Development of an MRI-compatible ECG...

D I P L O M A T H E S I S

D E V E L O P M E N T O F A N M R I - C O M PAT I B L E E C GS Y S T E M

csaba hajdu

supervisors

Dr Dávid LégrádyBME

Béla MihalikMediso

Budapest University of Technology and EconomicsFaculty of Natural Sciences

Institute of Nuclear TechniquesMay 2012

colophon

This thesis project was executed within the framework of the MedicalPhysics specialization of the Physics MSc course at the Institute ofNuclear Techniques, Faculty of Natural Sciences, Budapest Universityof Technology and Economics.

This document was typeset using the typographical look-and-feelclassicthesis developed by André Miede. The style was inspiredby Robert Bringhurst’s seminal book on typography “The Elements ofTypographic Style”. classicthesis is available for both LATEX and LYX:

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Ö N Á L L Ó S Á G I N Y I L AT K O Z AT ( D E C L A R AT I O N O FI N D E P E N D E N T W O R K )

Kijelentem, hogy jelen szakdolgozat saját munkám eredménye, aztönállóan, nem megengedett segédeszköz igénybevétele nélkül készí-tettem el. A szakdolgozatban csak a megadott forrásokat használtamfel. Minden olyan részt, amelyet szó szerint, vagy azonos értelem-ben, de átfogalmazva más forrásból vettem, egyértelmuen, a forrásmegadásával jelöltem.

Budapest, 2012. május

Hajdu Csaba

A B S T R A C T

Cardiac gating is an important technique used in many differentmodalities of medical imaging to eliminate artifacts resulting fromthe motion of the heart. It is often implemented with the use of anelectrocardiograph (ECG).

This thesis project was executed at Mediso Medical Imaging Sys-tems. The main objective was the development of an ECG systemaimed at cardiac gating, to be used in the pre-clinical (small animal)and clinical (human) imaging devices of the company.

The ECG system is based on a microcontroller and an ECG-specificanalog frontend. Prototype hardware was created using developmentkits and the appropriate firmware was developed. Since the tests car-ried out with the prototype system confirmed the suitability of theconcept, the final hardware was designed. The process is explainedin detail.

Cardiac gating also finds use in Magnetic Resonance Imaging (MRI),but this causes challenges in ECG acquisition. Measurements werecarried out to assess the usability of the prototype system in MRI.These results are also reported.

K I V O N AT

A szívkapuzás fontos technika, amelyet számos különbözo orvosiképalkotó modalitás esetében használnak a szív mozgásából eredomutermékek kiküszöbölésére. A szívkapuzást gyakran elektrokardio-gráf (EKG) használatával valósítják meg.

Ez a diplomamunka a Mediso Orvosi Berendezés Fejleszto és Szer-viz Kft.-nél készült. A fo célja egy szívkapuzásra szolgáló rendszerkifejlesztése volt, a vállalat preklinikai (kisállat) és klinikai (humán)képalkotó készülékeivel való használatra.

Az EKG rendszer egy mikrokontrolleren és egy EKG-specifikus ana-lóg frontend áramkörön alapul. Fejlesztokészletek felhasználásávalprototípus hardvert alkottam, és kifejlesztettem az azon futó szoftvert.A prototípus rendszerrel lefolytatott tesztek alátámasztották, hogy azelképzelés megfelel a célnak, így megterveztük a végleges hardvert.Ezt a folyamatot a dolgozat részletesen leírja.

Szívkapuzást mágneses rezonancia képalkotó berendezésben (MRI-ben) is alkalmaznak, de ebben az esetben kihívást jelent az EKG mé-rése. A prototípus rendszer MRI-ben való használhatóságának vizs-gálatára méréseket hajtottam végre, amelyek leírása szintén szerepela dolgozatban.

A C K N O W L E D G M E N T S

I would like to express my gratitude to all those people who havecontributed to the completion of this project with their assistance andencouragement.

I am extremely grateful to my supervisors, Dr Dávid Légrády andBéla Mihalik for their invaluable support from the first steps of theproject to the very end.

Many thanks to Miklós Czeller for his assistance in writing this the-sis and to Attila Lantos for some truly great ideas that helped me outof tight spots. It is a pleasure to have had a chance to cooperate withSándor Török in the design of the hardware. I really appreciate thehelp of Magor Babos, Sándor Hóbor, Péter Koncz, Domokos Máthéand Zoltán Nyitrai in the organization and execution of small animalECG measurements.

I am grateful to all the colleagues in my office for an inspiringworking environment. I am also very thankful to everyone else atMediso who lended a hand during my work. Special thanks to themanagement of the company for letting me tackle this demandingproject.

Last but not least, this work can only be dedicated to my familyfor the love, support and inspiration they’ve given me all the waythrough.

v

C O N T E N T S

1 introduction 1

1.1 Electrocardiography (ECG) . . . . . . . . . . . . . . . . 1

1.1.1 Physiological background . . . . . . . . . . . . . 1

1.1.2 Recording an ECG . . . . . . . . . . . . . . . . . . 2

1.2 Cardiac gating . . . . . . . . . . . . . . . . . . . . . . . . 3

1.3 ECG in MRI . . . . . . . . . . . . . . . . . . . . . . . . . 4

2 specifications 5

2.1 Specifications of the ECG system . . . . . . . . . . . . . 6

3 prototyping 8

3.1 Choice of architecture . . . . . . . . . . . . . . . . . . . 8

3.1.1 The ADS1298R IC . . . . . . . . . . . . . . . . . . . 9

3.2 The ECG prototype . . . . . . . . . . . . . . . . . . . . . 9

3.2.1 The ADS1258 MDK . . . . . . . . . . . . . . . . . . 9

3.2.2 The ADS1298R ECG FE-PDK . . . . . . . . . . . . . 10

3.2.3 The ECG prototype system . . . . . . . . . . . . . 11

3.3 Firmware development . . . . . . . . . . . . . . . . . . . 12

3.3.1 The firmware of the ADS1258 MDK . . . . . . . . 12

3.3.2 The firmware of the ECG prototype system . . . 14

4 hardware design 20

4.1 Choice of microprocessor . . . . . . . . . . . . . . . . . 20

4.2 Hardware design considerations . . . . . . . . . . . . . 21

4.2.1 Patient protection . . . . . . . . . . . . . . . . . . 22

4.2.2 Power supplies . . . . . . . . . . . . . . . . . . . 22

4.2.3 ECG hardware . . . . . . . . . . . . . . . . . . . . 24

4.2.4 Small animal respiratory measurement . . . . . 25

4.2.5 Microcontroller unit . . . . . . . . . . . . . . . . 26

4.2.6 Communication interfaces . . . . . . . . . . . . . 26

4.3 The hardware . . . . . . . . . . . . . . . . . . . . . . . . 27

5 measurements 28

5.1 ECG signal acquisition . . . . . . . . . . . . . . . . . . . 28

5.1.1 ECG simulator . . . . . . . . . . . . . . . . . . . . 28

5.1.2 Human ECG . . . . . . . . . . . . . . . . . . . . . 30

5.1.3 Small animal ECG . . . . . . . . . . . . . . . . . . 30

5.2 Performance in MRI . . . . . . . . . . . . . . . . . . . . 33

5.2.1 Initial measurements . . . . . . . . . . . . . . . . 34

5.2.2 Small animal measurements . . . . . . . . . . . 34

5.2.3 Discussion . . . . . . . . . . . . . . . . . . . . . . 37

6 summary 39

6.1 Accomplishments . . . . . . . . . . . . . . . . . . . . . . 39

6.2 Possibilities of improvement . . . . . . . . . . . . . . . . 39

a appendix 40

vi

L I S T O F F I G U R E S

Figure 1.1 Schematic representation of normal ECG. . . . 2

Figure 2.1 Block diagram of the ECG system. . . . . . . . . 5

Figure 3.1 Block diagram of the ADS1298R. . . . . . . . . . 9

Figure 3.2 Photo of the ADS1298R ECG FE-PDK. . . . . . . . 10

Figure 3.3 Photo of the ECG prototype system. . . . . . . . 11

Figure 3.4 IIR filter frequency response of the ADS1258 MDK. 13

Figure 3.5 FIR filter frequency response of the ADS1258 MDK. 13

Figure 3.6 Flowchart of the ECG prototype system firmware. 15

Figure 3.7 Screenshot of the PC application for ECG display. 16

Figure 3.8 Frequency response of the DC removal filter. . 17

Figure 3.9 Response of the human band-pass filter. . . . . 18

Figure 3.10 Response of the animal band-pass filter. . . . . 18

Figure 3.11 Impulse response of the human band-pass filter. 18

Figure 3.12 Frequency response of the notch filter. . . . . . 19

Figure 4.1 The architecture of the Concerto MCU family. . 21

Figure 4.2 Frequency response of the antialiasing filter. . 25

Figure 4.3 Rendered visualization of the ECG board. . . . 27

Figure 5.1 ECG simulator output. . . . . . . . . . . . . . . 29

Figure 5.2 ECG simulator output, corrupted by 50Hz noise. 29

Figure 5.3 Human ECG recording. . . . . . . . . . . . . . . 30

Figure 5.4 Human stress ECG recording. . . . . . . . . . . 31

Figure 5.5 The anesthetized rat fitted with ECG electrodes. 32

Figure 5.6 Rat ECG recording. . . . . . . . . . . . . . . . . 32

Figure 5.7 Hamster ECG recording. . . . . . . . . . . . . . 33

Figure 5.8 Background spectrum measured inside the MRI. 35

Figure 5.9 Spectrum of a hamster ECG within MRI. . . . . 36

Figure 5.10 Spectrum of a hamster ECG within MRI, zoomed. 36

Figure 5.11 Spectrum of a hamster ECG during MRI sequence. 37

L I S T O F TA B L E S

Table 2.1 Design parameters of the ECG system. . . . . . 7

vii

L I S T I N G S

Listing A.1 Configuration of the ADS1298R. . . . . . . . . . . 40

A C R O N Y M S

AD Analog-to-Digital

ADC Analog-to-Digital Converter

AFE Analog Frontend

CT Computed Tomography

CAN Controller Area Network

CMRR Common-Mode Rejection Ratio

DSP Digital Signal Processor

ECG electrocardiograph

EVM Evaluation Module

FIR Finite Impulse Response

GPIO General Purpose Input/Output

IC Integrated Circuit

IIR Infinite Impulse Response

LCD Liquid Crystal Display

MCU Microcontroller Unit

MDK Medical Development Kit

MRI Magnetic Resonance Imaging

PDK Performance Demonstration Kit

PET Positron Emission Tomography

PGA Programmable Gain Amplifier

PSRR Power Supply Rejection Ratio

viii

acronyms ix

RLD Right Leg Drive

SAR Successive Approximation Register

SPI Serial Peripheral Interface

TI Texas Instruments

UART Universal Asynchronous Receiver/Transmitter

USB Universal Serial Bus

WCT Wilson Central Terminal

1I N T R O D U C T I O N

This thesis describes the development of an electrocardiograph (ECG)system designed for cardiac gating. This chapter is aimed at high-lighting the significance of cardiac gating in pre-clinical (animal) andclinical (human) medical imaging.

Section 1.1 discusses electrocardiography based on [1]. Assuming abasic knowledge of the anatomy of the heart, the physiological back-ground of human ECG is explored, without delving into the clinicalsignificance of ECG traces. Next, the practical aspects of ECG recordingrelevant to this project are reviewed.

Section 1.2 gives an overview of cardiac gating, and Section 1.3deals with the challenges of ECG measurement in Magnetic ResonanceImaging (MRI) machines.

1.1 electrocardiography (ecg)

1.1.1 Physiological background

As the heart undergoes depolarization and repolarization during thecardiac cycle, the electrical currents that are generated spread notonly within the heart, but also throughout the body. This electricalactivity generated by the heart can be measured by an array of elec-trodes placed on the body surface. The recorded tracing is called anelectrocardiogram (ECG, or EKG). Figure 1.1 shows the schematic rep-resentation of a "typical" human ECG tracing. The different waves thatcomprise the ECG represent the sequence of depolarization and repo-larization of the atria and ventricles.

The P wave represents the wave of depolarization that spreads fromthe sinoatrial (SA) node throughout the atria, and is usually 80-100 msin duration. The brief isoelectric period after the P wave representsthe time in which the impulse is traveling within the atrioventricular(AV) node and the bundle of His.

The period of time from the onset of the P wave to the beginning ofthe QRS complex is termed the P-R interval, which normally rangesfrom 0.12 to 0.20 seconds in duration. This interval represents thetime between the onset of atrial depolarization and the onset of ven-tricular depolarization.

The QRS complex represents ventricular depolarization. Heart ratecan be calculated by determining the time interval between QRS com-plexes. The duration of the QRS complex is normally 0.06 to 0.1 sec-

1

1.1 electrocardiography (ecg) 2

Figure 1.1: Schematic representation of normal ECG. Courtesy of Wikipedia.

onds. This relatively short duration indicates that ventricular depolar-ization normally occurs very rapidly.

The isoelectric period (ST segment) following the QRS is the time atwhich the entire ventricle is depolarized.

The T wave represents ventricular repolarization and is longer induration than depolarization, since conduction of the repolarizationwave is slower than the wave of depolarization.

The Q-T interval represents the time for both ventricular depolar-ization and repolarization to occur. This interval can range from 0.2to 0.4 seconds depending upon heart rate.

There is no distinctly visible wave representing atrial repolariza-tion in the ECG because it occurs during ventricular depolarization.Because the wave of atrial repolarization is relatively small in am-plitude, it is masked by the much larger ventricular-generated QRS

complex.

1.1.2 Recording an ECG

By convention, in a 5-electrode ECG configuration, electrodes are posi-tioned on each arm and leg, and one electrode is placed on the chest.The limb electrodes are referred to as Left Arm (LA), Right Arm (RA),Left Leg (LL) and Right Leg (RL), while the chest electrode is referredto as V1. LA, RA, LL and V1 are used as input electrodes in monitor-ing the electrical activity of the heart, whereas RL is electrically drivenby the Right Leg Drive (RLD) circuitry to reduce the common-mode

1.2 cardiac gating 3

voltage on the other electrodes. In general, the RL signal is obtainedas the average of the other limb electrodes.

The conventional ECG leads are formed from the electrode signals.The ECG leads are subdivided into the following categories:

• Standard limb leads: I, II, III

• Augmented limb leads: aVL, aVR, aVF

• Chest lead: V1

The leads are formed according to the following rules:

I = LA − RA

II = LL − RA

II I = LL − LA

aVL = LA − 12· (RA + LL)

aVR = RA − 12· (LA + LL)

aVF = LL − 12· (LA + RA)

V1 = V1 −13· (LA + RA + LL)

The standard limb leads are bipolar because the lead voltage is mea-sured between two electrodes, while the other leads are unipolar be-cause they are measured with respect to the Wilson Central Termi-nal (WCT) voltage, which is defined as VW = 1

3 · (LA + RA + LL).In practice, ECG signal acquisition may be implemented with dif-

ferential amplifiers. In this case, the standard limb leads may be ob-tained directly by connecting the appropriate electrodes to the inputsof the differential amplifiers. The chest lead may be obtained by gener-ating the WCT voltage and measuring the chest electrode with respectto it. The augmented limb leads may be calculated digitally from theother leads.

In the case of small animal measurements, three electrodes are gen-erally used. The electrode configuration may be LA, RA and LL, oralternatively, LA, RA and RL to provide feedback for common-modesignal reduction.

1.2 cardiac gating

Cardiac gating is a technique used to reduce artifacts due to heartmotion in medical imaging.

The heart is in motion during the cardiac cycle. It completes thecontraction required for its pump function during the systolic phase,

1.3 ecg in mri 4

then relaxes in the diastolic phase. Regardless of the imaging modal-ity in use, it is desirable to create images of the heart while it is sta-tionary in order to minimize motion artifacts. The diastolic periodsof lesser cardiac motion are ideal candidates for artifact-free imaging,however, the temporal resolution of current imaging techniques is notsufficient for the creation of images in a single stationary period. Thisproblem can be addressed with the use of ECG-synchronized tech-niques to record and combine data from multiple stationary periodsfor motion-free imaging.

The occurrence of the QRS complex in the ECG corresponds to theperiod of greatest heart motion. Therefore, by recording QRS triggersalong with the image data, data from the periods of lesser motioncan subsequently be extracted for the reconstruction of motion-freeimages (retrospective ECG gating). Moreover, the occurrence of QRS

complexes can be predicted on the fly from the previous ECG data,which can be used in Computed Tomography (CT) imaging for re-ducing the output power of the X-ray tube during systole in order toreduce patient dose (prospective ECG triggering) [2].

Cardiac gating has been proven to be efficient in cardiac CT andcoronary angiography [2], cardiac Positron Emission Tomography(PET) [3] and even in MRI diffusion tensor imaging of the brain [4].

1.3 ecg in mri

As discussed above, ECG acquisition in MRI is clinically relevant. How-ever, it is a challenging task.

In addition to the inherent distortion of the ECG waveform in MRI

systems operating at high field strengths, the static, gradient and RF

electromagnetic fields of the MRI system can cause additional arti-facts in the ECG signal [5]. Moreover, the ECG electrode leads may actas antennas, guiding radio-frequency interference into the MRI bore,thereby generating imaging artifacts or even causing image acquisi-tion to fail.

An existing MRI-compatible ECG system for human applications em-ploys long MRI-compatible cables and filtering in order to leave theelectronics outside of the MRI chamber [6], but solutions allowing themonitor to be placed near the patient are also available [7, 8].

Solutions also exist for small animal applications [9, 10]. The doc-umentation available on-line reveals very limited detail about thesesystems, in particular with respect to the MRI architectures and fieldstrengths they are compatible with. However, both systems appear torely on MRI-compatible ECG electrodes and lead wires, and the elimi-nation of artifacts in the ECG signal by digital filtering.

2S P E C I F I C AT I O N S

The thesis project was executed at Mediso Medical Imaging Systems,Hungary. The company’s specifications for the ECG system project re-quire the development of a modular ECG system. The main moduleshould implement the acquisition of the ECG signals with QRS com-plex detection, trigger generation and transmission for cardiac gatingin pre-clinical and clinical imaging machines, along with pre-clinicalrespiratory measurement and triggering. The slave module shouldimplement a temperature control loop for small animal systems, mea-suring and regulating the temperature of the animal bed. Each deviceshould implement two channels, i.e. it should be able to operate withtwo patients (animals) simultaneously, with a shared microprocessor(see Figure 2.1). Although the possibility to visualize signal wave-forms is required, the project is not aimed at the development of adiagnostic quality ECG system.

The thesis deals with the development of the main module, andonly describes details pertaining to the ECG functionality.

Figure 2.1: Block diagram of the ECG system.

5

2.1 specifications of the ecg system 6

2.1 specifications of the ecg system

An excerpt of the original specifications by Mediso follows.

1. Input/output

• Digitization of signals from 4 ECG electrodes in parallel for7-lead ECG

• RLD bias electrode

• ECG cables with standard connectors should be usable

• Communication interfaces: IEEE 1588 Ethernet, UniversalSerial Bus (USB), Controller Area Network (CAN)

2. Electronics, signal processing

• Digitization of human and rat/mouse ECG signals

• Automatic QRS complex detection, trigger generation andtransmission

• Configurable ECG preamplifier gain

• Power line interference filter

• Switchable high- and low-pass filters

• Automatic detection and reporting of ECG electrode faults

• Protection against overvoltages from defibrillators

3. Safety

• Patient isolation: at least 4 kV from communication inter-faces and power network

• Defibrillator protection: at least 5 kV at inputs

• Compliance with the IEC 60601-2-25 standard for medicalelectrical equipment

4. Design parameters (see Table 2.1)

2.1 specifications of the ecg system 7

Table 2.1: Design parameters of the ECG system.

Min Typ Max

Supply voltage (DC) 9 V 24 V 36 V

Number of ECG electrodes 4 + 1

Analog preamplification 1x 6x 12x

AD converter resolution 12 bits

Input bandwidth 0.05 Hz 250 Hz

Low pass filter frequency (human) 35 Hz

Low pass filter frequency (animal) 75 Hz

High pass filter frequency 0.05 Hz

Power line filter notch frequency 50 Hz /60 Hz

Input sensitivity 10 µV

CMRR 100 dB

Input voltage range ±300 mV

Input impedance 20 MΩ

Input-referred noise 15 µV

Heart rate (human) 400 bpm

Heart rate (animal) 800 bpm

Trigger latency 100 ms

Trigger jitter 10 ms

3P R O T O T Y P I N G

3.1 choice of architecture

Many digital ECG designs are based on discrete electronic compo-nents. Depending on the level of complexity used, the entire ana-log signal processing stage is implemented using numerous separateIntegrated Circuits (ICs) up to the point of Analog-to-Digital (AD) con-version. Publicly available examples include simple, 2-electrode ECGmonitor circuit designs by Analog Devices [11] and by Texas Instru-ments (TI) [12], and the ADS1258 Medical Development Kit (MDK) byTI [13].

However, at present several Analog Frontend (AFE) ICs are avail-able that implement a significant portion of the analog functionalityrequired for ECG in one piece of silicon [14]. This might include leadsignal preamplification, an RLD DC bias circuit, generation of the WCT

voltage used as reference voltage, ECG lead-off detection, respirationmeasurement over the ECG electrodes and AD conversion.

In order to facilitate hardware development and accelerate the de-sign, I decided to execute the project based on an AFE IC. Two optionswere commercially available for consideration:

• the ADS119x/129x1 family by TI,

• the ADAS10002 by Analog Devices.

The features put forward by both candidates are very similar. In con-trast to TI’s high-end ICs, the ADAS1000 only has 5 input channels, butthis would be sufficient to implement the 4+1 electrode ECG requiredby the specifications (see Chapter 2). However, the ADAS1000 is still inthe pre-release phase at the time of writing this document, thereforeTI’s offer was the reasonable choice.

The TI ADS129x family offers better performance than the ADS119x,notably in terms of resolution, noise and Common-Mode RejectionRatio (CMRR). Optionally, it also integrates the possibility to imple-ment respiration measurement over ECG electrodes [15]. Moreover, itis relatively inexpensive, thus it was chosen for development.

The prototyping phase was carried out using an ADS1298R IC, butthe final product does not require all the input channels it offers and,depending on the configuration, the respiration capability might also

1 http://www.ti.com/ww/en/analog/ads1298/index.shtml?DCMP=analog_

signalchain_mr&HQS=ads1291-pr

2 http://www.analog.com/en/analog-to-digital-converters/ad-converters/

adas1000/products/product.html

8

http://www.ti.com/ww/en/analog/ads1298/index.shtml?DCMP=analog_signalchain_mr&HQS=ads1291-pr

http://www.ti.com/ww/en/analog/ads1298/index.shtml?DCMP=analog_signalchain_mr&HQS=ads1291-pr

http://www.analog.com/en/analog-to-digital-converters/ad-converters/adas1000/products/product.html

http://www.analog.com/en/analog-to-digital-converters/ad-converters/adas1000/products/product.html

3.2 the ecg prototype 9

Figure 3.1: Block diagram of the ADS1298R [15].

be unnecessary, so one of the less expensive pin-compatible variantsmay be used in the end-product.

3.1.1 The ADS1298R IC

The ADS1298R3 is an 8-channel AFE meant for biopotential measure-ments (see Figure 3.1). It features eight low-noise Programmable GainAmplifiers (PGAs) and eight high-resolution Analog-to-Digital Con-verters (ADCs) for fully parallel data acquisition at a wide range ofconfigurable data rates. It offers low power consumption and smallinput-referred noise alongside a high CMRR. It provides built-in RLD

circuitry, lead-off detection and WCT circuitry for ECG. It also inte-grates support for respiration impedance measurement over ECG elec-trodes.

The ADS1298R provides a convenient Serial Peripheral Interface (SPI)for configuration and measurement data readout, thus it requiresonly a limited number of additional digital control signals [15].

3.2 the ecg prototype

3.2.1 The ADS1258 MDK

At the beginning of development, an ECG MDK based on TI’s ADS12584

IC was already available at Mediso. This development kit consistsof an Evaluation Module (EVM)5 by Spectrum Digital based on TI’s

3 http://www.ti.com/product/ads1298r

4 http://www.ti.com/product/ads1258

5 http://support.spectrumdigital.com/boards/evm5505/revd/

http://www.ti.com/product/ads1298r

http://www.ti.com/product/ads1258

http://support.spectrumdigital.com/boards/evm5505/revd/


Figure 3.2: Photo of the ADS1298R ECG FE-PDK.

TMS320VC55056 Digital Signal Processor (DSP), and a piggy-back mod-

ule hosting the ADS1258 and accompanying circuitry. The PerformanceDemonstration Kit (PDK) also includes the firmware running on theDSP implementing ECG signal acquisition and processing, and a PC

application which receives the ECG waveforms over a serial link andplots them.

Since the ADS1258 is merely a 16-channel ADC and all ECG-relatedfunctionality is implemented using external components, this IC wasnot considered for design. However, the TMS320VC5505 EVM has provedto be essential in later development (see Section 3.2.3), and I alsoreused the PC application supplied with the MDK (see Section 3.3).

3.2.2 The ADS1298R ECG FE-PDK

To start experimenting with the AFE I’ve chosen, I ordered an ADS1298R

PDK. The kit contains the MMB0 Modular EVM motherboard that hostsa TI TMS320VC5509

7 DSP, and the ADS1298R ECG AFE on a piggy-backboard. The assembled system is shown in Figure 3.2.

Once out of the box and wired up to a PC, the demo kit acquiredECG signals perfectly, yet it wasn’t usable for further developmentbecause of the lack of documentation and development tools for the

6 http://www.ti.com/product/tms320vc5505

7 http://www.ti.com/product/tms320vc5509

http://www.ti.com/product/tms320vc5505

http://www.ti.com/product/tms320vc5509


Figure 3.3: Photo of the ECG prototype system connected to an ECG simulator.The acquired ECG waveforms are visible on the LCD display.

MMB0 board. According to TI, “The MMB0 is not intended to be a fullembedded development tool, it is an evaluation platform.”8

3.2.3 The ECG prototype system

Fortunately, the two PDKs share the same piggy-back interface, hencemounting the ADS1298R piggy-back module on the TMS320VC5505 EVM

is possible. The piggy-back interface provides all the necessary sig-nals for the SPI interface used in the communication with the ADS1298R

IC and the digital control signals. Since the EVM offers excellent devel-opment and debug support through TI’s Eclipse-based Code Com-poser Studio suite, it is an ideal platform for a detailed explorationof the features of the ADS1298R AFE. The EVM also features a colorAMOLED9 Liquid Crystal Display (LCD) and a Universal AsynchronousReceiver/Transmitter (UART) port which were useful for visualizingthe ECG waveforms both locally and through data transmitted to a PC

(see Section 3.3).Figure 3.3 shows the ECG prototype system connected to an ECG

simulator (see Section 5.1.1). The digitized output of the simulator isdisplayed on the LCD screen.

8 Official comment on http://e2e.ti.com/support/data_converters/precision_

data_converters/f/73/t/151713.aspx, retrieved on 09/05/2012.9 Active-matrix organic light-emitting diode.

http://e2e.ti.com/support/data_converters/precision_data_converters/f/73/t/151713.aspx

http://e2e.ti.com/support/data_converters/precision_data_converters/f/73/t/151713.aspx

3.3 firmware development 12

3.3 firmware development

Since the ECG prototype system is implemented using the DSP moduleof the ADS1258 MDK, several features of its firmware are based on thefirmware supplied with the MDK by TI.

3.3.1 The firmware of the ADS1258 MDK

Following are the features of the firmware supplied with the ADS1258

MDK, as listed in TI’s application note [13]. I also appended brief expla-nations, mainly focusing on how they relate to the features requiredin the firmware of the ECG prototype system (see Section 3.3.2).

Data acquisition through ADC

The firmware establishes communication with the ADS1258 IC over theSPI bus for configuration and data retrieval. The ADS1298R also has anSPI interface, however, the protocol is different. In addition to adapt-ing the protocol, I rewrote the entire SPI implementation in the ECG

prototype system firmware for clarity.

Lead-off detection

ECG lead-off detection is implemented using external circuitry on theADS1258 MDK board. The firmware takes care of the communicationwith these. Since the ADS1298R implements lead-off detection inter-nally and the status information can be read out over SPI, this featureis not required in the ECG prototype system.

DC signal removal

The firmware implements a first-order digital Infinite Impulse Re-sponse (IIR) filter for baseline restoration of the ECG signal. The fre-quency response of the filter is shown in Figure 3.4. The filter is im-plemented in platform-independent C code and I reused it in theprototype firmware almost without modifications.

Multi band-pass filtering

The firmware implements a digital Finite Impulse Response (FIR) fil-ter. The coefficients of the filter realize a low-pass filter for the elim-ination of high-frequency noise with a notch for the suppression ofpower line interference. Figure 3.5 shows the frequency response ofthe filter with coefficients realizing a notch at 50 Hz.

The FIR filter is implemented in architecture-specific assembly code.I reused the implementation in the ECG prototype system firmwarewith different filter coefficients yielding different filter characteristics.


Figure 3.4: Frequency response of the IIR filter of the ADS1258 MDK [13]. Thefilter suppresses the DC component of the signal for baselinerestoration.

Figure 3.5: Frequency response of the FIR filter of the ADS1258 MDK [13]. Thefilter has a notch at 50 Hz to suppress power line interferenceand has a stopband with a very high attenuation above 150 Hzto filter out high frequency noise.


ECG leads formation

The firmware carries out ECG lead formation from the single endedinput signals with simple arithmetics according to the rules describedin Section 1.1.2. Since the ADS1298R has differential inputs, the arith-metic operations to perform are different.

QRS (heart rate) detection

The firmware implements the detection of the QRS complex (see Sec-tion 1.1.1) in the ECG signal for heart rate measurement. QRS detectionis a crucial feature required for cardiac gating, but this requires real-time detection with limited latency. However, this algorithm is onlyaimed at heart rate measurement, it has unacceptably high latencyand is unsuitable for the purposes of the ECG system.

Display of ECG data

The acquired ECG waveform is plotted on the AMOLED LCD screenwith a possibility to select the ECG lead to plot using the keys of theEVM5505. This feature was useful for demonstration purposes and hasbeen reused in the ECG prototype system with negligible modifica-tions.

UART communication

The acquired ECG data is transmitted over UART to the PC applicationfor display. This feature was also useful for demonstration and hasbeen reused in the ECG prototype system firmware.

3.3.2 The firmware of the ECG prototype system

The main purpose of the ECG system is to issue triggers for gatedimaging at the occurrence of QRS complexes with deterministic delay,i.e. limited and unvarying latency, and small jitter (see Chapter 2).The firmware has been designed with this requirement in mind. Mostof the project is implemented in platform-independent C code, withthe exception of the low-level CPU peripheral drivers and the FIR filter.

The flowchart of the ECG prototype system firmware is shown inFigure 3.6. A detailed description follows.

The main function

The main function performs the initialization of the entire ECG sys-tem.

It initializes the peripherals of the DSP: SPI for communication withthe ADS1298R, UART for data transfer to the PC, a Successive Approx-imation Register (SAR) ADC that reads out keypresses for LCD con-figuration, the LCD for ECG waveform display, and General Purpose


Figure 3.6: Flowchart of the ECG prototype system firmware.

Input/Outputs (GPIOs) for controlling the ADS1298R and debuggingfeatures.

It then initializes and configures the ADS1298R AFE. The register set-tings can be found in Listing A.1 (for detailed explanations, see [15]).The following set of main configuration parameters has proved to beusable in all cases tested so far (see Section 5.1):

• Sample rate set to 1000 SPS by default.

• The gain of all PGAs is set to 6.

• Lead-off detection is enabled for all ECG electrodes.

• The RLD and WCT signals are generated as the average of theLA, RA and LL signals (see Section 1.1.2).

Finally, it enters an infinite loop where, whenever data is available, itplots ECG waveforms to the LCD and transmits ECG data over UART tothe PC for display. It also monitors keypresses and updates the LCD

display configuration accordingly.Figure 3.7 shows a screenshot of the PC application. The ECG wave-

forms and actual measured heart rate of a rat are displayed as ac-quired by the ECG prototype system. The measurement configurationonly included the electrodes necessary for the calculation of Lead I(see Section 5.1.3), thus the waveform displayed for Lead II is calcu-lated and displayed incorrectly and should be considered an arith-metic artifact.


Figure 3.7: Screenshot of the PC application displaying the ECG waveformsand actual measured heart rate of a rat, acquired by the ECG

prototype system.

The DRDY interrupt subroutine

The ADS1298R is configured for continuous data acquisition, thus itprovides new data at the sampling rate specified in the configuration,signaling its availability through its Data Ready (DRDY) output signal.The prompt response of the ECG system to the availability of newdata is ensured by an interrupt mapped to the DRDY signal. Whenevernew data is available, the firmware reads it out over the SPI bus, thenexecutes the following steps of processing:

• Data preprocessing. Lead-off information is extracted from thestatus word received from the ADS1298R.The 24-bit output of the ADC is converted to 16-bit resolutionby truncation of a configurable number of bits. To allow for aflexible input configuration, the ADC channel values are sortedinto an internal buffer according to a changeable map. The inputvalues that contain signal from any disconnected electrode arezeroed out. Based on the lead-off status, one healthy lead isselected for QRS detection.

• Filtering.

– Baseline restoration. A first-order IIR filter adapted from theADS1258 MDK (see Section 3.3.1) is used for suppressing theDC component of the ECG signal. The frequency responseof the filter is shown in Figure 3.8.


Figure 3.8: Frequency response of the DC removal IIR filter. The filter restoresthe baseline of the ECG signal.

– Band-pass filtering. I reused the FIR filter implementationin the ADS1258 MDK with a set of custom coefficients I de-signed in Matlab for a 128-tap FIR filter. The lower stop-band of the band-pass filter reduces undesirable signal con-tributions from muscle movement, weakens the P and Twaves and softens the QRS complex, but since the project isnot aimed at the creation of a diagnostic quality ECG, thisis acceptable. The higher stopband is designed to filter outhigh frequency noise. Figure 3.9 and Figure 3.10 show thefrequency response of the filters used in human and smallanimal applications, respectively (see Chapter 2). Both fil-ters have linear phase in the passband, which is a desirablecharacteristic since it implies equal delay at all frequencies.FIR filters have a characteristic delay which is determinedby the location of the peak of the filter impulse response.Since both filters have this peak at half the number of taps,64 samples (see Figure 3.11), the delay introduced is 64 msat 1000 SPS.Due to the integer arithmetics used in the FIR filter im-plementation, the filter coefficients were converted fromdouble-precision floating point to integers. As a result, pre-serving the relatively flat response in the passband, thefilters have significant amplification. However, with suf-ficient care taken to avoid arithmetic overflows, this wasvery easily compensated.

– Notch filtering. Since the stopband of the band-pass filter forpreclinical applications lies above the frequency of powerline interference, in these applications, a separate filter isrequired for the suppression of these undesirable contribu-


Figure 3.9: Frequency response of the human band-pass FIR filter. Smallerheart rates allow for a lower cutoff frequency.

Figure 3.10: Frequency response of the small animal band-pass FIR filter.Higher heart rates require a wider passband.

Figure 3.11: Impulse response of the human band-pass FIR filter.


Figure 3.12: Frequency response of the IIR notch filter for power line inter-ference suppression. Notch frequency is 50 Hz. The filter has arelatively blunt notch to reduce transients.

tions. For this purpose, I designed an IIR filter in Matlab.Based on the coefficients obtained, I implemented this fil-ter as a cascade of two second-order IIR stages in platform-independent C code. Figure 3.12 depicts the frequency re-sponse of the filter with a 50 Hz notch.

• QRS detection. As discussed in Section 3.3.1, the QRS detection al-gorithm implemented in the ADS1258 MDK is unsuitable for thepurposes of the ECG system. Therefore, I implemented a detec-tion algorithm based on the Pan-Tompkins algorithm [16].The algorithm relies on the previously filtered signal. As men-tioned above, the band-pass filter distorts the P and T waves inthe ECG signal. It also softens the peak of the QRS complex, how-ever, by subsequent application of a five-point digital derivativefilter and squaring its output, the output has proved to be anexcellent metric for QRS detection in all cases tested (see Sec-tion 5.1). Pan and Tompkins applied a moving window averagefilter to this signal, which yields a series of pulses and allows forQRS detection through rising edge detection. I simply performthreshold crossing detection on the squared derivative with anadaptive threshold established based on the last five detectionamplitudes. Each detection inhibits further detections for a con-figurable amount of time, thereby avoiding multiple detectionsof the same QRS complex.

• UART and LCD flag generation. Not all samples are sent to theUART and LCD. The ratio of decimation is configurable and thecorresponding data ready flags, processed by the main loop, aregenerated accordingly.

4H A R D WA R E D E S I G N

I carried out the hardware design in cooperation with my colleagueSándor Török. Many design choices originate from his professionalexperience.

4.1 choice of microprocessor

The specification of the project requires the implementation of a vari-ety of communication interfaces (see Chapter 2). Among those speci-fied, the TI TMS320C5000 Ultra Low-Power DSP family supports USB, butnot IEEE 1588 Ethernet or CAN. These interfaces could have been real-ized using external ICs, but in order to keep the number of electroniccomponents to a minimum, I decided to search for a microprocessorthat has integrated support for all required interfaces. This means achange of architecture, but since a significant part of the ECG systemfirmware is platform-independent high-level C code, porting the codeis possible with reasonable effort.

In order to provide ample processing power for filtering the ECG

signal, I started looking for another DSP. Among the manufacturers Iconsidered - TI, Analog Devices and Freescale -, TI appeared to havethe most detailed documentation, and they offer excellent on-linetools for microprocessor selection1. In addition, I had already famil-iarized myself with their design tools, therefore I decided to choose amicroprocessor by TI.

In TI’s high performance DSP & ARM CPU line, I was left with twocandidate families. The high-end DaVinci DSP family2 has severalmembers that offer all required communication interfaces but thecapabilities of these processors far exceed the requirements of theproject and they are also rather expensive. The selection tool also rec-ommended the Sitara family3. Even though they are not DSPs, theseARM-based CPUs are aimed at performance applications and seemedto offer sufficient processing power for the ECG application at an af-fordable price. However, before I could order a development kit, acolleague brought TI’s Concerto Microcontroller Unit (MCU) family4

to my attention. These microcontrollers feature all communication in-terfaces required by the specification, and development boards werereadily available at the office.

1 http://focus.ti.com/en/multimedia/flash/selection_tools/dsp/dsp.html

2 http://www.ti.com/lsds/ti/dsp/platform/davinci/device.page

3 http://www.ti.com/lsds/ti/dsp/platform/sitara/device.page

4 http://www.ti.com/mcu/docs/mcuproductcontentnp.tsp?sectionId=

95&familyId=2049&tabId=2743

20

http://focus.ti.com/en/multimedia/flash/selection_tools/dsp/dsp.html

http://www.ti.com/lsds/ti/dsp/platform/davinci/device.page

http://www.ti.com/lsds/ti/dsp/platform/sitara/device.page

http://www.ti.com/mcu/docs/mcuproductcontentnp.tsp?sectionId=95&familyId=2049&tabId=2743


4.2 hardware design considerations 21

Figure 4.1: The architecture of the Concerto MCU family [17].

The Concerto family is based on a very interesting architecture,which is shown in Figure 4.1. These MCUs combine an ARM Cortex-M3 core aimed at communication with a C2000 DSP core that offerssimilar performance to the C5000 DSP I had used.

I carried out preliminary tests with the development board. I portedthe most computationally intensive part of the firmware, the FIR fil-ter (see Section 3.3) to the C2000 DSP core, and I also experimentedwith the communication between the two cores. These tests suggestedthat the high-end Concerto F28M35H52C1

5 would be very suitable forthe ECG system project. Since it is quite reasonably priced and alsooffers an integrated recyclic ADC useful for small animal respiratorymeasurement (see Section 4.2.4), it was chosen for hardware develop-ment.

4.2 hardware design considerations

Since the specification of the ECG system requires the implementa-tion of two channels on a single board, the entire ECG hardware (seeSection 4.2.3) and small animal respiratory measurement stage (seeSection 4.2.4) is doubled.

Nearly all digital signal lines in the design feature series resistorsfor limiting transient currents.

The design features several LEDs driven by the MCU to provide adirect means of conveying information to the user.

5 http://www.ti.com/product/f28m35h52c

http://www.ti.com/product/f28m35h52c


4.2.1 Patient protection

The IEC 60601-2-25 standard for ECGs requires that in human applica-tions, the patient be electrically isolated from the power network andcommunication interfaces of the device. The breakdown voltage mustbe at least 4 kV.

The alternatives considered for the implementation of the isolationare the following:

• Isolation on the analog side, before the inputs of the ADS1298R.

• Isolation of the signal paths between the ECG AFE and the MCU,keeping the AFE in a separate power domain.

• Isolation of the external communication interfaces and power,keeping the MCU and the AFE in the same isolated power do-main.

Creating separate, isolated power domains for each ECG AFE and iso-lating the digital signal paths to the MCU offers several advantagesover the two other methods. Excellent methods are readily availablefor the isolation of on-board digital signal paths, making this alterna-tive less cumbersome than the medical quality isolation of the com-munication interfaces and more robust than the isolation of analogsignals. Moreover, this solution intrinsically fulfills the requirementsfor isolation between the two ECG stages for two patients, thus it ap-peared to be the best choice.

In order to provide the required isolation strengths, the portionsof the board containing the ECG AFEs have been protected againstleakage currents by incisions in the board layout (see Figure 4.3).

Additionally, the main power supply (see Section 4.2.2) and theCAN interfaces (see Section 4.2.6) are also electrically isolated, eventhough no medical quality isolation is provided in these cases.

4.2.2 Power supplies

The external components required for each regulator have been se-lected following the guidelines set forth in the respective datasheets.A number of ferrite bead chokes have been used throughout the de-sign for the suppression of high frequency interference on power sup-ply lines.

Main power supply

Since the highest supply voltage required in the ECG system is 5 V,this has been chosen as the output voltage of the main power supply.In order to comply with the requirement for a wide input voltagerange and provide electrical isolation between the power network and


the board, the TEN5-2411WI DC-DC converter by TracoPower has beenselected. This power supply provides a regulated output voltage of5 V with a maximal output current of 1 A, and offers an efficiency oftypically 78% [18]. Its output current is sufficient for the application,and since the sensitive components require 3.3 V power, its ripple willbe suppressed by additional linear regulators.

ECG power supplies

The ECG circuitry resides in a separate power domain, which must beisolated from the rest of the board to comply with the requirementsof the standard (see Section 4.2.1). In order to achieve this, the RV-0505S

DC-DC converter by Recom was used. This device possesses the medi-cal approval required by the application. With an input voltage of 5 V,it supplies a maximum output current of 400 mA at an unregulatedoutput voltage of 5 V, with standard efficiencies of 70-75% [19].

Since the ADS1298R requires 3.3 V power and the output of the iso-lated power supply is unregulated, additional regulation is necessary.In order to minimize the ripple of the output voltage, linear regu-lation is desirable. Moreover, to suppress interference from the digi-tal side of the IC to the analog side and thereby reduce the noise ofthe ADC, the best solution is having two separate regulators providepower to the analog and digital domains of the AFE. The TPS79201 byTI was chosen for its ultralow noise and high Power Supply RejectionRatio (PSRR) [20]. Its current sourcing capabilities are largely sufficientfor the requirements of the ECG stage.

CAN power supplies

The two CAN interfaces used (see Section 4.2.6) are also isolated. Theirisolated power domains are supplied by TME 0505S isolated DC-DC con-verters from TracoPower, which provide a maximal output current of200 mA at 5 V with an input voltage of 5 V, with a typical efficiencyof 70% [21].

MCU power supply

The F28M35H52C1 MCU can operate with a single 3.3 V power supplysince it has internal regulators supplying all other voltages it requires.TI’s TPS79601 was selected for its excellent performance similar to theregulators used for the ADS1298R and its higher current sourcing capa-bilities up to 1 A [22]. Since in this case, the suppression of noise to theanalog subsystem is not a critical issue, the same regulator suppliesboth digital and analog power, with a ferrite bead choke separatingthe two power domains to ensure high frequency noise reduction.


4.2.3 ECG hardware

The external components required by the ADS1298R AFE have beenselected following the guidelines of the datasheet [15].

Patient protection

As discussed in Section 4.2.1, medical quality electrical isolation isrequired in ECG systems. In addition to placing the ECG electronicsin an isolated power domain, this also requires the isolation of thedigital lines to and from the AFE. Traditionally, optocouplers wereused for this purpose, but this technology suffers from aging effectsin the LED and difficulties at higher signaling speeds. The iCouplertechnology by Analog Devices overcomes these limitations, it offersfar superior performance and significantly lower power consumption[23]. The ADuM2401 device chosen for isolation offers a suitable num-ber of input and output channels, can operate at the foreseen SPI busfrequency of 10 MHz and complies to the requirements of the IEC

60601 standard.Since the two ECG AFEs share the same SPI bus, additional buffers

gated with the respective SPI Enable signals were required on theMaster In Slave Out (MISO) lines to avoid two ADuM2401 outputs con-currently driving the MISO input of the MCU.

The clock signal is routed to both AFEs from the same 2.048 MHzclock generator residing in the main power domain through the elec-trical isolators.

The analog input stage

The ADS1298R features a Delta-Sigma (∆Σ) AD converter. The ∆Σ mod-ulator and the on-chip digital decimation filters can be used to filterout the noise at higher frequencies, thus the complexity of analogantialiasing filters required can be dramatically reduced with respectto Nyquist ADCs. Effectively, the input antialiasing filters are only re-quired to filter out any interference at frequencies around multiplesof fMOD, the sampling frequency of the modulator [15]. In High Res-olution mode, fMOD = fCLK/4 = 512 kHz.

Therefore, only a simple RC filter is required for antialiasing at theinput of the ADS1298R ICs, which was adapted from the circuit designput forward by TI in [24]. Figure 4.2 shows the magnitude responseof the antialiasing filter. Complemented by the input EMI filter withinthe ADS1298R IC [15], this ensures the required antialiasing.

A neon lamp was added in parallel to the filter in order to providethe defibrillator protection required by the specifications on the in-puts of the AFE IC. The neon lamp has a maximum strike voltage of90 V [25]. In conjunction with the resistor in series, it limits transient


Figure 4.2: Frequency response of the input antialiasing filter. The graphconfirms that, together with the EMI filter within the ADS1298R,the filter ensures the antialiasing required.

currents reaching the inputs of the ADS1298R to approximately 9 mA,which the inputs can withstand [15].

4.2.4 Small animal respiratory measurement

Based on previous experience, the SDP1108-R differential pressure sen-sor by Sensirion has been chosen for the purpose of respiratory mea-surement. It requires a 5 V DC power supply and provides a fullycalibrated analog voltage output. It offers a full scale pressure differ-ence of 500 Pa with superior accuracy, outstanding resolution and lowtemperature dependence through internal compensation [26].

The proposed measurement configuration consists of a tiny respi-ration sensor cushion6 the small animal lies on for measurement. Theoutput of the cushion is connected to the Hi terminal of the SDP1108-R,while the Lo terminal is left open, thus atmospheric pressure is usedas reference. The performance of the SDP1108-R makes it highly suit-able for measuring the small volume flows generated by the cushionthrough the breathing of the animal.

The analog output voltage of the SDP1108-R is connected to an ADC

input of the MCU for digitization. Since the output voltages rangefrom 0.25 V to 4 V and the ADC operates with a reference voltage of3 V, a voltage divider is required between the output and the input. Inaddition, an optional RC filter has been added to the design to ensurethe possibility of limiting high-frequency noise.

6 E.g. http://www.medicare.ie/mother-baby/infant-respiration-monitors-

rental-1/graseby-respiration-sensor.html.

http://www.medicare.ie/mother-baby/infant-respiration-monitors-rental-1/graseby-respiration-sensor.html

http://www.medicare.ie/mother-baby/infant-respiration-monitors-rental-1/graseby-respiration-sensor.html


4.2.5 Microcontroller unit

The quartz oscillator, decoupling capacitors, pullup/pulldown resis-tors and other required external components have been laid out ac-cording to the guidelines of the datasheet [27].

A JTAG interface has been implemented for programming and de-bugging.

The F28M35H52C1 offers a total of five SPI interfaces. Both ECG AFEs

are connected to the only one of those that is controlled by the DSP

core to allow for readout and data processing by the same core.In addition to the output of the pressure sensors (see Section 4.2.4),

two supply voltages have been connected to ADC inputs of the Con-certo through resistive dividers to allow monitoring the state of thepower supplies.

4.2.6 Communication interfaces

Ethernet

In addition to the Ethernet MAC in the Concerto, a transceiver IC andan RJ-45 connector is required for Ethernet communication. This cir-cuitry has been adapted from the circuit design of the TI H52C1 Con-certo ControlCard [28].

USB

The F28M35H52C1 includes the implementation of the physical layer,therefore only a USB connector is required for communication. Sincethe ECG system is only meant to be used as a USB device, a simpleUSB-B connector has been implemented in the design, along with pro-tection diodes on the data lines.

CAN

The ECG system design makes use of both CAN interfaces of the Con-certo. CAN is used as an external communication interface and alsofor connecting to the slave modules (see Chapter 2). 9-pin D-SUB maleconnectors are used.

To complement the isolated power supplies, TI’s ISO1050 isolatedCAN transceivers [29] have been used in the design for CAN interfaceisolation.

In addition to protection diodes on the CAN data lines, the slavemodule (“bed”) CAN circuitry features a solution that disables thelocal CAN termination resistor if the slave modules for both channelsare attached. In contrast, the external CAN interface complies to theprotocol in use at Mediso, thus it features a termination resistor thatcan be enabled externally through the D-SUB connector.

4.3 the hardware 27

Figure 4.3: Rendered visualization of the populated ECG printed circuitboard. Note the incisions protecting the ECG circuitry from leak-age currents.

4.3 the hardware

Based on the aforementioned considerations, the schematic (see Ap-pendix A) and layout design of the final printed circuit board havebeen completed. At the time of writing this thesis, the circuit boardis being manufactured. Figure 4.3 shows a rendered visualization ofthe populated printed circuit board.

5M E A S U R E M E N T S

Since no final ECG system hardware has been produced yet at the timeof writing this thesis, all measurements described in this chapter werecarried out using the ECG prototype system. However, the expectedperformance of the final hardware is very similar.

The output of the ECG system has not yet been calibrated for con-verting output values to voltages, thus all amplitude axes show valuesin arbitrary units.

5.1 ecg signal acquisition

5.1.1 ECG simulator

Initial ECG measurements were made with an ECG simulator, a devicefeaturing connectors for ECG lead wires and capable of generatingECG waveforms. The ECG system was connected to the simulator witha standard human ECG cable in a 5-electrode configuration, as shownin Figure 3.3. The following examples illustrate the performance ofthe system with input signals from the simulator.

Figure 5.1 shows a recording of the ECG simulator output with am-plitude set to 1 mV and heart rate set to 60 bpm. The unfiltered ECG

data features very characteristic P and T waves and QRS complex,along with a negligible contribution from power line interference. Inthis case, the unfiltered data would be directly usable for QRS de-tection, however, filtering was carried out for comparison. Since thebandpass filter for human applications was used, use of the notchfilter for power line interference suppression was not required.

Suppression of the DC component by the baseline restoration filteris well visible in the filtered data. The limited delay and waveformdistortion resulting from the FIR filter are also identifiable, however,these effects are acceptable (see Section 3.3.2). As a result, the discretederivative provides a perfectly usable QRS metric.

Figure 5.2 depicts a recording of the output of the simulator withthe same settings (note the different scale on the time axis), deliber-ately corrupted by 50 Hz power line noise by placing a soldering ironclose to the ECG system. The filtering does a remarkable job in elimi-nating power line interference and a usable QRS metric is produced.

28

5.1 ecg signal acquisition 29

Figure 5.1: Recording of the ECG simulator output.

Figure 5.2: Recording of the ECG simulator output, corrupted by 50Hz noise.This figure demonstrates the efficiency of the notch filter in elim-inating power line interference.


Figure 5.3: Human ECG recording. This figure illustrates the power of the fil-ters in suppressing power line interference and baseline wander.

5.1.2 Human ECG

Figure 5.3 shows the author’s ECG recording at rest, acquired in a 3-electrode configuration with LA and RA input electrodes, and the RLfeedback electrode connected to the appropriate limbs. The record-ing exhibits noticeable power line interference and breathing causessignificant baseline wander in the ECG trace. However, these distor-tions are eliminated by the DC suppression and bandpass filters. Thisyields a very high quality metric for QRS detection. The average heartrate during the measurement can be identified as approximately 75-80 bpm.

Figure 5.4 shows the author’s stress ECG recording while perform-ing squats. The baseline restoration filter performs remarkably oncemore, however, due to muscle movement, the unfiltered ECG dataexhibits sharp transitions the currently used filters cannot eliminatesatisfactorily. This leads to the presence of spurious pulses in the QRS

metric, thus unwanted QRS triggers.

5.1.3 Small animal ECG

To verify its capability to acquire the ECG signals of rodents, the ECG

system was tested with anesthetized small animals. These recordings


Figure 5.4: Human stress ECG recording. This figure demonstrates the chal-lenges faced in the processing of stress ECG signals.

were carried out in a 3-electrode ECG configuration with LA and RAinput electrodes and a feedback electrode, RL, connected to the limbsof the animal. 3M Red Dot neonatal, pre-wired, radiolucent moni-toring electrodes were employed with a standard, unshielded ECG

cable. The bandpass filter for small animal measurements was used,therefore the notch filter for power line interference was required (seeSection 3.3.2).

The photo of an anesthetized rat fitted with ECG electrodes can beseen in Figure 5.5. Figure 5.6 shows the ECG signal recording. The un-filtered signal suffers from significant power line interference. Due tothe transients of the notch filter, this interference is only attenuated,not completely eliminated. Filtering also reduces the amplitudes ofthe QRS complexes. However, both the unfiltered and the filtered sig-nal yield a usable QRS metric through the discrete derivative filter.The heart rate of the rat was measured to be around 235 bpm (seeFigure 3.7), which is in accord with the values found in the literature[30].

Figure 5.7 shows the ECG of a hamster. Surprisingly, the signal fea-tures inverted QRS complexes due to biological reasons. The signal ex-hibits limited baseline wander and negligible power line interference.In this case, filtering yields no obvious improvement with respect tothe unfiltered signal, and the amplitudes of the QRS complexes are re-


Figure 5.5: The anesthetized rat fitted with ECG electrodes.

Figure 5.6: Rat ECG recording. This figure illustrates the capability of theprocessing to create a usable QRS metric.

5.2 performance in mri 33

Figure 5.7: Hamster ECG recording. This figure demonstrates the ability ofthe processing to create a usable QRS metric.

duced. However, as was the case with the ECG of the rat, both filteredand unfiltered signals are usable for QRS detection. The heart rate ofthe hamster was measured to be around 430 bpm, which correspondsto the values found in the literature [31].

5.2 performance in mri

Mediso assembles permanent magnet MRI machines for small animalapplications. Compared to electromagnet-based devices, these ma-chines offer the advantage of a limited fringe field [32], thus metal-lic objects may be brought into the vicinity and ordinary electronicdevices may be operated near the machine. This means that ECG mea-surement in MRI might be possible by setting up the ECG system nextto the MRI machine and using MRI-compatible ECG electrodes withinthe bore of the MRI magnet.

The manufacturer claims that the 3M electrodes I used for smallanimal ECG measurements (see Section 5.1.3) are not MRI-compatible.Nevertheless, the electrodes are non-ferrous and the pre-attached leadwires are made of carbon. Moreover, Small Animal Instruments, Inc.use the same electrodes in their MRI-compatible ECG system [10], thusthese electrodes were good candidates for measurements in MRI.


5.2.1 Initial measurements

In order to assess the viability of measuring ECG as outlined above,I carried out initial measurements with an MRI water phantom andthe 3M electrodes within the magnet bore. The two ECG electrodesthat form the ECG lead under measurement were connected togetherwith approximately 100 kΩ contact impedance, which reasonably ap-proximates usual ECG contact impedances. This setup was placed inthe MRI animal bed underneath the phantom and inserted into theMRI bore. No actual signal source was connected to the electrodes,thus the measurement was expected to register background noise andeventual MRI contributions.

Figure 5.8 shows the result of the acquisitions. The upper plot de-picts the spectrum of the background acquired within the MRI bore,with no MRI sequence in progress. The spectrum is clearly dominatedby 50 Hz power line interference with significant harmonic content.The lower plot shows the spectrum of the data acquired during theexecution of a scout MRI sequence. I deemed the results promising,since MRI contributions are only visible around 260 Hz and 480 Hz,outside of the frequency band of interest, and should therefore beeasy to attenuate. It is noteworthy that 260 Hz corresponds to therepeat period of the radio frequency pulses in the scout sequence,3.8 ms. It should also be noted that although the spectra of the 50 Hzharmonics are visually similar, MRI interference appears to amplifyseveral harmonics.

The MRI images acquired of the phantom with the electrodes inplace were only slightly deteriorated, showing limited signs of inter-ference generated by the electrodes. The electrodes were not visibleon the MRI image.

5.2.2 Small animal measurements

ECG measurements

Based on the positive experience gained with the initial measure-ments, I attempted measuring the ECG of a hamster within MRI. Iused the same electrode configuration as in Section 5.1.3. Measure-ments with the hamster inside the MRI bore, but with the gradientand radio frequency systems of the MRI machine turned off, yieldedresults in excellent agreement with those obtained outside of the ma-chine. Thus, the field of the permanent magnet appears to have nonoticeable influence on the measurement.

Figure 5.9 shows the result of the measurements. The upper plot de-picts the spectrum of the hamster ECG acquired within the MRI bore,with no MRI sequence in progress. It is interesting to note that thespectrum appears to be discrete, which suggests that the heart rateof the hamster is very steady. The lower plot shows the spectrum of


Figure 5.8: Spectrum of the background signal acquired within the MRI bore,without MRI sequence in progress and during a scout sequence.

the data acquired during the execution of a scout MRI sequence. MRI

interference appears at the same frequencies that were identified ear-lier, however, in this case, it dominates the signal. This demonstratesa weakness of the filtering in use: Figure 5.10 shows that the lowfrequency spectrum of the hamster ECG is partially preserved, withsome frequency components diminished. However, the filtering can-not sufficiently attenuate the high-frequency interference, thus QRS

detection on the filtered signal fails.Figure 5.11 shows an ECG spectrum acquired during execution of

a spin echo MRI sequence. The high frequency components of thespectrum were attenuated by the small animal band-pass filter. ThisMRI sequence appears to cause a wide-band interference within thefrequency band relevant for ECG acquisition, along with some veryhigh peaks. QRS detection on this signal yields no usable results.

MRI measurements

In contrast to the phantom measurements described in Section 5.2.1,no usable MRI images of the hamster fitted with ECG electrodes couldbe acquired with the sequences tested.


Figure 5.9: Spectrum of a hamster ECG acquired within the MRI bore. Duringthe scout sequence, MRI artifact dominates the spectrum.

Figure 5.10: Spectrum of a hamster ECG acquired within the MRI bore,zoomed in. The spectrum has been partially preserved at lowfrequencies, even despite MRI artifact from the scout sequence.


Figure 5.11: Spectrum of a hamster ECG acquired within the MRI bore duringa spin echo sequence. The high frequency components wereattenuated by the small animal band-pass filter.

5.2.3 Discussion

At present, the interactions between the ECG system and the MRI ma-chine impair both ECG signal acquisition and MRI image creation.

MRI image creation

The comparison of MRI images acquired of the phantom and of thehamster, both in presence and absence of ECG electrodes, shows adegradation in the quality of the MRI images when the electrodes arepresent. The images suggest that this effect is due to radio-frequencyinterference caused by the presence of the ECG electrodes in the MRI

bore, which probably act as antennas in guiding interference into theMRI acquisition volume. However, the degradation is much more sig-nificant in the case of hamster measurements, where it yields unus-able images, whereas for phantom measurements, it merely causesgrainy artifacts but image quality remains acceptable. This impliesthat the body of the animal amplifies the radio-frequency interferenceguided into the MRI volume by the electrodes.

Nonetheless, in the case of phantom measurements, the ECG elec-trodes were connected together with a contact impedance (see Sec-tion 5.2.1), while in the case of hamster measurements, they wereconnected to the limbs of the animal (see Section 5.2.2). In order to


evaluate the role of the animal body in the amplification of the in-terference, phantom measurements should be carried out in a similarconfiguration, ensuring that the electrodes are physically separated.Since the phantom is made of plastic and is thus probably an insu-lator, appropriate contact impedances must be ensured between thedifferent electrodes. Due to the limited amount of time available af-ter the first animal MRI experiments, this measurement has not beencarried out yet.

Colleagues with MRI-related experience suggested adding 1 nF fil-tering capacitors between all ECG electrode lines and the commonground to reduce radio-frequency interference, but our measurementscarried out with the phantom showed no quantifiable improvementnevertheless.

ECG acquisition

A tentative simulation showed that by applying a band-pass filterwith sufficient attenuation in the higher stopband to the ECG signalcorrupted by interference from the scout sequence, the remaining low-frequency components (see Figure 5.10) can be used to produce an al-most usable QRS metric. This implies that in the case of this sequence,further tweaking of the already implemented digital filtering couldprobably be used to satisfactorily eliminate MRI interference from theECG signal.

However, several other sequences that were tested, e.g. spin echo,produce wide-band interference within the frequency band of inter-est for ECG measurement (see Figure 5.11). In these cases, the filter-ing used in the ECG prototype system gives little hope of eliminatingMRI interference, thus new filtering techniques need to be considered.Since the stray magnetic field of the solenoidal radio-frequency exci-tation coil of the MRI machine can be expected to be small, and asdiscussed in Section 4.2.3, the inputs of the ECG AFE are equippedwith sufficient analog filtering against out-of-band interference, digi-tal filtering will probably be appropriate.

Measurements also revealed that the position of the ECG cable hasa great influence on the sensitivity of the system to power line inter-ference. Further investigations could help establishing good practicesof cable layout.

6S U M M A RY

6.1 accomplishments

I spent the past year working at Mediso Medical Imaging Systems.During this time, based on two different development kits, I producedan ECG prototype system, which is fully functional with the firmwareI designed. I demonstrated the ability of the system to acquire humanand small animal ECG waveforms and detect QRS complexes.

Based on the experience gained with the prototype system, we de-signed the final ECG system board. The circuit board is being man-ufactured at the time of writing this thesis. Utilizing my work donefor the prototype and a demonstration board, I have completed thedevelopment of a great part of the firmware of the future ECG system.

6.2 possibilities of improvement

The measurements carried out so far show that the system is not yetable to perform satisfactorily in the MRI environment. The interactionsof the ECG system with MRI require further investigation in order toachieve MRI-compatibility.

The firmware developed for the final ECG system needs to be com-pleted and it should be tested with the final board as soon as thelatter is available.

The filters in use should be reviewed in order to eliminate theglitches encountered during the acquisition of human stress ECG.

The ECG output amplitudes need to be calibrated in order to allowvoltage readout, taking into consideration the amplification of theband-pass filters.

By keeping the currently used filters for QRS detection, and im-plementing another set of filters which satisfactorily preserve all keyfeatures of the ECG waveform for display, a diagnostic quality ECG

could probably be produced.

39

AA P P E N D I X

Listing A.1: Configuration of the ADS1298R.

// ADS1298R register values

Uint8 ADS1298RegVal[25] =

#if ECG_SAMPLERATE == 500

0x86, // Register CONFIG1: Hi-Res EN, data rate = 500SPS

#elif ECG_SAMPLERATE == 1000






#else

#error Sample rate not supported!

#endif

0x10, // Register CONFIG2: variable WCT chopping frequency

0xDD, // Register CONFIG3: RLD buffer EN; Vref = 2.4V

0x03, // Register LOFF: DC current source Loff detection

0x00, // Register CH1SET: normal operation, PGA gain = 6

0x00, // Register CH2SET: id.







0x06, // Register RLD_SENSP: channels 2 and 3 (LA, LL) in RLD

0x02, // Register RLD_SENSN: channel 2 (RA) in RLD

0xFE, // Register LOFF_SENSP: Loff EN on all chans but IN1P

0x02, // Register LOFF_SENSN: Loff EN on IN2N (RA)

0x00, // Register LOFF_FLIP: Loff curr direction: default

0x00, // Register LOFF_STATP (read only)

0x00, // Register LOFF_STATN (read only)

0x0F, // Register GPIO: all GPIOs set to input (unused)

0x00, // Register PACE: PACE detect buffer off

0xF0, // Register RESP: respiration switched off

0x22, // Register CONFIG4: Loff comparators powered up

0x0A, // Register WCT1: IN2P (LA) -> WCTA

0xE3 // Register WCT2: IN3P (LL) -> WCTB, IN2N (RA) -> WCTC

;

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R14

6

100n

FC

190

GN

DIS

O1

C12

210

uF21

C15

11u

F

GN

DIS

O1

R14

710

0

C22

010

nF

U14

TP

S79

201

GN

D=G

ND

ISO

1

4

365

1IN

PG

OU

TE

N

BYP

C19

110

0nF

GN

DIS

O1

10uF

C12

3

21

GN

DIS

O1

R15

530

K

GN

DIS

O1

BLM

21A

G10

2SN

1D

L8

L9

BLM

21A

G10

2SN

1D

15pF

C21

5

GN

DIS

O1

51K

R14

1

30K

R15

6

GN

DIS

O1

A1

Haj

du C

s., T

örök

S.

Cze

ller

Mik

lós

<DA

TE

>

Pow

er S

uppl

ies

Táp

egys

égek

Loca

ted

at s

heet

1 -

A1

Blo

ck P

ower

_Sup

plie

s P

age

2 of

3S

heet

4 O

F 1

8

EL-

23-5

0-00

EC

G fo

r H

uman

& S

mal

l-Ani

mal

EK

G (

Hum

án é

s K

isál

lat)

EC

G

2012

-04-

11

AB

CD

EF

GH

1234

Con

trol

ler

<Elle

nõr>

:

Dat

e <D

átum

>:

Pag

e <O

ldal

>

Pag

e N

umbe

r <L

apsz

ám>:

Dra

win

g nu

mbe

r <R

ajzs

zám

>:

NA

ME

<N

év>:

Titl

e <C

im>:

Des

igne

r <T

erve

zõ>:

Dat

e <D

átum

>:M

Doc

. Rev

.

R14

810

0

C19

210

0nF

GN

DIS

O1

C12

410

uF21

10uF

C12

5

21

L10

BLM

21A

G10

2SN

1D

GN

DIS

O1

1uF

C15

2

GN

DIS

O1

C19

310

0nFGN

DIS

O1

100

R14

9

100n

FC

194

GN

DIS

O1

BLM

21A

G10

2SN

1D

L11

GN

DIS

O1

10nF

C22

1

TP

S79

201

U15

GN

D=G

ND

ISO

1

4

365

1IN

PG

OU

TE

N

BYP

A3V

3IS

O1

3V3I

SO

1

GN

DIS

O1

VC

CIS

O1

RV

-050

5S

U18

15101312

2

1+V

in

-Vin

+Vou

t1

+Vou

t2

-Vou

t1

-Vou

t2

C25

510

0nF

GN

DIS

O1

GN

D100n

FC

195

10uF

C12

6

BLM

21P

G22

1SN

1D

L3V

CC

GN

D

C21

615

pF

GN

DIS

O2

R14

251

K

GN

DIS

O2

100

R15

0

100n

FC

196

GN

DIS

O2

C12

710

uF

C15

31u

F

GN

DIS

O2

R15

110

0

C22

210

nF

U16

TP

S79

201

GN

D=G

ND

ISO

2

INP

G

OU

TE

N

BYP

C19

710

0nF

GN

DIS

O2

10uF

C12

8

GN

DIS

O2

R15

730

K

GN

DIS

O2

BLM

21A

G10

2SN

1D

L12

15pF

C21

7

GN

DIS

O2

51K

R14

3

GN

DIS

O2

R15

210

0

C19

810

0nF

GN

DIS

O2

10uF

C12

91u

FC

154

C19

910

0nFGN

DIS

O2

100

R15

3

10nF

C22

3

RV

-050

5S

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+Vin

1

-Vin

2

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t1

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t2

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t1

-Vou

t2

VC

CIS

O2

GN

DIS

O2

GN

D=G

ND

ISO

2

TP

S79

201

U17 IN

PG

OU

TE

N

BYP

100n

FC

200

GN

DIS

O2

GN

DIS

O2

C13

010

uF

GN

DIS

O2

A3V

3IS

O2

A1

Haj

du C

s., T

örök

S.

Cze

ller

Mik

lós

<DA

TE

>

Pow

er S

uppl

ies

Táp

egys

égek

Loca

ted

at s

heet

1 -

A1

Blo

ck P

ower

_Sup

plie

s P

age

3 of

3S

heet

5 O

F 1

8

EL-

23-5

0-00

EC

G fo

r H

uman

& S

mal

l-Ani

mal

EK

G (

Hum

án é

s K

isál

lat)

EC

G

2012

-04-

11

AB

CD

EF

GH

1234

Con

trol

ler

<Elle

nõr>

:

Dat

e <D

átum

>:

Pag

e <O

ldal

>

Pag

e N

umbe

r <L

apsz

ám>:

Dra

win

g nu

mbe

r <R

ajzs

zám

>:

NA

ME

<N

év>:

Titl

e <C

im>:

Des

igne

r <T

erve

zõ>:

Dat

e <D

átum

>:M

Doc

. Rev

.

30K

R15

8

GN

DIS

O2

L13

BLM

21A

G10

2SN

1D

L14

BLM

21A

G10

2SN

1D

BLM

21A

G10

2SN

1D

L15

3V3I

SO

2

C25

610

0nF

GN

DIS

O2

Haj

du C

s., T

örök

S.

Cze

ller

Mik

lós

<DA

TE

>

DS

P

DS

P

A1

Loca

ted

at s

heet

1 -

D2

Blo

ck D

SP

Pag

e 1

of 1

She

et 6

OF

18

EL-

23-5

0-00

EC

G fo

r H

uman

& S

mal

l-Ani

mal

EK

G (

Hum

án é

s K

isál

lat)

EC

G

2012

-04-

11

AB

CD

EF

GH

1234

Con

trol

ler

<Elle

nõr>

:

Dat

e <D

átum

>:

Pag

e <O

ldal

>

Pag

e N

umbe

r <L

apsz

ám>:

Dra

win

g nu

mbe

r <R

ajzs

zám

>:

NA

ME

<N

év>:

Titl

e <C

im>:

Des

igne

r <T

erve

zõ>:

Dat

e <D

átum

>:M

Doc

. Rev

.

EC

G2_

MO

SI

EC

G2_

RE

SE

T

EC

G1_

RE

SE

T

EC

G1_

ST

AR

T

CA

NT

X

EC

G1_

DR

DY

VC

C=3

V3

SN

74LV

C12

5AD

U24

1

32

EC

G1_

CS

EC

G1_

SC

LK

EC

G1_

MO

SI

CA

NR

X

U24

SN

74LV

C12

5AD

VC

C=3

V3

EC

G2_

SC

LK

EC

G2_

DR

DY

EC

G2_

CS

EC

G2_

ST

AR

T

R87

100

100

R88

R89

100

100

R90

R97

100

100

R91

R92

100

R93

100

MC

AN

TX

100

R94

R95

100

100

R96

DS

P_C

ore

EC

G1C

S

EC

GS

CLK

EC

GM

OS

I

EC

G_M

ISO

EC

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DR

DY

EC

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ES

ET

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TA

RT

EC

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EC

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UP

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UP

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HM

DC

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N

ET

H_C

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H_C

OL

ET

H_T

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ET

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[3:0

]

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H_R

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H_R

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ET

H_R

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V

ET

H_I

NT

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ET

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ST

US

B_D

M

US

B_D

P

CA

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X

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MC

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MC

AN

RX

VC

C_M

EA

S

3V3_

ME

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Bed

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2

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Bed

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2

EC

G_L

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2

EC

G_L

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1

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1

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1

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US

BV

BU

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UP

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NA

UP

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ET

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DC

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DIO

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H_T

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[3:0

]

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N

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H_R

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ET

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[3:0

]

ET

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ET

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ET

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NT

R

R16

349

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49.9

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4

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549

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649

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167

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US

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P

MC

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RX

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SN

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4

65

EC

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O

EC

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MIS

O

VC

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SN

74LV

C12

5AD

U24G

ND

GN

D

GN

D

3V3 10

0nF

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VC

C_M

EA

SA

NA

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ME

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AN

A

Bed

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2

Bed

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2

Bed

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2

EC

G_L

ED

2

EC

G_L

ED

1

Bed

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D_G

1

Bed

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D_Y

1

Bed

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1

R22

310

K

R22

410

K

3V3

3V3

US

B_V

BU

SR

225

100K

T3

T4

GN

DG

ND

EC

G2_

MO

SI

EC

G2_

RE

SE

T

EC

G1_

RE

SE

T

EC

G1_

ST

AR

T

EC

G1_

DR

DY

EC

G_M

ISO

EC

G1_

CS

EC

G1_

CS

EC

G1_

SC

LK

EC

G1_

MO

SI

EC

G2_

SC

LK

EC

G2_

DR

DY

EC

G2_

CS

EC

G2_

CS

EC

G2_

ST

AR

T

EC

G1C

S

EC

GS

CLK

EC

GM

OS

I

EC

G1R

ES

ET

EC

G1S

TA

RT

EC

G2C

S

EC

G2R

ES

ET

EC

G2S

TA

RT

ET

H_M

DC

ET

H_M

DIO

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H_T

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N

ET

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ST

ET

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ET

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ET

H_C

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H_R

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R

ET

H_R

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ET

H_R

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V

ET

H_I

NT

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ET

H_T

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TH

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H_T

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HT

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TH

TX

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ET

HT

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TH

TX

D0ET

HM

DC

ET

HT

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N

ET

HR

ST

UP

1

UP

2

US

B_D

M

US

B_D

P

CA

NT

X

CA

NR

X

CA

N_T

X

MC

AN

TX

MC

AN

RX

MC

AN

_TX

EC

G1_

MIS

O

EC

G2_

MIS

O

VC

C_M

EA

S

3V3_

ME

AS

Bed

_LE

D_R

2

Bed

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D_Y

2

Bed

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D_G

2

EC

G_L

ED

2

EC

G_L

ED

1

Bed

_LE

D_G

1

Bed

_LE

D_Y

1

Bed

_LE

D_R

1

US

B_V

BU

SU

SB

VB

US

ET

H_T

XD

[3:0

]

ET

H_R

XD

[3:0

]

Haj

du C

s., T

örök

S.

Cze

ller

Mik

lós

<DA

TE

>

DS

P C

ore

DS

P M

ag

A1

Loca

ted

at s

heet

6 -

D1

Blo

ck D

SP

_Cor

e P

age

1 of

2S

heet

7 O

F 1

8

EL-

23-5

0-00

EC

G fo

r H

uman

& S

mal

l-Ani

mal

EK

G (

Hum

án é

s K

isál

lat)

EC

G

2012

-04-

11

AB

CD

EF

GH

1234

Con

trol

ler

<Elle

nõr>

:

Dat

e <D

átum

>:

Pag

e <O

ldal

>

Pag

e N

umbe

r <L

apsz

ám>:

Dra

win

g nu

mbe

r <R

ajzs

zám

>:

NA

ME

<N

év>:

Titl

e <C

im>:

Des

igne

r <T

erve

zõ>:

Dat

e <D

átum

>:M

Doc

. Rev

.

EC

G1C

S

CA

NR

X

CA

N_T

X

MC

AN

_TX

EC

G1_

DR

DY

MC

AN

RX

EC

G1R

ES

ET

EC

G1S

TA

RT

A3V

3

GN

D

EC

G2C

S

100n

FC

97

EC

G2_

DR

DY

GN

D

EC

G2R

ES

ET

EC

G2S

TA

RT

U34

F28

M35

H52

C1R

FP

T

GP

IO19

214

0

GP

IO19

314

1

GP

IO19

414

2

GP

IO19

514

3

GP

IO19

611

2

GP

IO19

711

1

GP

IO19

811

0

GP

IO19

910

9

U34

F28

M35

H52

C1R

FP

T

VD

DA

111

9

AD

C1V

RE

FH

I12

0

AD

C1I

NA

012

1

AD

C1I

NA

2/A

IO2

122

AD

C1I

NA

312

3

AD

C1I

NA

4/A

IO4

124

AD

C1I

NA

6/A

IO6

125

AD

C1I

NA

712

6

AD

C1I

NB

011

7

AD

C1I

NB

311

6

AD

C1I

NB

4/A

IO12

115

AD

C1I

NB

711

4

AD

C1V

RE

FLO

118

VD

DA

213

4

AD

C2V

RE

FH

I13

3

AD

C2I

NA

013

2

AD

C2I

NA

2/A

IO18

131

AD

C2I

NA

313

0

AD

C2I

NA

4/A

IO20

129

AD

C2I

NA

6/A

IO22

128

AD

C2I

NA

712

7

AD

C2I

NB

013

6

AD

C2I

NB

313

7

AD

C2I

NB

4/A

IO28

138

AD

C2I

NB

713

9

AD

C2V

RE

FLO

135

U34

F28

M35

H52

C1R

FP

T

PA

0_G

PIO

05

PA

1_G

PIO

16

PA

2_G

PIO

27

PA

3_G

PIO

38

PA

4_G

PIO

49

PA

5_G

PIO

512

PA

6_G

PIO

613

PA

7_G

PIO

714

PB

0_G

PIO

815

PB

1_G

PIO

918

PB

2_G

PIO

1019

PB

3_G

PIO

1120

PE

6_G

PIO

3022

PE

7_G

PIO

3123

PB

6_G

PIO

1426

PB

7_G

PIO

1527

PD

2_G

PIO

1828

PD

3_G

PIO

1929

PB

4_G

PIO

1230

PB

5_G

PIO

1331

PE

2_G

PIO

2632

PE

3_G

PIO

2733

PH

3_G

PIO

5135

PH

2_G

PIO

5036

PC

4_G

PIO

6837

PC

5_G

PIO

6938

PC

6_G

PIO

7039

PC

7_G

PIO

7140

PH

0_G

PIO

4841

PH

1_G

PIO

4942

PE

0_G

PIO

2443

PE

1_G

PIO

2545

PH

4_G

PIO

5246

PH

5_G

PIO

5347

PF

4_G

PIO

3648

PG

0_G

PIO

4049

PG

1_G

PIO

4150

PF

5_G

PIO

3751

PJ6

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IO62

53

PJ5

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IO61

56

PJ4

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IO60

57

PJ3

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IO59

60

PJ2

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IO58

61

PJ1

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IO57

62

PJ0

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IO56

63

PD

5_G

PIO

2164

PD

4_G

PIO

2065

PD

7_G

PIO

2368

PF

6_G

PIO

3869

PG

6_G

PIO

4670

PG

2_G

PIO

4271

PG

5_G

PIO

4572

PD

6_G

PIO

2273

PE

5_G

PIO

2976

PE

4_G

PIO

2877

PH

6_G

PIO

5479

PH

7_G

PIO

5580

PD

1_G

PIO

1798

PD

0_G

PIO

1610

2

PF

1_G

PIO

3310

3

PF

0_G

PIO

3210

4

GN

D

UP

1A

NA

UP

2A

NA

ET

HT

XD

3E

TH

TX

D2

ET

HT

XD

1E

TH

TX

D0

ET

HM

DC

ET

H_M

DIO

ET

HT

XE

N

ET

H_C

RS

ET

H_C

OL

ET

H_T

XC

LK

ET

H_R

XD

[3:0

]

ET

H_R

XE

R

ET

H_R

XC

LK

ET

H_R

XD

V

ET

H_I

NT

R

ET

HR

ST

US

B_D

MU

SB

_DP

EC

GS

CLK

EC

GM

OS

I

EC

G_M

ISO

100n

FC

98

U35

LT17

90-A

IS6-

3

64

VIN

VO

UT

L18

BLM

21A

G10

2SN

1DV

CC

1uF

C23

3 GN

D

C23

4

1uF

GN

D

VC

C_M

EA

SA

NA

3V3_

ME

AS

AN

A

A3V

3G

ND

Bed

_LE

D_R

1B

ed_L

ED

_Y1

Bed

_LE

D_G

1E

CG

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D1

EC

G_L

ED

2B

ed_L

ED

_G2

Bed

_LE

D_Y

2B

ed_L

ED

_R2

US

BV

BU

S

100

R22

6

R22

7100 10

0R

228

TP

21

TP

11

TP

31

EC

G1C

S

EC

G1_

DR

DY

EC

G1R

ES

ET

EC

G1S

TA

RT

EC

G2R

ES

ET

EC

G2S

TA

RT

ET

HT

XD

3E

TH

TX

D2

ET

HT

XD

1E

TH

TX

D0

ET

HM

DC

ET

H_M

DIO

ET

HT

XE

N

ET

H_C

RS

ET

H_C

OL

ET

H_T

XC

LK

ET

H_R

XE

R

ET

H_R

XC

LKE

TH

_RX

DV

ET

H_I

NT

R

ET

HR

ST

ET

H_R

XD

3

ET

H_R

XD

2E

TH

_RX

D1

ET

H_R

XD

0

US

B_D

MU

SB

_DP

EC

GS

CLK

EC

GM

OS

IE

CG

_MIS

O

EC

G2C

SE

CG

2_D

RD

Y

CA

NR

X

CA

N_T

X

MC

AN

_TX

MC

AN

RX

VR

EF

_3V

VR

EF

_3V

VR

EF

_3V

Bed

_LE

D_R

1B

ed_L

ED

_Y1

Bed

_LE

D_G

1E

CG

_LE

D1

EC

G_L

ED

2B

ed_L

ED

_G2

Bed

_LE

D_Y

2B

ed_L

ED

_R2

US

BV

BU

S

U34

F28

M35

H52

C1R

FP

T

X2

95X

193

EM

U0

83

EM

U1

86

TR

ST

85

TM

S87

TD

I88

TD

O84

TC

K89

XR

Sn

4

AR

Sn

144

VS

SO

SC

94

XC

LKIN

97

XC

LKO

UT

_BO

OT

382

BO

OT

281

BO

OT

152

BO

OT

078

NC

91

FLT

116

FLT

221

U34

F28

M35

H52

C1R

FP

T

VR

EG

12E

N10

1

VR

EG

18E

N11

3

VD

D12

_11

11

VD

D12

_24

24

VD

D12

_55

55

VD

D12

_58

58

VD

D12

_66

66

VD

D12

_75

75

VD

D12

_90

90

VD

D12

_99

99

VD

D18

_11

VD

D18

_108

108

VD

DIO

_22

VD

DIO

_33

VD

DIO

_10

10

VD

DIO

_17

17

VD

DIO

_25

25

VD

DIO

_34

34

VD

DIO

_44

44

VD

DIO

_54

54

VD

DIO

_59

59

VD

DIO

_67

67

VD

DIO

_74

74

VD

DIO

_92

92

VD

DIO

_96

96

VD

DIO

_100

100

VD

DIO

_105

105

VD

DIO

_106

106

VD

DIO

_107

107

VS

S14

5

Haj

du C

s., T

örök

S.

Cze

ller

Mik

lós

<DA

TE

>

DS

P C

ore

2

DS

P M

ag 2

A1

Loca

ted

at s

heet

6 -

D1

Blo

ck D

SP

_Cor

e P

age

2 of

2S

heet

8 O

F 1

8

EL-

23-5

0-00

EC

G fo

r H

uman

& S

mal

l-Ani

mal

EK

G (

Hum

án é

s K

isál

lat)

EC

G

2012

-04-

11

AB

CD

EF

GH

1234

Con

trol

ler

<Elle

nõr>

:

Dat

e <D

átum

>:

Pag

e <O

ldal

>

Pag

e N

umbe

r <L

apsz

ám>:

Dra

win

g nu

mbe

r <R

ajzs

zám

>:

NA

ME

<N

év>:

Titl

e <C

im>:

Des

igne

r <T

erve

zõ>:

Dat

e <D

átum

>:M

Doc

. Rev

.

3V3

3V3

GN

D

3V3

JTA

G

HE

AD

ER

7X

2

J33

131197531

1412108642

C24

0

2.2u

F2.

2uF

C24

1

R20

02.

2K

GN

D

3V3

R20

1

2.2K

GN

D

GN

D

X2

20M

hzC

218

15pF

C21

915

pF

GN

DG

ND

GND

R22

14.

7KR

222

4.7K

GND

C24

4

470n

F47

0nF

C24

5C

246

470n

F47

0nF

C24

7C

248

470n

F47

0nF

C24

9

C25

0

470n

F

C25

1

470n

F

GN

D

C99

100n

F100n

FC

100

C10

110

0nF

100n

FC

102

C10

310

0nF10

0nF

C10

4C

105

100n

F

100n

FC

106

C10

710

0nF10

0nF

C10

8C

109

100n

F

100n

FC

110

C11

110

0nF

GN

D

C11

210

0nF

100n

FC

113

C11

410

0nF10

0nF

C11

5

GN

DG

ND

GN

DG

ND

GN

DG

ND

GN

DG

ND

GN

DG

ND

GN

DG

ND

GN

DG

ND

GN

DG

ND

3V3

3V3

3V3

3V3

3V3

3V3

3V3

3V3

3V3

3V3

3V3

3V3

3V3

3V3

3V3

3V3

3V3

3V3

GN

D

T1

T2

GN

DG

NDC25

410

0nF

GN

D

TD

O

TD

O

TD

I

TD

I

TM

S

TM

S

TC

K

TC

K

TR

ST

TR

ST

GN

D

X1

X1

X2

X2

EM

U0

EM

U0

EM

U1

EM

U1

Haj

du C

s., T

örök

S.

Cze

ller

Mik

lós

<DA

TE

>

Pre

ssur

e S

enso

rs

Nyo

más

érz

ékel

ök

A1

Loca

ted

at s

heet

1 -

D2

Blo

ck P

ress

ure_

sens

or P

age

1 of

1S

heet

9 O

F 1

8

EL-

23-5

0-00

EC

G fo

r H

uman

& S

mal

l-Ani

mal

EK

G (

Hum

án é

s K

isál

lat)

EC

G

2012

-04-

11

AB

CD

EF

GH

1234

Con

trol

ler

<Elle

nõr>

:

Dat

e <D

átum

>:

Pag

e <O

ldal

>

Pag

e N

umbe

r <L

apsz

ám>:

Dra

win

g nu

mbe

r <R

ajzs

zám

>:

NA

ME

<N

év>:

Titl

e <C

im>:

Des

igne

r <T

erve

zõ>:

Dat

e <D

átum

>:M

Doc

. Rev

.

U25

SD

P11

08-R

2

3

1 VCC

OU

T

GND

dP

GN

D

L16

BLM

21A

G10

2SN

1DC

238

2.2u

FC

201

100n

F

GN

DG

ND

VC

C

UP

1

R18

520

K

UP

210

K

R18

7

VC

C

GN

DG

ND

GN

D

100n

FC

202

2.2u

FC

239B

LM21

AG

102S

N1D

L17

SD

P11

08-R

U26

2

3

1 VCC

OU

T

GND

dP

GN

D

C20

310

0nF

GN

D

GN

D

R18

8

10K

20K

R18

610

0nF

C20

4

GN

D

R99

100

100

R10

0U

P2

UP

1

Haj

du C

s., T

örök

S.

Cze

ller

Mik

lós

<DA

TE

>

TIT

LE

<CIM

>

A1

Loca

ted

at s

heet

1 -

A3

Blo

ck E

CG

_Inp

uts2

Pag

e 1

of 1

She

et 1

0 O

F 1

8

EL-

23-5

0-00

EC

G fo

r H

uman

& S

mal

l-Ani

mal

EK

G (

Hum

án é

s K

isál

lat)

EC

G

2012

-04-

11

AB

CD

EF

GH

1234

Con

trol

ler

<Elle

nõr>

:

Dat

e <D

átum

>:

Pag

e <O

ldal

>

Pag

e N

umbe

r <L

apsz

ám>:

Dra

win

g nu

mbe

r <R

ajzs

zám

>:

NA

ME

<N

év>:

Titl

e <C

im>:

Des

igne

r <T

erve

zõ>:

Dat

e <D

átum

>:M

Doc

. Rev

.

EC

G_C

2

EC

G_R

L2

EC

G_L

L2

EC

G_R

A2

EC

G_L

A2

ELE

C_R

A2

ELE

C_L

A2

47pF

C65

47pF

C66

GN

DIS

O2

MC

0801

0000

DS

610

K

R60

GN

DIS

O2

GN

DIS

O2

22K

R50

47pF

C67

47pF

C68

GN

DIS

O2

MC

0801

0000

DS

710

K

R61

GN

DIS

O2

GN

DIS

O2

22K

R51

R52

22K

GN

DIS

O2

GN

DIS

O2

R62

10K

DS

8

MC

0801

0000 G

ND

ISO

2

C69

47pF

C70

47pF

47pF

C71

47pF

C72

GN

DIS

O2

MC

0801

0000

DS

910

K

R63

GN

DIS

O2

GN

DIS

O2

22K

R53

R54

22K

GN

DIS

O2

GN

DIS

O2

R64

10K

DS

10

MC

0801

0000 G

ND

ISO

2

C73

47pF

C74

47pF

J6 J7 J8 J9 J10

ELE

C_R

L2

ELE

C_L

L2

ELE

C_R

A2

ELE

C_R

A2

ELE

C_L

A2

ELE

C_L

A2

EC

G_L

L2

EC

G_L

L2

EC

G_R

L2

EC

G_R

L2

EC

G_C

2

EC

G_C

2E

LEC

_C2

EC

G_R

A2

EC

G_R

A2

EC

G_L

A2

EC

G_L

A2

Haj

du C

s., T

örök

S.

Cze

ller

Mik

lós

<DA

TE

>

SA

Bed

CA

N In

terf

aces

Kis

álla

t ágy

CA

N in

terf

észe

k

A1

Loca

ted

at s

heet

1 -

F3

Blo

ck C

AN

_Int

f Pag

e 1

of 1

She

et 1

1 O

F 1

8

EL-

23-5

0-00

EC

G fo

r H

uman

& S

mal

l-Ani

mal

EK

G (

Hum

án é

s K

isál

lat)

EC

G

2012

-04-

11

AB

CD

EF

GH

1234

Con

trol

ler

<Elle

nõr>

:

Dat

e <D

átum

>:

Pag

e <O

ldal

>

Pag

e N

umbe

r <L

apsz

ám>:

Dra

win

g nu

mbe

r <R

ajzs

zám

>:

NA

ME

<N

év>:

Titl

e <C

im>:

Des

igne

r <T

erve

zõ>:

Dat

e <D

átum

>:M

Doc

. Rev

.

SD

1

BA

T75

4C

R14

451

K

R20

75.

1KR

208

5.1K

VC

CIS

O

GN

DIS

O

VC

CIS

O

Q1

2N39

04

GN

DIS

O

R20

936

0

U29

PS

7241

46

31

VC

CIS

O

VC

C1=

3V3

GN

D1=

GN

D V

CC

2=V

CC

ISO

GN

D2=

GN

DIS

O

U30

ISO

1050

7 623

TX

D

RX

DC

AN

L

CA

NH

R21

010

0

CA

NT

X

R10

1

100

CA

NR

XS

D2

NU

P21

05L

32

1

GN

DIS

O

F1

FU

SE

HO

LDE

R2

1

F2

FU

SE

HO

LDE

R2

1

VIN

VC

CIS

O C95

100n

F

GN

DIS

O

T5

GN

DIS

O

VC

C

RT

1

MIN

ISM

DC

020F

T

MIN

ISM

DC

020F

RT

2T

VC

C

GN

D100n

FC

252

3V3

SA

Bed

1 c

onne

ctor

J34

DS

UB

9 R

FE

MA

LE

1 2 3 4 56 7 8 9

GN

D_V

IN

GN

D

GN

D_V

IN

DS

UB

9 R

FE

MA

LE

J35

1 2 3 4 56 7 8 9

GN

DG

ND

ISO

GN

DIS

O

CA

NT

SW

2

GN

DIS

O

GN

DIS

O

CA

NT

SW

1

CA

NH

CA

NH

CA

NH

CA

NL

CA

NL

CA

NL

CA

NT

X

CA

NR

X

24V

PW

R1

24V

PW

R1

24V

PW

R2

24V

PW

R2

SA

Bed

1 c

onne

ctor

SA

Bed

2 c

onne

ctor

Haj

du C

s., T

örök

S.

Cze

ller

Mik

lós

<DA

TE

>

US

B In

terf

ace

US

B In

terf

ész

A1

Loca

ted

at s

heet

1 -

F3

Blo

ck U

SB

_Int

f Pag

e 1

of 1

She

et 1

2 O

F 1

8

EL-

23-5

0-00

EC

G fo

r H

uman

& S

mal

l-Ani

mal

EK

G (

Hum

án é

s K

isál

lat)

EC

G

2012

-04-

11

AB

CD

EF

GH

1234

Con

trol

ler

<Elle

nõr>

:

Dat

e <D

átum

>:

Pag

e <O

ldal

>

Pag

e N

umbe

r <L

apsz

ám>:

Dra

win

g nu

mbe

r <R

ajzs

zám

>:

NA

ME

<N

év>:

Titl

e <C

im>:

Des

igne

r <T

erve

zõ>:

Dat

e <D

átum

>:M

Doc

. Rev

.

SH

LD=G

ND

J31

US

B-B

90R

1 2 3D

AT

A-P

DA

TA

-M

VB

US

PR

TR

5V0U

2AX

D2

14

2

3

VC

C

GN

D

US

B_D

P

US

B_D

M

US

B_V

BU

SU

SB

_DM

US

B_D

P

US

B_V

BU

S

Haj

du C

s., T

örök

S.

Cze

ller

Mik

lós

<DA

TE

>

Isol

ator

s

Gal

vani

kus

levá

lasz

tás

A1

Loca

ted

at s

heet

1 -

C3

Blo

ck Is

olat

ors

Pag

e 1

of 1

She

et 1

3 O

F 1

8

EL-

23-5

0-00

EC

G fo

r H

uman

& S

mal

l-Ani

mal

EK

G (

Hum

án é

s K

isál

lat)

EC

G

2012

-04-

11

AB

CD

EF

GH

1234

Con

trol

ler

<Elle

nõr>

:

Dat

e <D

átum

>:

Pag

e <O

ldal

>

Pag

e N

umbe

r <L

apsz

ám>:

Dra

win

g nu

mbe

r <R

ajzs

zám

>:

NA

ME

<N

év>:

Titl

e <C

im>:

Des

igne

r <T

erve

zõ>:

Dat

e <D

átum

>:M

Doc

. Rev

.

MIS

O

EC

G2_

ST

AR

T

MO

SI

SC

LK

DR

DY

VD

D1=

3V3

GN

D1=

GN

D V

DD

2=3V

3IS

O1

GN

D2=

GN

DIS

O1

U6

AD

uM24

01B

RW

Z

7 6

103 4 5

14 1113 12V

OC

VO

B

VID

VO

A

VIC

VIB

VIA

VE

2

VO

D

VE

1

EC

G2_

DR

DY

100

R65

ST

AR

T2

CS

R66

100

100

R67

ST

AR

T

R68

49.9

VD

D1=

3V3

GN

D1=

GN

D V

DD

2=3V

3IS

O1

GN

D2=

GN

DIS

O1

U5

AD

uM24

01B

RW

Z

7 6

103 4 5

14 1113 12V

OC

VO

B

VID

VO

A

VIC

VIB

VIA

VE

2

VO

D

VE

1

3V3I

SO

1

CLK

SC

LK2

MO

SI2

MIS

O2

3V3

3V3I

SO

1

R69

100 V

DD

1=3V

3 G

ND

1=G

ND

VD

D2=

3V3I

SO

2 G

ND

2=G

ND

ISO

2

U7

AD

uM24

01B

RW

Z

7 6

103 4 5

14 1113 12V

OC

VO

B

VID

VO

A

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VIA

VE

2

VO

D

VE

1

100

R70

R71

100

49.9

R72

3V3

AD

uM24

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RW

Z

U8

VD

D1=

3V3

GN

D1=

GN

D V

DD

2=3V

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O2

GN

D2=

GN

DIS

O2

7 6

103 4 5

14 1113 12V

OC

VO

B

VID

VO

A

VIC

VIB

VIA

VE

2

VO

D

VE

1

3V3I

SO

2

R73

100 10

0

R74

R75

100

49.9

R76

3V3

3V3 R

77

49.9

100

R78

R79

100

100

R80

3V3I

SO

2

C75

100n

F

3V3

GN

D

100n

FC

76

3V3I

SO

1

GN

DIS

O1

100n

FC

77

3V3I

SO

1

GN

DIS

O1

3V3

GN

D100n

FC

78

3V3

GN

D100n

FC

79

3V3

GN

DC80

100n

FC

8110

0nF

3V3I

SO

2

GN

DIS

O2

C82

100n

F

3V3I

SO

2

GN

DIS

O2

EC

G2_

MIS

O

CLK

2

CS

2

DR

DY

2

EC

G2_

CS

EC

G2_

SC

LK

EC

G2_

MO

SI

EC

G1_

ST

AR

T

EC

G1_

DR

DY

EC

G1_

CS

EC

G1_

MIS

O

EC

G1_

SC

LK

EC

G1_

MO

SI

RE

SE

TE

CG

1_R

ES

ET

RE

SE

T2

EC

G2_

RE

SE

T

V33

=3V

3

U9

2.04

8MH

z 3.

3V

4

1O

E

OU

T

100n

FC

83

GN

D

3V3

R81

75 75R

82

ST

AR

T2

SC

LK

MO

SI

MIS

O

SC

LK2

MO

SI2

MIS

O2

CLK

2

CS

2

DR

DY

2

DR

DY

CS

ST

AR

T

CLK

EC

G2_

ST

AR

T

EC

G2_

CLK

EC

G2_

DR

DY

EC

G2_

MIS

O

EC

G2_

CS

EC

G2_

SC

LK

EC

G2_

MO

SI

EC

G1_

ST

AR

T

EC

G1_

CLK

EC

G1_

DR

DY

EC

G1_

CS

EC

G1_

MIS

O

EC

G1_

SC

LK

EC

G1_

MO

SI

RE

SE

TE

CG

1_R

ES

ET

RE

SE

T2

EC

G2_

RE

SE

T

A1

Fö

CA

N in

terf

ész

Mai

n C

AN

Inte

rfac

e

<DA

TE

>

Cze

ller

Mik

lós

Haj

du C

s., T

örök

S.

Loca

ted

at s

heet

1 -

F3

Blo

ck C

AN

_Int

f_M

ain

Pag

e 1

of 1

She

et 1

4 O

F 1

8

EL-

23-5

0-00

EC

G fo

r H

uman

& S

mal

l-Ani

mal

EK

G (

Hum

án é

s K

isál

lat)

EC

G

2012

-04-

11

AB

CD

EF

GH

1234

Con

trol

ler

<Elle

nõr>

:

Dat

e <D

átum

>:

Pag

e <O

ldal

>

Pag

e N

umbe

r <L

apsz

ám>:

Dra

win

g nu

mbe

r <R

ajzs

zám

>:

NA

ME

<N

év>:

Titl

e <C

im>:

Des

igne

r <T

erve

zõ>:

Dat

e <D

átum

>:M

Doc

. Rev

.

SD

3N

UP

2105

L

32

1

GN

DIS

OM

J32

DS

UB

9 R

MA

LE

1 2 3 4 56 7 8 9

GN

DIS

OM

C96

100n

F

GN

DIS

OM

VC

CIS

OM

3V3

GN

DC25

310

0nF

T6

GN

DIS

OM

VC

C1=

3V3

GN

D1=

GN

D V

CC

2=V

CC

ISO

M G

ND

2=G

ND

ISO

M

ISO

1050

U31 TX

D

RX

DC

AN

L

CA

NH

120

CA

NT

X

R10

2

100

CA

NR

X

CA

NH

CA

NL

CA

NT

X

CA

NR

X

Haj

du C

s., T

örök

S.

Cze

ller

Mik

lós

<DA

TE

>

Eth

erne

t Int

erfa

ce

Eth

erne

t int

erfé

sz

A1

Loca

ted

at s

heet

1 -

F4

Blo

ck E

ther

net_

Intf

Pag

e 1

of 1

She

et 1

5 O

F 1

8

EL-

23-5

0-00

EC

G fo

r H

uman

& S

mal

l-Ani

mal

EK

G (

Hum

án é

s K

isál

lat)

EC

G

2012

-04-

11

AB

CD

EF

GH

1234

Con

trol

ler

<Elle

nõr>

:

Dat

e <D

átum

>:

Pag

e <O

ldal

>

Pag

e N

umbe

r <L

apsz

ám>:

Dra

win

g nu

mbe

r <R

ajzs

zám

>:

NA

ME

<N

év>:

Titl

e <C

im>:

Des

igne

r <T

erve

zõ>:

Dat

e <D

átum

>:M

Doc

. Rev

.

U27

LAN

8710

A

33

3231 3029 28

27

2620 191815 13

12

111098 7

65 432

1

21 22232425 1417 16M

DIO

MD

C

CR

S

TX

D3

TX

D2

TX

D1

TX

D0

TX

EN

VDDA2

LED

2/nI

NT

SE

LLE

D1/

RE

GO

FF

XT

AL2

XT

AL1

/CLK

INVDDCR

RX

CLK

/PH

YA

D1

RX

D3/

PH

YA

D2

RX

D2/

RM

IISE

LR

XD

1/M

OD

E1

RX

D0/

MO

DE

0

VDDIO

RX

ER

/RX

D4/

PH

YA

D0

CO

L/C

RS

_DV

/MO

DE

2

nIN

T/T

XE

R/T

XD

4

nRS

T

TX

CLK

RX

DV

VDD1A

TX

NT

XP

RX

NR

XP

RB

IAS

VSSG

RO

UN

D

PO

WE

R

GN

D

R18

910

K

R19

12.

2K

3V3

3V375

R17

1R

172

7575R

173

R17

075

R17

475 75

R17

5R

176

75

R17

77575

R17

8

R20

2

12K

GN

D

X1

25M

Hz

X32

C24

2

33pF

C24

3

33pF

GN

D

R19

010

K

GN

D

R17

949

.9R

180

49.9

R18

149

.9R

182

49.9

R20

310

R20

410

C20

510

0nF

C20

610

0nF

U28

J001

1D01

BN

L

1413879101211653241T

XP

TX

CT

TX

N

RX

PR

XC

TR

XN

C_Y

LWA

_YLW

C_G

RN

A_G

RN

N.C

.C

HS

_GN

D3

CH

S_G

ND

2C

HS

_GN

D1

GN

DG

ND

L4 BLM

21P

G22

1SN

1D

L5 BLM

21P

G22

1SN

1D

3V3

2.2K

R19

2

3V3

3V3 C

161

10uF

C16

210

uFC

207

100n

F GN

DG

ND

100n

FC

208

C20

910

0nF

100n

FC

210

GN

DG

ND

GN

DG

ND

3V3

3V3

R20

533

0R

206

330

GN

D

GN

D

GN

D100n

FC

211

10uF

C16

3

GN

D

ET

H_T

XD

[3:0

]

R18

375 75

R18

4

2.2K

R19

3

3V3

3V3 R

194

2.2K

2.2K

R19

5

3V3

R19

62.

2K

GN

D

2.2K

R19

7

GN

DG

NDR

198

2.2K

2.2K

R19

9

GN

D

ET

H_T

XE

N

ET

H_R

ST

ET

H_T

XC

LK

ET

H_R

XD

[3:0

]

ET

H_C

OL

ET

H_C

RS

ET

H_R

XE

RE

TH

_RX

CLK

ET

H_R

XD

V

ET

H_I

NT

R

ET

H_M

DC

ET

H_M

DIO

EN

ET

_TX

PE

NE

T_T

XN

EN

ET

_RX

PE

NE

T_R

XN

EN

ET

_VD

DIO

EN

ET

_VD

DA

EN

ET

_VD

DA

EN

ET

_VD

DC

R

ET

H_T

XD

0E

TH

_TX

D1

ET

H_T

XD

2E

TH

_TX

D3

ETH_RXD0ET

H_R

XD

0

ETH_RXD1

ET

H_R

XD

1

ETH_RXD2

ET

H_R

XD

2

ETH_RXD3

ET

H_R

XD

3

ET

H_C

OL

ETH_COL

ET

H_C

RS

ET

H_R

XC

LK

ETH_RXCLK

ETH_RXERE

TH

_RX

ER

ET

H_R

XD

V

ET

H_I

NT

R

ET

H_R

ST

ET

H_T

XE

N

ET

H_M

DIO

ET

H_M

DC

ET

H_T

XC

LK

ET

H_T

XD

[3:0

]

ET

H_R

XD

[3:0

]

Haj

du C

s., T

örök

S.

Cze

ller

Mik

lós

<DA

TE

>

EC

G In

terf

ace

1

EK

G in

terf

ész

1

A1

Loca

ted

at s

heet

1 -

B4

Blo

ck E

CG

_Int

f Pag

e 1

of 1

She

et 1

6 O

F 1

8

EL-

23-5

0-00

EC

G fo

r H

uman

& S

mal

l-Ani

mal

EK

G (

Hum

án é

s K

isál

lat)

EC

G

2012

-04-

11

AB

CD

EF

GH

1234

Con

trol

ler

<Elle

nõr>

:

Dat

e <D

átum

>:

Pag

e <O

ldal

>

Pag

e N

umbe

r <L

apsz

ám>:

Dra

win

g nu

mbe

r <R

ajzs

zám

>:

NA

ME

<N

év>:

Titl

e <C

im>:

Des

igne

r <T

erve

zõ>:

Dat

e <D

átum

>:M

Doc

. Rev

.

GN

DIS

O1

GN

DIS

O1

10uF

C11

610

uFC

117

GN

DIS

O1

GN

DIS

O1

GN

DIS

O1

C13

11u

F

1uF

C13

2C13

31u

F

A3V

3IS

O1

C13

41u

FC

8410

0nF

GN

DIS

O1

GN

DIS

O1

GN

DIS

O1

100n

FC

853V

3IS

O1

GN

DIS

O1 1u

FC

135

10uF

C15

510

0nF

C86

GN

DIS

O1

1nF

C16

4

GN

DIS

O1

AD

S12

98R

IZX

G

U10

G8

E5

E6

E7

F5

G7

F7

F8

H8

E8

D6

B8

G6

H3H4

F6H7D7

C7

G5

A8

D5

G3

C5

B7

B5H6

A5H5D4E3F3

D8C8

A7C6B6A6B4A4C4A3B3C3

E4

G4

F4

A1

A2

B1

B2

C1

C2

D1

D2

E1

E2

F1

F2

G1

G2

H1

H2

D3

WC

TIN

1NIN

1PIN

2NIN

2PIN

3NIN

3PIN

4NIN

4PIN

5NIN

5PIN

6NIN

6PIN

7NIN

7PIN

8NIN

8PR

ES

P_M

OD

NR

ES

P_M

OD

PR

ES

V1

RLDINVRLDOUT

RLDINRLDREFAVDD_1AVDD_2AVDD_3AVDD_4AVDD_5AVDD1

DVDD1DVDD2

TESTN_PACE_OUT2TESTP_PACE_OUT1AVSS_1VCAP1AVSS_2

VCAP2AVSS_3

VCAP3

AVSS_4

VCAP4

AVSS_5

AVSS1

PWDN

DGND1

DGND2DGND3DAISY_IN

VREFNVREFP

RE

SE

T

CLK

SE

LD

RD

YD

OU

TD

INS

CLK CS

ST

AR

T

GP

IO1

GP

IO2

GP

IO3

GP

IO4

CLK

DR

DY

_O

DO

UT

_O

R10

310

K

3V3I

SO

1

R83

100

100

R84

DIN

SC

LK CS

ST

AR

T

CLK

RE

SE

T

GN

DIS

O1

R12

5

40.2

K

C16

8

2.2n

FR12

910

ME

G

2.2n

F

C16

9

10M

EG

R13

0

GN

DIS

O1

A3V

3IS

O1

A3V

3IS

O1

GN

DIS

O1

40.2

K

R12

6

2.2n

F

C17

0R13

110

ME

G

10M

EG

R13

2

C17

1

2.2n

F

C17

6

100n

F

C17

7

100n

F

ELE

C_L

A

ELE

C_R

A

C18

0

1.5n

F

R13

7

1ME

G

RL

RA LA LL

GN

DIS

O1

C10

KR

106

21

10K

R10

72

1R

108

10K

21

10K

R10

92

1R

110

10K

21

10K

R11

12

1R

112

10K

21

R11

310

K2

1

A3V

3IS

O1

VCAP1

WC

T

IN2N

IN2P

IN3P

IN4P

IN5N

IN5N

IN5P

IN5P

IN6N

IN6N

IN6P

IN6P

IN7N

IN7N

IN7P

IN7P

IN8N

IN8N

IN8P

IN8P

RE

SP

_MO

DN

RE

SP

_MO

DN

RE

SP

_MO

DP

RE

SP

_MO

DP

RLD

INV

RLDINV

RLD

OU

T

RLDIN

RLD

OU

T|R

LDIN

RLDOUT

3V3ISO1

PWDN

PWDN VR

EF

N

VREFP

RE

SE

T

RE

SE

T

DR

DY

DR

DY

DO

UT

DO

UT

DIN

DIN

SC

LK

SC

LK

CS

CS

GP

IO1

GP

IO2

GP

IO3

GP

IO4

CLK

CLK

DR

DY

_O

DO

UT

_O

IN1N

IN1N

IN1P

IN1P

ST

AR

T

ST

AR

T

<DA

TE

>

Cze

ller

Mik

lós

Haj

du C

s., T

örök

S.

EC

G In

terf

ace

2A

1E

KG

inte

rfés

z 2

Loca

ted

at s

heet

1 -

B3

Blo

ck E

CG

_Int

f2 P

age

1 of

1S

heet

17

OF

18

EL-

23-5

0-00

EC

G fo

r H

uman

& S

mal

l-Ani

mal

EK

G (

Hum

án é

s K

isál

lat)

EC

G

2012

-04-

11

AB

CD

EF

GH

1234

Con

trol

ler

<Elle

nõr>

:

Dat

e <D

átum

>:

Pag

e <O

ldal

>

Pag

e N

umbe

r <L

apsz

ám>:

Dra

win

g nu

mbe

r <R

ajzs

zám

>:

NA

ME

<N

év>:

Titl

e <C

im>:

Des

igne

r <T

erve

zõ>:

Dat

e <D

átum

>:M

Doc

. Rev

.

GN

DIS

O2

GN

DIS

O2

C11

810

uFC

119

10uF

GN

DIS

O2

GN

DIS

O2

GN

DIS

O2

1uF

C14

1 C14

21u

F

1uF

C14

3

A3V

3IS

O2

C14

41u

FC

8910

0nF

GN

DIS

O2

GN

DIS

O2

GN

DIS

O2

100n

FC

903V

3IS

O2

GN

DIS

O2

1uF

C14

5

10uF

C15

610

0nF

C91

GN

DIS

O2

1nF

C16

6

GN

DIS

O2

H3H4

F6H7D7

C7

G5

A8

D5

G3

C5

B7

B5H6

A5H5D4E3F3

D8C8

A7C6B6A6B4A4C4A3B3C3

E4

G4

F4

A1

A2

B1

B2

C1

C2

D1

D2

E1

E2

F1

F2

G1

G2

H1

H2

D3

AD

S12

98R

IZX

G

U11

G8

E5

E6

E7

F5

G7

F7

F8

H8

E8

D6

B8

G6

WC

TIN

1NIN

1PIN

2NIN

2PIN

3NIN

3PIN

4NIN

4PIN

5NIN

5PIN

6NIN

6PIN

7NIN

7PIN

8NIN

8PR

ES

P_M

OD

NR

ES

P_M

OD

PR

ES

V1

RLDINVRLDOUT

RLDINRLDREFAVDD_1AVDD_2AVDD_3AVDD_4AVDD_5AVDD1

DVDD1DVDD2

TESTN_PACE_OUT2TESTP_PACE_OUT1AVSS_1VCAP1AVSS_2

VCAP2AVSS_3

VCAP3

AVSS_4

VCAP4

AVSS_5

AVSS1

PWDN

DGND1

DGND2DGND3DAISY_IN

VREFNVREFP

RE

SE

T

CLK

SE

LD

RD

YD

OU

TD

INS

CLK CS

ST

AR

T

GP

IO1

GP

IO2

GP

IO3

GP

IO4

CLK

RE

SE

T

DR

DY

_O

DO

UT

_O

10K

R11

4

3V3I

SO

2

100

R85

R86

100

DIN

SC

LK CS

ST

AR

T

CLK

GN

DIS

O2

40.2

K

R12

7

2.2n

F

C17

2

10M

EG

R13

3

C17

3

2.2n

F R13

410

ME

G

GN

DIS

O2

A3V

3IS

O2

A3V

3IS

O2

GN

DIS

O2R

128

40.2

K

C17

4

2.2n

FR13

510

ME

G

R13

610

ME

G

2.2n

F

C17

5

100n

F

C17

8

100n

F

C17

9

ELE

C_L

A

ELE

C_R

A

1.5n

F

C18

1

1ME

G

R13

8

RL

RA LA LL C

R11

710

KR

118

10K

R11

910

K

R12

010

K2

1R

121

10K

21

R12

210

K2

110

KR

123

21

10K

R12

42

1

A3V

3IS

O2

GN

DIS

O2

VCAP1

WC

T

IN2N

IN2P

IN3P

IN4P

IN5N

IN5N

IN5P

IN5P

IN6N

IN6N

IN6P

IN6P

IN7N

IN7N

IN7P

IN7P

IN8N

IN8N

IN8P

IN8P

RE

SP

_MO

DN

RE

SP

_MO

DN

RE

SP

_MO

DP

RE

SP

_MO

DP

RLDINV

RLD

INV

RLDIN

RLD

OU

T

RLDOUT

RLD

OU

T|R

LDIN

3V3ISO2

PWDN

PWDN VR

EF

N

VREFP

RE

SE

T

RE

SE

T

DR

DY

DR

DY

DO

UT

DO

UT

DIN

DIN

SC

LK

SC

LK

CS

CS

GP

IO1

GP

IO2

GP

IO3

GP

IO4

CLK

CLK

DR

DY

_O

DO

UT

_O

IN1N

IN1N

IN1P

IN1P

ST

AR

T

ST

AR

T

Haj

du C

s., T

örök

S.

Cze

ller

Mik

lós

<DA

TE

>

Fee

dbac

k LE

Ds

Vis

szaj

elzö

LE

D-e

k

A1

Loca

ted

at s

heet

1 -

F2

Blo

ck F

eedb

ack_

LED

s P

age

1 of

1S

heet

18

OF

18

EL-

23-5

0-00

EC

G fo

r H

uman

& S

mal

l-Ani

mal

EK

G (

Hum

án é

s K

isál

lat)

EC

G

2012

-04-

11

AB

CD

EF

GH

1234

Con

trol

ler

<Elle

nõr>

:

Dat

e <D

átum

>:

Pag

e <O

ldal

>

Pag

e N

umbe

r <L

apsz

ám>:

Dra

win

g nu

mbe

r <R

ajzs

zám

>:

NA

ME

<N

év>:

Titl

e <C

im>:

Des

igne

r <T

erve

zõ>:

Dat

e <D

átum

>:M

Doc

. Rev

.

D3

LED

R/Y

/G 3

mm

HM

L

R21

233

0R

214

300

R21

627

0

VC

CV

CC

VC

C

U32

74H

CT

041213

74H

CT

04

U32

1011

U32

74H

CT

04

89

74H

CT

04

U33

1213

U33

74H

CT

04

89

74H

CT

04

U33

1011

VC

CV

CC

VC

C

270

R21

733

0R

213

300

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