Heart beat monitor using AT89S52 microcontroller

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We , in this project are measuring the heart beat using the pulse oximetry logic. The timer we have set for counting the heart beat is 30s. There is a set point we can decide, after 30 s the heartbeat would be shown on the LCD along with a buzzer sound (if it exceeds the set point).

Transcript of Heart beat monitor using AT89S52 microcontroller

  • 1. Submitted By: Sushil Kumar Mishra (05311502809) BVCOE, New Delhi-63 1 BHARATI VIDHYAPEETHS COLLEGE OF ENGINEERING A-4, PASCHIM VIHAR, ROHTAK ROAD, NEW DELHI- 110063 AFFILIATED TO GURU GOBIND SINGH INDRAPRASTHA UNIVERSITY, DELHI-1100006 (2009-2013)

2. Heart beat monitor 2 A heart rate monitor is a personal monitoring device which allows one to measure his or her heart rate in real time or record the heart rate for later study. It is largely used by performers of various types of physical exercise. Widely used in hospitals for checking the health of patient(s)Fig. 1 Wrist band for calculating heart beat 3. Why Monitoring? 3 More than 2 million people are at high risk of having heart attack. It would be helpful if there was a way for these people to monitor their heart. So we have a problem. That is the way our project focuses on how we can utilize this problem and find a solution. 4. Measurement of Heart rate 4 Stethoscope --- inaccurate Electrocardiogram costly & not user friendly 5. Average Heart Rate 5 Average Heart RateAge 140Newborn 85 907 years 80 8514 years 70 80Adult 6. Microcontroller and why Microcontroller not Microprocessor? 6 A microcontroller is a single-chip microcomputer which contains RAM , ROM , CPU , I/O ports , ADC and other peripherals. It has fixed amount of RAM , ROM , I/O ports. It is also called embedded microcontroller because it is designed for embedded systems performing specific tasks only. Microprocessor only has CPU , ALU, stack pointer, program counter and other registers ,clock timing circuit. Microprocessor does not have RAM, ROM and I/O ports It requires large space and its cost is higher as compared to microcontroller. 7. Embedded systems 7 An embedded system is a computer system designed for specific control functions within a larger system, often with real-time computing constraints. It is embedded as part of a complete device often including hardware and mechanical parts. By contrast, a general-purpose computer, such as a personal computer (PC), is designed to be flexible and to meet a wide range of end-user needs. Embedded systems control many 8. What we have done? ? ? 8 We , in this project are measuring the heart beat using the pulse oximetry logic. The timer we have set for counting the heart beat is 30s. There is a set point we can decide, after 30 s the heartbeat would be shown on the LCD along with a buzzer sound (if it exceeds the set point). 9. What we have used ? ? ? 9 We are using an AT89S52 microcontroller for this project A transformer for stepping down the voltage. Full wave rectifier for conversion of AC to DC. 7805 voltage regulator to give a 5v dc voltage. An LM324 IC which is used as three stage trans impedance amplifier in this board. LCD showing the heart beat A buzzer which will be activated when heart beat exceeds set point. 10. Software we used ? ? ? 10 KEIL uVision3 IDE SPI flash programmer 11. AT89S52 11 Atmel AT89S52 is a powerful microcontroller which provides a highly-flexible and cost- effective solution to many embedded control applications. It is programmable compatible with 8051 uc. 12. Pin diagram 12 13. 13 14. Top view of our project 14 15. Hardware implementation 15 Transformer Full wave rectifier 7805 voltage regulator Buzzer LM324 Potentiometer LED + LDR used as sensor LCD Circuit diagram of project 16. Transformer 16 Centre tapped transformer. 9-0-9 v at the output. Rating of 1A current. It is centre tapped to have both -ve and +ve half cycle of AC waveform to contribute to direct current. Transforming energy using mutual induction. TTL logic circuitry can not work on voltage of 220v so we are stepping down it to 9v 17. Full wave rectifier 17 Converting both polarities of input ac voltage to one of the constant polarity at its output dc current. Yields a higher mean output voltage . Our circuitry can only work on dc voltage. 18. LM7805-VOLTAGE REGULATOR 18 It has 5V Regulated output voltage. Input voltage range:- 5V- 18V The voltage source in circuit may have fluctuation and would not give fixed output voltage. Pin1-input ,Pin2- ground, Pin3-output Heat sink is used for dissipating heat into surrounding air to protect 19. Buzzer 19 A buzzer or beeper is an audio signaling device, which may be mechanical, electromechanical, or piezoelectric. Typical uses of buzzers and beepers include alarm devices, timers and confirmation of user input such as a mouse click or keystroke. In this project , we are using for the case in which the measured HEART BEAT RATE passes the set point. 20. LM324 20 This consist of four independent high- gain frequency-compensated operational amplifiers that are designed specifically to operate from a single supply over a wide range of voltages. Operation from split supplies also is possible if the difference between the two supplies is 3 V to 32 V (3 V to 26 V for the LM2902), and VCC is at least 1.5 V more positive than the input common- mode voltage. The low supply-current drain is independent of the magnitude of the supply voltage. 21. Uses of LM324 21 Applications include transducer amplifiers, dc amplification blocks, and all the conventional operational-amplifier circuits that now can be more easily implemented in single-supply-voltage systems. For example, the LM124 can be operated directly from the standard 5-V supply that is used in digital systems and provides the required interface electronics, without requiring additional 15-V supplies. 22. Pulse oximetry logic 22 We monitor the heart beat by pulse oximetry technique. In this project we use innovative technique to measure the heart beat measurement. This is achieved by pulse oximetry logic. We use this technique to get the pulse from body and to amplify the signal and display this data on the LCD . The light emitted from the LEDs were transmitted through the skin and detected by light dependent resistor. LDR were then connected to a amplifier that converted the current to an appropriately- enhanced voltage signal. Change of signal is further converted into pulse .We count the pulses with the help of the AT89S52 microcontroller. 23. Heartbeat measurement using LED-LDR sensor 23 Finger is illuminated by red light being emitted by red led. When heart will expand then there will be more blood in blood vessels as a consequence more absorption of red light will occur and lesser amount of red light will fall on LDR, decrease in resistance of LDR will be less and large current will through LDR. When heart will contract then there will be no blood in blood vessels as a consequence no absorption of red light will occur and full amount of red light will fall on LDR, decrease in resistance of LDR will be large and small current will through LDR. 24. 24 25. Circuit diagram 25 26. HOW ? ? ? 26 Transformer steps down 220V to 9-0-9V. Full wave rectifier converts the ac into dc. 7805 voltage regulator regulates the voltage to 5V, which is the operating voltage of our microcontroller. LCD is interfaced with microcontroller. LED - LDR sensor is used to count the Pulses. It consists of a red LED and LDR . Crystal (11.059MHz) is used to generate a stable clock signal for the microcontroller. 27. HOW ? ? ? 27 Pin 9 is used as the reset circuit pin. LM 324 is used as a three stage trans impedance amplifier. LEDS are used to indicate the supply, and counting of heart beat. There is a buzzer on the board which will be activated if the measure heart beat exceeds set point. Code is burnt on the controller using SPI programmer. 28. What is happening on-board ? 28 Transformer is making the ac voltage 220 volt to step down to 9-0-9 volt ac. Full wave rectifier is rectifying that voltage to get larger average dc voltage. 7805 is regulating the output voltage to 5v. Sensor consist of red LED and LDR is generating the output signal inversely proportional to absorption of red light caused by blood. Transimpedence amplifier is converting current signal to voltage signal ,amplifying signal and change in signal and also filtering the signal also. 29. Contd.. 29 Microcontroller is counting the no of pulses using counter T0 within 30 seconds of timer T1. It also lets the user to set the average pulse rate with which it will compare and make buzzer to sound if it found deviation. Microcontroller is displaying the result i.e pulse rate on LCD on which patient can see his heart beat. 30. LED LDR sensor 30 LED LDR 31. project 31 32. PCB back side diagram 32 33. Board back side photo 33 34. Applications 34 Have become a widely used training aid for a variety of sports. Hospitals / Dispensaries Better and accurate method of measuring heart beat. At homes A set point can help in determining whether a person is healthy or not checking his/her heart beat and comparing with set point. 35. 35 In-accurate method of calculating heartbeat. Logic used in very simple. Therefore, results may vary as for a sophisticated instrument for the same purpose 36. EEG, ECG and other health parameters can also be monitored. Continuous monitoring and future diagnosis can be performed via the same system (TELEMEDICINE). More than a single patient at different places can be monitored using single system. 36 37. Any Queries ? ? ? 37