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