Team Pacemaker

Apparatus for the Analysis of Heart Sounds

Electronic Stethoscope / EKG Device

Luke Philips

Ryan Laterza

Min Dong Bian

Sarah Makhija

Project Objectives

• Provide objective means of analyzing cardiac acoustics– Aid in diagnosis of heart murmurs

• Amplified signal from stethoscope, EKG– Synchronized signals

• Handheld device, portable memory, graphical display

Design Summary

Medical Doctor

SoundStethoscope

Electrocardiogram Action Potential1

1

Reads

11 Amplfies1

1

Listens

11 Records 1* Conducts

11 Emit

Heart

Valve

Cardiac Muscle

4

1 Has

1

1 Has

11 Treats

Current Domain Model

Design Summary (cont.)

Medical Doctor

Sound

Hardware Device

SD Card

Action Potential

11

Reads 1

1

Records

1

1

Writes

1

1

Records 1* Conducts

11 Emit

Heart

Valve

Cardiac Muscle

4

1 Has

1

1 Has

1

1 Treats

Software Utility

1

1

Generates

Three Dimensional Plot

1

1

Analyzes

Future Domain Model

Project Diagram

Preliminary Graphical Displays

•Dr. Weinberger’s data files•No accompanied EKG data

EKG Triggering & Averaging

10 sec. FFT of Filtered Stethoscope

Data

Mixed Signal Microcontroller TI MSP430F1611

MSP430F1611 Features

• Program Memory Type Flash  • Program Memory 48 kB• RAM 10 kB• I/O Pins 48  • ADC 12-bit SAR 

– 8 Software Programmable Input Channels– 200 ksps Maximum Conversion Rate

• Integrated Peripherals DMA, 2 12-bit DAC• Interface 2 Hardware SPI or UART• Pin/Package 64LQFP

Programming the Microcontroller

• MSPGCC – Free C Compiler TI MSP430 Family– Windows and Unix Compatible– Supports the MSP430F1611 MCU– Supports JTAG Interfacing

• Interface Used to Download Code from the PC to the MCU via a Serial/Parallel/USB Adapter

Example C Code“Blinking Lights”

#include "hardware.h"

void delay(unsigned int d) {int i;for (i = 0; i<d; i++) {

nop();nop();}

}

int main(void) {int i;int o = 0;WDTCTL = WDTCTL_INIT; P1OUT = P1OUT_INIT; P2OUT = P2OUT_INIT; P1SEL = P1SEL_INIT;

P2SEL = P2SEL_INIT; P1DIR = P1DIR_INIT; P2DIR = P2DIR_INIT; P1IES = P1IES_INIT; P2IES = P2IES_INIT;P1IE = P1IE_INIT;P2IE = P2IE_INIT;while (1) { //main loop, never ends..

for (i=0; i<8; i++, o++) {P1OUT = (1<<i) | (0x80>>(o&7));delay(0x4fff);}

}}

EKG

Amplifier Circuit Design

Amplifier Implementation

1. LF155/LF156…./LF356 JFET input Operational Amplifiers

Applications:•Precision High Speed Integrators

•Fast D/A & A/D Converters

•High Impedance Buffers

•Wideband, low noise, low drift amplifiers

Advantages

2. Single-Supply CMOS Operational Amplifiers

OR…

Features

Applications

Simple Circuit Testing for Optimal Design

OPA 335 LF356

3. Bypass Capacitors

0.1 nF & 4.7 nF

Before & After Adding Amplifier

EKG Schematic

Title

Size Document Number Rev

Date: Sheet of

<Doc> <RevCode>

EKG schematic

A

1 1Wednesday, March 01, 2006

Differential Amplifier INA321

Right Electrode

Left Electrode

DAC1

<Value>

3

1516

11

1

14

-

+

U2A

EL2360C-N

3

1312

11

5

14

-

+

U2BEL2360C-N

R1

100K

R2

100K

R3

RESISTOR

R4

RESISTOR

R5

1M

R6

1M

R7

10K

R81M

R9800

R10

RESISTOR

R11

RESISTOR

R122.2M

R132.2M

C1

01nF

C2

4.7nF

Power & User Interface

Power• Power Supply

– “wall wart” interface• Supplies up to

9VDC/300mA

– Regulated 5V/3.3V– Stand alone Battery

Charger• AC12050615A-01

single cell charger

– Numerous Adjustable Voltage Regulators

Power• Battery

– ED053455-2C• 860mAh Polymer

Lithium Ion Battery• High Energy Density• Low Cost• 3.7V Nominal Working

Voltage• Low Weight - 0.65oz

(18.5g)• Excellent Temperature

Performance• Self-Discharge: <8%

(per month)

Power• Intelligence

– TI-TPS65011• Multi-Channel 1-cell

Li-Ion Power Mgmt IC

• 2DC/DC, 2 LDOs, I2C interface

TPS65011 Regulated Outputs(#) 4 Vin(Min/Max)(V) 2.5/6 Vout(Min/Max)(V) 2.5/3.3 Vout2 Adj(Min/Max)(V) 0.85/1.8 Iout3(A) 0.2 Iout4(A) 0.2 Vout3 Adj(Min/Max)(V) 0.9/6 Vout4 Adj(Min/Max)(V) 1.8/3

UI

LCD, two stages:– Hantronix HDM08216L

• 8x2

– Seiko Backlight Graphic LCD

UI

• Keypad • Low power Keypad Interface With the MSP430

• interrupt driven• Low power if all keys are

pressed and held simultaneously

• No crystal required• Minimal external

components• Suitable for MSP430

Updated Schedule & Division of Labor

Milestone 1 – Data sampling; Power device; EKG Circuit

Milestone 2 – UI / Software Integration

Expo – Device able to acquire and display data

Thank You!

Questions/Comments?