Digital Stethoscope

http://people.ece.cornell.edu/....land/courses/ece4760
The purpose of this project was to design and implement a digital stethoscope to serve as a platform for potential computer aided diagnosis (CAD) applications for the detection of cardiac murmurs. The system uses a custom-built sensor to capture heart sounds at 8 kHz and converts them to electrical signals to be processed by an ATmega644 microcontroller. The captured signals are outputted via pulse-width modulation to a standard 3.5 mm audio socket for real-time auscultation. In addition, the stethoscope uses a 1MB external Flash memory chip to record and playback audio waveforms. For the user interface, the system includes a 4-line 20-character wide LCD display and a 16-button keypad. Real-time and recorded data can also be visualized using a MATLAB interface that runs on a separate PC and connects to the stethoscope system via the USART interface on the microcontroller. The MATLAB interface also uses the transmitted data to calculate and display the patient's average heart rate in beats per minute.