A Project Report Phase-I

On

Project

MICROCONTROLLER BASED CLINICAL THERMOMETER

UNDER THE SUPERVISION OF

ANAMIKA BASU (DAS). &

MADHMITA SARKAR.

Department of Electronics & Communication Engineering

B.P.Poddar Institute of Management & Technology.

PODDAR VIHAR: 137, V.I.P Road, Kolkata- 700 052.

2010-11.

-: SUBMITTED BY:-

NAME COLLEGE UNIV. ROLL. REG. NO. ROLL.

Somrita Ghosh. 0923-61 071150103086 071150103201086

Devraj Mandal. 0923-80 071150103006 071150103101006

Somdeb Mandal. 0923-81 071150103101 071150103101101

Jaideep Mitra. 0923-83 071150103003 071150103101003

STREAM- ECE.

SECTION- B.

YEAR- 4TH

CHAPTER:-1

INTRODUCTION

Electronics engineering, also referred to as electronic engineering, is an engineering discipline which uses the scientific knowledge of the behavior and effects of electrons to develop components, devices, systems, or equipment (as in electron tubes transistors ,integrating circuits, and printed circuit boards) that uses electricity as part of its driving force. Both terms denote a broad engineering field that encompasses many subfields including those that deal with power, instrumentation engineering telecommunications, semiconductor circuits design, and many others.

One of the very important fields of electronics is DIGITAL ELECTRONICS. Digital Electronics basically deals with discrete digital signal & provides a very high accuracy & sensitivity. Due to this digital circuits are used in more enhanced way in all disciplines of engineering.

The application of digital electronics in the field of electronic measurements has provided a higher degree advantage of reliability, sensitivity & accuracy in the field of measurement of natural variables like Temperature, Pressure etc.

With the advent of the first 4-bit microprocessor 4004 from Intel Corporation in 1971, there has been a silent revolution in the domain of digital system design, which has shaken many facets of the current technological progress. In the last 38 years the world has seen an evolution of microprocessors, whose impact on today’s technological scenario is phenomenal.

This evolution is possible because of tremendous advances in the semiconductor process technology. The first microprocessor 4004 contained only ten thousand transistors while the component

density increased more than threefold in less than decade’s time. Immediately after the introduction of the 4004, Intel Corporation introduced the first 8-bit microprocessor 8008 in 1972; these processors were, however, not successful because of their inherent limitations. In 1974, Intel released the first general purpose 8-bit microprocessor 8080. This CPU also was not functionally complete & the first 8-bit functionally complete CPU was introduced in the year 1977.

Thereafter the development of microprocessor technology is based on one sole aim of providing a more powerful & efficient computing machine. To improve processor’s performance, the possible ways are suggested below:-

a) Increasing the processor & system clock rate.b) Optimizing & improving the instruction set.

c) Executing multiple instructions in one cycle & incorporating parallelism in the CPU architecture.

While studying microprocessor based system design, one may note that a stand alone microprocessor is not self sufficient. It requires other components like memory & input/output devices to form a minimum workable system configuration. To have all these components in a discrete form and to assemble them on a PCB, is usually not an affordable solution for the following reasons:-

The overall system cost of a microprocessor based system built around a CPU, memory and other peripherals is high.

A large sized PCB is required for assembling all these components, resulting in an enhanced cost of the system.

Design of such PCBs require a lot of effort & time and thus the overall product design requires more time.

Due to the large size of PCB and the discrete components used, physical size of the product is big and hence is not handy.

As discrete components are used, the system is neither reliable nor it is easy to troubleshoot such a system.

Considering all these problems, Intel decided to integrate a microprocessor along with I/O ports and minimum memory into a single package. Another frequently used peripheral, a programmable timer, was also integrated to make this device a self-sufficient one. This device which contains a microprocessor and the above mentioned components has been named a MICROCONTROLLER.

Design with microcontroller has the following advantages:-

As the peripherals are integrated into a single chip, the overall system cost is very low.

The size of the product is small as compared to the microprocessor based system.

The system design requires a very little effort and is easy to troubleshoot and maintain.

As the peripherals are integrated with a microprocessor, the system reliability is more.

Though a microcontroller may have on-chip RAM, ROM and I/O ports, additional RAM, ROM, I/O ports may be interfaced externally, if required.

The microcontrollers with on-chip ROM provide a software security feature which is not available in microprocessor based system.

All these features are available in a 40 pin package as in an 8 bit microprocessor.

As a microcontroller contains most of the components required to form a microprocessor based system, it is sometimes called a SINGLE CHIP MICROCOMPUTER. Since it also has the ability to easily implement simple control functions, it is most frequently called a MICROCONTROLLER.

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CHAPTER:-2

LITERATURE SURVEY

DEVELOPMENT OF THERMOMETER TECHNOLOGY:-

With the development of science & technology we have a development of thermometer. It is discussed below-

There are five different types of thermometers:

• Bimetal.

• Glass Column.

• Digital – Thermistor.

• Digital – Thermocouple.

• Infrared.

This brochure is designed to help you understand how these types of thermometers vary in technology, features and price.

Bimetal Thermometers:-

Bimetal (or dial) thermometers are durable, inexpensive and recalibratable. Some are designed to leave in the oven and others are not, but all bimetal thermometers use the same basic technology to measure temperature.

Metal expands and contracts when heated and cooled. Different metals expand or contract at different rates. Bimetal thermometer sensors are constructed of two different metals bonded together. When heated, the combination will bend because one metal is expanding faster than the other. A bimetal strip can be wound in the shape of a coil, similar to the mainspring of a clock. In this shape the coil will wind, or unwind, as the temperature changes. If one end of the coil is held so that it cannot move, the other end will be free to move. A pointer is attached to the free end, and the temperature registers on the dial beneath the pointer. The scale is calibrated to the bimetal coil. Bimetal coils vary in length from just over one inch to up to two inches.

Advantage:

Easy to use, recalibratable, no batteries required. A cost effective alternative to digital thermometers.

Disadvantages:

Speed of operation- The thermometer has to be inserted past the top of the bimetal coil.(approximately 1.25-2 inches long.) Good quality bimetal thermometers have a dimple on the stem that anchors the coil as well as showing how far to insert the thermometer for an accurate reading.

Glass Column Thermometers:-

These thermometers feature a food-safe fluid sealed in a glass tube. Plastic is used as a glass substitute in some inexpensive competitive models. A reservoir, or bulb, at the bottom of the column contains the bulk of the fluid, which expands or contracts as the temperature changes. A temperature scale is

printed on or near the column, and the temperature is read from the scale.

Glass column thermometers are among both the most expensive, and the least expensive, thermometers available. The difference is in the quality of glass and the fluid, and the care with which the thermometer is calibrated when it is manufactured.

Advantages:

Most are very economical, easy to understand.

Disadvantages:

Glass can break.

Digital Thermometers – Thermistor:-

The most popular style of digital thermometer features a thermistor, a thermally sensitive object about the size of a head of a pin that is located in the thermometer’s tip. It exhibits a change in electrical resistance with a change in its temperature. The resistance is measured by passing a small, measured direct current (dc) through it and measuring the voltage drop produced. It provides an unusually accurate and stable response in less than 8 seconds.

Advantages:

Thermistor digital thermometers are much less expensive than digital thermocouple thermometers.

Disadvantages:

Speed of response compared to a thermocouple electronic thermometer.

Digital Thermometers – Thermocouple:-

Thermocouple technology makes these digital thermometers the fastest on the market, showing temperature in about 2 seconds, with high accuracy and a high temperature range. Because of this, thermocouple digital thermometers are by far the mostly widely used for industrial purposes. Thermocouple digital thermometers are designed to check for final cooking temperatures. Because of their speed, they can be used to quickly check temperature in a number of places, which is especially helpful with large food items such as turkeys or roasts. Their thin probe also facilitates use with thin foods such as hamburgers and pork chops. The thermocouple is a device that generates electricity when heat is applied to its tip. It consists of two different types of metal wires that are both electrical conductors, joined together at one end and connected to a voltage-measuring device at the other end. When the junction of the two metals is heated or cooled, a voltage is created that can be correlated to temperature. Thermocouples are available in different combinations of metals or calibrations. The most common calibrations are J, K, T, and E, each of which measures a different temperature range. The maximum temperature changes with the diameter of the wire used.

Advantages:

Speed of response (2-5 seconds) and accuracy, recalibratable, good for high temperature readings.

Disadvantages:

Much more expensive than bimetal or digital thermometers using Thermistor technology.

Infrared Thermometers:-

These specialized thermometers can quickly measure the surface temperature of an object without touching it. Infrared thermometers are used to measure surface temperatures only, not internal temperature. Because they operate remotely, they are helpful when it is not possible or practical to physically contact the object being measured (which may be very hot, small or distant). Remote operation also eliminates any possibility of cross-contamination. This technology uses infrared light rays (between microwave and ultraviolet radiation) to measure this temperature. All objects give off radiation (emissivity).

Advantages:

Fast and accurate surface temperature measurement.

Disadvantages:

Does not take internal temperature (except combination unit). Does not do well measuring shiny surfaces or gold.

WHY GO FOR MICROCONTROLLER BASED DIDGITAL THERMOMETER?

Microcontroller Based Digital Thermometer can accurately the temperature determine and measure, digital display, not a pointer or mercury display.  

Digital thermometer is easier to read than glass thermometer, it can for you and your family fast and convenient. Digital thermometer can measure your body temperature quickly, and can ensure accuracy for your health and your family’s health in real-time monitoring. A versatile, professional-quality instrument, it can once again ensure the accuracy of the ear or forehead use more convenient.

   Digital thermometer has a wide range of applications, can be used to measure gas, liquid and solid temperature. In many fields it to appear, such as hospitals and schools. Digital probe thermometer, there are two general types: thermocouple digital thermometer and thermistor digital thermometer.

    Microcontroller based Digital thermometer, compact, stylish, do not contain mercury, the use would not damage to the environment.

As it is a microcontroller based application the reliability & compatibility of the device is very high.

MICROCONTROLLER:-

ATMEL AT89C51 (8-BIT MICROCONTROLLER WITH 4-K FLASH MEMORY):-

FEATURES:-

• Compatible with MCS-51™ Products

• 4K Bytes 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

The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K bytes of Flash programmable and erasable read only memory (PEROM). The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the industry-standard MCS-51 instruction set 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.

BLOCK DIAGRAM AT89C51:-

PIN DIAGRAM OF AT89C51:-

CHAPTER:-3

PROBLEM FORMULATION

BASIC PLAN OF THE PROJECT:-

RANGE OF TEMPERATURE- 95 F – 110 F. {for clinical application}

BASIC BLOCK DIAGRAM OF THE CIRCUIT

IC DESCRIPTION---->>>>>

LM 35-- 3 terminal, precision temperature sensor(with linear function of scale factor ± 10.0 mV/˚ C). N.B.—we may use LM 34 sensor which directly shows linear operation with mV/˚ F scale factor (as application is clinical).

ADC 0804—Analog – Digital Converter.

AT89C51—Microcontroller.

LCD MODULE—16 Character × 2-line LCD Module.(ALTRENATIVE OPTION—use of seven segment display )

Another very important part of the circuit is the 5 volt power supply circuit. This circuit must be built prior to use of microcontroller & other ICs like temperature sensor, analog-digital converter etc.

CHAPTER:-4

PLAN OF WORK

The most important thing for successful completion of a project is team work and proper planning for the work. So we concentrated in this matter and a plan was made that how we will proceed.

In the following table we shown our total panning for this particular project-

STEPS TIME DURATION

Study of Project Idea July,2010

Study of suitable ICs for the Project

August,2010

Selection of proper ICs for the project

September,2010

Completion of Power Supply Circuit

October,2010

Interfacing & programming for Microcontroller

November,2010-February,2011

Analysis of reliability & accuracy of the project

March,2011

CHAPTER:-5

RESUTLS

SELECTION OF SUITABLE ICs:- LM 35-- 3 terminal, precision temperature

sensor(with linear function of scale factor ± 10.0 mV/˚ C). N.B.—we may use LM 34 sensor which

directly shows linear operation with mV/˚ F scale factor (as application is clinical).

ADC 0804—Analog – Digital Converter.

AT89C51— 8 Bit Microcontroller.

IC7805--- 5-V Voltage Regulator.

POWER SUPPLY CIRCUIT:---

DESCRIPTION OF IC 7805 VOLTAGE REGULATOR:--

Features:-

• Output Current up to 1A

• Output Voltages of 5, 6, 8, 9, 10, 12, 15, 18, 24V

• Thermal Overload Protection

• Short Circuit Protection

• Output Transistor Safe Operating Area Protection.

BRIDGE RECTIFIER:-

A diode bridge is an arrangement of four (or more) diodes in a bridge configuration that provides the same polarity of output for either polarity of input. When used in its most common application, for conversion of an alternating current (AC) input into direct current a (DC) output, it is known as a bridge rectifier. A bridge rectifier provides full-wave rectification from a two-wire AC input, resulting in lower cost and weight as compared to a rectifier with a 3-wire input from a transformer with a center-tapped secondary winding.

BLOCK DIAGRAM OF BRIDGE RECTIFIER:-

CHAPTER:-6

CONCLUSION

Plan of works defines how the planning for the work is done, which includes how the work has been divided in different modules and segment for enhancing the efficiency of its outcome.

The first few stages of the project is properly done for the partial fulfillment of the project. The study of project idea & study of suitable microcontroller has been properly done in order to achieve proper operation of the system. Also the selection of temperature sensor & other peripherals are done in such a order that suits the application of the device.

Though the steps are very carefully done but also the timeline to complete the project is properly maintained (as mentioned in project plan) in order to complete the total project in proper time.

The design of the power supply circuit is done in such a way that it fulfills the requirement of the power supply required for the microcontroller & other peripherals.

CHAPTER:-7

REFERENCES

The following books and websites proved to be very helpful while developing this project.

AYALA, 8051 Microcontroller.

A K RAY and K M BHURCHANDI, Advanced Microprocessor & Peripherals.

www.google.com

www.wikipedia.com

ACKNOWLEDGEMENT

We, Somrita Ghosh & Devraj Mandal & Somdeb Mandal & Jaideep Mitra, 4th year, ECE, Section-‘B’ are sincerely thankful to our project guides Prof. Anamika Basu(Das) & Prof. Madhumita Sarkar for their gracious & valuable direction regarding the project “MICROCONTROLLER BASED CLINICAL THERMOMETER”.

(SOMRITA GHOSH.)

(DEVRAJ MANDAL.)

(SOMDEB MANDAL.)

(JAIDEEP MITRA.)