heart rate project design

www.electronicsengineeringprojects.comHEART BEAT MONITORING

MINIPROJECT REPORT

Submitted in partial fulfilment of the requirements

For the award of the degree of

Bachelor of Technology

In

Electronics and Communication Engineering

Of

S UBMITTED BY

.............................................

REGISTER NO:-.................

PLACE:-...........................

DATE:-......./......./............

DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING

BONAFIDE CERTIFICATE

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www.engineeringminiprojects.com

www.electronicsengineeringprojects.comThis is to certify that the mini project entitled “HEART BEAT MONITORING” is abonafide record of the work done by.............................. (............................)of sixth semester B.Tech in Electronics and Communication Engineering, towards the partial fulfilment of the requirements as a part of the curriculum for the award of the Degree of Bachelor of Technology, by

ACKNOWLEDGMENT 2


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I would like to express my sincere gratitude to all those who helped in making of this project.

.

I am also grateful to all my friends and classmates for helping me to make this project.

.......................................................

ABSTRACT

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www.electronicsengineeringprojects.com This paper describes the design of a simple, low-cost microcontroller based heart rate measuring device with LCD output. Heart rate of the subject is measured from the finger using sensors and the rate is then averaged and displayed on a text based LCD.

The LCD of the heart beat monitor shows the beat per minute.The sensor part consists of sensing elements,LDR(light dependent resistor) and LED(light emitting diode),a comparator module,a low pass filter.Heart beat is sensed by the sensing elements and the comparator produces an amplified square wave output.The comparator output is given to a low pass filter and the filter output is fed to one of the digital inputs of PIC 16F877a type microcontroller.The microcontroller output ports drives the LCD.

CONTENTS

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www.electronicsengineeringprojects.comBonafide Certificate………………………………………………………………......................02

Acknowledgements………………………………………………….....................................03

Abstract............................................................................................……………04

Introduction................................................................….................................06

Block diagram.................................................................................................08

Circuit diagram...............................................................................................09

PCB layout......................................................................................................11

Photograph.....................................................................................................12

Program..........................................................................................................13

Application......................................................................................................17

Conclusion......................................................................................................18

References......................................................................................................19

INTRODUCTION Heart rate measurement is one of the very important parameters of the human cardiovascular system. The heart rate of a healthy adult at rest is around 72 beats per minute (bpm). Athletes normally have lower heart rates

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www.electronicsengineeringprojects.comthan less active people. Babies have a much higher heart rate at around 120 bpm, while older children have heart rates at around 90 bpm. The heart rate rises gradually during exercises and returns slowly to the rest value after exercise. The rate when the pulse returns to normal is an indication of the fitness of the person.

Heart rate is simply and traditionally measured by placing the thumb over the subject’s arterial pulsation, and feeling, timing and counting the pulses usually in a 5 second period. Heart rate (bpm) of the subject is then found by multiplying the obtained number by 12. This method although simple, is not accurate and can give errors when the rate is high. More sophisticated methods to measure the heart rate utilize electronic techniques. Electro-cardiogram (ECG) is one of frequently used and accurate methods for measuring the heart rate. ECG is an expensive device and its use for the measurement of the heart rate only is not economical. Low-cost devices in the form of wrist watches are also available for the instantaneous measurement of the heart rate. Such devices can give accurate measurements but their cost is usually in excess of several hundred dollars, making them uneconomical. Most hospitals and clinics in the UK use integrated devices designed to measure the heart rate, blood pressure, and temperature of the subject. Although such devices are useful, their cost is usually high and beyond the reach of individuals.

This paper describes the design of a very low-cost device which measures the heart rate of the subject by clipping sensors on one of the fingers and then displaying the result on a text based LCD. Advantage of such a design is that it can be expanded and can easily be connected to a recording device or a PC to collect and analyse the data for over a period of time.

BLOCK DIAGRAM

Infrared RX

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Infrared TX

Figure shows the block diagram of the proposed device. Basically, the device consists of an LED and an LDR. The transmitter-sensor pair is clipped on one of the fingers of the subject. The LED emits infrared light to the finger of the subject. The LDR detects this light beam and measures the change of blood volume through the finger artery. This signal, which is in the form of pulses is then amplified and filtered suitably and is fed to a low-cost microcontroller for analysis and display. The microcontroller counts the number of pulses over a fixed time interval and thus obtains the heart rate of the subject. Several such readings are obtained over a known period of time and the results are averaged to give a more accurate reading of the heart rate. The calculated heart rate is displayed on an LCD in beats-per-minute in the following format:

Rate = nnn bpm

Where nnn is an integer between 1 and 999.

PIC16F877a

This powerful (200 nanosecond instruction execution) yet easy-to-program (only 35 single word instructions) CMOS FLASH-based 8-bit microcontroller packs Microchip's powerful PIC® architecture into an 40- or 44-pin package. 256 bytes of EEPROM data memory,self programming and 2

Comparators 8 channels of 10-bit ADC and 2 capture/compare/PWM functions synchronous serial port can be configured as either 3wire Serial

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Microcontroller

Comparator and filter

LCD finger

www.electronicsengineeringprojects.comPeripheral Interface (SPI™) or the 2-wire Inter-Integrated Circuit (I²C™) bus

Universal Asynchronous Receiver Transmitter (UART).

PIC16F877 is a microcontroller, which contain CPU, memory, peripherals etc all in a single chip. It is a 40 pin DIP flash type reprogrammable memory.Pins are arranged as 5 ports (A(5),B(8),C(8),D(8) and E(3)).Ports A and E become analog inputs,so they have to set up for digital I/O if required. Port B is used for downloading the program to chip flash ROM and can generate an interrupt. Port C is used to access timers and serial ports.Port D act as slave port.Port E provides the control pins for this function.

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www.electronicsengineeringprojects.comPINDESCRIPTION

CIRCUIT DIAGRAM 9



The circuit diagram of the measurement device is shown in Figure. The circuit basically consists of an operational amplifier, a low-pass filter, a microcontroller, and an LCD. The operational amplifier is set for higher values of gain. During the laboratory trials it was found necessary to use a low pass filter in the circuit to filter out any unwanted high frequency noise from nearby equipment. The cut-off frequency of the filter was chosen as 10Hz. The output time response of the amplifier and filter circuit is pulses. The output of the amplifier and filter circuit was fed to one of the digital inputs of a PIC16F877a type microcontroller. The microcontroller output ports drive the LCD as shown in Figure. The circuit operates when a push-button switch connected to RA4 port of the microcontroller is pressed.

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PCB LAYOUT

SENSOR

MICROCONTROLLER

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www.electronicsengineeringprojects.com PHOTOGRAPH

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www.electronicsengineeringprojects.com PROGRAM#include <16F877A.h>

#device adc=8

#FUSES NOWDT //No Watch Dog Timer

#FUSES HS //High speed Osc (> 4mhz for PCM/PCH) (>10mhz for PCD)

#FUSES NOPUT //No Power Up Timer

#FUSES NOPROTECT //Code not protected from reading

#FUSES NODEBUG //No Debug mode for ICD

#FUSES NOBROWNOUT //No brownout reset

#FUSES NOLVP //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O

#FUSES NOCPD //No EE protection

#FUSES NOWRT //Program memory not write protected

#use delay(clock=20000000)

#use rs232(baud=9600,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8)

#include <lcd.c>

int x=0,bpm;

void main()

{

lcd_init();

lcd_gotoxy(1,1);

lcd_putc("start");

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www.electronicsengineeringprojects.com lcd_gotoxy(1,2);

lcd_putc("tmr set");

delay_ms(2900);

setup_timer_0( RTCC_EXT_L_TO_H);

set_timer0(0);

delay_ms(5000);

lcd_putc("\f");

lcd_gotoxy(1,1);

lcd_putc("dlay cmpt");

x=get_timer0();

lcd_gotoxy(1,2);

lcd_putc("timer read");

lcd_gotoxy(1,1);

printf(lcd_putc,"val%d",x);

bpm=x*24;

lcd_putc("\f");

printf(lcd_putc,"bpm%d",bpm);

// TODO: USER CODE!!

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www.electronicsengineeringprojects.com APPLICATION

· Digital Heart Rate monitor

· Patient Monitoring System

· Bio-Feedback control of robotics and applications

CONCLUSION 15



The design of a low-cost microcontroller based device for measuring the heart pulse rate has been described. The device has the advantage that it can be used by non-professional people at home to measure the heart rate easily and safely.

The device can be improved in certain areas as listed below:

• A graphical LCD can be used to display a graph of the change of heart rate over time

• Sound can be added to the device so that a sound is output each time a pulse is received.

• The maximum and minimum heart rates over a period of time can be displayed.

• Serial output can be attached to the device so that the heart rates can be sent to a PC for further online or offline analysis.

• Warning or abnormalities (such as very high or very low heart rates) can be displayed on the LCD or indicated by an LED or a buzzer.

REFERENCE

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e-mail: [email protected]

e-mail: [email protected]

http://www.grmin.com

http://www.heartratemonitor.co.uk http://cosycommunications.com

http://microchip.com

http://www.crownhill.co.uk

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heart rate project design