ADVANCED DIGITAL STETHOSCOPE

PHASE I SECOND REVIEW

BY E.MURUGA LAKSHMI

(ROLL NO:12) 

Project Guide:Dr. E.JANARTHANAN

Department of ECE

OBJECTIVE

The main objective of our project is :

To design and implement a digital stethoscope using

microcontroller to serve as a platform for potential

computer aided diagnosis (CAD) applications for the

detection of cardiac murmurs.

It can Amplify, Play and Record heart signals in real time.

OBJECTIVE

Capture a cardiac signal using a custom-built acoustic

sensor and an analog-to-digital converter

Output a real-time audio signal based on the sampled input

using a digital-to-analog converter

Record and playback captured signals using external Flash

memory

OBJECTIVE

Transmit real-time and recorded serial data via the USART for visualization and analysis

To identify and remove the noise which pollutes the audio output signal during reading and writing of the Flash memory.

Implementation of software FIR filters for

diagnosing specific problem.

MOTIVATION

• To assist the physician to easily diagnose the problem from the waveform output

• Detect the cardiac murmurs significantly to identify the problem

• Recording the signal will be useful for remote monitoring of the patients

• It will be useful for inexperienced physicians.

HARDWARE SYSTEM

MicrocontrollerROM/RAM

Signal conditioning

SENSOR

Speaker & interface

LCD SCREEN

KEYBOARD

PC/MATLAB

FLASH MEMORY

SYSTEM SOFTWARE HIGH LEVEL OVERVIEW

WORK DONE IN I REVIEW

• Compared the development boards MCB2100,MCB2140, AT91SAM9263-EK for final selection of board.

• Familiarized the keil software by simulating with simple programs

• MCB 2140 board is selected to carry out the project.

WORK COMPLETED TILL II REVIEW

• Studied features of A/D converter in LPC 21482 ADC ,14 channels with 10 bit precisionStudied special function registers associated

with ADC.ADC REGISTERS:

ADCR,ADGDR,ADDR,ADSTAT,ADINTEN• Written program to convert any analog signal to

digital signal in LPC2148

WORK DONE TILL II REVIEW

ALGORITHM:Initialize ADC0/ADC1 and select any channelConfigure the ADCR register and PINSEL

registerManually tell ADC to start conversionStop all conversion and start to read valuesConstantly read the conversion results from

ADDR

SOURCE CODE

#include <LPC214X.H> //Header file for LPC 2148• int result=0; //variable declaration• int main (void) // call main function• {• void init_adc(void); // call ADC initialisation

• while(1) //continue infinitely• {• result=adcRead(); // get result from read function• }• }

SOURCE CODE

• void init_adc(void) • {• PINSEL0 |= 0x00003000; // Enable pin corresponding to AD1.O (P0.6)• AD1CR &= 0x00000000; // Clear All Bit Control• AD1CR |= 0x00000001; // Select ADC = AIN8• // CLKDive => Pclk / (x +1) <4.5Mhz• AD1CR |= 0x00000600; // ADC Clock = VBP (PCLK) / 7 1.55us• AD1CR |= 0x00010000; //Burst (Continuous) = 1 = Conversion• AD1CR &= 0xFFF1FFFF; // CLKS 11 cycles(10 bit resolution)• AD1CR |= 0x00200000; // PDN = 1 = Active ADC Module• AD1CR &= 0xFF3FFFFF; // TEST [1:0] = 00 = normal mode• AD1CR &= 0xF7FFFFFF; // EDGE = 0 • AD1STAT = 0x00010101;• }

SOURCE CODE

• int adcRead(void) // READ sub routine• {• AD1CR= 0X00200D01; // Select channel 0• AD1CR |=0x01000000; //start AD conversion• result = AD1GDR; // read data • while((result& 0x80000000)==0); // do till DONE bit is

set• result=(result>>6)&0x03FF; // bit 6:15 is 10 bit ADC

VALUE• return (result);• }

RESULT

WORK TO BE DONE FOR PHASE I

• Design the acoustic sensor • Generate PWM signal for audio playback• Storing the signal in flash memory for later playback

REFERENCES• Haibin Wang; Jian Chen; Yuliang Hu; Zhongwei Jiang; Choi Samjin; ,

"Heart Sound Measurement and Analysis System with Digital Stethoscope," Biomedical Engineering and Informatics, 2009. BMEI '09. 2nd International Conference on , vol., no., pp.1-5, 17-19 Oct. 2000

• Ying-Wen Bai; Cheng-Hsiang Yeh; , "Design and implementation of a remote embedded DSP stethoscope with a method for judging heart murmur," Instrumentation and Measurement Technology Conference, 2009. I2MTC '09. IEEE , vol., no., pp.1580-1585, 5-7 May 2009

• El-Bendary, N.; Al-Qaheri, H.; Zawbaa, H.M.; Hamed, M.; Hassanien, A.E.; Qiangfu Zhao; Abraham, A.; , "HSAS: Heart Sound Authentication System," Nature and Biologically Inspired Computing (NaBIC), 2010 Second World Congress on , vol., no., pp.351-356, 15-17 Dec. 2010