iPacemaker

IMPLANTABLE PACEMAKER WITH WI-FI AND GSM

CONNECTIVITY

MAIN PROJECT REPORT

Submitted by

NIDHISH ROY

LADVINE D ALMEIDA

ELDHO JOSE

DILEEP DINESH

in partial fulfillment for the award of the degree of

Bachelor of Technology

in

ELECTRONICS AND BIOMEDICAL ENGINEERING

GOVERNMENT MODEL ENGINEERING COLLEGE

Thrikkakara

Cochin University of science and technology

April 2013

GOVERNMENT MODEL ENGINEERING COLLEGE

THRIKKAKARA

KOCHI

DEPARTMENT OF ELECTRONICS & BIOMEDICAL ENGINEERING

Cochin University of Science and Technology

BONAFIDE CERTIFICATE

This is to certify that the project entitled

……………………………………………………………………………………

Submitted by

……………………………………………………………………………………

is a bonafide work done by them under our supervision.

Dr. Jessy John Mrs. Sincy P S

HEAD OF DEPARTMENT & PROJECT GUIDE PROJECT CO-ORDINATOR

I

ACKNOWLEDGEMENT

At this moment of accomplishment, we are presenting our work with great pride and

pleasure, we would like to express our sincere gratitude to all those who helped us in the

successful completion of project.

First of all, we would like to thank our Principal Prof. Dr. V P Devassia, who

provided us with all facilities and support for the development of our work.

We would like to thank our project guide Dr. Jessy John, Head of Department of

Electronics and Biomedical Engineering for helping us in the successful accomplishment of

this project.

We would also like to thank our coordinator Mrs. Sincy P S, Assistant professor who

gave us constant guidance and support throughout this journey of turbulence.

We also thank Mrs. Bella, Mrs. Geethu, Mrs. Vidhya Lab technicians, Department

of Electronics and Biomedical Engineering for their constant support and encouragement for

our project.

We express our sincere thanks to all our lecturers at the college, all our seniors and our

entire batch mates for their constant support.

Above all we thank almighty for the ever abiding kind blessings.

II

ABSTRACT

Our proposal is to improve the flexibility of the Implantable device (IMD)

programming through the use of an embedded user friendly web interface stored in

microcontroller which replaces use of software and a dedicated programmer for

programming. The important feature is the Wi-Fi alliance complaint hardware which

supports every wireless device to establish connection with the IMD.

Global system for mobiles (GSM) connectivity can be used in absence of Wi-Fi in

remote areas helping in Telemetry.

Wireless protection in case of WiFi is enabled through WPA2 security with AES

Encryption and HTML Web interface which has inherent security capabilities.

Significant power saving has been implemented in project through power down

modes.

III

TABLE OF CONTENTS

SL NO. TOPIC PAGE NO.

LIST OF FIGURES

LIST OF TABLES

VII

IX

LIST OF SYMBOLS AND ABBREVATIONS X

1. INTRODUCTION 1

2. STATE OF ART TECHNOLOGY 3

3. LITERATURE REVIEW 4

4. RELATED THEORY

4.1 TYPES OF PACEMAKERS 5

4.1.1 VENTRICULAR PACING 5

4.1.1.1 VENTRICULAR ASYNCHRONOUS 5

4.1.1.2 VENTRICULAR INHIBITED 6

4.1.1.3 VENTRICULAR TRIGGERED 6

4.1.2 ATRIAL PACING SYSTEMS 6

4.1.2.1 ATRIAL ASYNCHRONOUS 6

4.1.2.2 ATRIAL INHIBITED 7

IV

4.1.2.3 ATRIAL TRIGGERED 7

4.1.3 DUAL CHAMBER PACING SYSTEMS 7

4.1.3.1 AV SYNCHRONOUS 7

4.1.3.2 ATRIAL SYNCHRONOUS 7

4.2 PACING – THE UPSI CODE 8

4.3 ARDUINO 8

4.4 WI-FI 10

4.5 OSI MODEL 12

4.6 HYPERTEXT TRANSFER PROTOCOL 16

4.7 DEVICE FIRMWARE 19

4.8 GSM 20

4.9 COSM 21

5. DESIGN OF WORK

5.1 BLOCK DIAGRAM OF CIRCUIT 23

5.2 BLOCK LEVEL TREATMENT 23

5.2.1 ECG ACQUISITION CIRCUIT 23

5.2.1.1 INSTRUMENTATION AMPLIFIER 24

5.2.1.2 LOW PASS FILTER 26

5.2.1.3 HIGH PASS FILTER 28

5.2.2 QRS DETECTION CIRCUIT 29

V

5.2.2.1 BAND PASS FILTER 31

5.2.2.2 PRECISION RECTIFIER 32

5.2.2.3 PEAK DETECTOR AND COMPARATOR 32

5.2.3 PROCESSING AND PACING CIRCUITRY 33

5.2.4 ARDUINO WIFI SHEILD 34

5.2.5 GSM MODULE 36

5.3 PCB DESIGN 38

5.3.1 PROCESSING AND PACING CIRCUIT 39

5.3.2 ECG ACQUISITION 39

5.4 FLOW CHART OF DEVICE 40

5.4.1 FLOW CHART OF PACING CIRCUIT 40

5.4.2 FLOW CHART OF COMMUNICATION CIRCUIT 40

5.5 USER INTERFACE 42

5.5.1 HOME PAGE 42

5.5.2 SETTINGS PAGE 43

5.5.3 LIVE ECG 43

5.5.4 DATA LOG 44

6. IMPLEMENTATION 45

6.1 SYSTEM REQUIREMENTS 45

6.2 HARDWARE REQUIREMENTS 45

VI

6.3 SOFTWARE REQUIREMENTS 45

6.4 TESTING AND RESULTS 47

7. CONCLUSION 49

8. FUTURE WORKS 50

REFERENCES 51

APPENDIX A - COMMUNICATION PROGRAM 52

APPENDIX B – PACING PROGRAM 59

APPENDIX C – HTML HOME PAGE 62

APPENDIX D – HTML SETTINGS PAGE 64

APPENDIX E – HTML DATALOG PAGE 66

APPENDIX F – ATMEGA328P DATASHEET 68

VII

LIST OF FIGURES

FIGURE 4.1 VENTRICULAR ASYNCHRONOUS 6

FIGURE 4.2 VENTRICULAR INHIBITED 6

FIGURE 4.3 VENTRICULAR TRIGGERED 6

FIGURE 4.4 ATRIAL ASYNCHRONOUS 6

FIGURE 4.5 ATRIAL INHIBITED 7

FIGURE 4.6 ATRIAL TRIGGERED 7

FIGURE 4.7 ATRIO-VENTRICULAR SYNCHRONOUS 7

FIGURE 4.8 ATRIAL SYNCHRONOUS 8

FIGURE 5.1 IPACEMAKER BLOCK DIAGRAM 23

FIGURE 5.2 ECG ACQUISITION BLOCK 23

FIGURE 5.3 ECG ACQUISITION CIRCUIT 24

FIGURE 5.4 AD620 INTERNAL DIAGRAM 25

FIGURE 5.5 AD620 PINOUT 26

FIGURE 5.7 LOW PASS FILTER 27

FIGURE 5.8 LM741 PINOUT 27

FIGURE 5.9 HIGH PASS FILTER 28

FIGURE 5.10 GAIN STAGE 29

FIGURE 5.11 QRS DETECTION BLOCK 30

FIGURE 5.12 QRS DETECTION CIRCUIT 30

VIII

FIGURE 5.13 LM324 PINOUT 31

FIGURE 5.14 BANDPASS CIRCUIT 31

FIGURE 5.15 PRECISION RECTIFIER 32

FIGURE 5.16 PEAK DETECTOR AND COMPARATOR 33

FIGURE 5.17 PROCESSING AND PACING CIRCUIT 33

FIGURE 5.18 ARDUINO WI-FI SHEILD 35

FIGURE 5.19 GSM MODULE 38

FIGURE 5.20 PCB FOR PACING AND PROCESSING 39

FIGURE 5.21 PCB FOR ECG CIRCUIT 39

FIGURE 5.22 FLOW CHART FOR PACING 40

FIGURE 5.23 FLOW CHART FOR COMMUNICATION 41

FIGURE 5.24 HOME PAGE 42

FIGURE 5.25 SETTINGS PAGE 43

FIGURE 5.26 LIVE ECG 44

FIGURE 5.27 DATA LOG 44

FIGURE 5.28 FULL CIRCUIT DIAGRAM 46

FIGURE 5.29 ECG ACQUISITION HARDWARE 47

FIGURE 5.30 ECG ON CRO 47

FIGURE 5.31 QRS DETECTION AND PACING HARDWARE 47

FIGURE 5.32 PACING OUTPUT 47

IX

LIST OF TABLES

TABLE 1 PACING INDICATION 5

TABLE 2 STD. VALUE GAIN RESISTORS FOR AD620 25

X

LIST OF SYMBOLS AND ABBREVIATIONS

fc

Centre Frequency

Af Feedback Gain

WPA WiFi Protected Access

DSSS Direct Sequence Spread Spectrum

OFDM Orthogonal Frequency Division Multiplexing

ISM Industrial Scientific and Medical Band

MAC Medium Access Control

IMD Implantable Device

Q Figure of Merits

UART Universal Asynchronous Receive Transmit

FTDI Future Technology Devices International

1

Chapter 1

INTRODUCTION

Artificial pacemaker is one of the modern marvels in the medical science.

Electronic pacemakers play a vital role in today‘s society, providing approximately half a

million people with a better quality and prolonged life. Numerous advancements have

been made in pacemaker technology over the last fifty years, making current pacemakers

highly sophisticated cardiac rhythm managers capable of correcting a myriad of complex

heart abnormalities. The primary function of a typical pacemaker is to sense a person‘s

heartbeat, and pace the heart via electric stimulation when irregularities are detected. This

is accomplished in many different ways due the variances found in heart conditions.

A pacemaker uses electrical impulses, delivered by electrodes contacting the heart

muscles, to regulate the beating of the heart. Pacemakers find applications, either because

the heart's native pacemaker is not fast enough, or there is a block in the heart's electrical

conduction system. Basic pacemaker consist of two parts, an electronic unit which

generates stimulating impulses of controlled rate and amplitude, known as pulse

generator; and the lead which carries electrical impulses from the pulse generator to the

heart.

Modern pacemakers are sophisticated electronic devices, capable of providing

assistance on demand, i.e. when the excitatory and conductive system of the heart fails to

operate normally. In order to accommodate specific patient needs, modern pacemakers

can be programmed by setting particular parameters in such way that the resulting

pacemaker therapy is optimal for the patient. Unfortunately, reprogramming a pacemaker

is not an easy task: both sufficient time and knowledge of pacemaker functionality and

possible pacemaker therapy must be available. It has been observed that due to a lack of

one or both of these factors, in many patients, a given pacemaker therapy is suboptimal:

in many implanted pacemakers even the original factory settings are kept unchanged.

Today, the pacemaker technology is moving fast, and the role of software in pacemaker

functioning is increasing, yielding pacemaker devices that are almost annually enhanced

in their capabilities.

The iPacemaker is new generation implantable pacemaker that provides leading

edge pacing technology through ECG sensing and QRS detection circuitry, Micro-

controllers which runs software for pacing algorithms and user interface and wireless

connectivity devices – Wi-Fi and GSM for reprogramming the device.

2

A notable aspect of the project is the use of embedded web server stored in the

microcontroller in replacement for the software to be installed on the computer for

wireless device programming and monitoring. WPA2 security for Wi-Fi with AES

encryption provides solid protection for the device. The embedded web interface in

microcontroller is designed using HTML3.0. The HTML 3.0 specification provides a

number of new features, and is broadly backwards compatible with HTML 2.0.

Moreover, HTML 3.0 adds relatively little complexity to a browser making it suitable for

embedded applications. GSM facility in the device improves its scope to be programmed

anywhere with SMS containing pacing parameters code and password. It also helps the

doctor to view the status of the device and patient conditions from remote areas which

paves the way for Telemetry. The Real-time monitoring of the device world-wide over

the internet is implemented through COSM interface. COSM, formerly pachube provides

software as a service (SaaS) for monitoring sensor networks.

The project is developed using Arduino technology which is a new open-source

physical computing platform which is simple, cheap and has extensible hardware and

software support. In short, our project provides a viable solution to problems existing in

life-saving implantable devices and delivers a sophisticated device to improve the life

conditions of millions of cardiac patients over the world.

3

Chapter 2

STATE OF ART TECHNOLOGY

Cardiac pacemakers often requires replacement or reprogramming since ICD can

be subject to malfunction, instability issues or variations in pacing parameters. Existing

pacemaker systems make use of wireless programmer – stand alone or networked with a

computer for programming the implanted device. These programming devices normally

includes display screen, keyboard, programming head that provides communication link

between the programmer and the patient‘s implantable device through RF transmission,

Electrode leads for ECG acquisition, etc. Various facilities implemented in the

programmer include viewing patient ECG, collecting diagnostic data, evaluating

parameter settings, programming pacemaker parameters and rate responsive setup.

Currently using pacemakers possess a disadvantage that a dedicated programmer

with its associated programmer is required for programming the device greatly affecting

the flexibility of reprogramming and monitoring of the device. Maintaining an assured

permanent connectivity with the device helps in monitoring of device anywhere over the

world and thereby improves the lifestyle conditions of the patient.

The solution proposed to overcome the above disadvantages include the use of

webserver embedded in the microcontroller which provides options for checking the

overall status of the device, monitoring of the patient ECG, reprogramming the implanted

device etc., Moreover assured connectivity with the device can be established through

making use of GSM facility allowing the device to be monitored by sending an SMS

containing request code. The power utilisation came to be a significant issue when

wireless connectivity is provided for the device, However many power-down modes

already present in GSM and Wi-Fi helps in handling these issues.

4

Chapter 3

LITERATURE REVIEW

The goal of pacemaker follow-up is not only to predict the end-of-life (EOL) of

the pulse-generator but also to detect malfunctions and optimize pacing system

performance and longevity. In the prospective study conducted by regional university

general hospital of patras in the paper ‗A Long Term Follow-up of Patients with a

Permanent Pacemaker: Necessity of Specific Programmer‘, they evaluated the

effectiveness of pacemaker follow-up with the use of magnet rate measured by the mini-

clinic compared with a complete set of tests using pacemaker programmers, in the

absence of a trans telephonic monitoring. They analysed the possible pacemaker

dysfunction-related symptoms, the device malfunctions, and the necessity for specific

parameter corrections. [1]

Motivated by desire to improve patient safety, and mindful of conventional trade-

offs between security and power consumption for resource constrained devices, the study

conducted in the thesis ‗Pacemakers and Implantable Cardiac Defibrillators: Software

Radio Attacks and Zero-Power Defences‘ introduced three new zero-power defences

based on RF power harvesting. Studies conducted by them shows that providing security

and privacy on an IMD involves health risk factors and tight resource constraints.

Another risk to IMD availability is excessive power consumption by mechanisms other

than those needed for the device‘s primary function. Solution proposed by them in the

situation is zero-power authentication that similarly harvests RF energy to power a

cryptographically strong protocol that authenticates requests from an external device

programmer at no cost to the battery. In general, security is more compact, discriminable,

and most importantly, can be implemented in generalized networks such as Wi-Fi with

zero power utilisation.

In the article, ‗Telemonitoring of the Pacemaker‘ by Duke University Medical

Centre, the implementation of Telemonitoring through GSM was suggested which could

provide a practical substitute to the time-consuming and expensive in-office visits.

However reliability is an issue here because of any interference caused by relying on

most widely used and available network. [2]

5

Chapter 4

RELATED THEORY

The rhythmic beating of the heart is due to the triggering pulses that originate in

an area of specialized tissue in the right atrium of the heart. This area is known as the

sino-atrial node. In abnormal situations, if this natural pacemaker ceases to function or

becomes unreliable or if the triggering pulses does not reach the heart muscles because of

blocking by damaged tissues, the natural and normal synchronization of the heart action

gets disturbed. When monitored, this manifests itself through a decrease in the heart rate

and changes the ECG waveform. By providing external electrical stimulation impulses to

the heart muscle, it is possible to regulate the heart rate. These impulses are given by an

electronic instrument called a pacemaker.

The basic operation of the pacing circuit is as follows. When the sensing part of

the circuit does not sense any abnormality of the normal heart rhythm no signal will be

sent from the microcontroller to pace and so nothing will happen and the switch will

remain open. Once the sensing circuit notices the heart beat slowing down the

microcontroller will send a signal to the pacing circuit causing the switch to close and

thus completing the circuit. This pulse can be programmed to be of various amplitudes

and widths. These values for any specific person are determined in tests when pacemaker

is first implanted. Once the heart goes back to a normal rhythm the switch opens and

pacemaker gets ready for the next pulse. [3]

The pulse amplitude as well as the pulse width has to be variable to account for

physiological differences between people. The pulse amplitude has to be variable from

between 1.2V to 7V. The timing is also incredibly important in delivering a pulse. A

pulse at the wrong time could cause the heart to go into ventricular fibrillation. Whether

a pulse is administered as well as the timing of the pulse is controlled by the

microcontroller.

4.1 TYPES OF PACEMAKERS

4.1.1 Ventricular Pacing Systems

4.1.1. 1VOO – Ventricular Asynchronous

In this mode the pacemaker stimulates at a fixed rate and voltage. There is no

sensing and hence the pacemaker will continue to pace irrespective of the underlying

6

rhythm. The pacemaker will capture the heart if the impulse delivered falls outside the

refractory period of the intrinsic beat.

Fig 4.1 Ventricular Asynchronous

4.1.1. 2 VVI-Ventricular inhibited

Spontaneous impulses are sensed and the subsequent output is stopped. If no

spontaneous impulses occur the pacemaker will pace at the regular rate at which the

pacemaker is set.

Fig 4.2 Ventricular Inhibited

4.1.1. 3VVT- Ventricular Triggered

In this mode when a spontaneous ventricular intrinsic beat is seen the output of

the pacemaker is delivered. It must be noted that the beat will not be fully captured by the

pacemaker as the output delivered will fall in the refractory period of the intrinsic beat

and make no contribution to the depolarisation of the heart (this is called a pseudo-fusion

beat).

Fig 4.3 Ventricular Triggered

4.1.2 Atrial Pacing Systems

4.1.2. 1AOO – Atrial Asynchronous

This mode is rarely used. As in VOO, the pacemaker stimulates at a fixed rate

irrespective of the underlying rhythm.

Fig 4.4 Atrial Asynchronous

7

4.1.2. 2AAI – Atrial Inhibited

This mode is the same as the VVI mode except the lead is positioned next to atrial

myocardium and therefore the pacemaker will inhibit when an intrinsic atrial beat is seen.

Fig 4.5 Atrial Inhibited

4.1.2. 3AAT – Atrial Triggered

In this mode when a spontaneous atrial intrinsic beat is seen the output of the

pacemaker is delivered. It must be noted that the beat will not be fully captured by the

pacemaker as the output delivered will fall in the refractory period of the intrinsic beat

and make no contribution to the depolarisation of the heart (this is called a pseudo-fusion

beat).

Fig 4.6 Atrial Triggered

4.1.3 Dual Chamber Pacing Systems

4.1.3.1 DOO – AV Synchronous

The ‗D‘ in the USCI code stands for dual, meaning atria and ventricle. In this

instance, both chambers are paced at a fixed rate with no sensing, irrespective of the

underlying rhythm. This mode is rarely used and can be seen with application of a magnet

on most DDD pacemaker models.

Fig 4.7 Atrio-ventricular Synchronous

4.1.3. 2Atrial Synchronous (VAT)

This mode occurs when the atrial intrinsic rate is sensed and the ventricular

chamber is paced. The pacemaker output is triggered to a sensed event, that event being a

8

sinus P wave. In this way AV synchrony is maintained and the response will be

physiological because it will follow the intrinsic rate of the sinus node.

Fig 4.8 Atrial Synchronous

4.2 PACING – THE USCI CODE

The USCI code is the standard code for labelling the mode of pacing.

1s t

letter – chamber(s) paced

2n d

letter – chamber(s) sensed

3r d

letter – Mode of action

Either the atria or ventricles can be paced and hence either pure atrial, pure ventricular or

both atrial and ventricular pacing can be employed. Therefore modes of AAI, VVI, VVT,

VAT, DDI, DDD and others may be chosen. The mode of action is either inhibited (I),

where the pacemaker will suppress its output if an intrinsic beat is seen or triggered (T),

where the output of a pacemaker is triggered to a sensed event.[4]

The revised code is as follows:

I II III IV V

Chamber(s)

paced

Chamber(s)

sensed

Response to

sensing

Rate modulation Multisite

pacing

O = None O = None O = None O = None O = None

A = Atrium A = Atrium T = Triggered R = Rate

modulation

A = Atrium

V = Ventricle V = Ventricle I = Inhibited V = Ventricle

D = Dual (A+V) D = Dual (A+V) D = Dual

(A+V)

D = Dual

(A+V)

Table 1 Pacing indication

4.3 ARDUINO

Arduino is an open source electronic prototyping platform based on flexible, easy

to use hardware and software. The hardware consists of a simple open hardware design

9

for the Arduino board with an Atmel AVR processor and on-board input/output support.

The software consists of a standard programming language compiler and the boot loader

that runs on the board. Arduino can sense the environment by receiving input from a

variety of sensors and can affect its surroundings by controlling lights, motors, and other

actuators. The microcontroller on the board is programmed using the arduino

programming language (based on Wiring) and the Arduino development environment

(based on Processing). Arduino projects can be stand-alone or they can communicate with

software running on a computer (e.g. Flash, Processing, MaxMSP).The boards can

be built by hand or purchased preassembled.

The Arduino Uno is a microcontroller board based on the ATmega328. It has 14

digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a

16 MHz ceramic resonator, a USB connection, a power jack, an ICSP header, and a reset

button. An important aspect of the Arduino is the standard way that connectors are

exposed, allowing the CPU board to be connected to a variety of interchangeable add-on

modules known as shields. Some shields communicate with the Arduino board directly

over various pins, but many shields are individually addressable via an I²C serial bus,

allowing many shields to be stacked and used in parallel. Official Arduino have used the

megaAVR series of chips, specifically the ATmega8, ATmega168, ATmega328,

ATmega1280, and ATmega2560. A handful of other processors have been used by

Arduino compatibles. Most boards include a 5 volt linear regulator and a 16 MHz crystal

oscillator (or ceramic resonator in some variants), although some designs such as the

LilyPad run at 8 MHz and dispense with the on-board voltage regulator due to specific

form-factor restrictions. An Arduino's microcontroller is also pre-programmed with a

boot loader that simplifies uploading of programs to the on-chip flash memory, compared

with other devices that typically need an external programmer. Serial Arduino boards

contain a simple level shifter circuit to convert between RS-232-level and TTL-level

signals. Current Arduino boards are programmed via USB, implemented using USB-to-

serial adapter chips such as the FTDI FT232.

Arduino hardware is programmed using a Wiring-based language (syntax and

libraries), similar to C++ with some slight simplifications and modifications, and a

Processing-based integrated development environment. [5]

10

Features

Microcontroller ATmega328

Operating Voltage 5V

Input Voltage

(recommended) 7-12V

Input Voltage (limits) 6-20V

Digital I/O Pins 14 (of which 6 provide PWM output)

Analog Input Pins 6

DC Current per I/O Pin 40 mA

DC Current for 3.3V Pin 50 mA

Flash Memory 32 KB (ATmega328) of which 0.5 KB used by boot

loader

4.4 Wi-Fi

Wi-Fi is a popular technology that allows an electronic device to exchange data

wirelessly (using radio waves) over a computer network, including high-speed Internet

connections. The Wi-Fi Alliance defines Wi-Fi as any "wireless local area network

(WLAN) products that are based on the (IEEE) 802.11 standards". A device that can use

Wi-Fi can connect to a network resource via a wireless network access point. Such an

access point (or hotspot) has a range of about 20 meters indoors and a greater range

outdoors. Hotspot coverage can comprise an area as small as a single room with walls

that block radio waves or as large as many square miles — this is achieved by using

multiple overlapping access points.

IEEE 802.11 is a set of standards for implementing wireless local area network

(WLAN) computer communication in the 2.4, 3.6 and 5 GHz frequency bands. The

802.11 family consist of a series of half-duplex over-the-air modulation techniques that

use the same basic protocol. The most popular are those defined by the 802.11b and

802.11g protocols, which are amendments to the original standard.802.11b and 802.11g

use the 2.4 GHz ISM band and can control their interference and susceptibility to

interference by using direct-sequence spread spectrum (DSSS) and orthogonal frequency-

division multiplexing (OFDM) signalling methods, respectively. 802.11a uses the 5 GHz

U-NII band, which, for much of the world, offers at least 23 non-overlapping channels

rather than the 2.4 GHz ISM frequency band, where adjacent channels overlap.

11

802.11b has a maximum raw data rate of 11 Mbit/s and uses the same media

access method defined in the original standard. However, 802.11b devices suffer

interference from other products operating in the 2.4 GHz band which include microwave

ovens, Bluetooth devices, baby monitors, cordless telephones and some amateur radio

equipment. 802.11g works in the 2.4 GHz band but uses the same OFDM based

transmission. It operates at a maximum physical layer bit rate of 54 Mbit/s exclusive of

forward error correction codes and has more immunity to interference. 802.11g hardware

is fully backward compatible with 802.11b hardware.

The communication through Wi-Fi is managed by four-layer set of protocols: the

first manages the physical media where the connection is established, the second (Internet

Protocol) allows exchange of basic data units called datagrams, then TCP (Transmission

Control Protocol) provide reliable, connection- oriented, full-duplex streams. Finally

there is an application layer that implements high level services.

Each connected device is designated by a 32-bit number, usually written as four

numbers separated by dots (eg. 158.110.1.3). To this number may also associate a name,

composed by labels separated by dots (eg. hydrus.cc.uniud.it) through the DNS protocol

(STD13). On a single computer, many connections may be active at the same time; to

allow this; a port number is also associated to each connection. Some port number is

reserved to specific application protocols allowing the easy retrieval of such applications.

To send a message on a network, an application has to put its data in a structure called

packet or datagram, and address them correctly. Every computer on the network can talk,

as a peer, with any other computer.

TCP/IP is a ―connectionless‖ protocol. Information is transferred in ―packets‖.

Each of these packets is sent through the network individually. On the basic TCP/IP

protocol, other more abstract protocols – application protocols- have been developed to

carry out specific tasks; these protocols usually follow the client/server architecture.

Client/server is a computational architecture that involves client processes

requesting services from server processes. Client programs usually manage the user

interface part of application; validate data entered by the user and send messages to a

server program, requesting the server to perform a service. Server programs generally

receive requests from client programs, perform tasks to satisfy the requests and send

responses to clients. The server may run on another machine on the network, and

manages shared resources such as data, devices and communication links. The

12

communication between client and server is carried out according to a set of precise rules

called client- server protocol. [5]

4.5 OSI MODEL

Every communication network follows OSI model - The Open Systems

Interconnection (OSI) model (ISO/IEC 7498-1) is a product of the Open Systems

Interconnection effort at the International Organization for Standardization. It is a

prescription of characterizing and standardizing the functions of a communications

system in terms of abstraction layers. Similar communication functions are grouped into

logical layers. A layer serves the layer above it and is served by the layer below it. OSI

had two major components: an abstract model of networking, called the Basic Reference

Model or seven-layer model, and a set of specific protocols.

There are seven layers, labelled 1 to 7, with layer 1 at the bottom. Each layer is

generically known as an N layer. A service data unit (SDU) is a specific unit of data that

has been passed down from an OSI layer to a lower layer, and which the lower layer has

not yet encapsulated into a protocol data unit (PDU). An SDU is a set of data that is sent

by a user of the services of a given layer, and is transmitted semantically unchanged to a

peer service user.

1. The physical layer defines electrical and physical specifications for devices. In

particular, it defines the relationship between a device and a transmission medium,

such as a copper or fibre optical cable. This includes the layout of pins, voltages,

line impedance, cable specifications, signal timing, hubs, repeaters, network

adapters, host bus adapters (HBA used in storage area networks) and more.

The major functions and services performed by the physical layer are:

Establishment and termination of a connection to a communications

medium.

Participation in the process whereby the communication resources are

effectively shared among multiple users. For example, contention

resolution and flow control.

Modulation or conversion between the representation of digital data in user

equipment and the corresponding signals transmitted over a

communications channel. These are signals operating over the physical

cabling (such as copper and optical fibre) or over a radio link.

13

Parallel SCSI buses operate in this layer, although it must be remembered that

the logical SCSI protocol is a transport layer protocol that runs over this bus.

Various physical-layer Ethernet standards are also in this layer; Ethernet

incorporates both this layer and the data link layer. The same applies to other

local-area networks, such as token ring, FDDI, ITU-T G.hn and IEEE 802.11, as

well as personal area networks such as Bluetooth and IEEE 802.15.4.

2. The data link layer provides the functional and procedural means to transfer data

between network entities and to detect and possibly correct errors that may occur

in the physical layer. Originally, this layer was intended for point-to-point and

point-to-multipoint media, characteristic of wide area media in the telephone

system. Local area network architecture, which included broadcast-capable multi-

access media, was developed independently of the ISO work in IEEE Project 802.

The ITU-T G.hn standard, which provides high-speed local area networking over

existing wires (power lines, phone lines and coaxial cables), includes a complete

data link layer which provides both error correction and flow control by means of a

selective repeat Sliding Window Protocol.

The functions of data link layer:-

Framing

Physical Addressing

Flow Control

Error Control

Access Control

Media Access Control(MAC)

3. The network layer provides the functional and procedural means of transferring

variable length data sequences from a source host on one network to a destination

host on a different network (in contrast to the data link layer which connects hosts

within the same network), while maintaining the quality of service requested by the

transport layer. The network layer performs network routing functions, and might

also perform fragmentation and reassembly, and report delivery errors. Routers

operate at this layer, sending data throughout the extended network and making the

Internet possible. [5]

The network layer may be divided into three sub layers:

14

1) Sub network access – that considers protocols that deal with the interface to

networks, such as X.25;

2) Sub network-dependent convergence – when it is necessary to bring the level

of a transit network up to the level of networks on either side.

3) Sub network-independent convergence – handles transfer across multiple

networks.

A number of layer-management protocols, a function defined in the

Management Annex, ISO 7498/4, belong to the network layer. These include

routing protocols, multicast group management, network-layer information and

error, and network-layer address assignment. It is the function of the payload that

makes these belong to the network layer, not the protocol that carries them.

4. The transport layer provides transparent transfer of data between end users,

providing reliable data transfer services to the upper layers. The transport layer

controls the reliability of a given link through flow control, segmentation/de-

segmentation, and error control. Some protocols are state-and connection-oriented.

This means that the transport layer can keep track of the segments and retransmit

those that fail. The transport layer also provides the acknowledgement of the

successful data transmission and sends the next data if no errors occurred.

Tunnelling protocols operate at the transport layer, such as carrying non-IP

protocols such as IBM's SNA or Novell's IPX over an IP network, or end-to-end

encryption with IPsec. While Generic Routing Encapsulation (GRE) might seem to

be a network-layer protocol, if the encapsulation of the payload takes place only at

endpoint, GRE becomes closer to a transport protocol that uses IP headers but

contains complete frames or packets to deliver to an endpoint. L2TP carries PPP

frames inside transport packet. [5]

Although not developed under the OSI Reference Model and not strictly

conforming to the OSI definition of the transport layer, the Transmission Control

Protocol (TCP) and the User Datagram Protocol (UDP) of the Internet Protocol

Suite are commonly categorized as layer-4 protocols within OSI.

5. The session layer controls the dialogues (connections) between computers. It

establishes, manages and terminates the connections between the local and remote

application. It provides for full-duplex, half-duplex, or simplex operation, and

establishes check pointing, adjournment, termination, and restart procedures. The

OSI model made this layer responsible for graceful close of sessions, which is a

15

property of the Transmission Control Protocol, and also for session check pointing

and recovery, which is not usually used in the Internet Protocol Suite. The session

layer is commonly implemented explicitly in application environments that use

remote procedure calls.

6. The presentation layer establishes context between application-layer entities, in

which the higher-layer entities may use different syntax and semantics if the

presentation service provides a mapping between them. If a mapping is available,

presentation service data units are encapsulated into session protocol data units,

and passed down the stack. This layer provides independence from data

representation (e.g., encryption) by translating between application and network

formats. The presentation layer transforms data into the form that the application

accepts. This layer formats and encrypts data to be sent across a network. It is

sometimes called the syntax layer.

The original presentation structure used the Basic Encoding Rules of

Abstract Syntax Notation One (ASN.1), with capabilities such as converting an

EBCDIC-coded text file to an ASCII-coded file, or serialization of objects and

other data structures from and to XML. [5]

7. The application layer is the OSI layer closest to the end user, which means that

both the OSI application layer and the user interact directly with the software

application. This layer interacts with software applications that implement a

communicating component. Such application programs fall outside the scope of the

OSI model. Application-layer functions typically include identifying

communication partners, determining resource availability, and synchronizing

communication. When identifying communication partners, the application layer

determines the identity and availability of communication partners for an

application with data to transmit. When determining resource availability, the

application layer must decide whether sufficient network or the requested

communication exists.

In synchronizing communication, all communication between applications

requires cooperation that is managed by the application layer. Some examples of

application-layer implementations also include:

On OSI stack:

o FTAM File Transfer and Access Management Protocol

o X.400 Mail

16

o Common Management Information Protocol (CMIP)

On TCP/IP stack:

o Hypertext Transfer Protocol (HTTP),

o File Transfer Protocol (FTP),

o Simple Mail Transfer Protocol (SMTP)

o Simple Network Management Protocol (SNMP).

Neither the OSI Reference Model nor OSI protocols specify any programming

interfaces, other than as deliberately abstract service specifications. Protocol

specifications precisely define the interfaces between different computers, but the

software interfaces inside computers, known as network sockets are implementation-

specific. For example Microsoft Windows' Winsock, and Unix's Berkeley sockets and

System V Transport Layer Interface, are interfaces between applications (layer 5 and

above) and the transport (layer 4). NDIS and ODI are interfaces between the media (layer

2) and the network protocol (layer 3). [5]

4.6 HYPERTEXT TRANSFER PROTOCOL (HTTP)

The Hypertext Transfer Protocol (HTTP) is an application protocol for distributed,

collaborative, hypermedia information systems. HTTP is the foundation of data

communication for the World Wide Web. [1]

Hypertext is a multi-linear set of objects, building a network by using logical links

(the so-called hyperlinks) between the nodes (e.g. text or words). HTTP is the protocol to

exchange or transfer hypertext. The standards development of HTTP was coordinated by

the Internet Engineering Task Force (IETF) and the World Wide Web Consortium

(W3C), culminating in the publication of a series of Requests for Comments (RFCs),

most notably RFC 2616, which defines HTTP/1.1, the version of HTTP in common use.

HTTP functions as a request-response protocol in the client-server computing

model. A web browser, for example, may be the client and an application running on a

computer hosting a web site may be the server. The client submits an HTTP request

message to the server. The server, which provides resources such as HTML files and

other content, or performs other functions on behalf of the client, returns a response

message to the client. The response contains completion status information about the

request and may also contain requested content in its message body. A web browser is an

example of a user agent (UA). Other types of user agent include the indexing software

used by search providers (web crawlers), voice browsers, mobile apps and other software

17

that accesses, consumes or displays web content. HTTP is designed to permit

intermediate network elements to improve or enable communications between clients and

servers. High-traffic websites often benefit from web cache servers that deliver content on

behalf of upstream servers to improve response time. Web browsers caches previously

accessed web resources and reuse them when possible to reduce network traffic. HTTP

proxy servers at private network boundaries can facilitate communication for clients

without a globally routable address, by relaying messages with external servers.

HTTP is an application layer protocol designed within the framework of the

Internet Protocol Suite. Its definition presumes an underlying and reliable transport layer

protocol and Transmission Control Protocol (TCP) is commonly used. However HTTP

can use unreliable protocols such as the User Datagram Protocol (UDP), for example in

Simple Service Discovery Protocol (SSDP). HTTP resources are identified and located on

the network by Uniform Resource Identifiers (URIs)—or, more specifically, Uniform

Resource Locators (URLs)—using the http or https URI schemes. URIs and hyperlinks in

Hypertext Mark-up Language (HTML) documents form webs of inter-linked hypertext

documents. [1]

HTTP/1.1 is a revision of the original HTTP (HTTP/1.0). In HTTP/1.0 a separate

connection to the same server is made for every resource request. HTTP/1.1 can reuse a

connection multiple times to download images, scripts, style sheets etc. after after the

page has been delivered. HTTP/1.1 communications therefore experience less latency as

the establishment of TCP connections presents considerable overhead.

An HTTP session is a sequence of network request-response transactions. An

HTTP client initiates a request by establishing a Transmission Control Protocol (TCP)

connection to a particular port on a server (typically port 80). An HTTP server listening

on that port waits for a client's request message. Upon receiving the request, the server

sends back a status line, such as "HTTP/1.1 200 OK", and a message of its own. The

body of this message is typically the requested resource, although an error message or

other information may also be returned.

HTTP defines methods (sometimes referred to as verbs) to indicate the desired

action to be performed on the identified resource. What this resource represents, whether

pre-existing data or data that is generated dynamically, depends on the implementation of

the server. Often, the resource corresponds to a file or the output of an executable residing

on the server. The HTTP/1.0 specification defined the GET, POST and HEAD methods

and the HTTP/1.1 specification added 5 new methods: OPTIONS, PUT, DELETE,

18

TRACE and CONNECT. By being specified in these documents their semantics are well

known and can be depended upon. Any client can use any method and the server can be

configured to support any combination of methods. If a method is unknown to an

intermediate it will be treated as an unsafe and non-idempotent method. There is no limit

to the number of methods that can be defined and this allows for future methods to be

specified without breaking existing infrastructure.

GET requests a representation of the specified resource. Requests using GET

should only retrieve data and should have no other effect. HEAD asks for the

response identical to the one that would correspond to a GET request, but without

the response body. This is useful for retrieving meta-information written in

response headers, without having to transport the entire content.

POST requests that the server accept the entity enclosed in the request as a new

subordinate of the web resource identified by the URL. The data Posted might be,

as examples, an annotation for existing resources; a message for a bulletin board,

newsgroup, mailing list, or comment thread; a block of data that is the result of

submitting a web form to a data-handling process; or an item to add to a database.

PUT requests that the enclosed entity be stored under the supplied URL. If the

URL refers to an already existing resource, it is modified; if the URL does not

point to an existing resource, then the server can create the resource with that

URL. DELETE deletes the specified resource.

TRACE echoes back the received request so that a client can see what (if any)

changes or additions have been made by intermediate servers. An OPTION

returns the HTTP methods that the server supports for specified URL. This can be

used to check the functionality of a web server by requesting '*' instead of a

specific resource.

CONNECT converts the request connection to a transparent TCP/IP tunnel,

usually to facilitate SSL-encrypted communication (HTTPS) through an

unencrypted HTTP proxy.

PATCH Is used to apply partial modifications to a resource. HTTP servers are

required to implement at least the GET and HEAD methods and, whenever

possible, also the OPTIONS method.

In HTTP/0.9 and 1.0, the connection is closed after a single

request/response pair. In HTTP/1.1 a keep-alive-mechanism was introduced, where a

19

connection could be reused for more than one request. Such persistent connections reduce

request latency perceptibly, because the client does not need to re-negotiate the TCP

connection after the first request has been sent. Another positive side effect is that in

general the connection becomes faster with time due to TCP's slow-start-mechanism.

Version 1.1 of the protocol also made bandwidth optimization improvements to

HTTP/1.0. HTTP pipelining further reduces lag time, allowing clients to send multiple

requests before waiting for each response. Another improvement to the protocol was byte

serving, where a server transmits just the portion of a resource explicitly requested by a

client. [1]

There are three methods of establishing a secure HTTP connection: HTTP Secure,

Secure Hypertext Transfer Protocol and the HTTP/1.1 Upgrade header. HTTP/1.1

Upgrade header is used for implementing security in our project.

A client request (consisting in this case of the request line and only one header) is

followed by a blank line, so that the request ends with a double newline, each in the form

of a carriage return followed by a line feed. The "Host" header distinguishes between

various DNS names sharing a single IP address, allowing name-based virtual hosting.

While optional in HTTP/1.0, it is mandatory in HTTP/1.1.

4.7 DEVICE FIRMWARE

Programming can always be improved in virtually any system. There always

exists the potential for problems due to the interpretation of compilers. Even a system

which has been thoroughly tested can still have numerous problems waiting to surface

under the right circumstances. Therefore it is our suggestion to investigate the code

thoroughly, and perform numerous tests to verify correct functionality. One suggestion

would be to use assembly language to implement the control functions. Lower level

languages, although difficult to use, provide a more concrete solution. In electronic

systems and computing, firmware is the combination of persistent memory and program

code and data stored in it. Typical examples of devices containing firmware are

embedded systems (such as traffic lights, consumer appliances, and digital watches),

computers, computer peripherals, mobile phones, and digital cameras. The firmware

contained in these devices provides the control program for the device. Firmware is held

in non-volatile memory devices such as ROM, EPROM, or flash memory. Changing the

firmware of a device may rarely or never be done during its economic lifetime; some

firmware memory devices are permanently installed and cannot be changed after

20

manufacture. Common reasons for updating firmware include fixing bugs or adding

features to the device. This may require physically changing ROM integrated circuits, or

reprogramming flash memory with a special procedure. Firmware such as the ROM BIOS

of a personal computer may contain only elementary basic functions of a device and may

only provide services to higher-level software. Firmware such as the program of an

embedded system may be the only program that will run on the system and provide all of

its functions. [5]

One improvement which could be made in programming would be to make all of

the parameters obtained from the specifications fully programmable by the end user.

That is, a simple user interface could be created to set the upper and lower rate limit,

pulse amplitudes, etc. Any system which is to be used by people other than Engineers

(Doctors in this case) should provide an intuitive and simple user interface. This is the

largest downfall of many systems which are produced.

4.8 GSM

GSM (Global System for Mobile Communications, originally Group Special

Mobile), is a standard set developed by the European Telecommunications Standards

Institute (ETSI) to describe protocols for second generation (2G) digital cellular networks

used by mobile phones. GSM is a cellular network, which means that cell phones connect

to it by searching for cells in the immediate vicinity. There are five different cell sizes in

a GSM network—macro, micro, pico, femto and umbrella cells. The GSM standard was

developed as a replacement for first generation (1G) analog cellular networks, and

originally described a digital, circuit switched network optimized for full duplex voice

telephony. This was expanded over time to include data communications, first by circuit

switched transport, then packet data transport via GPRS (General Packet Radio Services)

and EDGE (Enhanced Data rates for GSM Evolution or EGPRS).

Cell horizontal radius varies depending on antenna height, antenna gain and

propagation conditions from a couple of hundred metres to several tens of kilometres.

The longest distance the GSM specification supports in practical use is 35 kilometres.

There are also several implementations of the concept of an extended cell, where the cell

radius could be double or even more, depending on the antenna system, the type of terrain

and the timing advance. [1]

GSM was designed with a moderate level of service security. The system was

designed to authenticate the subscriber using a pre-shared key and challenge-response.

21

Communications between the subscriber and the base station can be encrypted. The

development of UMTS introduces an optional Universal Subscriber Identity Module

(USIM), that uses a longer authentication key to give greater security, as well as mutually

authenticating the network and the user – whereas GSM only authenticates the user to the

network (and not vice versa). The security model therefore offers confidentiality and

authentication, but limited authorization capabilities, and no non-repudiation.

The GSM network is structured into a number of discrete sections:

The Base Station Subsystem (the base stations and their controllers).

The Network and Switching Subsystem (the part of the network most similar to a

fixed network). This is sometimes also just called the core network.

The GPRS Core Network (the optional part which allows packet based Internet

connections).

The Operations support system (OSS) for maintenance of the network.

The ETSI GSM 07.05 (3GPP TS 27.005) specifies AT style commands for

managing the SMS feature of GSM.

AT commands instructions used to control a modem. AT is the abbreviation of

ATtention. Every command line starts with "AT" or "at". That's why modem commands

are called AT commands. Many of the commands that are used to control wired dial-up

modems, such as ATD (Dial), ATA (Answer), ATH (Hook control) and ATO (Return to

online data state), are also supported by GSM/GPRS modems and mobile phones.

Besides this common AT command set, GSM/GPRS modems and mobile phones support

an AT command set that is specific to the GSM technology, which includes SMS-related

commands like AT+CMGS (Send SMS message), AT+CMSS (Send SMS message from

storage), AT+CMGL (List SMS messages) and AT+CMGR (Read SMS messages). [1]

4.9 COSM

Cosm (formerly Pachube (pronounced Patch bay)) is an on-line database service

allowing developers to connect sensor-derived data to the Web and to build their own

applications based on that data. Cosm is a secure, scalable platform that connects devices

and products with applications to provide real-time control and data storage. Cosm's

provisioning service allows end users to pair their device with applications to control it or

use its data. Cosm web service that enables you to store, share & discover real-time

sensor, energy and environment data from objects, devices & buildings around the world.

22

The key aim is to facilitate interaction between remote environments, both

physical and virtual. Apart from enabling direct connections between any two responsive

environments, it can also be used to facilitate many-to-many connections: just like a

physical "patch bay" (or telephone switchboard). Cosm manages millions of data points

per day from thousands of individuals, organizations & companies around the world.

Pachube stores, converts & serves data in multiple data formats, which makes it

interoperable with both established web protocols & existing construction industry

standards. [5]

Cosm allows users to:

1. Embed real-time graphs & widgets in their website.

2. Analyse & process historical data pulled from any public Cosm feed.

3. Send real time alerts from any data stream to control your scripts, devices &

environments. Out-of-the-box configurable tools include a zoomable graph, a

mapping/tracking widget, an augmented reality viewer, SMS alerts & apps for

various smartphones.

4. Build mobile & web apps that create value: With a rapid development cycle &

dozens of code examples & libraries, Cosm's 'physical-to-virtual' API makes it

possible to build applications that add value to networked objects &

environments.

5. Share data & create communities: Cosm is built to encourage open ecosystems.

Examples: electricity meters, weather stations, building management systems, air

quality monitors, biosensors, Geiger counters.

Cosm is not just a social networking project for sensor data. Cosm evolved out three

strands of thought:

1. The geographical non-specificity of architecture these days as people live their

lives in constant connection with people in remote spaces.

2. A desire to open up the production process of ―smart homes‖ in reaction to

current trends for placing the design and construction process solely in the hands

of knowledgeable others.

Cosm makes use of CSV and JSON, as well as of Extended Environments Mark-

up Language (EEML), which extends the construction industry protocol IFC. An

extensive RESTful API makes it possible to both serve and request data in all formats.

Data can be pushed to Pachube using an HTTP PUT request (especially useful for those

operating behind firewalls or with non-static URLs). [5]

23

Chapter 5

DESIGN OF WORK

5.1 BLOCK DIAGRAM OF THE CIRCUIT

RX TX

SPI

Pacing pin

Fig 5.1 iPacemaker Block Diagram

5.2 BLOCK LEVEL TREATMENT

5.2.1 ECG Acquisition circuit

Fig 5.2 ECG Acquisition Block

This stage is used to acquire the ECG signal from the body using electrodes. It

consists of an instrumentation amplifier stage used to provide an initial gain to the signal

& is made using IC AD620. One of features of the AD620 instrumentation amplifier is

low current noise, this benefit allows its use in the Electrocardiography (ECG) monitors.

GSM MODULE

ECG ACQUISITION

QRS DETECTION CIRCUIT

PRECISION

RECTIFIER

BANDPASS

FILTER

ARUDUINO WIFI

SHIELD

THRESHOLD SET

BANDPA

SS

SIMLOCK

K

UART SIM300

MODEM

LED

MICROCONTROLLER

XTAL

OSC

INPUT

PORT/ADC SPI

OUTPUT

PORT

AVR

EEPROM

USART

SPI FLASH EEPROM

POWER

SUPPLY

WLAN

SIP

AT16 CONTROLLER

SLAVE

SELECT

FIRMWARE UPDATE

PORT

STATUS

LED

ICSP PROGRAMMER

INSTRUMENTATION

AMPLIFIER

SECOND ORDER

LOWPASS FILTER

SECOND ORDER

HIGHPASS FILTER

Instrumentation

Amplifier Low Pass Filter

Amplifier

High Pass Filter

24

AD620 can improve the dynamic range for better performance when low bias current and

low current noise coupled with the low voltage noise. It is followed by low pass and high

pass filter which is used to remove 50 Hz power line interference & other unwanted noise

from the signal.

Fig 5.3 ECG acquisition circuit

5.2.1.1 Instrumentation Amplifier

Fig 5.4 Instrumentation amplifier

ECG waveform is an important source for person‘s health, such that atrial

fibrillation can be detected by distortion in the p wave. Thus for correct evaluation of the

persons ECG, a precise device is needed to make the measurement misinterpretations

may prove fatal. For this reason the gain should be enough to make the signal observable,

however, it should be not large enough to saturate the devices. The following diagram

shows the internal diagram of AD620 which is useful in deriving the gain of the

instrumentation amplifier.

25

Fig 5.5 AD620 internal diagram

AD620 as seen in fig 5.12 is made of three operational amplifiers. The resistances

are precise thus it has great CMRR and can be used in commercial circuits. The resistance

between the two inverting inputs of the input operational amplifiers is called as Rg.

The resistance Rg defines the gain of the instrumentation amplifier such that for

the input stage of the differential amplifier the differential gain is:

GD = (1+2 R2 /RG)

The lowest gain possible with the above circuit is obtained with RG completely

open (infinite resistance), and that gain value is 1.

For the total gain of the devices one can refer to the look up table given below.

Table 2 Standard values of gain for AD620

Features of AD620

The AD620 is a low cost, high accuracy instrumentation amplifier that requires only one

external resistor to set gains of 1 to 1000. Furthermore, the AD620 features 8-lead SOIC

and DIP packaging that is smaller than discrete designs, and offers lower power (only 1.3

mA max supply current), making it a good fit for battery powered, portable (or remote)

applications.

26

1. Excellent DC performance

2. Low noise

3. Excellent AC specifications

The pin out of AD620 is given in the figure below.

Fig 5.6 AD620 pin out

Design

Gain= 200

From the above table,

Standard value RG = 200 Ω ~ 220 Ω

5.2.1.2 Low pass Filter

A low pass filter is an electronic circuit that passes low frequency signals but

attenuates (reduces the amplitude of) signals with frequencies higher than the cut-off

frequency. The actual amount of attenuation for each frequency varies from filter to filter.

It is sometimes called a high-cut filter, or treble cut filter when used in audio applications.

Normally we using second order low pass filter for eliminating noise from the ECG

signal. As with low-pass filters, high-pass filters have a rated cut-off frequency, above

which the output voltage increases above 70.7% of the input voltage. The capacitive high-

pass filter's cut-off frequency can be found with the formula.

F cut off = 1/2πRC

27

Fig 5.7 Low pass filter

The low pass filter and subsequent stages are designed using op-amp IC LM741.

Features of LM741

The LM741 series are general purpose operational amplifiers which feature

improved performance over industry standards like the LM709.

1. Over load protection on input and output.

2. No latch-up when the common-mode range is exceeded.

The pin out of LM741 is given in the figure below.

Fig 5.8 LM741 pin out

Design

Second Order Low Pass Filter

f= 1/(2πRC)

Let f= 20 HZ, C= 0.1 µF

R=1/(2πfC)= 1(2*3.14*20*0.1*10)= 83.69k~ 82k

Let gain= 1

28

1+Rf/R1= 1

Rf/R1= 0

Let Rf = 0k

Therefore cut off frequency become 20 HZ

5.2.1.3 High Pass Filter

Fig 5.9 High pass filter

The High Pass Filter is the exact opposite to the low pass filter. This filter has no

output voltage from DC (0Hz), up to a specified cut-off frequency (ƒc) point. This lower

cut-off frequency point is 70.7% or -3dB (dB = -20log Vout/Vin) of the voltage gain

allowed to pass. The High pass filter is pulled up to Vcc. The frequency range "below"

this cut-off point is generally known as the Stop Band while the frequency range "above"

this cut-off point is generally known as the Pass Band. The cut-off frequency or -3dB

point can be found using the formula,

ƒc = 1/(2πRC)

The phase angle of the output signal at ƒc is +45. Generally, the high pass filter is

less distorting than its equivalent low pass filter. High pass filter provides better operating

capabilities of IC and elimination of DC drift from ECG signal due to noise, motion

artefacts etc.

Design

Second Order High Pass Filter

f= 1/2π (R2R3C2C3)1/2

Let C2= C3= 100µF

f= 1 HZ

29

R2= R3= R

1= 1/2*3.14*R*100*10 ^ - 6

R = 2.361 kΩ ~ 2.2 kΩ

Therefore cut off frequency become 0.8 HZ

5.2.1.4 Intermediate stage amplifier

Full gain cannot be provided in instrumentation amplifier stage or filter stages.

Therefore it is necessary to provide a gain stage to provide proper amplification to signal.

A gain = 1 + RF / Rin

Fig 5.10 Gain stage

Design

Let gain= 3.5

1+Rf/R1= 3.5

Rf/R1= 2.5

Let Rf = 5.6k

Then R1= 2.2k

5.2.2 QRS Detection Block

Fig 5.11 QRS Detection Block

Band-pass Filter Precision Rectifier Peak Detector &

Comparator

30

This stage is used to detect the QRS complex in an ECG signal. It consist of a

Band-pass filter of centre frequency 17 Hz & bandwidth 6 Hz to separate QRS complex

from the ECG signal. A precision rectifier that follows rectifies the negative half cycle.

This is followed by a peak detector and a comparator. The threshold of QRS is set to 1/3rd

of its own value by a voltage divider. These circuits are all made using IC LM324.

Fig 5.12 QRS detection circuit

Features of LM324

LM324 is a low power quad operational amplifier, it has these features:

1. Internally frequency compensated for unity gain

2. Large DC voltage gain 100 dB

3. Wide bandwidth (unity gain) 1 MHz (temperature compensated)

4. Wide power supply range: Single supply 3V to 32V.

5. Very low supply current drain (700 μA)-essentially independent of supply voltage

6. Low input biasing current 45 nA (temperature compensated)

7. Low input offset voltage 2 mV and offset current: 5 nA

8. Input common-mode voltage range includes ground

9. Differential input voltage range equal to the power supply voltage

10. Large output voltage swing 0V to V+ – 1.5)

The pin out of LM324 is given in the figure below.

31

Fig 5.13 LM324 pin out

5.2.2. 1 Band-pass filter

A band-pass filter is a circuit which is designed to pass signals only in a certain

band of frequencies while attenuating all the bands outside it. The important parameters

to be considered in a band-pass filter are high & low cut off frequency (fh&fl), the

bandwidth (BW), the center-frequency (fc), center frequency gain & selectivity or Q.

A narrow band-pass filter with multiple feedbacks is used here.

Fig 5.14Bandpass circuit

Design

R3=Q/2πfcCAf

Bandwidth=6 hz

Fc=17 hz

Af=2

Let C5=C6=C7=C=.1µf

Q=fc/BW=2.83

32

R3=132.6kΩ= 150kΩ

R9=Q/2πfcC(2Q2-Af)=18kΩ

R4= Q/πfcC=530kΩ

5.2.2.2 Precision Rectifier

The precision rectifier, which is also known as a super diode, is a configuration

obtained with an operational amplifier in order to have a circuit behaving like an ideal

diode and rectifier. It can be useful for high-precision signal processing.

Fig 5.15 Precision rectifier

An alternative version is given on the right. In this case, when the input is greater

than zero, D3 is OFF and D1 is ON, so the output is zero because one side of R6 is

connected to the virtual ground, and there is no current through it. When the input is less

than zero, D3 is ON and D1 is OFF, and the output is like the input with an amplification

of –R6/R5.

This circuit has the benefit that the op-amp never goes into saturation; but its output must

change by two diode voltage drops (about 1.2V) each time the input signal crosses zero,

so the slew rate of the operational amplifier, and its frequency response (gain-bandwidth

product) still limit high frequency performance; especially for low signal levels -

although an error of less than 1% at 100kHz is possible.

5.2.2. 3 Peak Detector & Comparator

Peak detector is used for detecting peak levels of a signal. In the following circuit

a capacitor keeps the peak voltage level of the signal; optionally, a switch can be used for

resetting the detected level.

33

Fig 5.16 Peak Detector and Comparator circuit

Comparator used as a threshold detector, to detect heart beat event executed by

the heart and generate a pulse with each QRS wave. Comparator is used compare a

reference voltage of 1/3v of QRS with output of precision rectifier. If it exceeds the

reference voltage then comparator will drive the microcontroller such that no pacing sign.

5.2.3 Processing and Pacing Circuitry

Fig 5.17 Processing and Pacing Circuitry

This section mainly includes two microcontrollers with headers for connection

with the GSM and Wi-Fi module.

First microcontroller is the central processing device for controlling the Wi-Fi and

GSM module and providing parameters to the second microcontroller. The GSM Module

(SIM300) is interfaced with the microcontroller through UART (Rx & Tx) and the Wi-Fi

module interfaced through SPI containing SCK,MOSI,MISO,SS pins etc. The second

microcontroller is used exclusively for pacing. This helps in removing any interruption

caused during pacing due to device hangs, or when the microcontroller is busy with

34

transferring website or controlling GSM device etc. The power consumed is only a little

by using Atmega microcontrollers.

5.2.4 Arduino Wi-Fi Shield

The Arduino Wi-Fi Shield allows an Arduino platform developed device to

connect wirelessly using the 802.11 wireless specifications (Wi-Fi). It is based on the

HDG104 Wireless LAN 802.11b/g System in-Package. An Atmega 32UC3 provides a

network (IP) stack capable of both TCP and UDP. Wi-Fi library helps to write sketches

which make connections using the shield.

The Wi-Fi Shield can connect to wireless networks which operate according to the

802.11b and 802.11g specifications.

There is an on-board micro-SD card slot, which can be used to store files for

serving over the network. The on-board micro SD card reader is accessible through the

SD Library. When working with this library, SS is on Pin 4. Use the Wi-Fi library to

write sketches which connect to the internet using the shield. The Wi-Fi shield connects

to an Arduino board using long wire-wrap headers which extend through the shield. This

keeps the pin layout intact and allows another shield to be stacked on top. [5]

Features:

Connection via: 802.11b/g networks

Encryption types: WEP and WPA2 Personal

On-board micro SD slot

FTDI-style connection for serial debugging of Wi-Fi shield

Micro-USB for updating the Wi-Fi shield firmware

Open source firmware making it possible to add new protocols directly on the

shield.

The Wi-Fi Shield communicates with Arduino using the SPI bus (through the

ICSP header), so is compatible with any of the boards that have this type of bus.

ICSP headers.

Integrated antenna on the PCB.

Operating voltage 5V (supplied from the Arduino Board).

Use as a standalone Wi-Fi connected microcontroller.

35

Fig 5.18 Arduino Wi-Fi shield

36

Our device communicates with the Wi-Fi shield's processor using the SPI bus

(through the ICSP header). HDG104 and SD card share the SPI bus, only one can be

active at a time. Since both peripherals are used in our program, we used corresponding

libraries to take care of SPI sharing problems. The shield can connect to encrypted

networks that use either WPA2 Personal or WEP encryption or an open connection. On-

board Mini-USB connector can be used for updating the Atmega 32U using the Atmel

DFU protocol. The programming jumper adjacent to the power bus and analog inputs

should be left unconnected for typical use. It is only used for DFU programming mode.

An on-board FTDI connection enables serial communication with the 32U for debugging

purposes.

The shield contains a number of informational LEDs:

L9 (yellow): this is tied to digital pin 9

LINK (green): indicates a connection to a network

ERROR (red): indicates when there is a communication error

DATA (blue): indicates data being transmitted/received

5.2.5 GSM Module (SIM 300)

The GSM Module allows an Arduino board to connect to the internet,

make/receive voice calls and send/receive SMS messages. The shield uses a radio modem

M10 by Quectel. It is possible to communicate with the board using AT commands.

The GSM library has a large number of methods for communication with the shield.

The module uses digital pins 2 and 3 for software serial communication with the

M10. Pin 2 is connected to the M10‘s TX pin and pin 3 to its RX pin. [1]

SIM300 is a Tri-band GSM/GPRS engine that works on frequencies EGSM 900

MHz, DCS 1800 MHz and PCS1900 MHz SIM300 provides GPRS multi-slot class 10

capabilities and support the GPRS coding schemes CS-1, CS-2, CS-3 and CS-4. It has a

tiny configuration of 40mm x 33mm x 2.85 mm. The important features are the keypad

and SPI LCD interface, two serial ports and two audio channels.

SIM300 provide RF antenna interface with two alternatives: antenna connector

and antenna pad. The antenna connector is MURATA MM9329-2700. The SIM300 is

designed with power saving technique, the current consumption to as low as 2.5mA in

SLEEP mode. The SIM300 is integrated with the TCP/IP protocol; Extended TCP/IP AT

37

commands are developed for customers to use the TCP/IP protocol easily, which is very

useful for those data transfer applications.

The shield supports AIN1 and AOUT1 as audio interfaces; an analog input

channel and an analog output channel. The input, exposed on pins MIC1P/MIC1N, can be

used for both microphone and line inputs. An electret microphone can be used for this

interface. The output, exposed as lines SPK1P/SPK1N, can be used with either a receiver

or speaker. Through the modem, it is possible to make voice calls. In order to speak to

and hear the other party, you will need to add a speaker and microphone.

The SIM300 is designed with power saving technique, the current consumption to

as low as 2.5mA in SLEEP mode. [1]

Specifications:

Available with SIM 300 and SIM 900 GSM/GPRS engine.

Can be interfaced via RS 232 as well as TTL.

Operates on 7-9 Volts AC or 9-12 Volts DC Power.

Current Consumption: 250mA in normal operation may go to 2 Amps while

transmission.

Supports Voice, Data/Fax, SMS, GPRS and integrated TCP/IP stack.

Supports AT commands (GSM 07.07, 07.05 and enhanced AT commands).

Pin out for RS 232 Tx/Rx, TTL Tx/Rx, VCC, GND, MIC, Speaker, Power On,

and RTC.

Can configure Serial port baud rate between 1200 and 115200 bps (9600 default).

All software version based on V10.0.

The SIM300 don‘t provide the reset pin.

When customer use SIM300 audio function, don‘t need use MIC bias. It may

reduce the customer‘s BOM. The speaker‘s circuit is same as SIM100S.

Interfaces:

RS-232 Interface with Hardware Flow Control support. (5 signals - TX, RX, RTS,

CTS & GND through D-type 9 connector).

Serial port baud rate adjustable 1200 to115200 BPS.

4 pin 0.1" connector for Speaker & Mic connection.

8-pin flip type reliable SIM card holder.

DC socket for Power Adapter.

38

Rubber Duck GSM antenna or Magnetic Mount Antenna with approx. 3 metre

cable.

LED status for Power, Signal and Incoming Call.

Fig 5.19 SIM300 GSM Module

5.3 PCB DESIGN

The software used for PCB design is DIPTRACE. The program consists of four

main modules: Schematic Capture, PCB Layout, Component Editor and Pattern Editor.

Schematic and PCB design modules have number of verification features that help

control project accuracy on different design stages: The ERC function shows possible

errors in Schematic pin connections using defined rules and allows you to correct errors

step-by-step. DRC function checks the clearance between design objects, minimum size

of traces, and drills. Errors are displayed graphically and we can fix them step-by-step

and rerun the DRC in one click after any corrections. Net Connectivity Check verifies if

all nets of PCB are electrically connected. This feature uses traces; copper pour filled area

and shapes to control connectivity, then reports broken and merged nets with area details.

Comparing to Schematic allows you to check if routed PCB is identical with Schematic.

39

5.3.1 Circuit Array containing Pacing, Processing and QRS Detection

It is a single sided PCB with efficient placing of ICs for small size and reduced

track-length. The track width is 0.03 inch. Elliptical pads have been laid with diameter of

pads 0.07 inch and 0.088 inch. Tracks have angles of 45 degree or so (never 90 degree).

Fig 5.20 PCB for pacing, processing and QRS detection

5.3. 2 ECG Acquisition Circuit

PCB design has the similar design conditions with the previously described PCB.

Fig 5.21 ECG Acquisition Circuit

40

5.4 FLOW CHART OF DEVICE SOFTWARE

5.4.1 Flow chart of pacing circuit

Fig 5.22 Flow chart of pacing circuit

Delay within

refractory

period

Output pin

made high

Output signal

made low

Accept pacing

parameters

Delay =

pacing width

If

mode=1

If

mode=3

If

mode=

2

If

spontaneou

s signal

present

If signal

present

?

Yes

No

Yes

No

Yes

No

No

Yes

No

Yes

Cycle time = pacing interval

41

5.4.2 Flow chart of communication circuit

42

5.5 USER INTERFACE

The user interface, in the industrial design field of human–machine interaction, is

the space where interaction between humans and machines occurs. The goal of this

interaction is effective operation and control of the machine on the user's end, and

feedback from the machine, which aids the operator in making operational decisions.

The End-User interaction with the iPacemaker happens through HTML pages

embedded in the micro-controller. There are four pages available for the user to interact

with iPacemaker by monitoring and changing parameters. The four pages are Home page,

Settings page, Live ECG, and Data log. Detailed descriptions about the pages are given

below. The tabs above the web page allows to select different pages in the web interface.

5.5.1 Home page

Home page gives complete information about the pacemaker which includes both

general and technical information.

Fig 5.24 Home page

The General information includes patient name, age, hospital where pacemaker is

implanted, consulted doctor etc. Moreover, various technical details about the pacemaker

such as pacing rate, pacing voltage, pacing width, pacing voltage etc. Battery status

demands much relevance among technical parameters.

43

5.5.2 Settings page

Settings page can be used to change various parameters of the implant pacemaker.

The figure below shows the settings page used to vary parameters of the pacemaker.

Fig 5.25 Settings page

The variable parameters inside the pacemaker includes pacing mode, voltage of

pacing, pacing rate, pacing width, refractory period etc. If the parameters fall outside the

valid limit, then they are automatically reverted to original value. The values are reflected

inside microcontroller through GET request.

5.5.3 Live ECG

The Live ECG is an important part of this project. The Live ECG allows real-time

monitoring of ECG all over the world by logging in into COSM interface. COSM allows

pushing and pulling XML, JSON and CSV data to secure and scalable RESTful API and

socket-server for bi-directional interaction between devices and the web. Since only

relevant data is sent, only low bandwidth internet connection is required.

44

Fig 5.26 Live ECG

The debugging mode in COSM interface helps to check connection with device.

The facility to locate the device is already inherent in the interface.

5.5.4 Data log

Data logging helps in viewing already logged data in the SD card. The Data is

logged whenever doctor changes any parameter or critical events are detected.

Fig 5.27 Data log

RTC helps in logging data with time information.

45

Chapter 6

IMPLEMENTATION

6.1 System Requirements

Two disposable surface electrodes

Battery

Central controller board

Wi-Fi module

GSM module

6.2 Hardware Requirements

Battery (9v NiMH 48 pack)

Capacity – 2200mAh

Configuration – 3S1P-9v

Peak discharge – 30c

Pack weight – 185g

Lead wire should be insulated

Filters are provided for extracting QRS complex

Same power source for Wi-Fi, GSM and Central board

6.3 Software Requirements

Arduino ICSP programmer

Arduino 1.03

UART to Serial cable for debugging.

46

47

6.4 Testing and results

Different stages of the circuit and their implementation was shown below. The

ECG acquisition circuit with AD620 is much small and have greater noise reduction

capabilities. The completed hardware section for ECG acquisition is given below.

Fig 5.29 ECG acquisition hardware

The output from ECG acquisition circuit is given below.

Fig 5.30 Output (ECG) on a CRO

The QRS detection and processing circuitry is done on single pcb with minimum

distance among components for smaller pcb. All sections work on single supply of +5V.

Fig 5.31 QRS detection and processing hardware

The output from the QRS detection and corresponding pacing based on mode is

given below.

48

Fig 5.32 QRS pulse and corresponding pacing based on mode

The web interface (software-section) works normally without any bugs on many

commonly used browsers such as firefox, chrome etc. No noticeable security issues were

found.

49

Chapter 7

CONCLUSION

In short, our project aims at developing an implantable pacemaker which can be

tailor made for different patients as it provides option for re-programmability. The Wi-Fi

alliance compliant hardware supports almost every other wireless device to successfully

establish connection with the device. The Embedded Web-Server replaces the existing

technologies in pacemakers improving the flexibility of programming in a great way.

User friendly interface allows doctor to view patient information, change device values,

view logging etc., with much ease. GSM facilities have been provided for checking

parameters and changing it in remote areas where Wi-Fi absent, helping in Telemetry.

The State-of-Art technology was tested on debugging mode with serial interface

by wirelessly connecting remote computers and reported no bugs. The pacing circuit

works without any interruption and only minute offsets occur in pacing frequency which

can be ignored with confidence.

50

Chapter 8

FUTURE WORKS

The continued innovation in programmability and telemetry is paving way for

improving diagnostic capabilities of pacemakers. Systems are developing which can

facilitate storing of patient details and which can diagnose rhythm disturbances using

sophisticated algorithms. Sensors will be combined with electro-gram analysis to

differentiate between physiological and pathological alterations in hemodynamic in such

a way that appropriate adjustments can be initiated.

Imparting some amount of intelligence in pacemakers is one way of improving the

life conditions of cardiac patients. The daily activities including even lifting of arm

produce a cardiac output. It is recommended that the pacemaker is adjusted accordingly

to accommodate these body movements, so that the pacemaker‘s rate will match the

body‘s activity. [1]

Other suggestion for improving pacemakers is to allow them to be compatible

with large magnetic fields. A patient needs to avoid large magnetic fields as they can

cause pacemakers to reprogram its computer settings. One magnetic field that must be

avoided is magnetic resonance imaging (MRIs). MRIs are the gold standard for medical

imaging and current patients with pacemakers are unable to have a MRI. MRI compatible

pacemakers are now on development process. [2]

A development of much wider interest expected in the area is the implementation

of specific MAC protocols for medical devices. This can considerably reduce the power

consumption by the pacemakers by implementing specific modes like sleep mode, alarm

modes and by resorting to specialised network topology. Power efficiency is an important

requirement especially for a lifesaving implantable device working on battery.

The most innovative future technology in pacemakers is the ‗use of heart beats to

power pacemakers‘. The "energy-harvesting" device would run on piezoelectricity or

electricity by motion, and would require little power to operate. Researchers measured

induced vibrations in the chest. They then used a "shaker" to reproduce the vibrations in

the laboratory and connected it to a prototype cardiac energy harvester they developed.

Measurements of the prototype's performance, based on a wide range of simulated

heartbeats, showed the energy harvester generated more than 10 times the power required

by modern pacemakers.

51

REFERENCES

[1] Louis S.Y.Wong, Shohan Hossain, Andrew Ta, Jorgenb Edvinsson, Dominic H.Rivas,

Hans Nass, ―A very low power CMOS mixed signal IC for implantable pacemaker

applications‖, in IEEE journal of solid state circuits,Vol.39,No.12 December

2004,pp.2446-2455.

[2] Wikipedia, http://www.wikipedia.org

[3] Nikolaos Kavvadis, Periklis Neofotistos, Spiridon Nikolaidis,C.A. Kosmatopoulos

,Theodore Laopoulos, ―Measurement Analysis of the software related power consumption

in Microprocessors,‖ in the proc. of IEEE transaction on instrumentation and

measurement, Vol. 53,No.4,August 2004.

[4] Vivek Tiwari, Sharad Malik, Andrew Wolfemike, Tien Chien Lee, ―Instruction level

power analysis and optimization software,‖ in proc.of 9 The international conference on

VLSI design,‖ January 1996.pp.326-328

[5] Arduino open-source, http://www.arduino.cc

[6] Richard S. Sanders, Michel T. Lee, ―Implantable pacemakers,‖ in proc. of IEEE,

Vol.84, No.3, March 1996.pp.480-486.

52

APPENDIX-A

PROGRAM – COMMUNICATION

/*************************************************************

IPACEMAKER- MICROCONTROLLER1

By ladvine,dileep,eldho,nidhish

*************************************************************/

#include <SPI.h>

#include <WiFi.h>

#include <SD.h>

char ssid[] = "iPacemaker"; // Network SSID

char pass[] = "bombay123"; // Pass key

int status = WL_IDLE_STATUS; // the Wifi radio's

WiFiServerserver(80);

File myFile;

booleanHe_firsttime = true;

booleanHo_firsttime = true;

booleanSe_firsttime = true;

unsigned long lastConnectionTime = 0; // last time in mS

booleanlastConnected = false; //last connection time

const unsigned long postingInterval = 10*100; //delay of updates

void setup()

Serial.begin(9600); // GSM "Baud Rate"

Serial.print("Initializing SD card...");

pinMode(10, OUTPUT);

pinMode(4, OUTPUT);

digitalWrite(10, HIGH);

53

digitalWrite(4, HIGH);

delay(30);

if (!SD.begin(4))

Serial.println("initialization failed!");

else Serial.println("initialization done.");

if (WiFi.status() == WL_NO_SHIELD)

Serial.println("WiFi shield not present");

while(true); // don't continue

// attempt to connect to Wifi network:

while ( status != WL_CONNECTED)

Serial.print("Attempting to connect to Network named: ");

Serial.println(ssid); // print the network name (SSID);

status = WiFi.begin(ssid,pass);

delay(1000);

server.begin(); // start the web server on port 80

IPAddressip = WiFi.localIP();

Serial.print("IP Address: ");

Serial.println(ip); // you're connected now, so print ip address

/*************************************************************/

void loop()

WiFiClient client = server.available(); // listen for incoming clients

if (client)

54

Serial.println("new client");

String currentLine = ""; / / make a String to hold incoming data

String para = "";

String Smode= "";

String Svolt= "";

while (client.connected())

if (client.available())

char c = client.read(); // read a byte, then

Serial.write(c); // print it out the serial monitor

if (c == '\n')

// if the byte is a newline character

if(currentLine.length() == 0)

if((He_firsttime==true))

He_firsttime=false;

myFile = SD.open("Header1.txt");

while (myFile.available())

client.write(myFile.read());delay(2);

myFile.close();

client.println();

break;

55

else

currentLine = "";

else if (c != '\r')

currentLine += c; // add it to the end of the Line

if((currentLine.endsWith("GET /?link=1 HTTP/1.1"))&&(Ho_firsttime==true))

// HOME PAGE

Ho_firsttime=false;

myFile = SD.open("home.txt");

while (myFile.available())

client.write(myFile.read());delay(2);

myFile.close();

if((currentLine.endsWith("GET/?link=2HTTP/1.1")&&(Se_firsttime==true))

// SETTINGS PAGE

Se_firsttime=false;

myFile = SD.open("settings.txt");

while (myFile.available())

56

client.write(myFile.read());delay(2);

myFile.close();

if (currentLine.endsWith("GET /?link=3 HTTP/1.1"))

// LIVE ECG using COSM

WiFiClient client;

IPAddressserver(216,52,233,121);

while(1)

intecg = analogRead(A2);

if (!client.connected() &&lastConnected)

Serial.println();

Serial.println("disconnecting.");

client.stop();

if(!client.connected()&&(millis()lastConnectionTime>postingInterval))

if (client.connect(server, 80))

Serial.println("connecting...");

myFile = SD.open("home.txt");

while (myFile.available())

client.write(myFile.read());delay(2);

57

myFile.close();

client.print("sensor1,");

client.println(ecg);

else

Serial.println("connection failed");

Serial.println();

Serial.println("disconnecting.");

client.stop();

lastConnectionTime = millis();

lastConnected = client.connected();

if((currentLine.startsWith("GET/?Pa"))&&(currentLine.endsWith("Submit1=save

")))

// HOME PAGE

para=currentLine;

Smode=para.substring(16,17);

if(Smode.equals("1"))analogWrite(A0,1);

if(Smode.equals("2"))analogWrite(A0,2);

if(Smode.equals("3"))analogWrite(A0,3);

Serial.println();

58

Serial.println(Smode);

Svolt=para.substring(26,27);

if(Svolt.equals("1"))analogWrite(A1,1);

if(Svolt.equals("2"))analogWrite(A1,2);

if(Svolt.equals("3"))analogWrite(A1,3);

if(Svolt.equals("4"))analogWrite(A1,4);

if(Svolt.equals("5"))analogWrite(A1,5);

Serial.println(Svolt);

Serial.println(para.substring(36,39));

Serial.println(para.substring(56,59));

// close the connection

client.stop();

Serial.println("client disonnected");

59

APPENDIX-B

PROGRAM – PACING

constint QRS = 7;

constint Pin = A0; // the pin where pacing occurs

intPinState = 0; // initial pacing state

unsigned long flag=0;

longpreviousMillis = 0; // will store last time of pacing

longcurrentMillis;

intQRSv;

/****************************************************************/

int mode=3; // 1.NORMAL 2.VENT INHIBITED 3.VENT TRIGGERED

int volt=5; // Pacing Voltage

intrfpd=150; // Refractory period

/*****************************************************************/

void pacing(unsigned long interval1,unsigned long interval2)

if((currentMillis - previousMillis> interval1)&&(PinState == 0))

previousMillis = currentMillis;

PinState = volt;

analogWrite(Pin, PinState);

currentMillis = millis();

if((currentMillis - previousMillis> interval2)&&(PinState == volt))

previousMillis = currentMillis;

PinState = 0;

analogWrite(Pin, PinState);

60

/*************************************************/

void setup()

pinMode(QRS,INPUT);

volt = map(volt,0,5,0,255);

Serial.begin(9600);

/*************************************************/

void loop()

mode=analogRead(A1);

volt=analogRead(A2);

Serial.println(mode);

Serial.println(volt);

if(mode==1)

pacing(835,5); //NORMAL PACING

else

QRSv=0;

flag=millis();

while (QRSv==0)

61

QRSv=digitalRead(QRS);

if((millis()-flag)>900)pacing(835,5);

if(mode==3)

delay((120%rfpd)); //VENTRICULAR TRIGGERED

PinState = volt;

analogWrite(Pin, PinState);

delay(5);

PinState = 0;

analogWrite(Pin, PinState);

62

APPENDIX-C

HTML PAGE – HOME

HTTP/1.1 200 OK

Content-Type: text/html

Connection: close

<! DOCTYPE HTML>

<! doctype>

<html>

<body style="background-color: #C0C0C0; height: 82px;">

<h1 class="auto-style1">iPACEMAKER</h1>

<form method="get" class="auto-style3 >

<button name="link" style="width: 56px" value="1">HOME</button>

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;

<button name="link" style="width: 75px" value="2"> SETTINGS</button>

<button name="link" style="width: 69px" value="3">&nbsp; LIVE ECG</button>

<button name="link" style="width: 69px" value="4‖>DATA LOG</button></form>

<br />

<fieldset name="Group1" style="background-color: #CCCCCC">

<legend class="auto-style2"><strong><em>Summary</em></strong></legend>

&nbsp;&nbsp;&nbsp;<strong><br>&nbsp; NAME &nbsp;&nbsp; Shijin

Bose<br><br>&nbsp;&nbsp;&nbsp;<strong>AGE&nbsp;&nbsp;&nbsp;

:&nbsp;&nbsp;&nbsp; </strong>

22<strong><br><br>&nbsp;&nbsp; HOSPITAL&nbsp; :&nbsp; </strong>Medical Trust

Hospital, Cochin<strong><br><br>&nbsp; CONSULTED DOCTOR</strong> Dr.

63

MANU VARMA<strong>&nbsp; <em><span class="auto-style6" MBBS,MD,DM

(+918645645231)</span></em><br />PACING RATE&nbsp; : </strong>72

bpm<strong><br><br>PACING MODE&nbsp; : </strong>Ventricular -

Inhibited<br><br><strong>&nbsp; PACING VOLTAGE&nbsp; : </strong>3

volts<strong><br><br>&nbsp; REFRACTORY PERIOD&nbsp; : </strong>835

ms&nbsp;<strong><br><br>&nbsp; PULSE WIDTH&nbsp;&nbsp; : </strong>3

ms<strong><br></strong>

<br /></fieldset></body></html>

64

APPENDIX-D

HTML PAGE – SETTINGS

HTTP/1.1 200 OK

Content-Type: text/html

Connection: close

<!DOCTYPE HTML>

<!doctype>

<html><body style="background-color: #C0C0C0; height: 82px;">

<h1 class="auto-style1">iPACEMAKER</h1>

<form method="get" class="auto-style3">

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;

<button name="link" style="width: 56px" value="1">HOME</button>

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;

<button name="link" style="width: 75px" value="2"> SETTINGS</button>

<button name="link" style="width: 69px" value="3">LIVE ECG</button>&nbsp;

<button name="link" style="width: 69px" value="4">;DATA LOG</button>

</form>

<form method="GET"><div class="auto-style4"> PACING MODE:&nbsp;

<select name="Pacinmode">

<option selected="selected" value="1">FIXED RATE</option>

<option value="2">R-WAVE INHIBITED</option>

<option value="3">R-WAVE TRIGGERED</option>

</select><br />

65

PACING VOLTAGE:&nbsp;

<input class="auto-style3" name="pacingv" style="width: 28px" type="text" value="3"

/> (0-5 v)<br />

PACING RATE:&nbsp;&nbsp;

<input name="pacingr" style="width: 29px" type="text" value="835" /> ms<br />

PULSE WIDTH:&nbsp;&nbsp;

<input name="pulsew" style="width: 27px" type="text" value="3" /> ms<br />

REFRACTORY PERIOD:&nbsp; &nbsp;

<input name="refrpd" style="width: 28px" type="text" value="120" /> ms<br />

GSM ON AIR:&nbsp;&nbsp;

<input checked="checked" name="gsm" type="radio" value="1" />on&nbsp;&nbsp;

<input name="gsm" type="radio" value="0" />off<br />

<br />

<input name="Submit1" style="height: 23px" type="submit" value="save"

/>&nbsp;&nbsp;

<input name="Reset1" style="width: 47px; height: 23px" type="reset" value="reset"

/></div>

</form></body></html>

66

APPENDIX-E

HTML PAGE – DATA LOG

<! DOCTYPE HTML>

<! doctype>

<html>

<body style="background-color: #C0C0C0; height: 82px;">

<h1 class="auto-style1">iPACEMAKER</h1>

<form method="get" class="auto-style3">&nbsp;&nbsp;&nbsp;&nbsp;

<button name="link" style="width: 56px" value="1">HOME</button>

&nbsp;&nbsp;

<button name="link" style="width: 75px" value="2"> SETTINGS</button>

<button name="link" style="width: 69px" value="3"> LIVE ECG</button>

<button name="link" style="width: 69px" value="4">DATA LOG</button>

</form></body></html>