Download ECG Implementation on the TMS320VC5505

Application Report
SPRAB36B – June 2010
ECG Implementation on the TMS320C5515 DSP Medical
Development Kit (MDK)
Vishal Markandey .............................................................................................................................
ABSTRACT
The medical development kit (MDK) provides a development platform to TI medical customers, third
parties, and other developers. This application report focuses on the C5515 MDK; however, the analog
front ends that are included can also be used with other platforms.
Please be aware that an important notice concerning availability, standard warranty, and use in critical
applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of
this document.
NOTE:
Disclaimer Statement: Do not use this medical development kit for the purpose of
diagnosing patients.
This application report may not include all of the details necessary to completely develop the
design. It is provided as a reference and only intended to demonstrate the ECG application.
Contents
1
Introduction .................................................................................................................. 2
2
Front-End Architecture ..................................................................................................... 5
3
DSP Subsystem ........................................................................................................... 11
4
PC Application ............................................................................................................. 17
5
Installation .................................................................................................................. 17
6
Running the Demo Application .......................................................................................... 20
7
Options and Selections ................................................................................................... 21
8
References ................................................................................................................. 22
Appendix A
Front-End Board Schematics ................................................................................... 23
Appendix B
Front-End Board BOM ........................................................................................... 30
Appendix C Sensors and Accessories ....................................................................................... 33
Appendix D MEDICAL DEVELOPMENT KIT (MDK) WARNINGS, RESTRICTIONS AND DISCLAIMER .......... 34
List of Figures
1
MDK Hardware Overview .................................................................................................. 3
2
ECG Board ................................................................................................................... 4
3
ECG Front-End Block Diagram
4
De-Fibrillation Protection Circuit
5
6
7
8
9
10
11
12
........................................................................................... 6
.......................................................................................... 7
Right-Leg-Drive Circuit ..................................................................................................... 7
Lead-Off Detection Circuit ................................................................................................. 8
Lead I Formation ............................................................................................................ 9
LPF for Lead II .............................................................................................................. 9
Block Diagram of ADS1258 .............................................................................................. 10
Interface Between ADS1258 and DSP ................................................................................. 10
DSP Software Architecture ............................................................................................... 12
DC Removal Filter Response ............................................................................................ 13
SPRAB36B – June 2010
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
1
Introduction
www.ti.com
13
Pole and Zero Location for IIR Filter .................................................................................... 13
14
1Hz Signal Response via DC Removal Filter .......................................................................... 14
15
MBF Frequency Response ............................................................................................... 15
16
Buffer-Shifting Convolution Algorithm ................................................................................... 15
17
ECG Front-End Mounted on the C5515 EVM ......................................................................... 18
18
Input Dialog Box ........................................................................................................... 20
19
Display on the EVM LCD Screen........................................................................................ 21
20
ECG_I_II .................................................................................................................... 23
21
ECG_LEAD_V1_V2_V3 .................................................................................................. 24
22
ECG_LEAD_V4_V5_V6 .................................................................................................. 25
23
ECG_ADC .................................................................................................................. 26
24
ECG_LEAD_OFF_DET ................................................................................................... 27
25
Right Leg Drive ............................................................................................................ 28
26
PWR_CONN_INTRFCE .................................................................................................. 29
27
ECG Cable Details ........................................................................................................ 33
List of Tables
1
1
J22 Connector Interface .................................................................................................. 11
2
Release CD Contents ..................................................................................................... 19
3
Bill of Material .............................................................................................................. 30
Introduction
•
•
•
1.1
A number of emerging medical applications such as electrocardiography (ECG), digital stethoscope,
and pulse oximeters require DSP processing performance at very low power. The TMS320C5515
digital signal processor (DSP) is ideally suited for such applications. The C5515 is a member of TI's
C5000™ fixed-point DSP platform. To enable the development of a broad range of medical
applications on the C5515, Texas Instruments has developed an MDK based on the C5515 DSP. A
typical medical application includes:
An analog front end, including sensors to pick up signals of interest from the body
Signal processing algorithms for signal conditioning, performing measurements and running analytics
on measurements to determine the health condition
User control and interaction, including graphical display of the signal processing results and
connectivity to enable remote patient monitoring
Medical Development Kit (MDK) Overview
The MDK is designed to support complete medical applications development. It includes the following
elements:
• Analog front-end boards (FE boards) specific to the key target medical applications of the C5515
(ECG, digital stethoscope, pulse oximeter), highlighting the use of the TI analog components for
medical applications
• C5515 DSP evaluation module (EVM) main board
• Medical applications software including example demonstrations
C5000, Code Composer Studio are trademarks of Texas Instruments.
All other trademarks are the property of their respective owners.
2
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
SPRAB36B – June 2010
Introduction
www.ti.com
Figure 1 shows an overview of the MDK hardware, consisting of individual analog front-end boards for
ECG, digital stethoscope, pulse oximeter, and the C5515 DSP EVM. Any of the analog front-end boards
can be connected, one of at a time, to the C5515 EVM using universal connectors on the front-end boards
and the EVM. The analog front-end boards connect to the appropriate sensors for the ECG, digital
stethoscope or the pulse oximeter, and perform analog signal conditioning and analog-to-digital (A/D)
conversion of the signals from the sensor. Then, the digital signal is sent to the C5515 EVM where the
C5515 DSP performs signal processing algorithms for the application. The DSP is also responsible for
managing user control and interaction including graphical display of the signal processing results. The
signal processing results can also be transferred from the C5515 EVM to a PC for further display,
analysis, and storage using the PC application software that is provided with the MDK.
Digital
Stethoscope
Front End
Univ. FE Con
Pulse
Oximeter
Front End
Univ. FE Con
ECG
Front End
Common Platform
Data process, memory, display, user input, etc.
Color LCD Display
Univ. FE Con
Univ. FE Con
Front-End
Daughterboards
C5515 EVM
Keypad
Figure 1. MDK Hardware Overview
1.2
MDK ECG System
An electrocardiogram (ECG/EKG) is the recording of the electrical activities of the heart and is used in the
investigation of heart disease. The electrical waves can be measured by selectively placed electrodes
(electrical contacts) on the skin.
1.2.1
Key Features
The key features of the MDK ECG system are:
• 12 lead ECG output using 10 electrode input
• Defibrillator protection circuitry
• Diagnostic quality ECG with bandwidth of 0.05 Hz to 150 Hz
• Heartbeat rate display
• Leads off detection
• Real-time 12 lead ECG waveform display on EVM LCD screen, one lead selectable at a time
• Zoom option for the Y-axis (amplitude) on EVM LCD screen
• Real-time 12 lead ECG waveform display on PC, three leads at a time
• Zoom function on X-axis (time) and Y-axis (amplitude) on PC application
• Freeze screen option on PC Application
• Recording of ECG data and offline view option of recorded ECG data on PC application
SPRAB36B – June 2010
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
3
Introduction
1.2.2
www.ti.com
MDK Hardware
Several elements of the MDK ECG system are:
• C5515 EVM
• ECG front-end board
• ECG cable
1.2.2.1
C5515 EVM
The EVM comes with a full compliment of on-board devices that suit a wide variety of application
environments.
For further details on the C5515 EVM, see the Medical Devlopment Kit provided with your EVM.
Key components and interfaces of the C5515 EVM used in the MDK ECG system include:
• Texas Instrument's TMS320C5515 operating at 100 MHz
• User universal serial bus (USB) port via the C5515
• Inter-integrated circuit (I2C) /serial peripheral interface (SPI) electrically erasable programmable
read-only memory (EEPROM)
• External memory interface (EMIF), I2C, universal asynchronous receiver/transmitter (UART), SPI
interfaces
• SAR
• External IEEE Standard 1149.1-1990, IEEE Standard Test Access Port and Boundary-Scan
Architecture (JTAG) emulation interface
• Embedded JTAG controller
• Color LCD display
• Keys (user switches)
The EVM operates from a + 5 V external power supply or battery and is designed to work with TI’s Code
Composer Studio™ integrated development environment (IDE). Code Composer Studio communicates
with the EVM board through the external emulator, or on-board emulator.
1.2.2.2
ECG Front-End Board
Figure 2 shows the ECG front-end board. The potentials captured by the electrodes are passed through
the defibrillator protection (DP) circuit in the ECG front-end board. Then, the front end board derives 8 out
of 12 ECG leads and provides the digital input to the DSP subsystem. The front-end board can be
interfaced with the EVM board through a universal front-end connector. The front-end board is interfaced
with and powered by the C5515 EVM board through the universal front-end connector by using I2C and
I2S interfaces.
The 16 channel analog-to-digital converter (ADC) (ADS1258) on the front-end board is configured for 500
Hz sampling with 24-bit data resolution. ADC is interfaced with the C5515 using the SPI bus.
DB-15 Conn.
for Electrode
Connection
Figure 2. ECG Board
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ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
SPRAB36B – June 2010
Front-End Architecture
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1.2.2.3
ECG Cable
The ECG cable consists of four limb and six chest electrodes. This cable is connected to the front-end
board through the DB15 connector. The ECG electrodes pick up ECG signals from the ECG
simulator/patient and send them to the ECG front-end board; an off-the-shelf ECG cable is used. For more
details regarding ECG cable, see Appendix C.
1.2.3
MDK Software
The software for the MDK application includes:
• C5515 software application
• PC application
1.2.3.1
C5515 Software Application
The hardware is initialized by the DSP on the EVM. The DSP reads the digitized signals from the ADC
through the SPI interface. The DSP subsystem conditions the ECG signals by removing DC offset and
noise using digital filters. Then, the DSP subsystem derives the remaining four ECG electrodes, lead off
status, and heart rate. The DSP subsystem also displays one channel ECG wave form, lead off
information and heart rate on the LCD screen and sends the the ECG data to the PC application through
the UART interface.
1.2.3.2
PC Application
The PC application, which has to be installed on the PC, can be used for viewing the ECG waveform,
heart rate, and lead off information. It also provides options to zoom, store and playback the signals
transmitted from the EVM. The PC application can operate in two modes: online and offline.
2
Front-End Architecture
The front-end board has a DB15 connector to allow connection for 10 electrode ECG cables; it can be
interfaced with the EVM board through the universal front-end connector. The C5515 EVM board supplies
power to the front-end board through the universal front-end connector.
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ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
5
Front-End Architecture
www.ti.com
Figure 3 shows the ECG front-end board architecture.
Reference Voltage
Instrumentation
Amp
Crystal 32.768 KHz
REF5025
-5 V TPS60403
-2.5 V TPS72325
+2.5 V TPS73025
Low Pass Filter
150 Hz
Defibrillator
Protection
Power
supply
INA128
ADS1258
Defibrillator
Protection
ADC
SPI
INA128
I2C
OPA335
Front End
Connectors
DB15
Analog
MUX
Buffer
Defibrillator
Protection
I/O Expander
OPA335
RLD
Averaging of
RA,LA,LL signals
PCA9535
Lead Off Detection
Current Injection
TLV3404
Comparator
Figure 3. ECG Front-End Block Diagram
The front-end board contains the following stages:
• Defibrillator protection
• Right leg driving circuit
• Lead off detection
• Derives eight ECG leads using differential amplifier (instrumentation amplifier)
• Low-pass filtering (anti-aliasing)
• Analog-to-digital conversion (ADC)
2.1
Defibrillator Protection
WARNING
If defibrillator is used for development purposes, use of medical
grade EVM input power supply (Accessory Part Number: SL Power
AULT Model MW173KB0503F01) is strongly recommended. Use of
the Isolator (Accessory Part Number: MOXA Model Name: TCC-82)
that isolates the MDK from the PC is also strongly recommended.
These accessories provide additional supplemental protection to
development users from high voltages that may be present when
introducing defibrillator voltages during development simulation.
There may also be other voltage transients sourced from the
defibrillator to accompanying interface hardware such as a
personal computer when used in conjunction with the ECG/EVM
development hardware.
The defibrillator protection circuit protects the ECG system while the defibrillator is used on the patient.
6
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
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Copyright © 2010, Texas Instruments Incorporated
SPRAB36B – June 2010
Front-End Architecture
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The neon lamps and clamping diodes (zener diodes) are connected across the electrode input lines, to
provide protection from the defibrillator pulse. The neon lamps give the first level of protection and the
clamping diodes give the second level of protection. These shunting devices are used to bypass large
voltage applied during defibrillation. The neon lamp (NE2 series) shunts voltages above 70 V-80 V. Zener
diodes, with a breakdown voltage of 9.1 V, are used for shunting the voltage dropped across neon lamps
to a safe 11.6 V ( VCC + VZ = 2.5 + 9.1) before it appears across the instrumentation amplifiers. A current
limiting resistor (R1) of 20K with high energy withstanding capability (~ 2.5J) and power rating (> 1W) is
placed in the series on each input line, which limits the current flow. One more current limiting resistor
(R2) of 10K is put in between the neon lamp and the zener diodes to prevent high current from passing
through the zener diodes. Figure 4 depicts the protection circuitry.
-VCC
R1
R2
Vz
Electrode
To Instrumentaion
Amplifier
Neon
Lamp
+VCC
Figure 4. De-Fibrillation Protection Circuit
2.2
Right Leg Drive Circuit
A right-leg-drive circuit (RLD) is used as an alternative to the grounding of a patient with the MDK ECG
system. In the RLD circuit, an electrode attached to the right leg is driven by the output of an auxiliary
operational amplifier, where the common-mode voltage is sensed and amplified. The negative feedback of
a common-mode signal in this circuit drives the common-mode voltage low. In turn, the body’s
displacement current flows to the op-amp output circuit, which reduces the pickup of the ECG system and
effectively grounds the patient. The averaging is done with the electrode signals RA, LA and LL. OPA335
is used as the inverting amplifier for the RLD circuit. The gain of the RLD circuit design is -39.
Figure 5. Right-Leg-Drive Circuit
2.3
Lead-Off Detection
The lead-off detection circuit detects the lead status for all the electrodes except RL.The lead-off detection
has pull up registers, comparator (TLV3404) and an I2C port expander (PCA9535) as shown in Figure 6.
The ECG electrode leads, except RL, are connected to a pull up resistor (10 M); when any one of the
leads is disconnected, the voltage for that lead is pulled up to VCC (+ 2.3 V).
SPRAB36B – June 2010
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
7
Front-End Architecture
www.ti.com
The pull up circuit outputs are connected to the negative and positive terminals of the comparator, and set
to 500 mV (threshold voltage). When any lead gets disconnected, the output of the comparator for that
lead becomes 0 V. The output of the comparator is connected to the I2C port expander. The port
expander generates an interrupt to the DSP whenever there is any change in the input voltage. The
interrupt service routine at the DSP reads the output of the port expander using I2C lines and,
correspondingly, updates the lead-off status.
Figure 6. Lead-Off Detection Circuit
2.4
Lead Formation Using Instrumentation Amplifier
The following ECG leads are formed using instrumentation amplifier (INA128) and ECG electrode
combinations:
Lead I = LA – RA
Lead II = LL – RA
Lead V1 = V1 - (LA + RA + LL) / 3
Lead V2 = V2 - (LA + RA + LL) / 3
Lead V3 = V3 - (LA + RA + LL) / 3
Lead V4 = V4 - (LA + RA + LL) / 3
Lead V5 = V5 - (LA + RA + LL) / 3
Lead V6 = V6 - (LA + RA + LL) / 3
Where, RA, LL, LA and V1 to V6 are ECG electrodes.
Lead I is formed by connecting LA to the instrumentation amplifier’s non-inverting input, while RA is
connected to the inverting input. Lead II is formed by connecting LL to the instrumentation amplifier’s
non-inverting input, while RA is connected to the inverting input.
Uni-polar chest leads (Lead V1 to Lead V6) are formed by applying the corresponding electrodes to the
non-inverting input of the instrumentation amplifier, while the inverting input is connected with the average
of the RA, LA and LL signals. The average is calculated by addition using three equal value resistors.
8
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
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Copyright © 2010, Texas Instruments Incorporated
SPRAB36B – June 2010
Front-End Architecture
www.ti.com
Figure 7 shows the lead formation for Lead I.
Figure 7. Lead I Formation
The instrumentation amplifier also provides amplification of the weak input signal. The gain of the amplifier
is set to 8.35 by using a 6.8K (R4) nominal value precision resistor.
2.5
Low-Pass Filters (Anti-Aliasing)
An active first-order, low-pass filter (LPF) is used for anti-aliasing and for removing frequencies above 150
Hz from each of the ECG leads. The LPF has a cutoff at 150 Hz. The instrumentation amplifier output is
fed to the LPF filter input. Figure 8 shows the implementation for the LPF.
Figure 8. LPF for Lead II
2.6
Analog-to-Digital Conversion (ADC)
Analog signals are converted to digital before sending them to the DSP sub-system. LPF output is
connected as input to the ADC (ADS1258).
SPRAB36B – June 2010
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
9
Front-End Architecture
www.ti.com
ADS1258 is a 16-channel, 24-bit delta-sigma ADC. Figure 9 shows the block diagram of ADS1258.
AVDD
GPIO[7:0]
DVDD
VREF
ADS1258
Internal
Monitoring
GPIO
1
SPI
Interface
CS
DRDY
SCLK
DIN
DOUT
Oscillator
Control
START
RESET
PWDN
24-Bit
ADC
16:1
Analog
Input
MUX
Analog
Inputs
Digital
Filter
16
AINCOM
AVSS
MUX
OUT
Extclk
In/Out
ADC
IN
DGND
32.768 kHz
Figure 9. Block Diagram of ADS1258
The following configuration is used for the ADS1258:
Host to ADC interface
Sampling frequency
Data format
ADC mode used
Reference voltage
SPI
500 Hz
24-bit linear
Fixed channel mode
2.5 V
The eight ECG lead outputs from the LPF are connected to eight channels of the ADS1258. Using SPI
interface, the ADC is connected to the C5515 for 500 sps/channels with 24-bit resolution.
The ADS1258 is interfaced to C5515 DSP as shown in Figure 10.
SPI_CLK
SPI_OUT
SPI_IN
C5505 DSP
SPI_CS
ADS1258
SPI_START
SPI_DRDY
C5505 EVM
ECG FE
Figure 10. Interface Between ADS1258 and DSP
2.7
Front-End Connector
The front-end board is connected to the EVM through the universal front-end connector, which consists of
three connector interfaces with legends on the EVM: J20, J21, and J22.
10
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
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Copyright © 2010, Texas Instruments Incorporated
SPRAB36B – June 2010
DSP Subsystem
www.ti.com
2.7.1
J20 Connector Interface at C5515 EVM
The mating for this connector is maintained, but no signals are used by the ECG front-end board.
2.7.2
J21 Connector Interface at C5515 EVM
This connector carries the 5 V, 3.3 V and 1.8 V from the C5515 EVM. These voltages act as the primary
source for the ECG front-end board.
2.7.3
J22 Connector Interface at C5515 EVM
This connector carries GPIOs, I2C, SPI and interrupt (INT1) connections from the C5515 EVM to the
front-end board. Pin mapping for the used interfaces are shown in Table 1.
Table 1. J22 Connector Interface
Connector Pin Number
3
Signal Assigned
1
SPI_START
3
SPI_CLK
7
SPI_CS
11
SPI_IN
12
SPI_DRDY
13
SPI_OUT
15
I2C_INT
16
I2C_SCL
20
I2C_SDA
DSP Subsystem
The DSP software, running on the C5515 EVM, takes the digitized signal from the front-end board and
processes it the same. The DSP receives eight ECG lead data from the ADC through the SPI interface.
Then, filters are applied to remove DC signal, 50/60 Hz power line noise, and unwanted signals. The
filtered signal is used to detect the heart rate and to obtain four ECG leads: Lead III, aVR, aVL and aVF.
The software is designed to handle the following activities:
• Data acquisition through ADC
• Lead-off detection
• DC signal removal
• Multi band-pass filtering
• ECG leads formation
• QRS (HR) detection
• Display of ECG data
• UART communication
SPRAB36B – June 2010
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
11
DSP Subsystem
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Figure 11 shows the high-level architecture of DSP subsystem.
Lead Off Interrupt
Lead Off
Detection
FIR
Filters
QRS
Algorithm
(HR)
ECG Lead
Computation
(Lead Info)
4 ECG Leads
IIR
Filter
(DC Removal)
8 ECG Leads
SPI
8 Channel Data
Reader
Data
Acquisition
Timer Based
Interrupt
HR
From
ADC
Lead Off Status
I2C
From I2C
Expander
Display
RS232
UART
PC
Display
Figure 11. DSP Software Architecture
The various blocks of the DSP subsystem are described in the following sections.
3.1
Data Acquisition
Using the C5515 timer, an interrupt is generated every 250 ms to sequentially acquire 500 sps of eight
ECG leads. The interrupt service routine (ISR) issues a set channel number and (SOC) command to the
ADC to acquire 24-bits of ECG data for the selected channel. The acquired data is provided to the infinite
impulse response (IIR) filter module after downscaling to 20 bits; the data read for the same channel
happens after every 2 ms. The ADC is interfaced with the DSP through the SPI bus.
3.2
Lead-Off Detection
The lead status is read in the IIR for INTR1 of the C5515 (external interrupt 1). This interrupt is generated
in the front ECG board by the I2C port expander as and when the lead status is changed.
3.3
Interrupt Service Routine (IIR) Filter - DC Signal Removal
The DC signals from the eight ECG leads are removed by using the first-order IIR filter. The following
transfer function is used for the filter:
H (z ) =
Y (z )
X (z )
=
1 - z -1
1 - a z -1'
To provide DC attenuation of 22 dB, the value of alpha is chosen as 0.992. The IIR filter output is
downscaled to 16 bits and then provided to the finite impulse response (FIR) filter.
12
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
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Copyright © 2010, Texas Instruments Incorporated
SPRAB36B – June 2010
DSP Subsystem
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Figure 12 shows the frequency response for the filter.
Figure 12. DC Removal Filter Response
Figure 13 shows the pole and zero location for the IIR filter. The pole is located at z = 0.992 and zero at 1
in the Z plane.
Figure 13. Pole and Zero Location for IIR Filter
SPRAB36B – June 2010
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
13
DSP Subsystem
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Figure 14 shows 1 Hz signal response via the DC removal filter.
Figure 14. 1Hz Signal Response via DC Removal Filter
3.4
FIR Filter
The multi band-pass filter (MBF) is used for removing unwanted signals and power line noise from the DC
removed ECG lead data.
The MBF digital filter being used is the FIR hamming window with the order of 351, which provides cutoff
at 150 Hz and notch at 50/60 Hz; the notch frequency is compile-time programmable. This filter also
provides a very sharp cutoff at 150 Hz with attenuation of 60 dB at stop-band and notch at 8 dB
attenuation. The sampling frequency is 500 samples/second.
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ECG Implementation on the TMS320C5515 DSP Medical Development Kit
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Copyright © 2010, Texas Instruments Incorporated
SPRAB36B – June 2010
DSP Subsystem
www.ti.com
Figure 15 shows simulation results for the MBF.
Figure 15. MBF Frequency Response
Buffer-shifting convolution algorithm is used for the realization of the MBF filter. The filter window is shifted
for every filtered sample and to insert the new sample into the buffer as depicted in Figure 16.
x(n)
x(n-1)
x(n-2)
.....
x(n-L+2)
x(n-L+1)
New Data
Current time, n
Discarded
x(n)
x(n-1)
x(n-2)
.....
x(n-L+1)
Next time, n+1
Figure 16. Buffer-Shifting Convolution Algorithm
3.5
ECG Lead Computation
Eight ECG lead data from the MBF filter is fed to the ECG lead formation module. This module computes
the remaining four ECG lead data using the following formula:
Lead III = Lead II - Lead I
Lead aVR = - Lead II + 0.5 * Lead III
Lead aVL = Lead I - 0.5 * Lead II
Lead aVF = Lead III + 0.5 * Lead I
3.6
QRS (HR) Detection Algorithm
QRS detection is based on the first derivative of the Lead II ECG signal and threshold. Once five
consecutive QRS are detected, the heart rate is calculated by taking the average of the five RR intervals.
SPRAB36B – June 2010
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
15
DSP Subsystem
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The following steps are involved for calculating heart rate:
1. Calculate the first derivative of the Lead II ECG signal samples. The first derivative for any sample is
calculated as:
y0(n) = |x(n + 1) – x(n - 1)|
Where, y0(n) is the first derivative.
x(n + 1) is the sample value for (n + 1)th sample
x(n – 1) is the sample value for (n – 1)th sample
The initial 2sec of the first derivatives in a buffer are stored and the maximum value (P) in this buffer
are obtained.
2. Calculate the threshold as 0.7 * P.
3. Compare each of the first derivative values calculated with the calculated threshold.
4. Mark the ECG sample index (S1) of that particular sample, whenever a derivative crosses the
threshold.
5. Detect the QRS peak by scanning the next 40 derivatives (MAXIMA_SEARCH_WINDOW = 40) and
obtaining the maxima (M1). This maxima (M1) value is stored in another buffer.
6. Skip the next 50 samples (SKIP_WINDOW = 50) to take care of the minimum RR interval that can
occur in case of maximum detectable heart rate (i.e., 240 BPM), after detecting a QRS peak.
7. Detect the next five QRS peaks by repeating steps 3 to 6.
8. Calculate the RR interval as the number of samples between two consecutive QRS peaks.
9. Calculate heart rate using the following formula:
HR per Minute = (60 * Sampling Rate)/(Average RR interval for five consecutive RR intervals)
10. Recalculate threshold from the QRS peak values detected.
3.7
LCD Display
The LCD display shows the ECG, heart rate, and lead-off status. The display is controlled using the SW7
and SW8 keys on the EVM as mentioned in Section 7.1.1. For each of these keys, an interrupt is
generated and communicated to the DSP through the SAR interrupt. The interrupt service routine for the
key that is pressed takes care of the corresponding action for the interrupt.
3.8
Universal Asynchronous Receiver/Transmitter (UART)
The data sent to the PC through UART has eight ECG lead data; these signals are sent at 250 sps/lead.
The PC application derives the remaining four ECG leads using the Lead I and Lead II data. A
synchronization frame (header) of 5 bytes is also sent to the UART interface every 1 s. The packet
number, heart rate, and lead status values are sent along with the ECG header. The header is followed by
interleaved samples of eight ECG leads. The interval between the two ECG data packets is 500 ms. The
packet number gets incremented for every new sample sent.
The UART configuration is set as 115200 bps, 8 bits data, 1 stop bit and no parity.
16
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
SPRAB36B – June 2010
PC Application
www.ti.com
ECG Header
00
80
00
80
00
Packet
Number
Heart Rate
Lead
Status
(Low)
Lead
Status
(High)
ECG Data
Current Channel Low 8 Bits
4
Current Channel High 8 Bits
PC Application
The PC application is used for viewing the ECG waveform and ECG values. It also provides options to
zoom, store and playback the signals.
The PC application has two modes of operation: online and offline.
• Online mode: the ECG data is plotted in real-time as a scrolling display
• Offline mode: the recorded ECG data is displayed for analysis
Two timers run on the application for online mode: acquisition and display timer.
The acquisition timer is set for 100 ms intervals and reads the data from the serial port. After fetching the
data from serial port, it parses the stream of bytes to different variables like packet number, heart rate,
lead-off status and to the ECG data object containing the digital value of eight leads ECG samples. The
four non-acquired leads, Lead III, aVR, aVL and aVF data, are derived from Lead I and Lead II as follows:
Lead III = Lead II - Lead I
aVR = - Lead II + 0.5 * Lead III
aVL = Lead I - 0.5 * Lead II
aVF = Lead III + 0.5 * Lead I
The ECG data object for each sample is stored in a queue buffer.
The display timer is set to an interval of 60 ms and is used to plot the ECG wave forms, and update the
heart rate and lead-off status information on the screen. This timer is elapsed every 60 ms; in each
elapsed event 15 samples of the leads are plotted on the screen.
5
Installation
5.1
Components and Accessories Required
The following components and accessories are required for the MDK ECG installation.
• C5515 EVM with power supply
• ECG front-end board (ECG FE)
• Code Composer Studio v3.3
• RS232 cable
• USB cable
• 10 lead ECG patient cable
• C5515 DSP application software
• PC application software
SPRAB36B – June 2010
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
17
Installation
5.2
www.ti.com
Hardware Installation
1. Mount the ECG front-end board on top of the C5515 EVM at connectors J20, J21 and J22. Ensure that
there is a firm connection between the front-end board and the EVM.
JTAG Header J4
DB9 J14
DB15 P1
Power Jack J7
Power Switch SW4
Figure 17. ECG Front-End Mounted on the C5515 EVM
2. Connect the USB cable between the PC and the C5515 EVM for the debug mode of operation.
3. Connect the C5515 emulator JTAG cable to the C5515 EVM.
4. Connect the serial cable (UART) to the DB9 connector (J13) of the C5515 EVM and the other end to
the serial port of the PC, for viewing the signals on the PC application.
5. Connect the ECG cables to DB15 connector P1.
6. Connect the other end of the ECG cable (there are 10 leads) to an ECG simulator.
7. Power on the system using slide switch SW4 on the C5515 EVM.
NOTE: The ECG simulator has 10 connector points that are assigned to different electrodes, i.e.,
RA, RL, LA, etc. Ensure that the ECG leads are connected to the corresponding connectors
on the simulator.
5.3
5.3.1
Software Installation
System Requirements
The following installations are required to run the software provided with the MDK ECG kit.
• Code Composer Studio v3.3
• bios_5_32_01
• Spectrum Digital XDS510 USB driver for Code Composer Studio v_3.3
• .NET 2.0 frame work
18
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
SPRAB36B – June 2010
Installation
www.ti.com
Table 2 explains the content of the CD provided with the MDK ECG kit.
Table 2. Release CD Contents
S Number
Directory/Filename
Contains
1
ECGSystem_V_5_0
Project source code
2
Output
Contains three files:
ECGSystem.out
c5505evm.gel and
C5515 XDS510USB Emulator.ccs
3
PCApplication
Executable for PC application
4
BootImageCreation.zip
Folder that contains the following files:
bootImage.exe
convertBind0.bat
convertEnc0.bat
convertInsecure.bat
programmer.out
readme.txt
5
Document
Contains the following documents:
ReleaseNote.txt
Quick starter guide V6.0 doc
5.3.2
C5515 DSP Software (debug mode) Installation Steps
1. Copy the c5505evm.gel file from the CD to <CCS installation dir>/CC/GEL/.
2. Copy the ECGSystem directory from the CD to a local directory on the PC where Code Composer
Studio is installed.
5.3.3
C5515 DSP Software (standalone mode ) Installation Steps
1. Copy the BootImageCreation.zip file from the CD to a local directory on the PC where Code Composer
Studio is installed. This path needs to be used later for Flashing; ensure that there are no spaces in
the path name.
2. Copy the ECGSystem.out file from the CD to the < BootImageCreation> folder.
3. Execute convertInsecure.bat from the <BootImageCreation> folder to create the new
InsecureBootImage.bin file.
4. Open Code Composer Studio.
5. Power on the C5515 EVM.
6. Select Debug → Connect in Code Composer Studio to connect to the C5515 EVM.
7. Load programmer.out C5515 EVM from the < BootImageCreation> folder.
8. Select Debug → Run in Code Composer Studio.
SPRAB36B – June 2010
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
19
Running the Demo Application
www.ti.com
9. Enter 241:<BootImageCreation Folder>\InsecureBootImage.bin and press OK in the popup window
shown in Figure 18.
Figure 18. Input Dialog Box
10. Wait until Programming Complete.
11. Power off the C5515 EVM and disconnect.
5.3.4
PC Application Installation Steps
Prior to installing the PC application, ensure that .NET 2.0 framework is installed on the system. .NET 2.0
redistributable framework can be downloaded from the following URL:
http://www.microsoft.com/downloads/details.aspx?familyid=0856eacb-4362-4b0d-8eddaab15c5e04f5&displaylang=en.
1. Open the PCApplication folder on the CD and double click on C55x ECG Medical Development
Kit.msi.
2. Click Next on the welcome screen to continue the installation.
3. Browse to the folder where the application is installed. Select the installation mode for Everyone or Self
and click Next.
4. Click Next on the Confirmation screen. This installs the application into the specified folder.
5. Click Close to complete and exit the installation.
6
Running the Demo Application
The ECG application can be run in two modes: standalone and debug.
• Standalone mode, for running from Flash memory
• Debug mode, for loading and debugging using Code Composer Studio
6.1
Running in Standalone Mode
1. Complete the installation steps provided in Section 5.3.
2. Power on C5515 EVM using slide switch SW4.
3. Switch on the ECG simulator to view the ECG signal on the C5515 EVM.
6.2
Running in Debug Mode
1.
2.
3.
4.
5.
6.
7.
8.
20
Complete the installation steps provided in Section 5.3.
Power on the C5515 EVM using slide switch SW4.
Open Code Composer Studio.
Click on Debug → Connect in Code Composer Studio to connect to the C5515 EVM.
Click on Project → Open in Code Composer Studio and select the ECGSystem.pjt file.
Click on File → Load .out file in Code Composer Studio.
Execute the application.
Switch on the ECG simulator to view the ECG signal on the C5515 EVM.
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
SPRAB36B – June 2010
Options and Selections
www.ti.com
6.3
6.3.1
Running the PC Application
Online Mode
The following steps are required to view signals in online mode using the PC application:
1. Connect the RS232 cable between the PC COM port and the C5515 EVM.
2. Complete the installation steps provided in Section 5.3.
3. Open the PC application.
4. Select online mode and click OK.
5. Select the available COM port and click OK.
6. Signals transmitted from the C5515 EVM can be viewed on the PC application.
6.3.2
Offline Mode
The following steps are required to view signals in offline mode stored on the PC using the PC application:
1. Open the PC application.
2. Select offline mode and click OK.
3. Browse and select the previously saved .wav file and click OK.
4. View the static ECG waveforms along with the heart rate and lead-off status on the PC application.
7
Options and Selections
7.1
On the C5515 EVM
7.1.1
ECG Display on the C5515 EVM Side
The ECG display on the LCD screen starts by showing the ECG Monitor followed by lead and heart rate;
by default, ECG Lead II is displayed.
SW7 switch on the EVM can be pressed to view one channel after the other. Pressing the switch displays
the next ECG lead in a cyclic manner: II, I, III, aVR, aVL, aVF, V1, V2, V3, V4, V5 and V6.
The SW8 switch on the EVM can be used for the zoom in and zoom out feature for the ECG waveform.
Low, Medium (default) and High are the three levels of zooming provided.
If all 10 leads are connected, a green color dot is displayed at the lead status location on the EVM display.
In case any one lead fails, the failed lead name is displayed at the lead status location. If more than one
lead off is detected, a red color dot is displayed at the lead status location.
Displaying Lead
Lead Status
Figure 19. Display on the EVM LCD Screen
SPRAB36B – June 2010
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
21
References
7.1.2
www.ti.com
PC Application
By default, three leads are displayed simultaneously. The sequence of the leads are I, II, III, aVR, aVL,
aVF, V1, V2, V3, V4, V5 and V6. Lead-off status and heart rates are displayed on the screen and the
values are refreshed once every second. The serial port connection status (RS232) for the device is
displayed on the status bar.
The following features are available on the PC application.
• Next (up arrow) - This button can be used to view the next three lead wave forms.
• Previous (down arrow) - This button can be used to view the previous three lead wave forms.
• Scaling on Amplitude - This button can be used to vertically zoom in and zoom out of the ECG
waveform display on the PC application.
• Scaling on Time - This button can be used to horizontally zoom in and zoom out of the ECG
waveform display on the PC application.
• Start Recording - This can be used to start the recording of the ECG waveform. During recording, this
same button is used for the Stop Recording operation. Note that after the start recording option is
selected, the zoom options get disabled.
• Stop Recording - This can be used to stop recording and save the ECG waveform as an .ECG file. It
can be played back using the PC application in offline mode.
• Freeze - This button can be used to view a static waveform. Particular portions of the waveform can be
viewed by moving the Left and Right cursors during the Freeze option.
• Unfreeze - Pressing this button enables the waveform to be in continuous scrolling mode.
• Cancel: This can be used to close the form.
8
References
•
22
TMS320VC5505 DSP Medical Development Kit (MDK) Quick Start Guide (SPRUGO1)
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
SPRAB36B – June 2010
SPRAB36B – June 2010
Copyright © 2010, Texas Instruments Incorporated
DB15_LL
DB15_ LA
DB15_RA
R16
R10
R2
10K
DS1
MC08010000
R3
10K
DS2
MC08010000
R11
22K
10K
DS3
MC08010000
R17
+2.5_VCC
9.1V
D6
9.1V
D5
-2.5_VCC
+2.5_VCC
9.1V
D4
9.1V
D3
-2.5_VCC
DEFIBRILLATOR PROT ECT ION (DP3)
22K
D2
9.1V
+2.5_VCC
DEFIBRILLATOR PROT ECT ION (DP2)
22K
D1
9.1V
C98
22nF
D NI
C100
22nF
D NI
C99
22nF
D NI
3
2
1
3
2
1
+2.5_VCC
RA
6.8K
3
2
1
8
LA 3
2
1
6
LL
RA
LA
10M
R19
8
3
2
1
6
L E AD_II
GAIN 8.35
INA128
Vo
0.1uF
C6
C8 0.1uF
5
Ref
-2.5_VCC
4
Rg2
Vin+
V-
V+
U3
VinRg1
7
+2.5_VCC
TP8
TP9
L EAD_I
GAIN 8.35
INA128
Vo
0.1uF
C5 0.1uF
5
Ref
-2.5_VCC
4
Rg2
Vin+
V-
V+
U2
VinRg1
7
C2
INST RUMENTAT ION AMPLIFIER (IA2)
+2.5_VCC
LL
RA
6.8K
R9
10M
CON3 -2.5_VCC
J3
R12
LL
RA
LA
CON3 -2.5_VCC
J2
R4
10M
R1
INST RUMENTAT ION AMPLIFIER (IA1)
+2.5_VCC
+2.5_VCC
CON3 -2.5_VCC
J1
R13
R5
10K
10K
0E
R18
R14
0E
R8
R6
0E
0E
0.1uF
C7
0.1uF
C3
5
6
3
2
4
V-
V+
8
In+
In-
D NI
V-
V+
1
C1
0.1uF
7
OPA2335
Out
U1B
C4 0.1uF
OPA2335
Out
U1A
+2.5_VCC
-2.5_VCC
In+
In-
D NI
LPF_I
TP17
L PF_II
LOW PASS FILT ER (LPF2)
Fc=159Hz
TP16
LOW PASS FILT ER (LPF1)
Fc=159Hz
A.1
DEFIBRILLATOR PROT ECT ION (DP1)
-2.5_VCC
www.ti.com
Appendix A Front-End Board Schematics
Front-End Board Schematics
The schematics for the ECG front-end board are shown below:
Figure 20. ECG_I_II
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
23
24
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
DB15_V3
V3
DB15_V2
V2
DB15_V1
V1
R40
R32
R24
10K
DS4
MC08010000
R25
10K
DS5
MC08010000
R33
22K
10K
DS6
MC08010000
R41
+2.5_VCC
9.1V
D12
9.1V
D11
-2.5_VCC
+2.5_VCC
9.1V
D10
9.1V
D9
-2.5_VCC
DEFIBRILLATOR PROT ECT ION (DP6)
22K
9.1V
D8
9.1V
D7
+2.5_VCC
DEFIBRILLATOR PROT ECT ION (DP5)
22K
DEFIBRILLATOR PROT ECT ION (DP4)
-2.5_VCC
C101
22nF
D NI
C103
22nF
D NI
C102
22nF
D NI
R36
R28
R20
3
2
1
+2.5_VCC
V1
3
2
1
+2.5_VCC
V2
3
2
1
+2.5_VCC
V3
CON3 -2.5_VCC
J6
6.8K
AVG_LA_RA_LL
CON3 -2.5_VCC
J5
6.8K
AVG_LA_RA_LL
CON3 -2.5_VCC
J4
6.8K
AVG_LA_RA_LL
5
INA128
Vo
6
8
3
7
5
6
INA128
Vo
10M
R43
8
3
2
1
5
6
INA128
Vo
R37
TP12
LEAD_V3
GAIN 8.35
0.1uF
C21 0.1uF
Ref
-2.5_VCC
4
Rg2
Vin+
V-
V+
U8
VinRg1
7
C18
R29
TP11
LEAD_V2
GAIN 8.35
0.1uF
C16 0.1uF
Ref
-2.5_VCC
4
Rg2
Vin+
V-
V+
U6
VinRg1
INST RUMENTAT ION AMPLIFIER (IA5)
+2.5_VCC
10M
R35
2
1
C14
R21
TP10
LEAD_V1
GAIN 8.35
C13 0.1uF
Ref
-2.5_VCC
4
Rg2
Vin+
V-
V+
U5
VinRg1
0.1uF
C10
INST RUMENTAT ION AMPLIFIER (IA4)
+2.5_VCC
10M
R27
8
3
2
1
7
+2.5_VCC
INST RUMENTAT ION AMPLIFIER (IA3)
10K
10K
10K
0E
R42
R38
0E
R34
R30
0E
R26
R22
0E
0E
0E
C11
0.1uF
C19
0.1uF
C15
0.1uF
3
2
5
6
3
2
4
V-
V+
8
V-
V+
4
V-
V+
7
OPA2335
Out
U4B
Out
1
U7A
C17
0.1uF
C20 0.1uF
OPA2335
-2.5_VCC
In+
In-
8
C9
0.1uF
C12 0.1uF
D N I +2.5_VCC
In+
In-
D NI
1
OPA2335
Out
U4A
+2.5_VCC
-2.5_VCC
In+
In-
D NI
LPF_V1
TP20
LPF_V3
LOW PASS FILT ER (LPF5)
Fc=159Hz
LPF_V2
LOW PASS FILT ER (LPF4)
Fc=159Hz
TP19
TP18
LOW PASS FILT ER (LPF3)
Fc=159Hz
Front-End Board Schematics
www.ti.com
Figure 21. ECG_LEAD_V1_V2_V3
SPRAB36B – June 2010
SPRAB36B – June 2010
Copyright © 2010, Texas Instruments Incorporated
DB15_V6
V6
DB15_V5
V5
DB15_V4
V4
R64
R56
R48
10K
DS7
MC08010000
R49
10K
DS8
MC08010000
R57
22K
10K
DS9
MC08010000
R65
22nF
D NI
9.1V
+2.5_VCC
C106
22nF
D NI
C105
22nF
D NI
C104
D18
9.1V
D17
-2.5_VCC
+2.5_VCC
9.1V
D16
9.1V
D15
-2.5_VCC
DEFIBRILLATOR PROT ECT ION (DP9)
22K
9.1V
D14
9.1V
D13
+2.5_VCC
DEFIBRILLATOR PROT ECT ION (DP8)
22K
DEFIBRILLATOR PROT ECT ION (DP7)
-2.5_VCC
R60
R52
R44
3
2
1
+2.5_VCC
V4
3
2
1
+2.5_VCC
V5
3
2
1
+2.5_VCC
V6
CON3 -2.5_VCC
J9
6.8K
AVG_LA_RA_LL
CON3 -2.5_VCC
J8
6.8K
AVG_LA_RA_LL
CON3 -2.5_VCC
J7
6.8K
AVG_LA_RA_LL
5
INA128
Vo
6
8
3
5
6
INA128
Vo
10M
R67
8
3
2
1
5
C30
INA128
Vo
6
R61
TP15
LEAD_V6
GAIN 8.35
0.1uF
C32 0.1uF
Ref
-2.5_VCC
4
Rg2
Vin+
V-
V+
U12
VinRg1
7
R53
TP14
LEAD_V5
GAIN 8.35
C29 0.1uF
Ref
-2.5_VCC
4
Rg2
Vin+
V-
V+
U11
VinRg1
0.1uF
INST RUMENTAT ION AMPLIFIER (IA8)
+2.5_VCC
10M
R59
2
1
7
C26
R45
TP13
LEAD_V4
GAIN 8.35
C24 0.1uF
Ref
-2.5_VCC
4
Rg2
Vin+
V-
V+
U9
VinRg1
0.1uF
INST RUMENTAT ION AMPLIFIER (IA7)
+2.5_VCC
10M
R51
8
3
2
1
7
C22
INST RUMENTAT ION AMPLIFIER (IA6)
+2.5_VCC
10K
10K
10K
0E
R66
R62
0E
R58
R54
0E
R50
R46
0E
0E
0E
0.1uF
C31
0.1uF
C27
0.1uF
C23
5
6
3
2
5
6
8
4
V-
V+
In+
In-
D NI
V-
V+
7
OPA2335
Out
U7B
1
0.1uF
C25
7
OPA2335
Out
U10B
C28 0.1uF
OPA2335
Out
U10A
+2.5_VCC
V-
V+
-2.5_VCC
In+
In-
D NI
In+
In-
D NI
LPF_V4
LPF_V5
TP23
LPF_V6
LOW PASS FILT ER (LPF8)
Fc=159Hz
TP22
LOW PASS FILT ER (LPF7)
Fc=159Hz
TP21
LOW PASS FILT ER (LPF6)
Fc=159Hz
www.ti.com
Front-End Board Schematics
Figure 22. ECG_LEAD_V4_V5_V6
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
25
1uF
C45
+2.5_VCC
5
3
2
DNC2
DNC1
VOUT
8
1
6
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
-2.5_VCC
7
GND NC
REF5025
4
TRIM
TEMP
VIN
U16
ADC VOLTAGE REFERE NCE
10uF
C79
R80
0.1uF
C46
1K
100E
100uF
C47
R81
D NI
0E
R123
3
4
2
V-
U15
-2.5_VCC
In+
V+
In-
5
C48 0.1uF
OPA335
1
0.1uF
C38
Out
+2.5_VCC
10uF
C43
0.1uF
C44
0E
0E
0E
0E
TP30
TP29
TP28
0E
R69
0E
R71
0E
R75
0E
R78
0E
R121 0E
R120 0E
R79
0E
R122
R77
R72
R70
R68
Layout note: Move C44 as clos e to
U13.31 & U13.30 pins a s possible
and C33 close to U 13.6 pin
SPI_CLK
S P I_IN
SPI_START
SPI_CS
10K 10K
R73 R74
+2.5_VCC
LPF_I
L PF_II
LPF_V1
LPF_V2
LPF_V3
LPF_V4
LPF_V5
LPF_V6
30
31
10
11
12
22
23
26
27
4
3
2
1
48
47
46
45
40
39
38
37
36
35
34
33
C50
0.1uF 10uF
C49
VREFN
VREFP
PWDN
RESET
CLKSEL
SCLK
DIN
START
CS
AIN0
AIN1
AIN2
AIN3
AIN4
AIN5
AIN6
AIN7
AIN8
AIN9
AIN10
AIN11
AIN12
AIN13
AIN14
AIN15
U13
10uF
AVDD
6
AINCOM
32
0.1uF
+2.5_VCC
-2.5_VCC
ADCINN
ADCINP
DOUT
DRDY
CLKIO
GPIO0
GPIO1
GPIO2
GPIO3
GPIO4
GPIO5
GPIO6
GPIO7
9
8
7
44
43
41
42
24
25
13
14
15
16
17
18
19
20
21
ADS1258
XTAL2
XTAL1
PLLCAP
MUXOUTP
MUXOUTN
3.3_VCC
DVDD
C34
AVSS
5
C33
DGND
28
GND_PAD
49
26
29
AD C
10K
10K
51E
R112
R114
R116
R118
32.768KHz
C39 22nF
C37 2.2nF
10K
10K
R110
C107
10uF
C35
0.1uF
0E
10K
10K
10K
10K
C42 4.7pF
Y1
C40 4.7pF
R76
R119
R117
R115
R113
R111
47E
TP31 TP32
SPI_OUT
S P I_DRDY
3
4
2
V-
U14
-2.5_VCC
In+
V+
In-
5
C36
C41 0.1uF
OPA335
1
0.1uF
Out
+2.5_VCC
TP24
Front-End Board Schematics
www.ti.com
Figure 23. ECG_ADC
SPRAB36B – June 2010
Copyright © 2010, Texas Instruments Incorporated
0E
0E
R132 0E
R131
R130 0E
R129
R128 0E
R127 0E
R126 0E
R125 0E
0.1uF
C97
0.1uF
C96
0.1uF
C95
0.1uF
C94
0.1uF
C93
0.1uF
C92
0.1uF
C91
0.1uF
C90
0.1uF
C89
Note: If LPF not required put a 0 ohm
jumper on the resistor path and do not
populate capacitors
V6
V5
V4
V3
V2
V1
LL
LA
RA
R124 0E
V6'
V5'
V4'
V3'
V2'
V1'
LL'
L A'
R A'
100K_POT
R92
-2.5_VCC
C55
1uF
100K_POT
T HRSH_VOL
TP44
T HRSH_VOL
T HRSH_VOL
T HRSH_VOL
T HRSH_VOL
+2.5_VCC
R83
C54
T HRSH_VOL
T HRSH_VOL
T HRSH_VOL
T HRSH_VOL
TP40
TP39
TP38
TP37
10nF
V6'
V5'
V4'
V3'
V2'
V1'
LL'
L A'
TP36
TP35
TP34
TP41
T HRSH_VOL
R A'
TP33
2
3
6
5
9
10
13
12
2
3
6
5
9
10
13
12
3
4
C51
1
0.1uF
IN1IN1+
IN2IN2+
IN3IN3+
IN4IN4+
U20
IN1IN1+
IN2IN2+
IN3IN3+
IN4IN4+
U18
100K100K100K100K100K100K100K100K
0.1uF
14
14
8
7
1
0.1uF
21
2
3
4
5
6
7
8
9
10
11
13
14
15
16
17
18
19
20
0.1uF
I2C I/O EXPANDER
8
C56
R84 R85 R86 R87 R88 R89 R90 R91
C52
3.3_VCC
7
TLV3404
OUT4
OUT3
OUT2
OUT1
3.3_VCC
R82
100K
C53
1
TLV3404
OUT4
OUT3
OUT2
OUT1
3.3_VCC
IN+ GND
TLV3401
2
OUT
IN- VCC
U17 5
3.3_VCC
LEAD OFF DET ECT ION COMPARATORS
4
VCC
GND
11
4
VCC
GND
11
U19
A0
A1
A2
PA0
PA1
PA2
PA3
PA4
PA5
PA6
PA7
PB0
PB1
PB2
PB3
PB4
PB5
PB6
PB7
INT
23
22
1
PCA9535
SDA
SCL
3.3_VCC
24
VCC
GND
SPRAB36B – June 2010
12
LOW PASS FILT ERS Fc = 15.9Hz
R94
4.7K
R93
10K
TP25 TP26 TP27
4.7K
R95
I2C_SDA
I2C_SCL
I2C_INT
www.ti.com
Front-End Board Schematics
Figure 24. ECG_LEAD_OFF_DET
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
27
28
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
LL
OUT
OUT
1
OUT
-2.5_VCC
IN+ VTLV2221
2
4
+2.5_VCC
-2.5_VCC
IN+ VTLV2221
2
4
+2.5_VCC
-2.5_VCC
5
U24
3
IN- V+
1
4
IN+ VTLV2221
2
5
U22
3
IN- V+
1
BUFFER FOR LA,RA&LL signals
RA
LA
5
U21
3
IN- V+
+2.5_VCC
C57
0.1uF
C65
0.1uF
C64
0.1uF
C62
0.1uF
C60
0.1uF
C58
0.1uF
10K
10K
10K
10K
R100
R103
R104
R105
BUFF_LL
10K
R98
B U FF_RA
10K
R97
B UFF_LA
TP43
TP42
WILSON T ERMINAL
AVG_LA_RA_LL
RLD_VOL
RLD_VOL
R99
10K
RL DRIVE CKT
3
4
390K
5
2
V-
-2.5_VCC
In+
U23
C61
C63 0.1uF
390K
GAIN -39
1 R133
0.1uF
OPA335
Out
+2.5_VCC
V+
In-
R96
C59 47pF
+2.5_VCC
9.1V
D20
R101
9.1V
D19
10K
DS10
MC08010000
R102
DEFIBRILLATOR PROT ECT ION (DP10)
-2.5_VCC
22K
DB15_RL
Front-End Board Schematics
www.ti.com
Figure 25. Right Leg Drive
SPRAB36B – June 2010
S PI_IN
SPI_OUT
I2C_INT
SPI_CS
SPI_START
SPI_CLK
TP1
C76
100uF
C75
0.1uF
5_VCC
2
4
6
8
10
1
3
5
7
9
J11
2
4
6
8
10
12
14
16
18
20
1
3
5
7
9
11
13
15
17
19
2
4
6
8
10
12
14
16
18
20
TP3
3.3_VCC
C77
0.1uF
I2C_SDA
I2C_SCL
S P I_DRDY
BRD_DET1
BRD_DET0
TP4
TP2
1.8_VCC
DUMMY_CONN
J12
DATA_CONN
1
3
5
7
9
11
13
15
17
19
POWER_CONN
J10
C78
100uF
10uF
C80
L2
5_VCC
1uF
C70
IN
4
Copyright © 2010, Texas Instruments Incorporated
10K
10K
0E
R107
D NI
0E
R109
1uF
C71
-2.5_VCC
+2.5_VCC
0.1uF
C88
TP5
10uF
C81
-5_VCC
3.3uH
DECOUPLING +2.5V & -2.5V
10uF
C87
L3
1
1
0
0
1
STETH
SPO2
BRD_DET0
1
ECG
BRD_DET1
FRONT END BOARD DET ECT ION MEC HANISM
BRD_DET1
R108
R106
BRD_DET0
3.3_VCC
3.3_VCC
1
TPS60403
OUT
5
CFLY+
3
GND
1uF
CFLY-
U26
BEAD
2
C67
EVM GND- FE GND ISOLAT ION
L1
10uF
C86
3.3uH
-5V INVERTER
3
2
1
DB15_V6
DB15_V1
DB15_V5
DB15_LL
DB15_V4
DB15_LA
DB15_ V3
DB15_RA
DB15_V2
DB15_RL
CON3
J13
2.2uF
C74
-5_VCC
0.1uF
C66
5_VCC
EN
IN
U27
RLD_VOL
3
2
3
1
EN
IN
U25
4
5
8
15
7
14
6
13
5
12
4
11
3
10
2
9
1
4
C82
10uF
C84
L5
10uF
L4
ECG ELECT RODE CO NNECTOR
2.2uF
C72
2.2uF
C68
0.01uF
C73
0.01uF
C69
CONNECTOR DB15
P1
TPS72325
NR
OUT
5
LDO -2. 5V
TPS73025
NR
OUT
LDO +2.5V
GND
2
GND
SPRAB36B – June 2010
1
CONNECTOR INT ERFACE
C83
3.3uH
10uF
C85
TP7
-2.5_VCC
10uF
TP6
+2.5_VCC
3.3uH
www.ti.com
Front-End Board Schematics
Figure 26. PWR_CONN_INTRFCE
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
29
www.ti.com
Appendix B Front-End Board BOM
B.1
Front-End Board BOM
Table 3 provides the bill of material for the digital stethoscope front-end board.
Table 3. Bill of Material
30
Ite
m
Quantit
y
Value
Reference
Description
Part Number
Manufacturer
DNI
1
17
0.1 mF
C1,C4,C9,C12,C17,
C20,C25,C28,C89,
C90,C91,C92,C93,
C94,C95,C96,C97
CAP CERM 0.10 mF 50 V 5%
0805 SMD
08055C104JAT2A
AVX
Corporation
DNI
2
49
0.1 mF
C2,C3,C5,C6,C7,
C8,C10,C11,C13,
C14,C15,C16,C18,
C19,C21,C22,C23,
C24,C26,C35,C36,
C38,C41,C44,C46,
C27,C29,C30,C31,
C32,C33, 48,C49,
C51,C52,C53,C56,
C64,C65,C66,C75,
C77,C88 C57,C58,
C60,C61,C62,C63
CAP CERM 0.10 mF 50 V 5%
0805 SMD
08055C104JAT2A
AVX
Corporation
3
5
10 mF
C34,C43,C50,C79, C107 CAP TANT LOESR 10 mF 16 V
10% SMD
TPSB106K016R080
0
AVX
Corporation
4
1
2.2 nF
C37
CAP CERM 2200 pF 5% 50 V
NPO 0805
08055A222JAT2A
AVX
Corporation
5
1
22 nF
C39
CAP CER 22000 pF 50 V X7R
0805
08055C223J4T2A
AVX
Corporation
6
2
4.7 nF
C40,C42
CAP CER 4.7 pF 50 V NPO 0805
08055A4R7BAT2A
AVX
Corporation
7
5
1 mF
C45,C55,C67,C70, C71
CAP CERM 1.0 mF 10% 25 V
X7R 0805
08053C105KAZ2A
AVX
Corporation
8
3
100 mF
C47,C76,C78
CAP ELECT 100 mUF 16 V TK
SMD
EEE-TK1C101P
Panasonic-ECG
9
1
10 nF
C54
CAP CER 10000 pF 16 V NPO
0805
0805YA103JAT4A
AVX
Corporation
10
13
47 pF
C59
CAP CERM 47 pF 5% 50 V NPO
0805
08055A470JAT2A
AVX
Corporation
11
3
2.2 mF
C68,C72,C74
CAP CER 2.2 mUF 25 V X7R
0805
08053C225MAT2A
AVX
Corporation
12
2
0.01 mF
C69,C73
CAP CERM 0.01 10% 50 V X7R
0805
08055C103KAT2A
AVX
Corporation
13
8
10 mF
C80,C81,C82,C83,C84,
C85, C86,C87
CAP CER 10 mF 16 V X5R 0805
EMK212BJ106KG-T Taiyo Yuden
14
9
22 nF
C98,C99,C100,C101,C1
02,
C103,C104,C105,C106
CAP CER 22000 pF 50 V X7R
0805
08055C223J4T2A
AVX
Corporation
15
10
MC08010000
DS1,DS2,DS3,DS4,DS5, Neon lamp
DS6,
DS7,DS8,DS9,DS10
MC08010000
Multicomp
16
20
9.1 V
D1,D2,D3,D4,D5,D6,D7,
D8,
D9,D10,D11,D12,D13,D
14,
D15,D16,D17,D18,D19,
D20
DIODE ZENER 1W 9.1 V
SOD-106
PTZTE259.1B
ROHM
17
10
CON3
J1,J2,J3,J4,J5,J6,J7, J8,
J9,J13
CONN HEADER 3POS .100
VERT TIN
22-28-4030
Molex
18
1
POWER_CONN
J10
Elevated Female Header 5x2
BB02-KD102-T03100000
Gradconn
19
1
DATA_CONN
J11
Elevated Female Header 10x2
BB02-KD202-T03100000
Gradconn
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
SPRAB36B – June 2010
Front-End Board BOM
www.ti.com
Table 3. Bill of Material (continued)
Ite
m
Quantit
y
Value
Reference
Description
Part Number
Manufacturer
20
1
DUMMY_CONN
J12
Elevated Female Header 10x2
BB02-KD202-T03100000
Gradconn
21
1
BEAD
L1
FERRITE BEAD 470 Ω 0805
BK2125HM471-T
Taiyo Yuden
22
4
3.3 mH
L2,L3,L4,L5
INDUCTOR POWER 3.3 mH 1.3A
SMD
VLF4012AT3R3M1R3
DK Corporation
23
1
CONNECTOR
DB15
P1
CONN D-SUB RCPT R/A 15POS
PCB AU
745782-4
Tyco
Electronics
24
9
10M
R1,R9,R19,R27,R35,R4
3, R51,R59,R67
RES 10.0MΩ 1/8W 1% 0805
SMD
CRCW080510M0FK Vishay
EA
25
10
22K
R2,R10,R16,R24,R32,R
40,R48,R56,R64,R102
RES 22KΩ 1W 5% 2512 SMD
CRCW251222K0JN
EG
Vishay
26
10
10K
R3,R11,R17,R25,
R33,R41,
R49,R57,R65,R101
RES 10KΩ 1/2W 5% 2010 SMD
CRCW201010K0JN
EF
Vishay
27
8
6.8K
R4,R12,R20,R28,R36,
R44, R52,R60
High Precision Chip Resistor
6.8KΩ
Y162406K8000T9R
Vishay
28
15
10K
R5,R13,R21,R29,R37,
R45,R53,R61,R97, R98,
R99,R100,
R103,R104,R105
High Precision Chip Resistor
10KΩ
Y162410K0000T9R
Vishay
29
38
0E
R6,R8,R14,R18,R22,
R26,R30,R34,R38,
R42,R46,R50,R54,
R58,R62,R66,R68,
R69,R70,R71,R72,
R75,R77,R78, R79,
R119,R120,R121,
R122,R124,R125,
R126,R127,R128,
R129,R130,R131, R132
RES 0.0 Ω 1/8W 5% 0805 SMD
CRCW08050000Z0
EA
Vishay
30
11
10K
R73,R74,R93,R110,
R111,R112,R113,
R114,R115,R116, R117
RES 10.0KΩ 1/8W 1% 0805 SMD CRCW080510K0FK
EA
Vishay
31
1
47E
R76
High Precision Chip Resistor 47
Ω
Y162447R0000T9R
Vishay
32
1
1K
R80
RES 1.00KΩ 1/8 W 1% 0805
SMD
CRCW08051K00FK
EA
Vishay
33
1
100E
R81
High Precision Chip Resistor 100
m
Y1624100R000T9R
Vishay
34
9
100K
R82,R84,R85,R86,
R87,R88,R89,R90, R91
RES 100KΩ 1/8W 1% 0805 SMD
CRCW0805100KFK
EA
Vishay
35
2
100K_POT
R83,R92
POT 100KΩ 4MM SQ CERMET
SMD
3314G-1-104E
Bourns Inc
36
2
4.7K
R95,R94
RES 4.70KΩ 1/8W 1% 0805 SMD CRCW08054K70FK
EA
Vishay
37
2
390K
R96,R133
High Precision Chip Resistor
390KΩ
TNPW0805390KBY
TA
Vishay
38
2
10K
R108,R106
RES 10.0KΩ 1/8W 1% 0805 SMD CRCW080510K0FK
EA
Vishay
DNI
39
3
0E
R107,R109,R123
RES 0.0 Ω 1/8W 5% 0805 SMD
CRCW08050000Z0
EA
Vishay
DNI
40
1
51E
R118
RES 51 Ω 1/8W 5% 0805 SMD
CRCW080551R0JN
EA
Vishay
41
4
OPA2335
U1,U4,U7,U10
IC OP AMP CMOS SGL SPLY
8-MSOP
OPA2335AIDGKT
TI
42
8
INA128
U2,U3,U5,U6,U8,U9,U11 IC LOW PWR INSTR AMP
, U12
8-SOIC
INA128UA
TI
43
1
ADS1258
U13
IC ADC 24 BIT 125 ksps 48-QFN
ADS1258IRTCT
TI
44
3
OPA335
U14,U15,U23
IC OP AMP CMOS SGL SPLY
SOT-23-5
OPA335AIDBVT
TI
45
1
REF5025
U16
IC PREC V-REF 2.5 V LN
8-SOIC
REF5025AID
TI
SPRAB36B – June 2010
DNI
DNI
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
31
Front-End Board BOM
www.ti.com
Table 3. Bill of Material (continued)
32
Ite
m
Quantit
y
Value
Reference
Description
Part Number
Manufacturer
46
1
TLV3401
U17
IC OUT COMPARATOR
NANOPWR SOT23-5
TLV3401IDBVR
TI
47
2
TLV3404
U18,U20
COMPARATOR LW POWER R-R TLV3404IDR
14-SOIC
TI
48
1
PCA9535
U19
IC REMOTE 16-BIT I/O EXP
24-TSSOP
PCA9535PWR
TI
49
3
TLV2221
U21,U22,U24
IC RAIL-TO-RAIL OP AMP
SOT-23-5
TLV2221CDBVR
TI
50
1
TPS73025
U25
IC LDO REG HI-PSRR 2.5 V
SOT23-5
TPS73025DBV
TI
51
1
TPS60403
U26
IC UNREG CHRG PUMP V INV
SOT23-5
TPS60403DBVT
TI
52
1
TPS72325
U27
IC LDO REG 200MA 2.5 V
SOT23-5
TPS72325DBVT
TI
53
1
32.768KHz
Y1
CRYSTAL 32.7680 KHz 12.5 pF
CYL
C-001R
32.7680KA:PBFREE
Epson
Toyocom
Corporation
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
DNI
SPRAB36B – June 2010
www.ti.com
Appendix C Sensors and Accessories
C.1
ECG Cable Details
Figure 27. ECG Cable Details
Cable details: 10 lead ECG cable for philips/hp -snap, button (Part No: 010302013)
http://www.biometriccables.com/index.php?productID=692
Cable details: 10 lead ECG cable for philips/hp -Clip-on type (P/n-010303013A)
http://www.biometriccables.com/index.php?productID=693
Other compatible cables for MDK: HP/Philips/Agilent Compatible 10 Lead ECG cable
C.2
ECG Sensor
Sensor details: Disposable Electrodes - Medico Lead - Lok
Vendor name: Medico Electrodes International Link : http://www.medicoleadlok.com/
Other compatible parts: Any Ag/AgCl solid gel ECG electrode on the market.
SPRAB36B – June 2010
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
33
www.ti.com
Appendix D MEDICAL DEVELOPMENT KIT (MDK) WARNINGS, RESTRICTIONS AND
DISCLAIMER
Not for Diagnostic Use: For Feasibility Evaluation Only in Laboratory/Development Environments.
The MDK may not be used for diagnostic purposes.
This MDK is intended solely for evaluation and development purposes. It is not intended for diagnostic use
and may not be used as all or part of an end equipment product.
This MDK should be used solely by qualified engineers and technicians who are familiar with the risks
associated with handling electrical and mechanical components, systems and subsystems.
Your Obligations and Responsibilities.
Please consult the TMS320VC5505 DSP Medical Development Kit (MDK) Quick Start Guide (SPRUGO1)
prior to using the MDK. Any use of the MDK outside of the specified operating range may cause danger to
the users and/or produce unintended results, inaccurate operation, and permanent damage to the MDK
and associated electronics. You acknowledge and agree that:
• You are responsible for compliance with all applicable Federal, State and local regulatory requirements
(including but not limited to Food and Drug Administration regulations, UL, CSA, VDE, CE, RoHS and
WEEE,) that relate to your use (and that of your employees, contractors or designees) of the MDK for
evaluation, testing and other purposes.
• You are responsible for the safety of you and your employees and contractors when using or handling
the MDK. Further, you are responsible for ensuring that any contacts or interfaces between the MDK
and any human body are designed to be safe and to avoid the risk of electrical shock.
• You will defend, indemnify and hold TI, its licensors and their representatives harmless from and
against any and all claims, damages, losses, expenses, costs and liabilities (collectively, "Claims")
arising out of or in connection with any use of the MDK that is not in accordance with the terms of this
agreement. This obligation shall apply whether Claims arise under the law of tort or contract or any
other legal theory, and even if the MDK fails to perform as described or expected.
WARNING
If defibrillator is used for development purposes, use of medical
grade EVM input power supply (Accessory Part Number: SL Power
AULT Model MW173KB0503F01) is strongly recommended. Use of
the Isolator (Accessory Part Number: MOXA Model Name: TCC-82)
that isolates the MDK from the PC is also strongly recommended.
These accessories provide additional supplemental protection to
development users from high voltages that may be present when
introducing defibrillator voltages during development simulation.
There may also be other voltage transients sourced from the
defibrillator to accompanying interface hardware such as a
personal computer when used in conjunction with the ECG/EVM
development hardware.
WARNING
To minimize risk of electric shock hazard, use only the following
power supplies for the EVM module: Medical Development
Applications: SL Power AULT Model MW173KB0503F01.
34
ECG Implementation on the TMS320C5515 DSP Medical Development Kit
(MDK)
Copyright © 2010, Texas Instruments Incorporated
SPRAB36B – June 2010
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