Kevin Chen ECE 445 March 1, 2015 Team 44: Aaron Mann Elizabeth Dennis

35 Pages·2015·0.65 MB·English

Personal Diagnostic Device
Design Review
TA: Kevin Chen
ECE 445
March 1, 2015
Team 44: Aaron Mann
Elizabeth Dennis
Table of Contents
I. Introduction
1. Statement of Purpose
2. Objectives
2.1 Goals
2.2 Functions
2.3 Benefits
2.4 Features
II. Design
1. Block Diagrams
2. Block Descriptions
3. Simulations
4. Flow Charts
5. Schematic
III. Requirements and Verifications
1. Requirements and Verification
2. Power Analysis
IV. Cost and Schedule
1. Cost Analysis
1.1 Labor
1.2 Parts
1.3 Grand Total = Labor + Parts
2. Schedule
VII. Safety Statement
VIII. Ethics Statement
IX. References

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1.0 Introduction
1.1 Statement of Purpose
The symptoms of myocardial infarction are often confused with symptoms of other
conditions. Whether a patient falsely identifies the symptoms of indigestion or panic attacks
with of a heart attack, or feels symptoms but forgoes the emergency room at the risk of incurring
high medical bills in case of a false alarm, the core issue is the uncertainty and ambiguity of the
symptoms. Our group plans to build an on-site heart attack detector that will diminish this
uncertainty by allowing the users to find out if their symptoms are actually those of myocardial
infarction without having to step foot in a hospital.

1.2 Objectives
1.2.1 Goals
- Get more patients who need to see doctors into hospitals and stop wasting on
those who don’t
- Allow individuals to make the diagnose themselves and remove the length of time
and cost of a hospital visit from the decision process when symptoms are felt.
1.2.2 Functions
- Diagnose the user with myocardial infarction
- Take user pulse
- Transmit data with user location and diagnosis for assistance
1.2.3 Customer Benefits
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- Cheaper than current means
- Faster than current means
- Allow the user to be responsible for their own diagnosis
- Allow EMTs and nurses to better diagnose patients
- Catch smaller heart attacks easier that would in other cases go untreated and lead
to death
1.2.4 Features
- The device will feature a chemical strip for detecting troponin I/T in the users
blood
- There will a pulse sensor give the pulse of the user
- A simple display will output an interpretable diagnosis to the user
- A simple easy to take series of questions will be for smartphone users
- The device will be able to send the user information to a second location for
outside assistance
- The device will have a minimal use design enabling it to be as simple as to use as
possible

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2.0 Design
2.1 Block Diagram

Figure 1: Basic Block Diagram of Personal Diagnostics Device
2.2 Block Descriptions
2.2.1 Power
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Figure 2: Power Module of Personal Diagnostics Device
The 9V battery will be responsible for powering all modules of the personal diagnostic
device: microcontroller, display, Bluetooth, and sensor control. The buck regulator
(LT3988) takes the input of 9V DC battery and provides an output of 3.3V, 1A and 5V,
1A. The Bluetooth 4.0 module, microcontroller, LED drivers, and the color sensor will
need 3.3V to function. The 5.0V is used in the pulse sensor for op-amp rails, the source to
drive the IR emitter and IR detector input, and the collector voltage of the transistor.
Below in Table 1 is a power analysis of the components this power source will drive. In
Figure 2, a switch is also present, to turn the device off/on.
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Figure 3: Power Source Schematic
Table 1: Power Analysis for Personal Diagnostic Device
Part Name Module Voltages Needed Current Used Power
(V) (mA) (mW)
MSP430F5510 Microprocess 3.3 7 23.1
or
BLE112 Bluetooth 3.3 36 118.8
TMD3782 Color Sensor 3.3 3 9.9
HSDL-4420 Pulse Sensor 5 5uA to 500mA 2500
HSDL-5420 Pulse Sensor 5 5uA to 500mA 2500
Transistor Pulse Sensor 5 200 1000
MAX6954 Display 3.3 60 198
Total Power (W) 6.3498

Power Calculation:
Using the table above and the assumption that the transistor and the IR emitter and
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detectors will not exceed their partner components in the their current usage (a safe
assumption given the operation of the parts in question) we will calculate the battery life
of our device.
The battery being used is a 9V alkaline battery from Duracell that produces
500mAh.With pulse sensors and the transistors using 30mA our calculation for battery
life is:

This suggests 2.5 hours of battery for continuous usage. There are a few assumptions
made in the above calculations. The first is that the Bluetooth module will be in
operation during the entire use which is not true, it will only transmit data near the end of
the use of the device. Another assumption was that all pieces of the devices are in
parallel and no current will run through both devices.

2.2.2 Microcontroller
The microcontroller is the MSP430F550 from Texas instruments. This device will
be configured to have three SPI communication lines (two for the LED drivers and one
for the Bluetooth 4.0 module) and one I2C communication line (for the color sensor).
This microcontroller will be programmed via communication through the computer by
JTAG pins. With these communication lines, the microcontroller can initialize the
settings desired for the color sensor (i.e. proximity of reading, gain, wait times to read the
colored strip), LED drivers (i.e. intensity of message), and Bluetooth 4.0 module.
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This package also has an ADC. When the analog output of the pulse sensor comes
to the microcontroller, the microcontroller can convert this data to digital outputs and
then manipulate the data to determine the beats per minute. The flowchart in Figure 4
describes how we will utilize the internal clock of our microcontroller to turn our changes
in the infrared detection into beats per minutes. Rather have the user place their finger
inside the ring for 60 seconds, we using only 15 seconds and multiplying by 4. The a
while loop will run on the microcontroller inner clock adding up to 15 seconds. During
that fifteen seconds the microcontroller will look for changes from the IR detector. These
changes will increment a variable that stores the beats detected. To prevent a single beat
carrying over from clock cycle to clock and being countered more than once is a second
variable, a parity bit of sorts. This bit will be set high if a pulse have just been detected
and will only allow for a new pulse to be registers if it is set back to low.
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Figure 4: Flowchart for Personal Diagnostics Device Sensor Input
After calculating beats per minute, the microcontroller will communicate with the
LED driver connected to the three 16-segment displays to display the result on the LEDs.
The microcontroller is also responsible for interpreting the color sensor’s output. In the
event that the strip changes color to reveal a positive result, it is up to the microcontroller
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