optical heart monitor / jump drive group 6
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
Optical Heart Monitor / Jump Drive
Group 6
Sponsor: Calit2Mentor: 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: PSPICE Simulation
HR Circuitry: Circuit data
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: Eagle layout
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
2 21 1 2 2( ) ( )
1 2b t t b t ty a e a e
Signal Filtering
Convolution of matched filter (f) and input signal (g)
m
f g n f m g n m
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
Gantt Chart