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A Project Report on Heartbeat Monitoring using GSM Modem.
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Heartbeat Monitoring System CHAPTER 1 INTRODUCTION This chapter gives the brief description about the need for wireless patient monitoring system and its importance. This chapter also gives the brief description about scope of the project and design methodology. Patient Monitoring System is a process where a surgeon can continuously monitor more than one patient at a time in remote place. 1.1 Proposed Work Some severe diseases and disorders e.g. heart failure needs close and continual monitoring procedure after diagnosis, in order to prevent mortality or further damage as secondary to the mentioned diseases or disorders. Monitoring these types of patients, usually, occur at hospitals or healthcare centers. Heart arrhythmias for instance, in many cases, need continual long-term monitoring. However, the patients are often too early released, owing to need of hospital bed for another patient on the waiting list, who needs to be hospitalized immediately. 1.2 Scope of the Work Long waiting time for hospitalization or ambulatory patient monitoring/treatment, are other well-known issues for both the healthcare institutions and the patients. This project provides healthcare authorities to maximize the quality and breadth of healthcare services by controlling costs. As the population increases and demand for services increases, the ability to maintain the quality and availability of care, while effectively managing financial and human resources, is achieved by this project. The use of modern communication technology in this context is the sole decisive factor that makes such communication system successful. 1.3 Design Methodology 1 Heartbeat Monitoring System In transmitter circuit the Heat Beat is measured by LED and LDR, then it is applied to the microcontroller. The Microcontroller maintains the records of the measured readings. It compares the measured heart beat with the normal readings and checks it is within the normal range or not. If it is normal, then it keeps record of the same and the readings in SMS(Short Messaging Service) form to the specified mobile number. The time specified for sending message is given by the user. 2 Heartbeat Monitoring System CHAPTER 2 SYSTEM DESCRIPTION 2.1 INTRODUCTION Embedded systems are one of the emerging technologies which are touching every nook and corner of the mind. “It is impossible to live without these embedded gadgets”-says ELECTRONICS magazine. From the above statement, the liveliness of embedded system can be understood. Data communications is one of the most rapidly growing commercial market areas today, especially “wireless communications”. In the past few years, wireless data communications has grown from an obscure and expensive curiosity into a practical and affordable communication and networking technology. The convenience of wireless is very appealing as not to deal with running cables to and from devices in order to interconnect them, and wireless devices can be moved to any location within the transmission range, while still being able to communicate and broadcast data. Due to this, it is expected that wireless data communications will become even more popular and more extensively used in the medical field. Currently the most popular method of wireless communications is radio frequency transmission. As these devices have a very low power consumption and power output, perhaps more importantly devices can achieve good data transmission rates. 2.2 BLOCK DIAGRAM Sensor Module 8-Bit Micro controller GSM Modem Transmitter Block Diagram 3 Heartbeat Monitoring System In the block diagram shown above, the microcontroller AT89C2051 receives the signal from the sensors and is transmitted through the transmitter. The receiver then receives the transmitted signal and is fed to the microcontroller. Microcontroller displays the received signal. Here AM is used for transmission and reception of signals. The sensors include temperature sensor and heart beat sensor. LCD display is used for displaying the data. 2.3 HEART BEAT SENSOR This block is used to sense the heart beat with the help of an LED and an LDR. A continuous light from the LED should fall on the LDR and the finger of the patient is to be placed in between the LED and LDR. The slight variation in the skin due to the heart beat is read by the LDR. The LDR output is fed to an operational amplifier to the digital level (0 and 5) which is then fed in to the microcontroller. 2.4 MICROCONTROLLER The microcontroller AT89S51 is used to get the data from the decoder and send the data over GSM Network. 2.5 GSM Modem This GSM-Modem should be a plug and play GSM 900 / GSM 1800 / GSM 1900 modem. A direct and easy integration with RS232 and with in voltage range for the power supply. A SIMCOM's GSM/GPRS modem is suitable for the GSM-SMS Transceiver System. The features of SIMCOM-Modem: • Triband GSM GPRS modem(EGSM 900/1800/1900 MHz) • Designed for GPRS, data, fax, SMS and voice applications • GPRS multi-slot class 10 • GPRS mobile station class B • Designed for GPRS, data, fax, SMS and voice applications • Fully compliant with GSM Phase 2/2+ specifications • Built-in TCP/IP Protocol • Built-in RTC in the module • AT Command based 4 Heartbeat Monitoring System CHAPTER 3 HARDWARE DESCRIPTION 3.1 MICROCONTROLLER The AT89S51 is a 40 pin DIP, low-voltage, high-performance CMOS 8-bit microcomputer with 4 Kbytes of flash programmable and erasable read only memory (PEROM). 3.1.1 Features of AT89S51 • • • • • • • • • • • • • • Compatible with MCS-51 Products 4 Kbytes of Reprogrammable Flash Memory Endurance: 1,000 Write/Erase Cycles 2.7 V to 6 V Operating Range Fully Static Operation: 0 Hz to 24 MHz Two-Level Program Memory Lock 128 x 8-Bit Internal RAM 32 Programmable I/O Lines Two 16-Bit Timer/Counters Six Interrupt Sources Full Duplex UART Serial Channel Watchdog Timer Flexible ISP Programming Low Power Idle and Power Down Modes 3.1.2 Description The device is manufactured using Atmel’s high density nonvolatile memory technology and is compatible with the industry Standard MCS-51 instruction set and pin out. By combining a versatile 8-bit CPU with flash on a monolithic chip, the Atmel AT89S51 is a powerful microcomputer which provides a highly flexible and cost effective solution to many embedded control applications. 5 Heartbeat Monitoring System 3.1.3 Flash Memory Flash memory is a type of EEPROM, which has a grid of columns and rows with a cell that has two transistors at each intersection. A thin oxide layer separates the two transistors from each other. One of the transistor is known as the floating gate and other as the control gate. The floating gate’s only link to the row, or ‘word line’, is through the control gate. As long as this link is in place, the cell has a value of ‘1’. This value can be changed to ‘0’ using the Fowler-Nordheim tunneling process. Tunneling is used to alter the placement of electrons in the floating gate. An electrical charge, usually 10-13 volts, is applied to the floating gate. The charge comes from the column, or bit line, which enters the floating gate and drains to ground. This charge causes the floating gate transistor to act like an electron gun. The excited electrons are pushed through and trapped on the other side of the thin oxide layer, giving it a negative charge. These negatively charged electrons act as a barrier between the control gate and the floating gate. A special device called cell sensor monitors the level of the charge passing through the floating gate. If the flow through the gate is greater than 50 percent of the charge, it has a value of ‘1’. When the charge passing through the gate drops below the 50 percent threshold, the value changes to ‘0’. A blank EPROM has all of the gates fully open, giving each cell a value of ‘1’. The electrons in the cells of a flash memory chip can be returned to the normal ‘1’ state by application of an electric field (a higher-voltage charge). Flash memory uses incircuit wiring to apply the electric field to the entire chip or to the predetermined sections known as blocks. The targeted area of the chip is erased, which can be rewritten. Flash memory works much faster than traditional EEPROMs because instead of erasing one byte at a time, it erases a block or the entire chip and then rewrites it. An ideal memory sub-system is one which has high density, can be read fast and preserve data in non-volatile condition, and is easy to program/reprogram and costeffective. Different memory technologies meet one or more of these requirements very 6 Heartbeat Monitoring System well, but have certain limitations that prevent the product from becoming a genuine solution, especially in newer applications. Flash memory is a non-volatile memory combining the advantages of EPROM/EEPROM, ROM, and DRAM. There may be differences between the specific technologies used by different manufacturers but their basic principle is same. For example, Intel Flash memory use NOR gates, while Samsung memory uses NAND gates. The technology used by Intel is further classified based on the core memory cell. The first technology is the original single-bit/cell flash memory which allows a single bit of information to be stored in each cell (1=erased and 0=programmed). The second and the most recent technology uses a multi-level cell structure, for example, Intel Strata Flash memory. This technology allows two bits of information to be precisely stored in a single transistor. Programming a cell (charge placement) and reading (sensing) must be precisely controlled in order to have four states within a single transistor. According to Intel, the multi-level cell flash memory employs a reliable NORbased architecture and is ideally suited for high-density applications. 3.1.4 Pin Configuration Figure 4.1: Pin configuration of AT89S51 3.1.5 Block Diagram 7 Heartbeat Monitoring System Figure 4.2: Block Diagram of AT89S51 3.1.6 Pin Description of AT89S51 VCC Supply voltage. 8 Heartbeat Monitoring System GND Ground. Port 0 Port 0 is an 8-bit open drain bi-directional I/O port. As an output port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high-impedance inputs. Port 0 can also be configured to be the multiplexed low-order address/data bus during accesses to external program and data memory. In this mode, P0 has internal pullups. Port 0 also receives the code bytes during Flash programming and outputs the code bytes during program verification. External pull-ups are required during program verification. Port 1 Port 1 is an 8-bit bidirectional I/O port. Port pins P1.2 to P1.7 provides internal pull-ups. P1.0 and P1.1 requires external pull-ups. P1.0 and P1.1 also serves as the positive input (AIN0) and negative input (AIN1), respectively, of the on-chip precision analog comparator. The Port 1 output buffers can sink 20 mA and can drive LED displays directly. When 1s are written to Port 1 pins, they can be used as inputs. When pins P1.2 to P1.7 are used as inputs and are externally pulled low, they will source current because of the internal pull-ups. Port 1 also receives code data during Flash programming and program verification. Port 2 Port 2 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 2 output buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups. Port 2 emits the high-order address byte during fetches from external program memory and during accesses to external data memory that use 16-bit addresses (MOVX @ DPTR). In this application, Port 2 uses strong internal pull-ups when emitting 1s. 9 Heartbeat Monitoring System During accesses to external data memory that use 8-bit addresses (MOVX @ RI), Port 2 emits the contents of the P2 Special Function Register. Port 2 also receives the high-order address bits and some control signals during Flash programming and verification. Port 3 Port 3 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 3 output buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the pull-ups. Port 3 receives some control signals for Flash programming and verification. Port 3 also serves the functions of various special features of the AT89S51, as shown in the following table. RST Reset input. All I/O pins are reset to 1’s as soon as RST goes high. Holding the RST pin high for two machine cycles, while the oscillator is running will reset the device. Each machine cycle takes 12 oscillator or clock cycles. XTAL1 Input to the inverting oscillator amplifier and input to the internal clock operating circuit. 10 Heartbeat Monitoring System XTAL2 Output from the inverting oscillator amplifier. 3.2 HEARTBEAT SENSOR Heart beat sensor is designed to give digital output of heat beat when a finger is placed on it. When the heart beat detector is working, the beat LED flashes in unison with each heart beat. 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. 3.2.1 Features • Microcontroller based SMD design • Heat beat indication by LED • Instant output digital signal for directly connecting to microcontroller • Compact Size • Working Voltage +5V DC 3.2.2 Applications • Digital Heart Rate monitor • Patient Monitoring System • Bio-Feedback control of robotics and applications 3.2.3 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. 11 Heartbeat Monitoring System • 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 heart beat. The output is active high for each beat and can be given directly to microcontroller for interfacing applications. 3.2.4 The 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 in finger 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 heart beat. Following figure shows signal of heart beat and sensor signal output graph. Fig.2 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. 12 Heartbeat Monitoring System Fig.3 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 25year old, this range is about 140-170 beats per minute while for a 60-year old it is typically between 115 and 140 beats per minute. 13 Heartbeat Monitoring System 3.2.5 Operation Microcontroller Board: The board used for the proposed project is a general purpose development board for 89S51 microcontroller. The board contents the components required the microcontroller properly. The DIO pins of microcontroller are available on the connector. Microcontroller uses capacitor C1 and resistor R1 for resetting the microcontroller. The Crystal oscillator used here with 2 capacitors U1,U2 is of 11.0952MHZ. Microcontroller also checks for data within the range heartbeat(65 to 85 ) and if the condition is not satisfied takes the appropriate action like sending an SMS. HEART BEAT SENSOR The Microcontroller AT89S51 is used to sense the heart Beat. The Red high intensity light emitted by led initially falls on LDR .This is the condition where the heartbeat is calibrated to zero using resistor R 16. When a patient places his finger in between LED and LDR the light is restricted by the finger .The intensity of light penetration decreases if the blood is pumped into the finger .If the blood is not pumped then the light intensity is high .This high and low light intensity helps to measure heartbeat .Actually light falling on LDR cuts due to blood movement .The duration of light disturbed is measured which gives the time duration of each heart beat pulse ,inverse of this time gives the heartbeat count per minute .This signal is amplified in two stages using dual operational amplifiers.R17 resistor is used to adjust the square wave pulse 14 Heartbeat Monitoring System obtained, C4 is used as feedback capacitor .The output after amplification is obtained at pin number 7 of OP-AMP and fed to microcontroller. D 1 +5V R5 330E D3 100n C4 8 R11 7 LM 358 D2 R17 100K R13 100K 100K R18 47K R16 330E 1K 3 470n C5 2 6 1 IC2 4 5 R10 220E D1 R12 10K Finger High Intensity The heart beat is sensed with help of an LED and LDR arrangement. The LED is a high intensity type LED. Here the LDR is the sensor. As Sensor, a photo diode or a photo transistor can be used. The skin may be illuminated with visible (red) or infrared LEDs using transmitted or reflected light for detection. The very small changes in reflectivity or in transmittance caused by the varying blood content of human tissue are almost invisible. Pulse Diagram R14 RED LED R15 15 Heartbeat Monitoring System The various noise sources may produce disturbance signals with amplitudes equal or even higher than the amplitude of the pulse signal. Valid pulse measurement therefore requires extensive preprocessing of the raw signal. The new signal processing approach presented here combines analog and digital signal processing in a way that, both parts can be kept simple but in combination, they are very effective in suppressing disturbance signals. The setup described here, uses a red LED for transmitted light illumination and a LDR as detector. With only slight changes in the preamplifier circuit the same hard- and software could be used with other illumination and detection concepts. The detectors photo current (AC Part) is converted to voltage and amplified by an operational amplifier (LM358). POWER SUPPLY +12V IC1 C1 1 LM7805 3 C2 47uF/16V +5V D1 L1 230V AC 230/0-12V D2 1N4007 1N4007 D3 D4 1N4007 1000uF/25V 2 1N4007 Figure 4.14: Power Supply The 230 V from the ac mains is converted into 12 V by using a step down transformer. The output of the transformer is converted into dc by the bridge rectifier and is given to the voltage regulator .The voltage regulator (LM7805) is used to maintain a constant output voltage of 5 V which is applied to the circuit. 16 Heartbeat Monitoring System CHAPTER 5 SOFTWARE DESCRIPTION 5.1 FLOWCHART FOR TRANSMITTER Start Measure Heartbeat Ye s No Is Normal No Ye s Send SMS Timer Expired The figure shows the software flowchart diagram of the programming. The main program has two loops one is to check the whether the heartbeat is normal or not, and second loop is a timer loop, for the timer. On power ON, the microcontroller reads the pulses on the DIO. The count of pulses in minute compared with the normal pulse count of a human. If the difference between the count exceeds, the microcontroller send a SMS to the mobile number provided by the user. Similarly, the timer is set for user defined time is fired, the microcontroller sends the last count or status to the specified mobile number. 17 Wireless Patient Monitoring System CHAPTER 6 RESULT The Heartbeat Monitoring System is the part of Patient Monitoring System, can be extended to measure other parameters of patien like ECG & temperature etc. Temperature is measured using DS1820, which gives temperature to current conversions in 200ms and it does not require any external circuitry. Hence it is simple and easy to measure temperature. This measured temperature is displayed over an LCD display via microcontroller. Heart Beat is measured by passing an high intensity red light through a finger which is collected by LDR, amplified and displayed over an LCD display via microcontroller. These two measured parameters are encoded and transmitted via GSM Modem. On receiving the readings and current status of patient, the doctor can take necessary actions or suggest his sub-ordinates for the same. 18 Wireless Patient Monitoring System CHAPTER 7 CONCLUSION Biomedical engineering (BME) is the application of engineering principles and techniques to the medical field. It combines the design and problem solving skills of engineering with medical and biological sciences to improve patient’s health care and the quality of life of individuals. A medical device is intended for use in the diagnosis of disease, or in the cure, treatment, or prevention of diseases. Thus in Implementation of Wireless Systems for Patient Monitoring System, the heart beat and body temperature are successfully sensed. Temperature is measured using DS1820, where it follows on board proprietary temperature measurement technique. Heart beat is measured using LED, LDR and operational amplifier. Hence both parameters are displayed on a LCD display. Then both the parameters are transmitted and displayed in a distant location. This project will eventually reduce man power in the very near future. 19 Wireless Patient Monitoring System CHAPTER 8 FUTURE SCOPE • • 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. 20 Wireless Patient Monitoring System CHAPTER 9 REFERENCES  “THE 8051 MICROCONTROLLER AND APPLICATIONS”. ARCHITECTURE, PROGRAMMING KENNETH .J.AYALA (Second Edition).  “THE 8051 MICROCONTROLLER AND EMBEDDED SYSTEMS” MUHAMMAD ALI M A ZI D I , JANICE G I L L I S P I E M A ZI D I , ( F o ur t h E d i t i o n ) . WEBSITES www.alldatasheets.com www.atmel.com www.electronicforu.com www.8052.com 21 Wireless Patient Monitoring System CHAPTER 10 APPENDIX 11.1 Pin Details of AT89S51 Port3 Table 11.1: Pin details of AT89S51 Port3 11.2. Pin Description of Heartbeat Monitor Module Board has 3-pin connector for using the sensor. Details are marked on PCB as below. Table 11.3: Pin Description of HT12E 22 Wireless Patient Monitoring System 11.3 Specifications of GSM Modem • • • • • • • • • Triband GSM GPRS modem(EGSM 900/1800/1900 MHz) Designed for GPRS, data, fax, SMS and voice applications GPRS multi-slot class 10 GPRS mobile station class B Designed for GPRS, data, fax, SMS and voice applications Fully compliant with GSM Phase 2/2+ specifications Built-in TCP/IP Protocol Built-in RTC in the module AT Command based 23 Wireless Patient Monitoring System Chapter 11 INSTRUCTION SET 24 Wireless Patient Monitoring System 25 Wireless Patient Monitoring System 26 Wireless Patient Monitoring System 27 Wireless Patient Monitoring System 28