venkteshwar institute of technology

8/3/2019 Venkteshwar Institute of Technology

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Venkteshwar Institute Of Technology

Electronics & Communication

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VENKTESHWAR INSTITUTE OF TECHNOLOGY

HEART RATE MEASUREMENT

A Major Project submitted to

RAJIV GANDHI PROUDYOGIKI VISHWAVIDHYALAYA, BHOPAL

Towards partial fulfillment of the degree of

BACHELOR OF ENGINEERING

YEAR 2011-2012

DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING

SUBMITTED BY: GUIDED BY:

ANKIT MALVIYA (0838EC071008) Mr. SANJAY VERMA

ANUJ DUBEY (0838EC071013) SUBMITTED TO:

AVESH KHAN (0838EC071019) Mr. VIKALP THAKUR


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ACKNOWLEDGEMENT

Expressing gratitude is one of the most difficult tasks as words often fall short in reflecting any

individuals feeling. It is our privilege to acknowledge those who helped and guided us

throughout our journey of making this project and we undertake this task with utmost sincerity.

We are thankful to Mr. Abhishek Rawat, H.O.D of Electronics & Communication

department, without his guidance and generous support this project wouldnt have been

possible. We are indebted to him for his helpful solutions and comments enriched by his useful

tips which helped us in improving the project from time to time.

We are thankful to express deep sense of gratitude to Mr. for his able supervision, constructive criticism,

affectionate treatment, encouragement and providing us adequate facilities for completion of the

project.


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SANWER ROAD, INDORE

CERTIFICATE

This is to certify that Final year students of Bachelor of Engineering in Electronics and

Communication Engineering at Venkteshwar Institute of Technology, have successfully

completed their Major Project entitled HEART RATE MEASUREMENT for partial fulfillment of

the degree of bachelor of engineering and given satisfactorily efforts in their project.

INTERNAL EXTERNAL


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SANWER ROAD, INDORE

CERTIFICATE

This is to certify that Final year students of Bachelor of Engineering in Electronics and

Communication Engineering at Venkteshwar Institute of Technology, have successfully

completed their Major Project entitled HEART RATE MEASUREMENT for partial fulfillment of

the degree of bachelor of engineering and given satisfactorily efforts in their project.

HEAD OF DEPARTMENT PROJECT GUIDE


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CONTENT


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Heart Beat Sensor

Heart beat sensor is designed to give digital output of heart beat when

a finger is placed on it. When the heart beat detector is working, thebeat LED flashes in unison with each heartbeat. This digital output can

be connected to microcontroller directly to measure the Beats per

Minute (BPM) rate. It works on the principle of light modulation by

blood flow through finger at each pulse.

Features

Heat beat indication by LED

Instant output digital signal for directly connecting to

Microcontroller

Compact Size

Working Voltage +5V D


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Applications

Digital Heart Rate monitor

Patient Monitoring System

Bio-Feedback control of robotics and applications


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Specification

Parameter Value

Operating Voltage +5V DC regulatedOperating Current 100mA

Output Data Level 5V TTL Level

Heart Beat Measurement Indicated by LED and

Output high pulse

Light source 660nm super red LED

Pin Details

Board has 3-pin connector for using the sensor. Details are marked on

PCB as below.

Pin Name Details1 +5V Power supply Positive

input

2 OUT Active High output

3 GND Power supply Ground


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Using the Sensor

Connect regulated DC power supply of 5 Volts. Black wire is Ground,

Next middle wire is

Brown which is output and Red wire is positive supply. These wires are

also marked on PCB.

To test sensor you only need power the sensor by connect two wires

+5V and GND. You can leave the output wire as it is. When Beat LED is

off the output is at 0V.

Put finger on the marked position, and you can view the beat LED

blinking on each heartbeat.

The output is active high for each beat and can be given directly to

microcontroller for interfacing applications.


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Heart beat output signal


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Working

The sensor consists of a super bright red LED and light detector. The

LED needs to be super bright as the maximum light must pass spread infinger and detected by detector. Now, when the heart pumps a pulse of

blood through the blood vessels, the finger becomes slightly more

opaque and so less light reached the detector. With each heart pulse

the detector signal varies. This variation is converted to electrical pulse.

This signal is amplified and triggered through an amplifier which

outputs +5V logic level signal. The output signal is also indicated by a

LED which blinks on each heartbeat.


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Following figure shows signal of heart beat and sensor signal output

graph shows actual heart beat received by detector (Yellow) and the

trigger point of sensor (Red)after which the sensor outputs digital signal

(Blue) at 5V level.

Below figure shows target pulse rates for people aged between 20 and

70. The target range is the pulse rate needed in order to provide

suitable exercise for the heart. For a 25-year old, this range is about

140-170beats per minute while for a 60-year old it is typically between

115 and 140 beats per minute.


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Sample Application:

Sample code of this application is

// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

// -=-=-=-=- Hardware Defines -=-=-=-=-=-=-=

// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

sbit SENSOR = P1^0; //sensor is connected to this pin

unsigned int beatms;

float bpm;

char buf[20];

// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

// -=-=-=-=- Main Program -=-=-=-=-=-=-=

// -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

void main()

{

// -=-=- Intialize variables -=-=-=

lcdInit();

// -=-=- Welcome LCD Message -=-=-=

lcdClear();

lcdGotoXY(0,0); // 1st Line of LCD

// "xxxxxxxxxxxxxxxx"

lcdPrint("DIGITAL HEART");

lcdGotoXY(0,1); // 2nd Line of LCD

// "xxxxxxxxxxxxxxxx"

lcdPrint("BEAT MONITOR");

beatms=0; // will store duration between two pulses


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// -=-=- Program Loop -=-=-=

while(1)

{

while(SENSOR==0);// wait for high pulse from sensor

DelayNmS(10); // 10ms delay so that it does not listen to any noise

beatms = 10; // start counting beatms from 10ms since we have delay after pulse

while(SENSOR==1)// wait until signal is high

{

DelayNmS(1); //wait 1msec

beatms++; //keep incrementing counter each 1ms

}

while(SENSOR==0) //keep looping till signal goes back high, wait for next

{

DelayNmS(1); //wait 1msec

beatms++; //keep incrementing counter each 1ms

}

// beatms variable will now have time in ms between two high edge pulse

lcdClear();

lcdGotoXY(0,0);

lcdPrint("HEART RATE : ");

bpm = (float)60000/beatms; // see document of #1157 for this calculation

if(bpm > 200)

{

lcdGotoXY(0,1);

sprintf (buf, "Processing......"); // Invalid, Wait for next cycle

lcdPrint(buf);


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} else {

lcdGotoXY(0,1);

sprintf (buf, "%0.0f BPM", bpm); // Display reading in BPM

lcdPrint(buf);

}

}

}


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Board Dimensions (mm)

Board is provided with four PCB supports

Troubleshooting Notes

Getting false output all the time by LED blinking.o Note that the sensor works on principle of change of light,

so if you have placed sensor in the light which changes

rapidly like FAN just obstructing light source or place wheredirect light falls on it, It can have this problem. Relocate to a

place where there is no direct light falling on it.


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Getting false output randomly.oIt can happen due to power fluctuation. If you are using

LM7805 based power supply, use at least 1000F filtering

capacitor at 5V output of LM7805 as well as input of

LM7805 power supply. Getting output when finger is near it.

o Again same principle of light reflected by finger getsdetected as change in light level and it blinks. But since we

are using same code which ignores invalid values, this issue

is taken care of. If you want to have more accuracy, you can

sample the heart beat and do average of 5-10 sample

readings in your MCU.

After power on it takes 5-10 seconds to get detection of fingerpulse.

oThis is normal, after power up the first time, it can take 5-10seconds. After that, detection will be instant.

Not getting any LED blink at all.oMake sure you have given regulated +5V to board. Check

with multimeter. Any more voltage can damage the board.

Any less voltage and board will not work.

oAlso check if the output pin of board is not being pulled toGND or VCC in your application board. During testing youcan leave the OUT pin floating as the OUT pin status is

reflected by onboard LED.


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LED

A light-emitting diode (LED) is an electronic light source. LEDs are used

as indicator lamps in many kinds of electronics and increasingly forlighting. LEDs work by the effect of electroluminescence, discovered by

accident in 1907. The LED was introduced as a practical electronic

component in 1962. All early devices emitted low-intensity red light,

but modern LEDs are available across the visible, ultraviolet and infra

red wavelengths, with very high brightness.

LEDs are based on the semiconductor diode. When the diode is forward

biased (switched on), electrons are able to recombine with holes and

energy is released in the form of light. This effect is called

electroluminescence and the color of the light is determined by the

energy gap of the semiconductor. The LED is usually small in area (less

than 1 mm2) with integrated optical components to shape its radiation

pattern and assist in reflection.

LEDs present many advantages over traditional light sources includinglower energy consumption, longer lifetime, improved robustness,

smaller size and faster switching. However, they are relatively

expensive and require more precise current and heat management

than traditional light sources. Applications of LEDs are diverse. They are

used as low-energy indicators but also for replacements for traditional

light sources in general lighting, automotive lighting and traffic signals.

The compact size of LEDs has allowed new text and video displays and

sensors to be developed, while their high switching rates are useful in

communications technology.


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PRINTED CIRCUIT BOARD

A printed circuit board, or PCB, is used to mechanically support and

electrically connect electronic components using conductive pathways,

tracks, or traces, etched from copper sheets laminated onto a non-

conductive substrate. It is also referred to as printed wiring board

(PWB) or etched wiring board. A PCB populated with electronic

components is a printed circuit assembly (PCA), also known as a printed

circuit board assembly (PCBA).

PCBs are inexpensive, and can be highly reliable. They require much

more layout effort and higher initial cost than either wire-wrapped or

point-to-point constructed circuits, but are much cheaper and faster for

high-volume production. Much of the electronics industry's PCB design,

assembly, and quality control needs are set by standards that are

published by the IPC organization. Conducting layers are typically made

of thin copper foil. Insulating layers dielectric are typically laminated

together with epoxy resin prepreg. The board is typically coated with a

solder mask that is green in color. Other colors that are normally

available are blue and red.

There are quite a few different dielectrics that can be chosen to provide

different insulating values depending on the requirements of the circuit.

Some of these dielectrics are polytetrafluoroethylene (Teflon), FR-4,

FR-1, CEM-1 or CEM-3. Well known prepreg materials used in the PCB

industry are FR-2 (Phenolic cotton paper), FR-3 (Cotton paper and

epoxy), FR-4 (Woven glass and epoxy), FR-5 (Woven glass and epoxy),FR-6 (Matte glass and polyester), G-10 (Woven glass and epoxy), CEM-

1 (Cotton paper and epoxy), CEM-2 (Cotton paper and epoxy), CEM-3

(Woven glass and epoxy), CEM-4 (Woven glass and epoxy), CEM-5

(Woven glass and polyester). Thermal expansion is an important
http://en.wikipedia.org/wiki/Electronic_componenthttp://en.wikipedia.org/wiki/Conductor_%28material%29http://en.wikipedia.org/wiki/Signal_tracehttp://en.wikipedia.org/wiki/Industrial_etchinghttp://en.wikipedia.org/wiki/Laminatedhttp://en.wikipedia.org/wiki/Wire_wraphttp://en.wikipedia.org/wiki/Point-to-point_constructionhttp://en.wikipedia.org/wiki/Point-to-point_constructionhttp://en.wikipedia.org/wiki/Wire_wraphttp://en.wikipedia.org/wiki/Laminatedhttp://en.wikipedia.org/wiki/Industrial_etchinghttp://en.wikipedia.org/wiki/Signal_tracehttp://en.wikipedia.org/wiki/Conductor_%28material%29http://en.wikipedia.org/wiki/Electronic_component


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consideration especially with BGA and naked die technologies, and

glass fiber offers the best dimensional stability.


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BIBLIOGRAPHY

Sunrom Technologies

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