru to 460kHz.

It is possible, after adjusting the preferences in the timing programupoužít 24MHz crystal, which

will choose a higher frequency of LC oscillator adosáhnout greater precision in the smallest

ranges. 11.059MHz crystal suits, because to achieve the accuracy seems to be sufficient. LC

oscillator is tvořennapěťovým comparator with positive feedback. When measuring capacity and

C1 jsouL1 parallel oscillator oscillates with a maximum frequency. After připojeníměřené

capacity is appropriately lower frequencies. When measuring the inductance jeměřená

inductance connected in series with inductor L1, the resulting inductance jetedy total measured

inductance and inductance L1. When calibration is run parallel connected capacitor C2 C1,

whose capacity is accurately known. In the diagrams, written value 1nF, the program is blocked,

however, accurate measurement of the value-in this case 1005pF. Capacitors C3 and C4 are

28

tantalum. LCD display requires four data wires, the display contrast can be set by varying the

contrast resistor connected to the pin3 of the LCD display. Microcomputer is original from

Atmel, a type of AT89S52.

Control

Switching on the device with the lock button S1. Zdežádné not automatically shut down,

therefore we can not use the device again vypnout.9V battery will not give anyone free. If you

want to measure the capacity stisknemetlačítko S3 (which is dependent on inductance

measurement for S4). After pressing the S2 tlačítkapro calibration device is calibrated and ready.

If we measure the inductance, we can calibrate the S3 and S4 is off, or hold down the S4, but we

měřícísvorky shorted. Thus it is appropriate to eliminate inductance measuring lines.

Calculations

During calibration, the microcomputer performs the following operations:

Saves frequency measured before pressing S2tato frequency is called F1.

The actual frequency of the F2 and stored frequency F1vypočítá capacity of capacitor

C1

Calculated inductance L1

When measuring the inductance of the microcomputer performs

tentovýpočet

When measuring the capacity of the microcomputer performs this

calculation

Construction

29

Parts List

Designation Value

R1, R2, R3 100 k

R4 47

R5 1,

P1 5 to resistive trimmer (PT6VK005)

C1 1 nF capacitor foil

C2 1 nF capacitor foil (preferably as nejpřesněji1005 pF can pass)

C3, C4 10 F/10Vtantalový

C5, C10, C11 100 nF ceramic (blocking power)

C6, C7 22 pF ceramic

C8 1 Felektrolytický (to reset when turned on)

C9 47 F/10Velektrolytický

X1 11.059 MHz crystal

L1 150 H

IC1 LM311N voltage comparator

IC2 AT89C2051 microcontroller

IC3 78L05 5V stabilizer

A1 LCD 16x2 characters

20 pin of IC2 plinth (not necessarily)

S1 ISOSTAT 1 packet with lock (1 NO contact)

S2 ISOSTAT 1 packet with a latch (2 normally open contacts)

S3, S4 ISOSTAT 1 packet - catcher - one handles the other.

X3, X4 Measuring terminals

U-KM33B - cabinet

Clip for 9V battery

4 pieces of placeholders (or just two)

30

Capacitance meter

AT89C2051 based Capacitance meter

AT89C2051 is the simplified chip of AT89C51, which has only 2 ports. Although AT89c2051 is

same as AT89C51 it has an on-chip voltage comparator. With this comparator we can make

more additional functions such us analog to digital conversion and so on. In this article an digital

capacitance meter has been designed with the AT89C2051 microcontroller. It can measure

capacitance of values less than 2Microfarads. The value is displayed over the 7segment display.

Circuit Diagram

Capacitance meter code

#include <reg51.h>

unsigned char j,n,t,DispBuf[4];

unsigned int cap;

unsigned char code

BitTab[4]={0xbf,0xdf,0xef,0xf7};

unsigned char code

31

DispTab[11]={0xfe,0x70,0xed,0xf9,0x73,0xdb,0xdf,0xf0,0xff,0xfb,0x40};

sbit P1_2=P1^2;

sbit P3_6=P3^6;

main()

{ TMOD=0x11;

TH1=0xec;

TL1=0x78;

IE=0X88;

TR1=1;

for(;;)

;

}

Timer1() interrupt 3

{ TH1=0xec;

TL1=0x78;

t=BitTab[j];

P1=P1|0x78;

P1=P1&t;

t=DispBuf[j];

t=DispTab[t];

P3=t;

j++;

if(j==4)

j=0;

n++;

if(n==48)

{

n=0;

TH0=0;

32

TL0=0;

P1_2=1;

TR0=1;

for(;P3_6==0;)

;

TR0=0;

P1_2=0;

cap=TL0|(TH0<<8);

cap=cap-3;

if(cap>=2000)

{

DispBuf[3]=10;

DispBuf[2]=10;

DispBuf[1]=10;

DispBuf[0]=1;

}

if(cap<2000)

{

DispBuf[3]=cap%10;

cap=cap/10;

DispBuf[2]=cap%10;

cap=cap/10;

DispBuf[1]=cap%10;

DispBuf[0]=cap/10;

}

}

}

Home made square-wave generator and frequency meter

33

The frequency counter can measure square wave

This project can generate a square wave and also measure it. Two microcontrollers are used in

this circuit, one to generate square wave and other to measure and display the frequency of the

square wave. AT89C2051 is used to generate square wave and AT89S52 is used to measure the

frequency and display it over a 8 digit seven segment display.

The code is written in Keil C. Both microcontroller runs with 11.05mhz crystal.

Circuit Diagram

34

C code for square wave generator

#include <reg51.h>

sbit P1_0 = P1^0;

#define HIGH_BIT 0xFD

#define LOW_BIT 0xC0

void Timer0() interrupt 1

{

unsigned char i = 5;

TH0 = HIGH_BIT;

TL0 = LOW_BIT + 4 + 2;

P1_0 = 0;

while (i--); // 10 cycles = 10.85 ns

P1_0 = 1;

}

void main()

{

TMOD = 0x01;

// 11.0592 Mhz 10 ms

TH0 = HIGH_BIT;

TL0 = LOW_BIT;

EA=1;

ET0=1;

TR0=1;

for (;;) ;

}

C code for Frequency counter

#include <reg51.h>

unsigned long count = 0;

unsigned long show_count = 0;

unsigned char digest[11] =

{0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x83,0xF8,0x80,0x98,0xC6};

unsigned char scancode[8] = {0x1,0x2,0x4,0x8,0x10,0x20,0x40,0x80};

sbit P1_0 = P1^0;

#define HIGH_BIT 0xFB

#define LOW_BIT 0x80

void Disp(int id)

{

P2 = 0;

P2 = scancode[id];

P0 = 0xff;

switch (id)

{

35

case 0: P0 = digest[(show_count / 10000000) % 10]; break;

case 1: P0 = digest[(show_count / 1000000) % 10]; break;

case 2: P0 = digest[(show_count / 100000) % 10]; break;

case 3: P0 = digest[(show_count / 10000) % 10]; break;

case 4: P0 = digest[(show_count / 1000) % 10]; break;

case 5: P0 = digest[(show_count / 100) % 10]; break;

case 6: P0 = digest[(show_count /10) % 10]; break;

case 7: P0 = digest[show_count % 10]; break;

}

}

void Timer0() interrupt 1

{

static unsigned int scount = 0;

static unsigned char rcount = 0;

TH0 = HIGH_BIT;

TL0 = LOW_BIT + 34;

scount++;

if (scount == 800) //1 second

{

scount = 0;

show_count = count;

count = 0;

}else if (scount % 2 == 0)

{

rcount++;

if (rcount == 8) rcount = 0;

Disp(rcount);

}

count += (TH1 << 8) | TL1;

TH1 = TL1 = 0;

}

void main()

{

TMOD = 0x51;

// 11.0592 Mhz 1.152 ms

TH0 = HIGH_BIT;

TL0 = LOW_BIT;

//initalize output counter

TH1 = 0;

TL1 = 0;

EA=1;

ET0=1;

TR0=1;

TR1=1;

for (;;);

}

36

Capacitors

Capacitors store electric charge. They are used with resistors in timing circuits because it takes

time for a capacitor to fill with charge. They are used to smooth varying DC supplies by acting

as a reservoir of charge. They are also used in filter circuits because capacitors easily pass AC

(changing) signals but they block DC (constant) signals.

Capacitance

This is a measure of a capacitor's ability to store charge. A large capacitance means that more

charge can be stored. Capacitance is measured in farads, symbol F. However 1F is very large, so

prefixes are used to show the smaller values.

Three prefixes (multipliers) are used, µ (micro), n (nano) and p (pico):

µ means 10-6

(millionth), so 1000000µF = 1F

n means 10-9

(thousand-millionth), so 1000nF = 1µF

p means 10-12

(million-millionth), so 1000pF = 1nF

Capacitor values can be very difficult to find because there are many types of capacitor with

different labelling systems!

There are many types of capacitor but they can be split into two groups, polarised

and unpolarised. Each group has its own circuit symbol.

1) Polarised capacitors (large values, 1µF +)

Examples: Circuit symbol

2) Electrolytic Capacitors:

their leads will be marked + or -. They are not damaged by heat when soldering.

37

There are two designs of electrolytic capacitors; axial where the leads are attached to each end

(220µF in picture) and radial where both leads are at the same end (10µF in picture). Radial

capacitors Electrolytic capacitors are polarised and they must be connected the correct way

round, at least one of tend to be a little smaller and they stand upright on the circuit board.

It is easy to find the value of electrolytic capacitors because they are clearly printed with their

capacitance and voltage rating. The voltage rating can be quite low (6V for example) and it

should always be checked when selecting an electrolytic capacitor. If the project parts list does

not specify a voltage, choose a capacitor with a rating which is greater than the project's power

supply voltage. 25V is a sensible minimum for most battery circuits.

3) Tantalum Bead Capacitors

Tantalum bead capacitors are polarised and have low voltage ratings like electrolytic capacitors.

They are expensive but very small, so they are used where a large capacitance is needed in a

small size.

Modern tantalum bead capacitors are printed with their capacitance, voltage and polarity in full.

However older ones use a colour-code system which has two stripes (for the two digits) and a

spot of colour for the number of zeros to give the value in µF. The standard colour code is used,

but for the spot, grey is used to mean × 0.01 and white means × 0.1 so that values of less than

10µF can be shown. A third colour stripe near the leads shows the voltage (yellow 6.3V, black

10V, green 16V, blue 20V, grey 25V, white 30V, pink 35V). The positive (+) lead is to the right

when the spot is facing you: 'when the spot is in sight, the positive is to the

right'.

For example: blue, grey, black spot means 68µF

For example: blue, grey, white spot means 6.8µF

For example: blue, grey, grey spot means 0.68µF

4) unpolarised capacitors (small values, up to 1µF)

Examples: Circuit symbol:

Small value capacitors are unpolarised and may be connected either way round. They are not

damaged by heat when soldering, except for one unusual type (polystyrene). They have high

voltage ratings of at least 50V, usually 250V or so. It can be difficult to find the values of these

small capacitors because there are many types of them and several different labelling systems!

38

Many small value capacitors have their value printed but without a multiplier, so

you need to use experience to work out what the multiplier should be!

For example 0.1 means 0.1µF = 100nF.

Sometimes the multiplier is used in place of the decimal point:

For example: 4n7 means 4.7nF.

Capacitor Number Code

A number code is often used on small capacitors where printing is difficult:

the 1st number is the 1st digit,

the 2nd number is the 2nd digit,

the 3rd number is the number of zeros to give the capacitance in pF.

Ignore any letters - they just indicate tolerance and voltage rating.

For example: 102 means 1000pF = 1nF (not 102pF!)

For example: 472J means 4700pF = 4.7nF (J means 5% tolerance).

Colour Code

Colour Number

Black 0

Brown 1

Red 2

Orange 3

Yellow 4

Green 5

Blue 6

Violet 7

39

Capacitor Colour Code

A colour code was used on polyester capacitors for many years. It is now

obsolete, but of course there are many still around. The colours should be read

like the resistor code, the top three colour bands giving the value in pF. Ignore

the 4th band (tolerance) and 5th band (voltage rating).

For example:

brown, black, orange means 10000pF = 10nF = 0.01µF.

Note that there are no gaps between the colour bands, so 2 identical bands

actually appear as a wide band.

For example:

wide red, yellow means 220nF = 0.22µF.

5) Polystyrene Capacitors

This type is rarely used now. Their value (in pF) is normally printed

without units. Polystyrene capacitors can be damaged by heat when

soldering (it melts the polystyrene!) so you should use a heat sink (such as a crocodile clip). Clip

the heat sink to the lead between the capacitor and the joint.

Real capacitor values (the E3 and E6 series)

You may have noticed that capacitors are not available with every possible value, for example

22µF and 47µF are readily available, but 25µF and 50µF are not!

Why is this? Imagine that you decided to make capacitors every 10µF giving 10, 20, 30, 40, 50

and so on. That seems fine, but what happens when you reach 1000? It would be pointless to

make 1000, 1010, 1020, 1030 and so on because for these values 10 is a very small difference,

too small to be noticeable in most circuits and capacitors cannot be made with that accuracy.

To produce a sensible range of capacitor values you need to increase the size of the 'step' as the

value increases. The standard capacitor values are based on this idea and they form a series

which follows the same pattern for every multiple of ten.

The E3 series (3 values for each multiple of ten)

10, 22, 47, ... then it continues 100, 220, 470, 1000, 2200, 4700, 10000 etc.

Notice how the step size increases as the value increases (values roughly double each time).

Grey 8

White 9

40

The E6 series (6 values for each multiple of ten)

10, 15, 22, 33, 47, 68, ... then it continues 100, 150, 220, 330, 470, 680, 1000 etc.

Notice how this is the E3 series with an extra value in the gaps.

The E3 series is the one most frequently used for capacitors because many types cannot be made

with very accurate values.

6) Variable capacitors

Variable capacitors are mostly used in radio tuning circuits and

they are sometimes called 'tuning capacitors'. They have very

small capacitance values, typically between 100pF and 500pF

(100pF = 0.0001µF). The type illustrated usually has trimmers

built in (for making small adjustments - see below) as well as

the main variable capacitor.

Many variable capacitors have very short spindles which are

not suitable for the standard knobs used for variable resistors

and rotary switches. It would be wise to check that a suitable

knob is available before ordering a variable capacitor.

Variable capacitors are not normally used in timing circuits

because their capacitance is too small to be practical and the

range of values available is very limited. Instead timing circuits

use a fixed capacitor and a variable resistor if it is necessary to

vary the time period.

Variable Capacitor Symbol

Variable Capacitor

Photograph © Rapid Electronics

41

7) Trimmer capacitors

Trimmer capacitors (trimmers) are miniature

variable capacitors. They are designed to be

mounted directly onto the circuit board and

adjusted only when the circuit is built.

A small screwdriver or similar tool is required

to adjust trimmers. The process of adjusting

them requires patience because the presence of

your hand and the tool will slightly change the

capacitance of the circuit in the region of the

trimmer!

Trimmer capacitors are only available with

very small capacitances, normally less than

100pF. It is impossible to reduce their

capacitance to zero, so they are usually

specified by their mini

Micro controller code:

;**************************************************************************

$mod52

;project : freq count2.asm

;processor : 89S52 @11.0592Mhz

;hardware ;

;software : v1.0

;START DATE : 100419 10pm

;end_date :

;source : freq count1.asm

;remarks :

;**************************************************************************

;ports allocation

bzr equ p1.0 ; active high

diag equ p1.1

;ZCROSS equ p1.2

LCD_DATA equ p2 ; P2.4 to p2.7 as LCD data bits DB4 to DB7

BKLIT equ p2.0 ; LCD Backlight

LCD_DB7 equ p2.1 ; data bit 7, low nibble of port 2 is used for

data

LCD_DB6 equ p2.2 ; data bit 6

LCD_DB5 equ p2.3 ; data bit 5

LCD_DB4 equ p2.4 ; data bit 4

LCD_EN equ p2.5 ; lcd enable line

LCD_RS equ p2.6 ; LCD Register select

IrInput equ p3.2

Trimmer Capacitor Symbol

TrimmerCapacitor

Photograph

42

;**************************************************************************

;FLAGS

;**************************************************************************

UpdateLCD equ 0H

FBIT1 bit 01

;**************************************************************************

;internal variables

;**************************************************************************

V1 data 21h

V2 data 22h

V3 data 23h

V4 data 24h

Var1 data 27h

Var2 data 28h

Var3 data 29h

var4 equ r2

temp equ r3

temp1 equ r4

delay equ r5

tick equ r6

Freq equ r7

;4Byte hex 2 Dec conv variables

XX0 equ 30H

XX1 equ 31H

XX2 equ 32H

XX3 equ 33H

YY0 equ 34H

YY1 equ 35H

YY2 equ 36H

YY3 equ 37H

YY4 equ 38H

ZZ0 equ 39H

ZZ1 equ 3AH

ZZ2 equ 3BH

ZZ3 equ 3CH

ZZ4 equ 3DH

BITS equ 3EH

;**************************************************************************

;constants

;**************************************************************************

stack equ 60h

cx1 equ 06h

cx2 equ 45h

cx3 equ 19h

cx4 equ 99h

cx5 equ 99h

cx6 equ 99h

lx1 equ 05h

lx2 equ 18h

lx3 equ 04h

lx4 equ 39h

lx5 equ 99h

lx6 equ 99h

Config equ 28h ; 4 bit data, 2 lines, 5 by 7 character matrix

43

entryMode equ 06h ; increment cursor, do not shift display

offCur equ 0Ch ; cursor control instructions start here

lineCur equ 0Eh

blinkCur equ 0Dh

combnCur equ 0Fh

homeCur equ 02h

shLfCur equ 10h

shRtCur equ 14h

clrDsp equ 01h ; display control instructions start here

offDsp equ 0Ah

onDsp equ 0Eh

shLfDsp equ 18h

shRtDsp equ 1Ch

;**************************************************************************

;vector table

;**************************************************************************

org 0000h

ljmp LPOWER_ON ;Power ON Interrupt Vector

org 0003h ;external INT-0

reti

org 000bh

Ajmp TIMER0_ISR ;Timer 0 overflow Interrupt Vector

org 0013h ;external INT-1

reti

org 001bh ;Timer 1 overflow Interrupt Vector

Ajmp TIMER1_ISR ;Timer 0 overflow Interrupt Vector

org 0023h ;serial interrupt

reti

;**************************************************************************

org 0100h

;**************************************************************************

mov dptr,#prj

call disp_mess1

mov dptr,#by

call disp_mess2

call dly1S

call dly1S

call dly1S

call dly1S

call dly1S

;**************************************************************************

Lmainlp: ;main routine starts here

;**************************************************************************

clr UpdateLCD

mov dptr,#m_1

call disp_mess1

main: mov a,#86H

acall wrLCDcom4

mov TH0, #3CH

44

mov TL0, #0BAH

mov tick, #20

mov Freq, #0

mov TH1, #0

mov TL1, #0

setb TR0

setb TR1

abc: cpl p1.2

jnb UpdateLCD,abc

clr UpdateLCD

mov XX2,Freq

mov XX1,TH1

mov XX0,TL1

acall X2D

mov a,ZZ3

acall disp_num

mov a,ZZ2

acall disp_num

mov a,ZZ1

acall disp_num

mov a,ZZ0

acall disp_num

;;;;;;;;;;;;; Display component values ;;;;;;;;;;;;;;;;;;;

call clr_mess2

mov a,ZZ2

?cx1: cjne a,#cx1,?cx2

mov dptr,#mcx1

call disp_mess2

?cx2: cjne a,#cx2,?cx3

mov dptr,#mcx2

call disp_mess2

?cx3: cjne a,#cx3,?cx4

mov dptr,#mcx3

call disp_mess2

?cx4: cjne a,#cx4,?cx5

mov dptr,#mcx4

call disp_mess2

?cx5: cjne a,#cx5,?cx6

mov dptr,#mcx5

call disp_mess2

?cx6: cjne a,#cx6,?lx1

mov dptr,#mcx6

call disp_mess2

?lx1: cjne a,#lx1,?lx2

mov dptr,#mlx1

call disp_mess2

?lx2: cjne a,#lx2,?lx3

mov dptr,#mlx2

call disp_mess2

?lx3: cjne a,#lx3,?lx4

mov dptr,#mlx3

45

call disp_mess2

?lx4: cjne a,#lx4,?lx5

mov dptr,#mlx4

call disp_mess2

?lx5: cjne a,#lx5,?lx6

mov dptr,#mlx5

call disp_mess2

?lx6: cjne a,#lx6,?end

mov dptr,#mlx6

call disp_mess2

?end:

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

ajmp main

;**************************************************************************

disp_num:

mov DPTR,#hex_table

mov temp1,a

anl a,#0F0H

swap a

movc a,@a+DPTR

acall disp_digit

mov a,temp1

anl a,#0FH

movc a,@a+dptr

acall disp_digit

ret

;**************************************************************************

X2D: CALL CLEARYZ ;;Clear All YY and ZZ bytes

MOV YY0,#1 ;;DECIMAL ADDER = 1

; ;;

MOV R0,#XX3 ;;LOCATE HOW MANY BYTES WITH DATA

MOV B,#4 ;;POSSIBLE 8 BYTES W/DATA ON XX

BITS1: MOV A,@R0 ;;GET BYTE FROM INPUT REGISTER

CJNE A,#0,BITS2 ;;JUMP IF FOUND THE FIRST NON ZERO

DEC R0 ;;GO TO LOWER BYTE

DJNZ B,BITS1 ;;ONE BYTE DONE, GO AGAIN

;;

BITS2: MOV A,#8 ;;8 BITS PER BYTE, B CONTAINS BYTE #

MUL AB ;;A = QUANTITY OF BITS W/DATA

MOV BITS,A ;;SAVE

CJNE A,#0,X2DMAIN2 ;;B = NUMBER OF DIGITS W/DATA

RET ;;RETURN IF ONLY ZEROS AT XX

;;

X2DMAIN1: CALL X2DSHIFTD ;;SHIFT DECIMAL RESULT

X2DMAIN2: CALL X2DSHIFTH ;;SHIFT HEXA

JNC X2DMAIN3 ;;IF NOT CARRY, JUST SKIP IT

CALL X2DADD ;;ADD NEW RESULT

X2DMAIN3: DJNZ BITS,X2DMAIN1 ;;ONE BIT DONE, GO AGAIN

RET ;;GENERAL EXIT FROM THIS ROUTINE

;;ZZ0 - ZZ7 CONTAINS DECIMAL RESULT

;;

X2DSHIFTD: MOV R0,#YY0 ;;YY * 2 (DECIMAL)

MOV B,#4 ;;NUMBER OF BYTES

CLR C ;;NEED CARRY ZERO

X2DSHIFTD1: MOV A,@R0 ;;IGNORE LAST CARRY

ADDC A,@R0 ;;ADD BYTE TO ITSELF

46

DA A ;;DECIMAL ADJUST

MOV @R0,A ;;PUT IT BACK

INC R0 ;;GO TO UPPER BYTE

DJNZ B,X2DSHIFTD1 ;;DO IT 8 BYTES

RET ;;RETURN

;;

X2DSHIFTH: MOV R0,#XX3 ;;SHIFT XX7 --> XX0 RIGHT 1 BIT

MOV B,#4 ;;NUMBER OF BYTES

SHIFTR0B: CLR C ;;NEED CARRY ZERO

SHIFTR0B1: MOV A,@R0 ;;GET BYTE

RRC A ;;ROTATE RIGHT THROUGH CARRY BIT

MOV @R0,A ;;SAVE IT BACK

DEC R0 ;;GO TO LOWER BYTE

DJNZ B,SHIFTR0B1 ;;DO IT AGAIN "B" TIMES

RET ;;RETURN

;;

X2DADD: MOV R0,#ZZ0 ;; GET RESULT ZZ 8 BYTES REGISTER

MOV B,#4 ;; 8 BYTES

MOV R1,#YY0 ;; GET YY OPERATOR

CLR C ;; NEED CARRY OFF

X2DADD1: MOV A,@R0 ;; ZZ = ZZ + YY (8BYTES) W/DAA

ADDC A,@R1 ;; ADD BYTE TO BYTE 8 TIMES

DA A ;; DECIMAL ADJUST

MOV @R0,A ;; PUT IT BACK

INC R0 ;; BUMP POINTER NEXT BYTE

INC R1 ;; BUMP POINTER NEXT BYTE

DJNZ B,X2DADD1 ;; ONE BYTE DONE, GO AGAIN

MOV A,ZZ3 ;; LAST CARRY TO 9TH BYTE OF ZZ

ADDC A,#0 ;; JUST CARRY TO ZZ8

MOV ZZ3,A ;;

RET ;; RETURN

CLEARYZ:

mov r1,#9

clr A

mov r0,#YY0

CLEARYZ_1:

mov @r0,A

inc r0

djnz r1, CLEARYZ_1

ret

hex_table:

db '0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'

;**************************************************************************

; Time0 isr get IRaddr,IRdata, ;225us

;**************************************************************************

TIMER0_ISR:

djnz tick, TMR0_ISR_GO

clr TR1

clr TF1

clr TR0

clr TF0

setb UpdateLCD

cpl diag

reti

TMR0_ISR_GO:

47

mov TH0, #3CH

mov TL0, #0BAH

RETI

;----------------------------------------------------------------------------

---------

; Time1 isr get IRaddr,IRdata, ;225us

;----------------------------------------------------------------------------

---------

TIMER1_ISR:

inc Freq

RETI

;**************************************************************************

;delay routines

;**************************************************************************

Dly1: MOV R7,#31h

DJNZ R7,$

DJNZ ACC,Dly1

RET

dly25ms:

MOV VAR2,#45

MOV VAR1,#207

D25ms:DJNZ VAR1,D25ms

DJNZ VAR2,D25ms

RET

dly50ms:

call dly25ms

call dly25ms

ret

dly100ms:

MOV VAR2,#180

MOV VAR1,#72

D100ms:

DJNZ VAR1,D100ms

DJNZ VAR2,D100ms

RET

dly200ms:

call dly100ms

call dly100ms

ret

dly500ms:

MOV VAR3,#4

MOV VAR2,#132

MOV VAR1,#116

D5ms: DJNZ VAR1,D5ms

DJNZ VAR2,D5ms

DJNZ VAR3,D5ms

RET

dly1s:MOV VAR3,#8

MOV VAR2,#8

MOV VAR1,#236

TT1: DJNZ VAR1,TT1

DJNZ VAR2,TT1

DJNZ VAR3,TT1

RET

48

;**************************************************************************

messages:

;**************************************************************************

; org 0BDDH 1234567812345678

m_1: db 'FREQ: Hz',0

mcx1: db 'CX: 0.1 uF ',0

mcx2: db 'CX: 1.0 nF ',0

mcx3: db 'CX: 10 nF ',0

mcx4: db 'CX: ',0

mcx5: db 'CX: ',0

mcx6: db 'CX: ',0

mlx1: db 'LX: 1.0 UH ',0

mlx2: db 'LX: 1.0 mH ',0

mlx3: db 'LX: 15 mH ',0

mlx4: db 'LX: 100 uH ',0

mlx5: db 'LX: ',0

mlx6: db 'LX: ',0

prj: db 'LCF METER PRJ BY',0

by: db 'NARESH & BHASKAR',0

;**************************************************************************

;LCD ROUTINES END HERE

;**************************************************************************

end

Capacitance meter code

#include <reg51.h>

unsigned char j,n,t,DispBuf[4];

unsigned int cap;

unsigned char code

BitTab[4]={0xbf,0xdf,0xef,0xf7};

unsigned char code

DispTab[11]={0xfe,0x70,0xed,0xf9,0x73,0xdb,0xdf,0xf0,0xff,0xfb,0x40};

sbit P1_2=P1^2;

sbit P3_6=P3^6;

main()

{ TMOD=0x11;

TH1=0xec;

TL1=0x78;

IE=0X88;

TR1=1;

for(;;)

;

49

}

Timer1() interrupt 3

{ TH1=0xec;

TL1=0x78;

t=BitTab[j];

P1=P1|0x78;

P1=P1&t;

t=DispBuf[j];

t=DispTab[t];

P3=t;

j++;

if(j==4)

j=0;

n++;

if(n==48)

{

n=0;

TH0=0;

TL0=0;

P1_2=1;

TR0=1;

for(;P3_6==0;)

;

TR0=0;

P1_2=0;

cap=TL0|(TH0<<8);

cap=cap-3;

if(cap>=2000)

{

50

DispBuf[3]=10;

DispBuf[2]=10;

DispBuf[1]=10;

DispBuf[0]=1;

}

if(cap<2000)

{

DispBuf[3]=cap%10;

cap=cap/10;

DispBuf[2]=cap%10;

cap=cap/10;

DispBuf[1]=cap%10;

DispBuf[0]=cap/10;

}

}

}

51