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HEART BEAT COUNTER AND BODY TEMP SENSOR DISPLAY

Heart Beat Counter and Body Temperature Display

S.I.T,POLYTECNIC YADRAV Page 1


CONTENTS

Page no.

1. Introduction 03

2. Block diagram 04

3. Circuit diagram 06

4. Hardware requirement 09

5. Hardware description 10

6. Features 30

7. Advantages 31

8. Application 32

9. Flowchart 33

10. PCB layout 35

11. Conclusion 37

12. References 38

S. I. T.,POLYTECNIC YDRAV Page 2


1. INTRODUCTION

Heart rate measurement indicates the soundness of the human cardiovascular system.

This project demonstrates a technique to measure the heart rate by sensing the change in blood

volume in a finger artery while the heart is pumping the blood.

It consists of an infrared LED that transmits an IR signal through the fingertip of the

subject, a part of which is reflected by the blood cells. The reflected signal is detected by a photo

diode sensor. The changing blood volume with heartbeat results in a train of pulses at the output

of the photo diode, the magnitude of which is too small to be detected directly by a

microcontroller.

Therefore, a two-stage high gain, active low pass filter is designed using two Operational

Amplifiers (Op-Amps) to filter and amplify the signal to appropriate voltage level so that the

pulses can be counted by a microcontroller. The heart rate is displayed on 16x2 character LCD

display. The microcontroller used in this project is AT89C52.

The temperature of the body is also detected by the temperature sensor LM35 &

converted that low voltage signal by using ADC 0809. And it is displayed on same LCD.


MICRO-CONTROLLER

AT89C52

Temp.Sensor

Heart Beat Sensor

A to DConverter

Signal Amplifier

16X2Character LCD

Power Supply

Switches


2. BLOCK DIAGRAM



BLOCK DIGRAM DESCRIPTION:

Heart rate is the number of heartbeats per unit of time and is usually expressed in beats

per minute (bpm). In adults, a normal heart beats about 60 to 100 times a minute during resting

condition. The resting heart rate is directly related to the health and fitness of a person and hence

is important to know.

You can measure heart rate at any spot on the body where you can feel a pulse with your

fingers. The most common places are wrist and neck. You can count the number of pulses within

a certain interval (say 15 sec), and easily determine the heart rate in bpm.

This project describes a microcontroller based heart rate measurement system that uses

optical sensors to measure the alteration in blood volume at fingertip with each heart beat. The

sensor unit consists of an infrared light-emitting-diode (IR LED) and a photodiode, placed side

by side as shown below. The IR diode transmits an infrared light into the fingertip (placed over

the sensor unit), and the photodiode senses the portion of the light that is reflected back.

The intensity of reflected light depends upon the blood volume inside the fingertip. So,

each heart beat slightly alters the amount of reflected infrared light that can be detected by the

photodiode. With a proper signal conditioning, this little change in the amplitude of the reflected

light can be converted into a pulse. The pulses can be later counted by the microcontroller to

determine the heart rate.



3. CIRCUTI DIGRAM

Power Supply:

Even though this microcontroller can operate at different power supply voltages, why to test “Murphy’s low”?! A 5V DC is most commonly used. The circuit, shown in the figure, uses a cheap integrated three-terminal positive regulator LM7805, and provides high-quality voltage stability and quite enough current to enable the microcontroller and peripheral electronics to operate normally (enough current in this case means 1Amp).



Microcontroller Hardware Design:



Working of Circuit :

As shown in the above circuit diagram of heartbeat & temperature monitoring system,

the microcontroller used is AT89C52 which is having 4 IO ports. They are P0, P1, P2 & P3. Out

of these ports, the Port 0 is used for interfacing LCD. Port 1 & Port 2 is used for interfacing

ADC0808 and Port 3 is used for interfacing buzzer & switches to start & stop monitoring

heartbeats of human.

Initially the controller displays the "HEART BEAT & TMP MONITORING SYS” on

LCD on two lines of LCD for 2 seconds. Then the controller displays “Welcome” on 1st line &

temperature on 2nd line. The LM35 is the temperature sensor used in this project to measure the

body temperature of the human. This system displays the temperature in degree Celcius as well

as in degree Fahrenheit. So that the doctors will understand easily & provide the proper treatment

to the patient. The thermometer used by the doctors indicates the temperature both in celcius &

in Fahrenheit. Normally the body temperature range of the human in Fahrenheit is 94-97 degree

Fahrenheit. The formula for converting celcius to Fahrenheit is,

F=C*5/1.8

The controller converts analog voltage given by the LM35 sensor to the ADC into digital

format & display it on LCD. The LM35 gives 10mV/degree C. So the microcontroller remains

busy in converting the analog temperature value into digital & display continuously.

The switches used are “push to ON switch”. One is to start counting the heart beat &

second switch is used to stop the heartbeat counting. These two switches are taken on interrupt

so that the microcontroller need not to check whether the switch is pressed or not.

The start switch has low priority & stop switch has high priority. When any one switch is

pressed, the controller leaves its main job, that is displaying the temperature on LCD & starts

counting the heartbeat. It also starts the timer when first pulse is getting. The controller will stop

the timer when the second pulse is getting. Once two pulses has been got, then it does the simple

calculation which is given below:

Beats Per Minute, BPM=60000/time period between two pulses in mS.

When user presses stop switch then controller stop counting heartbeat & displays

“Welcome” message on 1st line & temperature on 2nd line continuously.



4. HARDWAER REQUIREMNT:

MICROCONTROLLER AT 89C52

LCD 16X2

ADC 0808

LM35

HEART BEAT SENSOR

AMPLIFIER

SWITCHES



5. HARDWARE DESCRIPTION:-

Microcontroller AT 89S52:-

PIN CONFIGURATION:



ARCHITECTURE:


CPU

InterruptControl

OSC BusControl

4kROM

Timer 1Timer 2

Serial

128 bytes RAM

4 I/O Ports

TXDRXD

External Interrupts

P0 P2 P1 P3Addr/Data


GENRAL DISCRIPTION

The AT89C52 is a low-power, high-performance CMOS 8-bit microcomputer with

8Kbytes 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 80C51 and 80C52 instruction set and pin out.

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 AT89C52 is a powerful microcomputer which provides a highly

flexible and cost effective solution to many embedded control applications.

Microcontroller can be compared to small stand alone computer, it is a very powerful

device, which is capable of executing a service of pre-programmed task and interfacing with

other hardware device. Being packed in tiny integrator circuit (IC) whose size and weight is

usually negligible, it is becoming the perfect controller for robots or any machines requiring

some kind of intelligent automation.

Today, microcontroller are an indispensible tool for the robotics hobbyist as well as for

the engineer. Starting in this field can be little difficult, because you usually can’t understand

how every thing works inside the integrating circuit, so you have to study the gradually, a small

part at a time, until you can figure out the whole image and understand how system is works.



FEATURES of Microcontroller:-

• Compatible with MCS-51™ Products

• 8K 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

• 4.0V to 5.5Voprating range.

• Fully static operation: 0 Hz to 30 MHz.

• Three-level program memory lock.

• 256 x 8-Bit Internal RAM

• 32 Programmable I/O Lines

• Three 16-Bit Timer/Counters

• Eight Interrupt Sources

• Programmable Serial Channel

• Low Power Idle and Power Down Modes



DISCRIPTION OF LCD 16X2:

There are pins along one side of a small printed board. These are used for connecting to the

microcontroller. There are in total of 14 pins marked with no (16 if it has back light). There

function is described in the table below:



PIN DESCRIPTION of LCD:

Function Pin No. Name Logic State Description

Ground 1 Vss - 0V

Power supply 2 Vdd - +5V

Contrast 3 Vee - 0 – Vdd

Control of operating

4 RS 01

D0 – D7 are interpreted as commandsD0 – D7 are interpreted as data

5 R/W 01

Write data (from controller to LCD)Read data (from LCD to controller)

6 E01From 1 to 0

Access to LCD disabledNormal operatingData/commands are transferred to LCD

Data / commands

7 D0 0/1 Bit 0 LSB

8 D1 0/1 Bit 19 D2 0/1 Bit 210 D3 0/1 Bit 311 D4 0/1 Bit 412 D5 0/1 Bit 513 D6 0/1 Bit 614 D7 0/1 Bit 7 MSB15 LED+ 1(VCC) Anode of Backlight LED.

16 LED- 0(GND) Cathode of Backlight LED.



Features / Specifications of LCD:

2 lines of 16 characters (Character size: 5.55mm High x 2.95mm Wide)

Screen Viewing area: 61 x 15mm. Black Bezel size: 70 x 27mm

Module dimensions: 80mm Wide x 36mm High x 9mm Deep (exc. connector) (15mm (in

connector))

Mounting holes: 2.5mm Dia. Hole Pitch:75 x 31mm.

Low power consumption: Approx 1mA @ 5 volts.

Generic industry standard HD44780 compatible controller.

Model Number: BTC-1620J-SAYA-N-B. ( YC-1602M series) (Made by Yeebo LCD

Ltd)

Non-RoHs

LCD ADVANTAGES:

Brightness

Sharpness

Small size

Light weight

Power consumption

LCD DISADVANTAGES:

Aspect ratio

Contrast

Viewing angle

Resolution

Cost



ADC0808/ADC0809:

PIN Diagram of ADC:

BLOCK DIAGRAM OF ADC:





General description OF ADC:

The ADC0808, ADC0809 data acquisition component is a monolithic CMOS device

with an 8-bit analog-to-digital converter, 8-channel multiplexer and microprocessor compatible

control logic. The 8-bit A/D converter uses successive approximation as the conversion

technique. The converter features a high impedance chopper stabilized comparator, a 256R

voltage divider with analog switch tree and a successive approximation register. The 8-channel

multiplexer can directly access any of 8-single-ended analog signals.

The device eliminates the need for external zero and full-scale adjustments. Easy

interfacing to microprocessors is provided by the latched and decoded multiplexer address inputs

and latched TTL TRI-STATE outputs. The design of the ADC0808, ADC0809 has been

optimized by incorporating the most desirable aspects of several A/D conversion techniques. The

ADC0808, ADC0809 offers high speed, high accuracy, minimal temperature dependence,

excellent long-term accuracy and repeatability, and consumes minimal power. These features

make this device ideally suited to applications from process and machine control to consumer

and automotive applications. For 16-channel multiplexer with common output (sample/hold port)

see ADC0816 data sheet.

The analog to digital converter chips 0808 and 0809 are 8-bit CMOS, successive

approximation converters. This technique is one of the fast techniques for analog to digital

conversion. The conversion delay is 100μs at a clock frequency of 640 KHz, which is quite low

as compared to other converters. These converters do not need any external zero or full scale

adjustments as they are already taken care of by internal circuits. These converters internally

have a 3:8 analog multiplexer so that at a time eight different analog conversion by using address

lines -ADD A, ADD B, ADD C. Using these address inputs, multichannel data acquisition

system can be designed using a single ADC.

The CPU may drive these lines using output port lines in case of multichannel

applications. In case of single input applications, these may be hardwired to select the proper

input. There are unipolar analog to digital converters, i.e. they are able to convert only positive

analog input voltage to their digital equivalent. These chips do no contain any internal sample

and hold circuit.



Features OF ADC:

Easy interface to all microprocessors

Operates ratiometrically or with 5 VDC or analog span

adjusted voltage reference

No zero or full-scale adjust required

8-channel multiplexer with address logic

0V to VCC input range

Outputs meet TTL voltage level specifications

ADC0808 equivalent to MM74C949

ADC0809 equivalent to MM74C949-1



LM35:

Pin Description:

General Description:-


Pin no Function Name

1 Supply voltage;5v (+35 to -2v) vcc

2 Output voltage (+6v to -1v) Output

3 Ground (0v) Ground


The LM35 series are precision integrated-circuit temperature sensors, whose output

voltage is linearly proportional to the Celsius (Centigrade) temperature. The LM35 thus has an

advantage over linear temperature sensors calibrated in ° Kelvin, as the user is not required to

subtract a large constant voltage from its output to obtain convenient Centigrade scaling. The

LM35 does not require any external calibration or trimming to provide typical accuracies of

±1⁄4°C at room temperature and ±3⁄4°C over a full −55 to +150°C

Temperature range.

Low cost is assured by trimming and calibration at the wafer level. The LM35’s low

output impedance, linear output, and precise inherent calibration make interfacing to readout or

control circuitry especially easy. It can be used with single power supplies, or with plus and

minus supplies.

As it draws only 60 μA from its supply, it has very low self-heating, less than 0.1°C

in still air. The LM35 is rated to operate over a −55° to +150°C temperature range, while the

LM35C is rated for a −40° to +110°C range (−10°with improved accuracy).

The LM35 series is available packaged in hermetic TO-46 transistor packages, while

the LM35C, LM35CA, and LM35D are also available in the plastic TO-92 transistor package.

The LM35D is also available in an 8-lead surface mount small outline package and a plastic TO-

220 package.



Features OF LM35:

Calibrated directly in ° Celsius (Centigrade)

Linear + 10.0 mV/°C scale factor

0.5°C accuracy guarantee able (at +25°C)

Rated for full −55° to +150°C range

Suitable for remote applications

Low cost due to wafer-level trimming

Operates from 4 to 30 volts

Less than 60 μA current drain

Low self-heating, 0.08°C in still air

Nonlinearity only ±1⁄4°C typical

Low impedance output, 0.1 W for 1 mA load



HEART BEAT SENSOR:

Optical heart-rate monitors are easy to understand in theory. If you’ve ever shined a flashlight through your finger tips and seen your heart-beat pulse (a thing most kids have done) you have a good handle on the theory of optical heart-rate pulse sensors.

In an optical heart-rate pulse sensor, light is shot into a finger tip or ear lobe. The light either bounces back to a light sensor, or gets absorbed by blood cells.

As you continue to shine light (into say a fingertip) and take light sensor readings, you quickly start to get a heart-beat pulse reading.



The theory is easy to understand. In practice, it hard to master DIY optical heart-rate sensors, or get them operational at all. There are many tutorials online and in publications describing how to make DIY heart-rate sensors. Through our own personal interests we’ve tried to follow online guides but have generally failed or had unsatisfactory results. As professors, year after year, we see our students attempt to follow these published guides and also either fail in getting anything to work, or get poor results. It could very well be human/user-error on our parts. But from our view, making an optical pulse sensor is easier said then done.

So, we set out to make our own optical heart-rate pulse senor that can be used in our own creative projects and also available to students, makers, game developers, mobile developers, artists, athletic trainers etc….

We had three goals for our sensor:1) It had to actually work and be “plug and play” into Arduino (or other microcontroller).2) It should be super small and easy to place (sew, glue, clip) into wearables, sports, arts, or gaming applications.3) It could be used as a teaching aid for instruction on working with sensors, data visualization, and bio-feedback.

As easy as many suspect to get reliable heart-rate data through optical means. We could get basic, gross, short-term data, but reliable readings assuming real-world scenarios and real-world user interaction is key. After more experimentation and development, we started to assemble a reliable heart-rate pulse sensor. We fabricated a few test boards and continued to iterate the design.

As we tired to “wear” the sensor, we discovered that we should make it look and feel like a 1/2 inch button. Its size allows it to clip to earlobs or fingertips easily. When we add “button holes” to the design it can be easily sewn or attached to various garments and fashion accessories. The final design turned into a button-sized PCB board that holds all the technology, hit all our goals, and is very cute and accessible to a novice or expert users/developers alike.



Power supply:-

Reset signal

In order that the microcontroller can operate properly, a logic 0 (0V) must be applied to

the reset pin RS. The push button connecting the reset pin RS to power supply VCC is not

necessary. However, it is almost always provided because it enables the microcontroller safe

return to normal operating conditions if something goes wrong. 5V is brought to this pin, the

microcontroller is reset and program starts execution from the beginning.

Clock signal

Even though the microcontroller has a built-in oscillator, it cannot operate without two

external capacitors and quartz crystal which stabilize its operation and determines its frequency

(operating speed of the microcontroller).



Switches and Push buttons:-

There are no simpler devices than switches and push-buttons. This is the simplest way of

detecting appearance of a voltage on the microcontroller input pin.

Nevertheless, it is not so simple in practice... It is about contact bounce- a common problem

with m e c h a n i c a l switches. When the contacts strike together, their momentum and

elasticity act together to cause bounce. The result is a rapidly pulsed electrical current instead of

a clean transition from zero to full current. It mostly occurs due to vibrations, slight rough spots

and dirt between contacts. This effect is usually unnoticeable when using these components in

everyday life because the bounce happens too quickly. In other words, the whole this process

does not last long (a few micro- or milliseconds), but it is long enough to be registered by the

microcontroller. When using only a push-button as a pulse counter, errors occur in almost 100%

of cases!



The simplest solution to this problem is to connect a simple RC circuit to suppress quick

voltage changes. Since the bounce period is not defined, the values of components are not

precisely determined. In most cases, it is recommended to use the values shown in figure below.

If complete stability is needed then radical measures should be taken. The output of the

circuit, shown in figure (RS flip-flop), will change its logic state only after detecting the first

pulse triggered by contact bounce. This solution is expensive (SPDT switch), but effecient, the

problem is definitely solved. Since the capacitor is not used, very short pulses can also be

registered in this way.



In addition to these hardware solutions, there is also a simple software solution. When a

program tests the state of an input pin and detects a change, the check should be done one more

time after a certain delay. If the change is confirmed, it means that a switch or push button has

changed its position. The advantages of such solution are obvious: it is free of charge, effects of

noises are eliminated and it can be applied to the poorer quality contacts as well. Disadvantage is

the same as when using RC filter, i.e. pulses shorter than program delay cannot be registered.



6. FEATURE OF HEART BEAT COUNTER AND BODY TEMP. DISPLAY

1. It has two switches:

a. 1st switch is to count heart rate in 20 sec mode.

b. 2nd switch is to count heart rate in per second mode.

2. LED is used as a light source & LDR is more sensitive to change in light which is taken

as sensing element.

3. Visible display of your heart rhythm.

4. The temperature sensor LM35 is used which give wide range of temperature value up to

2ºC - 150ºC.

5. Temperature is displayed on 16X2 character LCD both in º Celsius & º Fahrenheit.

6. This system is useful for checking heart beat rate & body temperature of any ill person in

the home.



7. Advantages :

1. Simple circuitry.

2. Can be used for viewing waveform of heartbeat on CRO.

3. LDR is low cost & highly sensitive element.

4. The system is useful in home also.


START

Initialization of 16x2 character LCD

Select channels of ADC

C


8. Applications:

1.E.C.G. machine.

2. Heart beat monitoring system.

3. Patient monitoring system

FLOWCHART:




Wait for H to L transition

Stop the running timer

Count the time

Calculate the BPM by using the formulaBPM=60000/time period between two pulses in mS.

Convert HEX to BCD, BCD to ASCII value

Display BPM rate on LCD

STOP switch pressed?

B

C

A HEART BEAT COUNTER AND BODY TEMP SENSOR DISPLAY



PCB Layout:





09. CONCLUSION:

This system is more useful for fast detection of heart beat of a patient i.e BPM is

displayed per second or at each heart beat.

Temperature is shown in ˚C & ˚F so that can be used in home also for detecting favors

of a person .

The cost of a system is minimum because of less hardware .

System response is faster as compared to other existing system.



10. References

Microcontroller 8051 by Mazidi

http://www.8051projects.net/t44530-p10/8051-discussion-forum/heart-beat-rate-

meter.htm#post_44935

http://www.kickstarter.com/projects/1342192419/pulse-sensor-an-open-source-

heart-rate-sensor-that

http://www.flickriver.com/photos/chuck_notorious/3734651131/

http://arduino.cc/forum/index.php?action=forum


http://arduino.cc/forum/index.php?action=forum

http://www.flickriver.com/photos/chuck_notorious/3734651131/

http://www.kickstarter.com/projects/1342192419/pulse-sensor-an-open-source-heart-rate-sensor-that

http://www.kickstarter.com/projects/1342192419/pulse-sensor-an-open-source-heart-rate-sensor-that

http://www.8051projects.net/t44530-p10/8051-discussion-forum/heart-beat-rate-meter.htm




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