180 likes | 283 Views
Optical Heart Monitor / Jump Drive Group 6. Sponsor: Calit2 Mentor: Paul Blair, Ph.D. Team: Kari Nip, Matt Chandrangsu, Jeffrey Chi. Agenda. Design Specifications Weekly Progress Gantt Chart Questions. Pulse Oximeter. Typically a 2 LED system
E N D
Optical Heart Monitor / Jump DriveGroup 6 Sponsor: Calit2 Mentor: Paul Blair, Ph.D. Team: Kari Nip, Matt Chandrangsu, Jeffrey Chi
Agenda • Design Specifications • Weekly Progress • Gantt Chart • Questions
Pulse Oximeter • Typically a 2 LED system • One red LED (660nm wavelength), one infared LED (910nm). • Absorption of these wavelengths is different in oxyhemoglobin and deoxygenated hemoglobin. • We only use 1 LED • Only care about heart rate, not oxygenation levels. • Still use a 2 LED device, as it is more readily available
ADC Specs • 10 Bit resolution • 65-260 µs Conversion Time • Up to 15 ksps at Maximum Resolution • Through Nyquist theory, the maximum signal input frequency is 7.5 kHz • Input heart beat signal (approx. 60 Hz) • Previous data found at 250 sps
HR Circuitry: OpAmp Specifications • LM358 chip – has two independent operational amplifiers on it • 100dB voltage gain • 3V – 32V supply voltage range • 2mV input offset voltage • 1MHz bandwidth
HR Circuitry: Sensor light
HR Circuitry • Received a commercial heart rate monitor PCB to investigate • Compared PSPICE simulations to circuit data • Familiarized with Eagle Layout editor
HR Circuitry: Simulation vs. lab At the maximum points of both output and input signal: Voltage gain (simulated) = 13.655 Voltage gain (circuit) = 9.337
HR Circuitry: Plans • Continue working with Eagle Layout editor • Refine PCB layout • Better component placement • Shorter traces • Use of vias to make PCB layout more concise
Signal Filtering Input Signal and Matched Filter
Signal Filtering • Convolution of matched filter (f) and input signal (g)
Signal Filtering: Plans • Make filtered function square wave signal • Develop further understanding of Matlab functions • Create filtering program in C
File Allocation Table • 0-10 File name (8 bytes) with extension (3 bytes) • 11 Attribute - a bitvector. Bit 0: read only. Bit 1: hidden. Bit 2: system file. Bit 3: volume label. Bit 4: subdirectory. Bit 5: archive. Bits 6-7: unused. • 12-21 Reserved (see below) • 22-23 Time (5/6/5 bits, for hour/minutes/doubleseconds) • 24-25 Date (7/4/5 bits, for year-since-1980/month/day) • 26-27 Starting cluster (0 for an empty file) • 28-31 Filesize in bytes
Interfacing with USB • Completed code to control LED’s on development board with button presses. • Currently researching USB storage code to find which functions to leverage. • Upcoming Tasks: • First: Going to merge LED control code with storage code. • Second: Implement button press controlled file modification