University of Manitoba Department of Electrical & Computer...

University of Manitoba

Department of Electrical & Computer Engineering

ECE 4600 Group Design Project

Final Project Report

Swimming Data Acquisition by Ultrasonic Detection

Final report submitted in partial satisfaction of the requirements for the degree of

Bachelor of Science in Electrical Engineering

by

Group 2

Andrew Maronese Adam Brown Evan Wilson

Academic Supervisor

Dean McNeill

Industry Supervisor

Daniel C. Card

Date of Submission

March 17, 2017

Copyright c© 2017 Andrew Maronese, Adam Brown, Evan Wilson

Abstract

It is common for a swimmer to keep track of their swimming times with a stopwatch

and mentally track their lap count. This poses an issue because the swimmer may forget

the number of laps while he or she is focusing on their technique. Furthermore it is difficult

for a swimmer to measure the time that each lap takes, so they end up averaging the total

swim time to estimate the particular lap time. This introduces a lot of inaccuracies and

does not give the swimmer sufficiently detailed information about their performance.

The swimming data acquisition by ultrasonic detection device is described in this re-

port as a solution to these problems. It is a device that is placed at the end of the pool

that tracks the swimmer and displays their lap data, and will log their progress over mul-

tiple sessions. It is designed to eliminate the inherent inaccuracies in tracking a swimmer’s

progress manually. This report outlines the design and implementation of the various sub-

systems of the swimming data acquisition device, from the power delivery system and data

acquisition/logging to the user controls and enclosure design. The design described in this

report was built and successfully acquires swimming data.

i

Contributions

Ada

mB

row

n

And

rew

Mar

ones

e

Eva

nW

ilson

Data Acquisition System • Data Logging System •

Controls and Monitoring Interface • Power Delivery System •

Enclosure • System Integration and Testing

Final Report Final Presentation

• = Design Lead

= Design Support

ii

Acknowledgements

The success of this project would not have been possible without consultation from indus-

try contacts as well as members of the Department of Electrical and Computer Engineering

at the University of Manitoba. The authors of this report would like to acknowledge the

following individuals for their contributions:

• Mr. Daniel Card was our industry supervisor as well as our client for the project. He

provided us with his expertise in electrical design and system testing. The mentoring

received throughout the project helped bring the project to completion through team

difficulties.

• Mr. Dean McNeill was our academic supervisor and provided insight and suggestions

throughout the design and final build of the project.

• Mrs. Chelsea Maronese is a speed swimming coach who helped in the initial brain-

storming which gave valuable insight into applications in this field.

• Mr. Sinisa Janic aided in the acquisition of materials and components in order to

build this project.

• Mr. Glen Kolansky provided rental components to allow testing and project progres-

sion while parts were being ordered.

• Dr. Derek Oliver provided extensive knowledge on the guidelines and team man-

agement techniques for the project. He also provided support and guidance through

team difficulties.

• UMIEEE provided a workspace and tools for the construction of this project.

• Mr. Cory Smit assisted with precise machining of the enclosure and acquisition of

mounting hardware.

iii

CONTENTS

Contents

Abstract i

Contributions ii

Acknowledgements iii

List of Figures vii

List of Tables viii

Nomenclature ix

1 Introduction 1

1.1 System Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2 Performance Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2 Data Acquisition System 3

2.1 Microcontroller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.1.1 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.1.2 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.2 Ultrasonic Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.2.1 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.2.2 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3 Data Logging System 12

3.1 SD Card Reader . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

3.1.1 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

3.1.2 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4 Controls and Monitoring Interface 16

4.1 Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

4.1.1 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

4.1.2 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4.2 Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

iv

CONTENTS

4.2.1 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4.2.2 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.3 Audible Feedback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

5 Power Delivery System 21

5.1 Battery Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

5.1.1 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

5.1.2 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

5.2 DC-DC Converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

5.2.1 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

5.2.2 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

5.3 Battery Protection Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

5.3.1 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

5.3.2 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

6 Enclosure 33

6.1 Physical and Display Considerations . . . . . . . . . . . . . . . . . . . . . . 33

6.1.1 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

6.1.2 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

6.2 Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

6.3 Peripheral Casings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

6.3.1 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

6.3.2 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

7 Integration and Assembly 41

7.1 Peripheral Electrical Systems Integration . . . . . . . . . . . . . . . . . . . 41

7.1.1 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

7.1.2 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

7.2 Power Delivery Integration . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

7.3 Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

7.3.1 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

8 Conclusion 46

8.1 Project Outcome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

8.2 Future Developments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

v

CONTENTS

References 47

A Appendix - Battery Test 48

B Appendix - Arduino Mega Schematic 49

C Appendix - Enclosure Dimensions 50

D Appendix - Peripherals Pin Assignment Table 51

vi

LIST OF FIGURES

List of Figures1 Overview of Subsystem Interaction . . . . . . . . . . . . . . . . . . . . . . . 2

2.1 Microcontroller Current Draw Test . . . . . . . . . . . . . . . . . . . . . . . 5

2.2 Object Detection Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.3 Sensor Distance Test Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.4 Sensor Beam Angle Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.5 Sensor Beam Angle Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3.1 SD Card Data Writing Unit Testing . . . . . . . . . . . . . . . . . . . . . . 14

3.2 Integrated Data Logging System . . . . . . . . . . . . . . . . . . . . . . . . 15

4.1 LCD Display Test at Joyce Fromson Pool . . . . . . . . . . . . . . . . . . . 18

4.2 Button Waterproofing Test . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

5.1 Battery Testing with Electronic Load at 100 mA . . . . . . . . . . . . . . . 24

5.2 DC-DC Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

5.3 DC-DC Converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

5.4 Monitor Images for Various Configurations . . . . . . . . . . . . . . . . . . 27

5.5 Software Shutdown Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

5.6 9.5V Shut-off Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

5.7 9.5V Shut-off Test Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

5.8 Auto Shutoff Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

6.1 Initial Waterproofing Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

6.2 1 m Drop Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

6.3 Internal Case Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

6.4 Mounting Top and Back Plates . . . . . . . . . . . . . . . . . . . . . . . . . 38

6.5 SOLIDWORKS Button Case Design . . . . . . . . . . . . . . . . . . . . . . 39

6.6 SOLIDWORKS Sensor Case Design . . . . . . . . . . . . . . . . . . . . . . 40

6.7 Integrated Button and Sensor Casings . . . . . . . . . . . . . . . . . . . . . 40

7.1 Shield Wiring Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

7.2 Final Shield Construction and Peripheral Integration . . . . . . . . . . . . . 42

7.3 Final Construction of the Swimmer’s Data Acquisition System . . . . . . . 44

A.1 Battery Test Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

B.2 Arduino Mega Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

C.3 Enclosure Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

D.4 Peripherals Pin Assignment Table . . . . . . . . . . . . . . . . . . . . . . . 51

vii

LIST OF TABLES

List of Tables1 Performance Metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2.1 Decision Matrix Evaluation Criteria . . . . . . . . . . . . . . . . . . . . . . 4

2.2 Microcontroller Decision Matrix . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.3 Ultrasonic Sensor Decision Matrix . . . . . . . . . . . . . . . . . . . . . . . 6

3.1 Data Logger Decision Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4.1 Display Decision Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5.1 Battery Energy Densities and Cell Voltages . . . . . . . . . . . . . . . . . . 22

5.2 Battery Decision Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

5.3 DC-DC Converter Decision Matrix . . . . . . . . . . . . . . . . . . . . . . . 26

6.1 Enclosure Decision Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

7.1 Lap Detection Test Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

viii

NOMENCLATURE

Nomenclature

ASCII American Standard Code for Information Interchange

AWG American Wire Gauge

CS Chip Select

dB Decibel

DC Direct Current

EEPROM Electronic Erasable Programmable Read Only Memory

GB Gigabyte

I/O Input/Output

IDE Integrated Development Environment

LED Light Emitting Diode

LCD Liquid Crystal Display

LiPo Lithium Polymer

MISO Master In Slave Out

MDF Medium-Density Fiberboard

MOSFET Metal-Oxide Semiconductor Field-Effect Transistor

ix

NOMENCLATURE

MOSI Master Out Slave In

NiCd Nickel-Cadmium

NiMH Nickel-Metal Hydride

OV Over Voltage

PCB Printed Circuit Board

PWM Pulse Width Modulation

RFID Radio Frequency Identification

SC Short-Circuit

SCK Serial Clock

SD Secure Digital

SPI Serial Peripheral Interface

TFT Thin Film Transistor

VGS Gate-Source Voltage

x

1 Introduction

1 IntroductionThe purpose of this project is to design and build a swimmer’s data acquisition device

with distance tracking, user controls, and memory storage capabilities. When placed on

the pool edge while the user swims it tracks their progress and store it to be evaluated

later. It is designed for recreational swimmers’ use as the level of precision is not intended

for competitive sport.

1.1 System Overview

The swimmer’s data acquisition device is placed on the edge of the pool, where it sends

out an ultrasonic wave that bounces off of the swimmer as they approach. The time taken

for the wave to travel to the swimmer and back is interpreted as a distance in the the

data acquisition subsystem. The controls and monitoring interface covers how the system

displays the lap time to the liquid crystal display (LCD) display and accepts user input to

start and stop the device.

When the swimmer is within a set distance from the wall the device logs the lap time

and number to an secure digital (SD) card in the data logging system. The data is logged

on an SD card in .csv format so it can easily be transferred to a computer and viewed later.

This format allows it to be opened in an Excel spreadsheet where the user can then make

graphs and analyze the data to reflect on their training.

The power delivery system powers all of these components at the required voltages and

offers protection for the lithium polymer rechargeable batteries as they are depleted. Fi-

nally the enclosure ensures that the whole system is both waterproofed and shock-proofed,

while keeping it simple to view the display, interact with the controls, and access the mem-

ory storage. The interactions of these subsystems can be seen in Figure 1 below.

1

1 Introduction

Figure 1: Overview of Subsystem Interaction

1.2 Performance Specifications

Table 1 outlines the target specifications and outcomes for each feature of the completed

device. The specifications were chosen to encompass all subsections of the project to ensure

every aspect is functional.

Table 1: Performance Metrics

Feature Target Specification Outcome Pass/Fail/Exceed

Manual Start/Stop Yes Yes Pass

Operating Temperature 0 to 40 C 0 to 40 C Pass

Sensor Dead-band Range 20 cm ± 5 cm 20 cm ± 5 cm Pass

Sensor Resolution ≤ 1 cm 0.5 cm Exceed

Annunciator Volume 80dB or loud enough to hear in water 75dB and audible underwater Pass

Lap Number Display 2 digit display 2 digit display Pass

Session Information Display 1 line of 16 characters display 2 line of 16 characters display Exceed

Data Logging ≥1 GB of storage 32 GB of storage Exceed

Water Resistance 10 cm depth for 1 hour ∼30 cm depth for 2 hours Exceed

Operating Time Active 200 hours/Inactive 8500 hours Upgraded to rechargeable Specification altered

batteries on client’s approval

2

2 DATA ACQUISITION SYSTEM

2 Data Acquisition SystemThe purpose of the data acquisition system is to detect the swimmer and calculate

the lap number and lap time. An ultrasonic sensor will detect the swimmer and relay the

information to a microcontroller, which will then process it in preparation for display and

storage.

2.1 Microcontroller

The microcontroller will be used to control a LCD, an ultrasonic sensor, a SD card, two

input buttons, a buzzer, and a battery monitoring circuit. In order to control these devices

it requires a minimum of 16 digital Input/Output (I/O) pins, 4 analog pins and Serial

Peripheral Interface (SPI) support. To handle the processing requirements it must have a

minimum clock speed of 16 MHz. As with the space restrictions the microcontroller must

also have a small form factor. Due to the team’s programming experience being mainly

in C/C++, the microcontroller should utilize those languages or have extensive software

support.

2.1.1 Design

An Arduino Mega was chosen as the microcontroller due to its low cost, easy to use inte-

grated development environment (IDE), online support, large quantity of I/O pins, and low

power consumption. The Beaglebone Green offered similar specs at a significantly higher

cost and the Arduino Uno didn’t meet the digital I/O requirements. The Nucleo-L476RG

offered similar specs at a comparable price but would have required extensive programming

experience with Nucleo devices. The Arduino Mega comes equipped with 16 analog and

54 digital I/O pins, 14 of which can be used for pulse width modulation (PWM) and 4 to

support SPI communication [1]. The process for selecting the microcontroller is outlined

below in Table 2.2. All decision matrices in the report use the criteria specified in Table 2.1.

3


Table 2.1: Decision Matrix Evaluation Criteria

Grades Weight

Poor 1

Below Average 2

Average 3

Good 4

Excellent 5

Table 2.2: Microcontroller Decision Matrix

Microcontrollers

Arduino Uno Arduino Mega Beaglebone Green Nucleo-L476RG

Cost Excellent Good Below Average Average

Size (L x W x H) Excellent Good Excellent Excellent

Clock Speed Average Good Excellent Below Average

Digital I/O pins Below Average Excellent Good Below Average

Analog pins Average Excellent Average Average

SPI Support Excellent Excellent Excellent Excellent

Online Support Excellent Excellent Good Average

Programming Software Excellent Excellent Average Average

Sum 33 37 31 26

Rank 2 1 3 4

Result No Yes No No

Lap Time Calculations

When the microcontroller starts the program, it creates a start time variable from the

internal clock. When a lap is completed, the microcontroller subtracts the start time from

the internal clock in order to calculate the elapsed lap time. The start time variable is then

updated to the completed lap time to allow for the calculation of the next lap.

2.1.2 Performance

The power requirements were to have the device run 200 hours in active mode or 8000

hours inactive. Therefore having low power consumption is a major factor in performance.

A current draw test was performed on the microcontroller to get a no load current draw

value.

4


Current Draw Test

To test the current draw from the Arduino Mega it was connected to a DC regulated

power supply where the applied voltage was increased while limiting the current to avoid

damaging the microcontroller. The voltage was increased up to the recommended operating

voltage of the controller and current draw value was observed under normal operation to

be 70 mA. In Figure 2.1 below, the total current draw at 9.3 V is seen on the DC regulated

power supply.

Figure 2.1: Microcontroller Current Draw Test

5


2.2 Ultrasonic Sensor

The ultrasonic sensor will be in an environment where it will be subjected to moisture

and possibly submerged underwater. Therefore the sensor must be waterproof or have a

waterproof housing. The enclosure dimensions must be small as per the requirements. As

such the sensor must have a small form factor to allow integration within the enclosure

and other components. The sensor must have a detectable range between 20 and 100 cm

with a beam width of 45 and a distance resolution of 1 cm. The sensor must use logic

level control to be compatible with the microcontroller. Finally the sensor must be energy

efficient to allow for a longer active time.

2.2.1 Design

When deciding which sensor to select for the project there were four main design criteria:

cost, size, resolution, and water resistance. With the costs of the enclosure, hardware,

waterproofing, and potential Printed Circuit Board (PCB) system integration, this left a

small portion of the budget for the remaining components. The enclosure size requirements

meant there was limited space for the sensor amidst other components. Since the majority

of the sensors on the market were able to meet the distance detection requirement, the

resolution criteria held more weight. Having a more accurate sensor would improve the

performance and help meet the performance goals. The decision making process is shown

in Table 2.3 below.

Table 2.3: Ultrasonic Sensor Decision Matrix

Ultrasonic Sensors

Maxbotix Sensor RPS-400-30 Sensor Senix Tough Sonic 3 JSN-SR04T Sensor

Cost Poor Poor Poor Excellent

Size Average Average Average Excellent

Range (cm) Excellent Excellent Excellent Good

Water Resistance Excellent Excellent Excellent Good

Input Voltage Below Average Below Average Below Average Excellent

Resolution Good Excellent Excellent Excellent

Detection Angle Average Average Good Good

Operating Temperature Excellent Excellent Excellent Good

Sum 28 29 30 36

Rank 4 3 2 1

Result No No No Yes

The JSN-SR04T waterproof ultrasonic sensor was chosen as it met and exceeded most

6


of our major and minor requirements. Though the other sensor had superior performance,

the high cost, large form factor and excessive input voltage requirements ruled them out.

With the low cost of the JSN-SR04T, two were able to purchased for a fraction of the other

models’ prices. This left a back up sensor if one was damaged in testing. The sensor’s Ar-

duino Mega compatibility and low power consumption simplified integration. The sensor

has a specified detection range between 25 and 450 cm with a beam angle of less than 50,

which exceeds the performance requirements [2].

Distance Measurement

The ultrasonic sensor is mounted through the front of the enclosure at a 12 angle

below the horizontal. This is to ensure the radiated waves hit the swimmer and reflect

back to the sensor. The angle was chosen due to the water level typically being lower than

the edge of the pool where the device is placed. The sensor’s effective range is between 25

and 450 cm leaving a dead-band area from 0 to 25 cm. Having the device resting above

the water with the angle adjustment allows the swimmer to record a lap before they enter

the dead-band.

The ultrasonic sensor operates by sending a 10 µs pulse to the trigger pin on the sensor.

This triggers the sensor to send an ultrasonic signal at 40 kHz for 8 periods. The sensor

waits for an echo signal to be received, at which point it calculates the distance based on

the time delay of the echo. This is shown in Equation 2.1, though the equation varies

as ultrasonic waves travel differently through different mediums [3]. For this project the

calculations were done in air.

Distance =(Signal Travel Time × Speed of Sound in Air)

2(2.1)

Lap Detection

To determine when the swimmer has completed a lap, the placement of the sensor in

relation to the swimmer and the surface of the water needed to be considered. At Joyce

Fromson Pool the curved pool coping has a width of 4 cm and the distance to the water

level was 14 cm. With these measurements the distance and angle that the sensor should

be from the edge of the pool can be calculated. This calculation will optimize the accuracy

of detecting a lap. A 3D printed sensor casing sets the angle of the sensor to 12. This

7


places the center of the beam width at 109.03 cm from the pool edge. With a beam width

of 22 and a coded lap detection range of 25 to 35 cm, the swimmer could be detected in

the desired range. This design is illustrated in Figure 2.2 below.

14 cm

109.03

22°

POOL EDGE

SENSOR

BEAM CENTER

WATER LEVEL

SWIMMER

10.00

LAP COMPLETION RANGE

Figure 2.2: Object Detection Diagram

Lap Calculations

The completion of a lap occurs when a swimmer touches the end of the pool. The sensor

tracks the position of the swimmer’s head as they approach the edge of the pool. The

microcontroller increments the lap counter once the swimmer is within the lap detection

range of 25 to 35 cm. Once the lap counter is updated, the sensor is not pinged for a buffer

period to allow the swimmer to turn around and leave the detection range. This is done

so that multiple laps are not recorded at the completion of one lap.

2.2.2 Performance

A test platform was built in order to confirm the sensor specifications that were claimed

in the data sheet. The accuracy of the sensor distance detection was tested as well as the

sensor beam width.

Sensor Distance Measurement Test

To test the accuracy of the sensor, paper was taped down with inch markings along

its edge. A board was placed at the 0 inches mark and secured at a 90 angle to allow

for optimal reflections when sliding the sensor. The sensor was placed 20 inches from the

8


board and the measurement system indicated a distance of 19.88 inches. The variation in

accuracy could be due to the board setup tolerances or if the humidity, temperature and

air pressure changed the wave propagation properties. However, this was well within the

performance metric of ≤ 1 cm (0.12 inches = 0.305 cm).

In order to test the dead-band distances, the sensor was moved relative to the board

until the measurements failed to update correctly. Through testing it was found that the

sensor dead-band was anything less than 8.16 inches (20.73 cm) and anything greater than

61.88 inches (154.64 cm). To ensure proper detection a minimum distance of 25 cm was

set so that no measurements were missed. The distance test setup is shown in Figure 2.3

below.

Figure 2.3: Sensor Distance Test Setup

Sensor Beam Width Measurement Test

The JSN-SR04T sensor data sheet specified a beam width of 50 degrees [2]. A beam

width measurement test was performed to validate this and find the sensor’s minimum

beam width to compare to the performance metric. The test schematic can be seen in

Figure 2.4 and the experimental test setup in Figure 2.5. The sensor was set at a known

distance of ∆X = 47.04 cm as measured from the sensor. The sensor was mounted in a test

housing at a height h = 9.21 cm. Using a separate wooden board with a known thickness

2.5 cm, the board was moved slowly down until a value of 44.54 cm was recorded. Once

9


the board was detected the height of the board was marked and the difference in height

∆Y was measured. Using the properties of a right angle triangle, half of the beam width

was calculated with Equation 2.2.

tan(θ) =Opposite

Adjacent(2.2)

Re-arranging for θ we get:

θ =tan−1(∆Y

∆X

)

θ =tan−1(18.42 cm − 9.21 cm

44.54 cm

)

θ =11.68 cm

(2.3)

47.04 cm

X

Y

9.21 cm

SENSOR

FRONT PLATEBACK PLATE

Figure 2.4: Sensor Beam Angle Schematic

10


Figure 2.5: Sensor Beam Angle Test

The results from the test confirmed that the sensor’s total beam width was 23.72,

which is much lower than the specified value. This allowed considerations to be made into

the sensor mounting angle to ensure that the swimmer is detected.

Sensor Waterproofing Test

The JSN-SR04T sensor was marketed as waterproof/water resistant so to verify this

claim it was subjected to a waterproofing test. The sensor exterior housing was epoxied

and left to dry to emulate its environment in the final product then submerged in 20 cm

of water while a test program was run. The sensor functioned as expected under these

conditions. Subsequently the sensor was left submerged for a total of 1 hour at the depth

of 20 cm before removal for further testing. The sensor performed as intended with no

signs of measurement errors. This exceeded the waterproofing performance metric for the

project.

11

3 DATA LOGGING SYSTEM

3 Data Logging SystemThe data logging system consists of an SD card reader interfaced with the Arduino

Mega microprocessor. The data logger is triggered whenever the sensor detects that a lap

is completed, at which point it stores the lap number and lap time to the SD card. The

SD card can then be removed after the session and the data transferred to a computer for

the user to view.

3.1 SD Card Reader

The data logging subsystem was an optional addition in the main scope of the project.

As such, it did not have design criteria specified in the product requirement statement,

so some criteria were defined. The options were evaluated based on cost, ease of imple-

mentation, storage capacity, and user friendliness. The options for this subsystem were to

either use an SD card and reader, store information on the Arduino’s Electronic Erasable

Programmable Read Only Memory (EEPROM), implement a Wi-Fi module to save data

to a server, or to not implement data storage and just track and display the user’s data

for the session.

3.1.1 Design

Data logging was included because it would drastically improve the project’s function-

ality by allowing the user to track their progress over multiple sessions. Furthermore the

data logging options were relatively inexpensive and easy to implement.

After evaluation, the SD card reader option was chosen over the Wi-Fi module and the

EEPROM storage. The Wi-Fi option would introduce difficulties for the user. It would

have required wireless internet connection in the pool facility which is not always an op-

tion, and it would introduce the added difficulty of connecting it initially. The EEPROM

storage method had the benefits of simplicity and no extra costs, but EEPROM cells can

only be written to a finite number of times before they burn out and cannot be replaced

easily [1]. That user difficulty plus the smaller EEPROM storage capacity led us to choose

the SD card reader option. This decision was made according to the data logger decision

matrix outlined in Table 3.1 below.

12


Table 3.1: Data Logger Decision Matrix

Data Logging Options

Ethernet SD Card No Long-Term EEPROM

Shield Reader Storage

Cost Average Good Exceptional Exceptional

Ease of Implementation Below Average Good Exceptional Exceptional

Storage Capacity Exceptional Good Poor Poor

User Friendliness Below Average Good Poor Average

Sum 12 16 12 15

Rank 3 1 3 2

Decision No Yes No Yes

The SD card reader requires the SPI communication pins on the Arduino Mega board.

The Master In Slave Out (MISO), Master Out Slave In (MOSI), Serial Clock (SCK), and

Chip Select (CS) pins on the card reader were connected to the corresponding SPI pins on

the Arduino Mega.

3.1.2 Performance

The data logging system was unit tested with a basic data logging Arduino program

that was designed to write a series of 20 random numbers in string format to a .csv file.

This was made to emulate the actual data that will be written to memory, as it will be a

time and lap count of similar length in string format. Initially it tested well and stored the

transmitted data onto the 32 GB SD card. However at a later stage when it was being in-

tegrated with the data acquisition and controls systems, corrupted data was being written

to memory.

This necessitated more unit testing so the testing program was again employed with

another SD card reader, another SD card, and the various combinations of these compo-

nents. It was determined that the card reader itself was causing the error and was unable

to initialize properly without corrupting the serial data on the serial monitor. The com-

parison between the card readers can be seen in Figures 3.1a and 3.1b, with the original

card reader’s serial monitor interface shown first in Figure 3.1a and the new card reader’s

performance below in Figure 3.1b.

13


(a) Faulty SD Card Reader Serial Monitor Output

(b) Replacement SD Card Reader Serial Monitor Out-put

Figure 3.1: SD Card Data Writing Unit Testing

14


With the replacement card reader the data logging subsystem was ready to be connected

to the other subsystems of the project. The data logging system can be seen integrated

with the data acquisition system in Figure 3.2.

Figure 3.2: Integrated Data Logging System

15

4 CONTROLS AND MONITORING INTERFACE

4 Controls and Monitoring Inter-face

An LCD and two waterproof buttons were chosen to provide visual data output and

manual control. Upon lap completion, the LCD displays the current lap number as well as

the elapsed time. This feature allows the user to see real time swim data without having

to turn off the device and read the data from the SD card. The two buttons provide start

and stop/reset functionality.

4.1 Display

The display feature has two mandatory features: it needs to be able display the current

lap number and completed lap time, and the display must be visible in a 200-600 lux

environment. The other factors that went into the decision were cost, number of electrical

connections, display output contrast, American Standard Code for Information Interchange

(ASCII) capability and efficiency.

4.1.1 Design

The selection process is outlined in Table 4.1 below. Seven segment displays were

considered but required more power and connections than the LCD, and the thin film

transistor (TFT) LCD is more expensive and displays less information. The LCD with two

rows of 16 characters was selected over the others primarily because of its ASCII capability,

good display contrast, and efficiency. The LCD is connected to the Arduino microcontroller

by six digital pins which send ASCII data to be displayed. A 10 kΩ potentiometer is used

to control the contrast ratio of the LCD. The LCD draws 1.2 mA at 5 V only using 7.2

mW of power which is well within the energy consumption limits.

16


Table 4.1: Display Decision Matrix

Display Options

LCD 2x16 TFT LCD 7 Segment

Cost Good Below Average Good

Connections Good Excellent Average

Display Output Contrast Good Good Excellent

ASCII Capable Excellent Excellent Poor

Efficiency Good Below Average Below Average

Sum 21 18 16

Rank 1 2 3

Result Yes No No

4.1.2 Performance

Display Testing

The display unit test involved running a simple program to display text and verify the

working order of the display. Next the contrast was adjusted in a bright room to ensure

the text would be visible in the 200-600 lux pool environment. The LCD was taken to the

Joyce Fromson Pool at University of Manitoba as part of testing for other components,

where the display visibility was confirmed. This test can be seen in Figure 4.1 below. The

LCD performed as intended and the text was adequately visible from the poolside.

17


Figure 4.1: LCD Display Test at Joyce Fromson Pool

4.2 Controls

Tactile controls are used to allow the user to start and stop/reset the program. The two

buttons used to control these functions need to be waterproof as they will be subjected to

the electrically hazardous pool environment. The controls are inset into the enclosure by

design as outlined in Section 6. This design eliminates some of the ruggedness requirement

as the controls are no longer exposed. The buttons still must have a small form factor to

reduce the size of the peripheral casing and the hole made for it in the enclosure.

4.2.1 Design

There were many buttons on the market that are waterproof, however the limited

enclosure space helped narrow down the choices. The majority of the remaining options

were around equal in cost, functionality, and size, and were all waterproof. The buttons

with a dome shape were selected for their good tactile response and load distribution if

contact was made with them. They were very inexpensive which permitted purchasing

multiple backups for stress and waterproof testing.

18


4.2.2 Performance

Input Testing

To test the selected buttons the exposed soldered leads were first epoxied to simulate

how they will be properly waterproofed in the button casing. Next they were submerged

in a bucket of water at a 10 cm depth. A multimeter was connected to the leads and con-

duction was confirmed when the button was pressed underwater. After passing the initial

test the button was left submerged for 1.5 hours before the conduction was tested again.

The button conducted properly only when the button was depressed. This test setup is

demonstrated in Figures 4.2a and 4.2b.

(a) 0L Indicates No Conduction (b) 0 Indicates Conduction

Figure 4.2: Button Waterproofing Test

4.3 Audible Feedback

An optional addition to the project was to implement audible feedback at the comple-

tion of a lap. This would indicate to the swimmer that the lap was completed and logged.

The purpose of this feature was to allow the swimmer to focus on their technique instead of

tracking their progression every lap. A piezoelectric buzzer was used to provide an audible

tone when the lap was completed.

The main requirement when selecting the buzzer was its Decibel (dB) rating because

19


the tone needed to be audible from underwater. The buzzer that was selected was the

TKD PS1440P02BT buzzer which has a decibel rating of 75 dB [4]. When tested at Joyce

Fromson Pool with a swimmer they were able to hear the tone above and below the water

at the completion of a lap.

20

5 POWER DELIVERY SYSTEM

5 Power Delivery SystemThe power delivery system consists of three parts: the battery, the converter system,

and the battery protection circuit. The power system is designed to be efficient, safe, and

light. The most energy dense battery option, a high efficiency DC-DC converter system,

and protection systems that allow for safe operation of the device were implemented to

achieve these design goals. The following sections will outline the decision making process

behind our design for these systems.

5.1 Battery Considerations

Proper battery design is important because all of the other subsystems rely on the

battery to work, and it can potentially be the most volatile and dangerous aspect. That is

why the battery decision criteria include the safety and stability of the battery, the energy

density (ampacity divided by mass), and the individual cell voltage. The ease of operation

for the user was also considered, as well as the cost. During the design phase it was found

that the system required a significant amount of power and a large battery pack would be

required to meet the active operation time requirement. A large battery pack would make

it difficult to meet the density requirement of ≤0.8 g/cm3.

5.1.1 Design

The batteries considered for this project were Lead-Acid, Nickel-Cadmium (NiCd),

Nickel-Metal Hydride (NiMH), Lithium-Polymer (LiPo), or a series of 8 D cell batteries.

Regarding ampacity, the device needed to achieve an active operation time of 200 hours

and 8000 hours inactive. Initially the design called for disposable D cell batteries but

it became apparent what mass of battery that would require. Equation 5.1 outlines the

minimum ampacity necessary considering the base current requirement of 100 mA for the

Arduino microcontroller with additional components.

100mA x 200 hours = 20000 mAh (5.1)

Each D cell operating at 1.5 volts has approximately 15000 mAh ampacity [5]. Equation

21


5.2 outlines the necessary number of cells to meet our 12 volt system voltage requirement.

12 V (total)

1.5 V (per cell)= 8 D cells (5.2)

At least two of these eight cell packs would be necessary to meet the ampacity require-

ments. Given that the mass of one D cell battery is 135 grams, Equation 5.3 gives the

battery mass required to power the system.

135 g × 8 × 2 = 2160 g (5.3)

Furthermore these calculations are made assuming the current draw is not significantly

larger than the base current requirement of 100 mA. The projected mass of 2.16 kilograms

is more than could be allotted for the batteries. One of the design criteria is that the whole

project has a density less than 0.8 g/cm3 so that it would float on water and this battery

mass would make that very extremely difficult. The overall density calculations are carried

out in Section 6.

The specific energy densities and cell voltages of all battery options are outlined in

Table 5.1. Though we considered D cells to have too low energy density per cell, they

are the second best option in that regard. This led to a revision of the 200 active hours

performance metric with the client.

Table 5.1: Battery Energy Densities and Cell Voltages

Batteries

D Cell Lead Acid NiCd NiMH LiPo

Cell Energy Density (Wh/kg) 154.3 30-50 45-80 60-120 181.8 – 265.3

Cell Voltage (nominal) 1.5 V 2 V 1.2 V 1.2 V 3.3 V

A change in the design was proposed to the client regarding switching to a recharge-

able battery and lowering the active operation time requirement. The client approved the

changes in the design and requirements. At approximately 1 hour per session it was estab-

lished that it is reasonable to have the unit only require charging once every 25 - 30 uses,

so the battery system was redesigned to have a minimum 30 hours active time. An added

benefit is that a rechargeable battery eliminates the expensive and time consuming need

22


to replace disposable batteries regularly.

The Turnigy 3s 5200 mAh LiPo battery was chosen primarily because it offers high

energy density while keeping costs low. It has 5200 mAh capacity, 12.6 V max to 9 V min,

JST-XH and XT60u connectors, and a durable design. The criteria used in this decision

are outlined in Table 5.2 below.

Table 5.2: Battery Decision Matrix

Batteries

D-Cell Lead Acid NiCd NiMH LiPo

Energy Density Good Poor Below Average Average Exceptional

Cell Voltage Below Average Average Poor Poor Good

Safety Good Average Average Average Below Average

Cost Good Below Average Average Average Average

User Friendliness Exceptional Below Average Average Average Below Average

Sum 19 11 12 13 16

Rank 1 5 4 3 2

Result No No No No Yes

The main wires to the battery cells are a 14 American Wire Gauge (AWG) size cable

capable of 5.9 A of power transmission. The smaller wire is a 24 AWG capable of 577 mA

of power transmission [11]. Since our device will only be conducting between 70 mA and

140 mA we will use the smaller 24 AWG wires to connect our circuit.

5.1.2 Performance

Unit testing was done on the battery to determine its amp hour characteristics. The

test shows how much the voltage drops over time as the battery is depleted under the

maximum expected load. The battery discharge test is shown in Figure 5.1 with the BK

Precision Programmable DC Electronic Load 8500 Series test apparatus [9].

23


Figure 5.1: Battery Testing with Electronic Load at 100 mA

The battery was drained for three hours at 100 mA current draw to simulate the device

load. The test returned a plot of battery voltage as a function of capacity. These results

were extrapolated and cross-referenced with the projected battery discharge characteris-

tics to give us an idea of when the voltage will reach the threshold where the battery

protection circuit shuts the device off. The battery started at 11.94 V and finished at

11.85 V. Assuming linear operation, the battery active operation time is approximately

3 hours/0.09V = 33.3 hours/V and the operating voltage range is about 2.6 V therefore

the operating time is roughly 2.6 V × 33.3 hours/V = 86.7 hours.

5.2 DC-DC Converter

The DC-DC converter has the function of receiving the battery voltage and stepping

it down to a stable 5 V output, while protecting the processor from harmful short circuit

(SC) currents and over voltages (OV). The lower voltage is necessary to power the micro-

controller and its subsystems.

There were many important considerations that went into choosing the converter such

as magnitude of the current output and efficiency. As the battery gets depleted there is

some variation in its output voltage, so the range of acceptable input voltages to the con-

verter must be considered. Finally the temperature rating and cost of the converter are

also taken into account.

24


5.2.1 Design

The DC-DC converter is designed to accept input voltages from 9 to 12.6 volts, though

the battery protection circuit will cease operation once the input voltage drops below

10 volts to protect the battery cells. Figure 5.2 below shows the layout of the DC-DC

converter as it accepts a range of input voltages and outputs the requisite 5 volts to power

the Arduino and components.

12-9.5V Input

1a

+

1b

−DC-DC 5V Output

2a

+

2b

−

Figure 5.2: DC-DC Conversion

The simplest option considered for the DC-DC converter was a linear regulator, but

that would have introduced immense losses and reduced the efficiency. A more expensive

converting option was needed to improve the battery lifetime and save on energy costs

in the long run. For this reason a buck converter was implemented. Buck, boost, and

buck-boost converters are highly efficient compared to linear regulators because they are

composed of non-resistive components [8].

The CUI Inc. DC-DC converter proved to be superior to the other options in all ways

except cost, though the cost was still relatively low and certainly justifiable for the benefits

it provided [10]. It has an 88% efficiency which will significantly reduce the energy cost

in the conversion. The device is easily mounted to the enclosure through two small screw

mounting holes. The screw terminal connectors make it easy to connect wires together.

The CUI Inc. DC-DC converter can be seen below in Figure 5.3. The decision matrix used

in this process can be seen in Figure 5.3.

25


Figure 5.3: DC-DC Converter

Table 5.3: DC-DC Converter Decision Matrix

DC-DC Converters

Linear Regulator CUI Inc LTC3703SelfDesign

Input Range Average Exceptional Average Poor

SC, OV protection Average Exceptional Poor Poor

Temperature rating Average Exceptional Exceptional Poor

Efficiency Low Exceptional Average Poor

Current output Low Exceptional Average Average

Cost Exceptional Poor Average Average

Sum 16 26 18 10

Rank 2 1 3 4

Result No Yes No No

Protection is crucial because a LiPo battery is capable of current output in the 1000A

range in the case of a short circuit. If that were to occur, a voltage difference with essen-

tially no resistance can produce enough current to release heat and combust. The CUI Inc.

DC-DC converter offers the short circuit protection necessary to avoid this.

5.2.2 Performance

Unit testing was carried out on the converter to verify its output performance across

the input range by connecting the the converter input to a power supply and measuring

26


the output. The desired 5 V output was observed across an even larger range of input

voltages than expected. The results at 3 different voltages can be observed in Figure 5.4a,

5.4b, and 5.4c below.

(a) DC-DC Converter Testing at 0.7V (b) DC-DC Converter Testing at 8.5V

(c) DC-DC Converter Testing at 13.8V

Figure 5.4: Monitor Images for Various Configurations

Figure 5.4a shows that the output is 0 volts when the input is low. The following two

Figures 5.4b and 5.4c display the experimental upper and lower limits of the input range;

13.8 V and 8.5 V respectively. These test results ensure that the device will work for all

ranges of inputs that we need.

27


These tests proved that the converter would work for the design. The converter could

be safely integrated into the complete design for system integration testing. Because there

is no feasible way of disconnecting the battery from the circuit when the battery voltage

reached 9V, the battery protection circuit was designed to do that.

5.3 Battery Protection Circuit

A battery protection system is necessary for LiPo batteries to prevent the cells from

becoming unbalanced and to stop the voltage from dropping dangerously low. Unbalanced

cells can cause dangerously high currents that would be dangerous to the user and device.

However cell balancing is not the most pressing issue for this application because the data

acquisition by ultrasonic detection device is expected to pull less than 200 mA. A large

current draw can cause more voltage drop on an outer cell than an inner cell and create

imbalance, but at such low currents the cells are self balancing.

Protection against low voltage operation is the concern for this application. If the

voltage drops below 3 V in any cell, it can become damaged. Damage can render the cell

unable to hold a charge, or in the worst case scenario the battery could light on fire or

explode [6][7].

5.3.1 Design

Two systems were designed for low voltage protection. The first method involves mon-

itoring the battery cell voltage using an Arduino analog pin. Arduino software was created

to automatically shut down the circuit if the cell voltage drops below a safety threshold.

The second low voltage protection method is electronically switching the circuit off when

the voltage drops below 10V. This reduces the life cycle of the device but ensures that it

is safe.

Software Voltage Protection

Figure 5.5 shows the connection to the analog input pin on the Arduino Mega via a

JST-XH connector. The connection enables us to monitor one of three cells on the battery,

from which we can determine when to open the circuit. The single cell maximum voltage

is 4.2 V, which is sufficiently lower than the Arduino’s analog input handling voltage. It is

28


possible to monitor all three cells with voltage dividers on the other two, but this would be

unnecessary and inefficient. The low current means the cells will stay balanced so monitor-

ing one is sufficient, and voltage dividers would waste power. By design when the voltage

of the single cell drops below 3V the circuit will be opened.

3.8V

3.8V

3.8V

7.6V

+

−

11.4V

+

−

100 MΩ

100 kΩ

Arduino

A0

Figure 5.5: Software Shutdown Circuit

The only cost to adding this into our system is the minimal energy lost by monitoring

the voltage on the cell. Given that the input resistance to the Arduino on its analog inputs

is 100 MΩ, the current being pulled from the battery to measure the voltage is a mere 50

nA. The software is meant to be the redundant protection system that only is triggered if

the hardware protection system fails.

Hardware Voltage Protection

The hardware voltage protection circuit consists of a Zener diode driving a Metal Oxide

Semiconductor Field Effect Transistor (MOSFET) switch with a fuse in series. When the

battery voltage is above the threshold set by the Zener breakdown voltage and the Gate-

Source Voltage (VGS), the MOSFET will close the circuit and allow conduction through

the load. Below the voltage threshold the MOSFET switch is off and no current will flow

through the load.

29


9 − 12.6V

Fuse

8.2V

+

−

R2

Q1

VGS

1.3V

+

−

Load

Figure 5.6: 9.5V Shut-off Circuit

As seen in Figure 5.6, the cutoff voltage is set at 9.5 V which will trigger before the

software protection at 9 V. The Zener diode requires 8.2 V to breakdown and allow con-

duction to the switch, and the MOSFET requires an additional 1.3 V to trigger the switch.

5.3.2 Performance

To ensure the proper operation of the shutoff circuit it was tested under different supply

voltages. A power supply with variable supply voltage and current limiting was utilized

with a test circuit. This circuit seen in Figure 5.7 used a Light Emitting Diode (LED) and

200 Ω resistor as a load to show what voltage was required to turn the circuit on and off.

The expected cutoff voltage was at 9.5 V.

30


9 − 12.6V

Fuse

8.2V

R2

Q1

Figure 5.7: 9.5V Shut-off Test Circuit

This test setup showed whether the output was on, off, or partially on based on the

LED brightness. The MOSFET’s operation at a low VGS is the reason why the circuit can

be partially on at a certain voltage. In this small region of operation the current flow is

limited instead of being on or off. The off, partially on, and on voltage ranges are shown

below in Figures 5.8a, 5.8b, and 5.8c respectively.

31


(a) Auto Shut-off Testing at 9.4V (b) Auto Shut-off Testing at 9.6V

(c) Auto Shut-off Testing 13.2V

Figure 5.8: Auto Shutoff Testing

The test results highlight the fact that the circuit works as expected in all voltage

ranges. The circuit remains fully off at 9.4 V and is partially on at 9.6, as the LED has

started to get brighter. The LED turned fully on after the input voltage was increased to

10 V. The final picture in Figure 5.8c is of the absolute peak input voltage of 13.2 V to

prove that the battery protection circuit is functional over the full range of voltages. The

positive test results validated the battery protection circuit design and allowed the final

integration and assembly to take place.

32

6 ENCLOSURE

6 EnclosureThe purpose of the enclosure is to contain all of the other components and meet several

crucial design metrics relating to durability, shock-proofing, and waterproofing. The enclo-

sure must allow the user access to the manual controls and give them sight of the display,

and let the ultrasonic sensor sit securely on the exterior at the desired angle. Subsections

of the enclosure include the enclosure base design, mounting of the components within the

enclosure, and peripheral casings for the user interaction components.

6.1 Physical and Display Considerations

The enclosure is required to satisfy several of the performance metrics relating to the

physical durability and size of the project. The enclosure has to be shockproof for a 1

meter drop test and water resistant at a 10 cm depth for 1 hour. It is required to have

dimensions no larger than 10.5 x 20.5 x 30.5 cm, a maximum mass of 1300 grams, and

density lower than 0.8 g/cm3 so that it will float. Furthermore it is necessary for an LCD

display to either be visible through the case or mounted and waterproofed on the outside.

6.1.1 Design

The initial base design for the enclosure was to 3D print an enclosure in pieces and

epoxy it together to waterproof it. However this would make it difficult to view the LCD

display as the 3D printed material is opaque, thus requiring some difficult waterproofing.

Another option considered early on was to build the case out of cut Plexiglas pieces that

would be secured together and waterproofed with epoxy. However this introduced more

problems with shock-proofing the case itself and the components inside, as it would be

difficult to mount them securely.

There were case options from OKW Enclosures and Serpac Enclosures that fit the size,

waterproofing and shock proofing requirements. Both options fit all of the requirements

and would make mounting easier. The OKW enclosure was chosen because the company

offered to send a free model for testing, thus eliminating the budget constraints. The de-

cision process is outlined in Table 6.1 below.

33

6 ENCLOSURE

Table 6.1: Enclosure Decision Matrix

Enclosures

OKW 3D Printed Plexiglass Serpac 193RC

Availability Average Good Good Average

Cost Exceptional Good Good Poor

Waterproof Exceptional Average Average Exceptional

Shock proof Exceptional Average Below Average Exceptional

Transparency Exceptional Poor Exceptional Exceptional

Sum 23 15 18 19

Rank 1 4 3 2

Decision Yes No No No

All cases considered would also meet the density requirement of less than 0.8 g/cm3

(less than water). The main component contributing to the weight of the project is the

battery, which only weighs 436 grams. The Arduino Mega weighs 37 grams. Erring on the

side of caution the other electrical/mounting components were estimated to be significantly

less than 500 grams. As shown in Equation 6.1 and Equation 6.2 even if the enclosure is

only half of the allotted 6565.125 cm3 in volume, the case would need to be more than 1.65

kg for it to be too dense to float.

0.8 g/cm3 =436 g + 37 g + 500 g + Enclosure Mass

6565.125 cm3/2(6.1)

Enclosure Mass =1653 g (6.2)

The 3D printed or Plexiglas enclosures could have been designed large enough within

the space restrictions to meet the density requirement easily. The OKW enclosure that

we chose was 602.9 grams and has dimensions 25.2x16.2x9 centimeters which gives 3674.16

cm3 volume [12]. As shown in Equation 6.3, its approximate density is 0.4265 g/cm3 which

is well below the requirement.

34

6 ENCLOSURE

Density =427 g + 37 g + 500 g + 602.9 g

3674.16 cm3= 0.4265 g/cm3 < 0.8 g/cm3 (6.3)

6.1.2 Performance

The performance of the base enclosure was assessed through some early unit tests;

specifically a waterproofing test shown in Figure 6.1 and a 1 meter drop test in Figure 6.2.

The enclosure passed the drop test showing no signs of damage.

The waterproofing test was carried out by weighing the enclosure down and leaving it

underwater for 1 hour with paper towels inside to indicate leakage. Upon opening it again,

there was only some slight indication of water on one edge. However the exterior of the

case was only lightly dried off before opening it and that edge was in the direction that

the lid was tilted to when opening the case. It is believed that opening the case was the

cause of the moisture there and that the enclosure passed the waterproofing test.

Figure 6.1: Initial Waterproofing Test

35

6 ENCLOSURE

Figure 6.2: 1 m Drop Test

6.2 Mounting

To ensure the components inside the enclosure are shock-proofed and secure, the mount-

ing design had to be considered. The OKW enclosure had multiple mounting standoffs

designed for a back plate. To save costs and shipping time a back plate was constructed

out of Medium-Density Fiberboard (MDF). OKW Enclosures were able to provide the

AutoCAD drawings in Figure 6.3 detailing the interior of the case and standoff locations

for back plate design and construction. The back plate offers a location to securely mount

the microcontroller, battery, DC-DC converter and battery protection circuit.

36

6 ENCLOSURE

Figure 6.3: Internal Case Dimensions

To refine the design and improve the aesthetics, a top plate was made to mount the

LCD, piezoelectric buzzer, and SD card reader, as well as to hide the wires and electronics

below. Mounting across two layers made more efficient use of the space which was already

restricted by the client’s specifications. To separate the two plates, 1-1/2” standoffs were

used. The integrated top and bottom plates can be seen in Figure 6.4 below.

37

6 ENCLOSURE

Figure 6.4: Mounting Top and Back Plates

6.3 Peripheral Casings

A challenge that the project faced was to successfully waterproof the entire enclosure

yet still allow the user to control it with two buttons to start and stop it and a power switch

to turn it on and off. These requirements meant that it was necessary to find waterproof

button and switch components, and also find a way to attach them on the outside of the

enclosure where they will not compromise the waterproofing. The same issue applied to

the ultrasonic sensor, because it cannot produce useful data through the enclosure.

6.3.1 Design

The first plan for this issue was to drill and cut holes for the buttons, switch, and sensor

into the case and secure them in place with epoxy that would waterproof the edges. The

problem with this is the low precision cuts that would be made. Precision is necessary, as

the outer lip of the circular buttons (meant to spread onto the outside of the enclosure)

has a diameter of only 19 mm, and the diameter of the inner section is 18 mm. Using a

circular drill bit would not return a ≤1 mm precision, and the button would likely not fit

38

6 ENCLOSURE

at all or fall through the hole.

This led to 3D modeling the peripheral casings as a solution. The 3D modeling and

printing offered very high precision to make sure the buttons, switch, and sensor would fit

tight in the casing and make waterproofing easier. Then a larger hole could be cut in the

enclosure for the casing to fit into, and could be made watertight by designing the lip of

the casing to protrude further out over the enclosure.

3D printing the casings made it easy to achieve a precise 12 angle for the sensor to

be mounted at. This angle was necessary to reliably detect the swimmer and this was

achieved in the 3D design.

Figure 6.5: SOLIDWORKS Button Case Design

39

6 ENCLOSURE

Figure 6.6: SOLIDWORKS Sensor Case Design

6.3.2 Performance

The models were made in SOLIDWORKS and printed with the UMIEEE lab 3D printer.

The holes for the peripheral casings were cut with the help of the University of Manitoba

Engineering Machine Shop. The peripheral casings secured to the enclosure can be seen

below in Figure 6.7.

Figure 6.7: Integrated Button and Sensor Casings

40

7 SYSTEM INTEGRATION

7 Integration and AssemblyAfter the completion of prototyping and unit testing, final integration and assembly of

the data acquisition by ultrasonic detection device could take place. The product needed

to be waterproof, durable, buoyant, and compact. These specifications guided the final

integration and assembly.

7.1 Peripheral Electrical Systems Integration

The electrical subsystems required a method of integration that kept them secure from

physical jarring within the enclosure. The electrical tolerances of the integration method

had to be taken into account, as well as the space it would require.

7.1.1 Design

Secure connection of all peripheral devices was the most vital design criteria in the final

electrical system integration. Assembling the electrical components on a PCB would save

space and reduce the electrical tolerances, and the soldered connections would be more

secure than jumper cables. However there was limited experience in PCB design among

the team members and long PCB shipping times meant that any mistakes could take weeks

to right. Simply connecting the electrical subsystems with jumper wires would not meet

the durability and shock-proofing requirements, so the decision was made to assemble the

electrical components on a custom Arduino shield.

The Arduino Mega shield integrates smoothly with the microcontroller headers and

give the flexibility to create more secure headers for the peripheral devices. Headers were

soldered to make connections between the shield and the Arduino Mega microcontroller.

The shield provides connections for the two buttons, LCD Display, buzzer, SD Card reader,

ultrasonic sensor, and battery monitoring input.

Male pin headers were soldered to the shield in order to make secure connection but still

allow for easy removal if a component malfunctions. A wiring diagram was created as seen

in Figure 7.1 to provide routing and soldering of microcontroller to header connections.

The final construction and integration of the shield can be seen in Figure 7.2 below.

41


Figure 7.1: Shield Wiring Diagram

n 5V Power n Ground n Signal

Figure 7.2: Final Shield Construction and Peripheral Integration

42


7.1.2 Performance

Once the peripherals were integrated with the Arduino Mega shield they needed to be

tested together. The final compiled code was uploaded to the system and the program

was ran. The buttons responded properly by starting and stopping/resetting the program.

The LCD displayed the distance measured from the sensor, and when a lap was detected

the SD card was successfully written to with the current lap number and time.

To finalize the lap detection, the device was taken to Joyce Fromson Pool where trials

were run. The detection range was set at 25-27 cm and increased until no lap detection

was missed over 10 measurements. We found the minimum detection range to be 25-31

cm. This test data can be seen in Table 7.1 below where ’X’ indicates a missed lap and,

’ ’ indicates a lap detected. This confirmed that the detection range set at 25-35 cm will

perform as needed.

Table 7.1: Lap Detection Test Data

Lap

Detection Range (cm) 1 2 3 4 5 6 7 8 9 10

25-27 X X X X X X X

25-28 X X X X X X

25-29 X X X X

25-30 X X

25-31

7.2 Power Delivery Integration

After the peripheral electrical systems were successfully integrated with each other,

the next step was to power them with the power delivery system instead of a computer.

First the rechargeable battery was interfaced with the DC-DC converter and the battery

protection circuit. After verification that the system was producing the desired voltage, it

was connected to the microcontroller.

A JST-XH connector was used to link up the battery with the protection circuit. This

connector was chosen with the user in mind because it allows the user to disconnect and

reconnect the battery easily for charging. Wires were securely soldered across the micro-

43


processor shield and the battery secured to the enclosure back plate with Velcro tape to

satisfy the shock-proofing requirements. The DC-DC converter’s mounting holes and wood

screws were utilized to secure it to the enclosure. Epoxy was used for mechanical support

at wire connection points.

The completed prototype circuit shown in Figure 7.2 was made to test the power

delivery system while integrated into the full system. The integrated system worked as

expected and these test results paved the way to the final assembly with the enclosure.

7.3 Assembly

Assembly of the final product began by epoxying the button housing and sensor housing

to the case in the gaps machined out for them. The sensor and buttons were then fed

through and epoxied in place to ensure a water tight fit. Following this the back plate was

mounted to the enclosure. The microcontroller, the DC-DC converter with the battery

protection circuit, and the LiPo battery were then mounted to the back plate with mounting

screws and Velcro tape. The LCD and the buzzer were mounted to the top side of the

top plate, while the SD card reader was secured to its underside. All of the electrical

connections were made from the peripherals to the microcontroller before the top plate

was attached to the bottom plate with the 1-1/2 inch board spacers. With everything

mounted to the interior, the clear enclosure top half was screwed to the bottom half to

complete the assembly and prepare for the final performance tests. The final assembled

build can be seen below in Figure 7.3.

Figure 7.3: Final Construction of the Swimmer’s Data Acquisition System

44


7.3.1 Performance

The final two tests that needed to be done were a drop test and a waterproofing test.

The drop test was performed to ensure the enclosure and the mounting of the components

could withstand a fall from 1 m height. The waterproofing test had the enclosure sub-

merged in 20 cm of water for 1 hour to test that the enclosure and the peripheral casings

were properly sealed.

Drop Test

For the final drop test the project’s electronics were removed to make sure they would

not be damaged if the test failed. However the mounts and connections for those compo-

nents were what needed to be tested, so they were replaced with stand-ins that resembled

the parts as closely as possible. A broken microcontroller with the same mounting hole spac-

ings was used in place of the Arduino Mega, and various other components were mounted

using the same methods the real components would use. The drop test was carried out on

all faces and corners of the enclosure. At the completion of the test the enclosure and com-

ponents showed no signs of damage or stress which validated it for the final waterproofing

test.

Final Waterproofing

After the drop test the stand-in internal components were left in place for the final

waterproofing test. This test would serve a second purpose of doubly verifying the previous

drop test by indicating small cracks with water leakage. The enclosure was stuffed with

paper towel to indicate leaks, before being submerged 20 cm below water level in a tub for

1 hour. When the enclosure was removed it was examined and returned no signs of leakage

externally. After drying the exterior and examining the interior paper towel padding, there

was again no sign of water penetration so the waterproofing of the enclosure was confirmed.

45

8 CONCLUSIONS

8 ConclusionThe purpose of this project was to design and build a functional swimmer’s data acqui-

sition device to track and log a swimmer’s progress over multiple sessions. The following

section highlights the outcomes and achievements made in this regard, and presents areas

where future work can be done to build on the project.

8.1 Project Outcome

In short, the goal of designing and building a functional swimming lap counter has been

achieved. The device meets or exceeds the design specifications laid out at the beginning of

the project. The device tracks the swimmer in the 20 to 154 cm range, interprets the track-

ing information and writes it to a removable SD card via SPI communication. A functional

user interface with buttons, switches, and displays was implemented and the processing

done by an Arduino microcontroller programmed in C/C++. Power was safely supplied

to all of the subsystems from a rechargeable LiPo battery and the enclosure waterproofed

and shock-proofed to tolerate the device’s environment.

Some design changes were made throughout the project’s duration but were dealt with

accordingly. Limitations on the battery life/overall mass and density parameters were

found. A major change to the design was made by switching from higher capacity dis-

posable batteries to rechargeable batteries which improved the design in many ways and

allowed the other design parameters to be met.

8.2 Future Developments

Improvements can be made to this design in several areas including the implementation

of Radio Frequency Identification (RFID), compressing the size, and improving the look

and feel. With a larger budget adding RFID capabilities would allow multiple swimmers

to track their progress at the same time in the same lane. This feature would require

more design into the user controls to start/stop tracking for multiple users and create the

necessity for active electronic devices on each user for identification. Using more energy

efficient components or smaller batteries, or compressing the electronics to a PCB would

maintain the same functionality while compressing the size of the unit.

46

9 Bibliography

References[1] ATmega640/V-1280/V-1281/V-2560/V-2561/V, Atmel Corporation, Datasheet, 2014.

[2] (2016). Ultrasonic Module JSN-SR04T Distance Measuring Transducer Sen-

sor, [Online]. Available:http://www.icstation.com/ultrasonic-module-sr04t-distance-

measuring-transducer-sensor-p-5046.html.

[3] S. Ramo, J. R. Whinnery, and T. V. Duzer, in Fields and Waves in Communication

Electronics. Hoboken, NJ: J. Wiley, 1993.

[4] Piezoelectronic Buzzers PS Series, TKD, Datasheet, May 2011.

[5] Duracell Copper Top Alkaline-Manganese Dioxide Battery, Duracell Batteries,

Datasheet.

[6] Microelectronic Circuits, A.S. Sedra and K.C. Smith, Oxford University Press, 7th

edition

[7] Basic Engineering Circuit Analysis, J. David Irwin and R. Mark Nelms, 11th Edition,

Wiley, 2015.

[8] Power Electronics, Daniel Hart, 2nd edition, McGraw-Hill, 2011. ISBN: 0073380679

[9] BK Precision , User Manual 8500 SERIES DC ELECTRONIC LOADS,

User Manual, Published in China, China, viewed 12 March 2017, https :

//bkpmedia.s3.amazonaws.com/downloads/manuals/en− us/85xxmanual.pdf .

[10] CUI inc , DC-DC CONVERTER, Datasheet, Published in USA, Tualatin, OR, viewed

16 March 2017, http : //www.cui.com/product/resource/pyb10 − t.pdf .

[11] Solaris, American Wire Gauge AWG Standards, Datasheet,

Published in USA, 1501 W Tufts Ave Suite 208 Englewood,

CO 80110, viewed 17 March 2017, https : //www.solaris −shop.com/content/American%20Wire%20Gauge%20Conductor%20Size%20Table.pdf .

[12] (2017) C7025084 In-Box, OKW Enclosures Inc. [Online]. Available:

https://www.okwenclosures.com/en/In-Box/C7025084.htm?var=afaebd21-c2e5-

11e2-8e2c-0050568225d7.

47

Appendix

A Appendix - Battery Test

Figure A.1: Battery Test Data

48

Appendix

B Appendix - Arduino Mega Schematic

3x2

M

+5V

GN

D

+5V

GN

D

8x1

F-H

8.5

GN

D

+5V

GN

D

47u

47u

GN

DG

ND

GND

GN

D

GR

EE

N

GND

+5V

M7

GN

D

NC

P111

7S

T50T

3G

100nG

ND

100n

100n

8x1

F-H

8.5

8x1

F-H

8.5

+3V

3

+5V

+5V

AT

ME

GA

2560-1

6A

U

100n

100n8

x1F

-H8.5

22p +

5V

GN

D

100n

GN

D

1u

YE

LLO

W

YE

LLO

W

US

B-B

_T

H

MF

-MS

MF

050-2

500m

A

+5V

100n

GN

D

YE

LLO

W

GND

100n

FD

N340P

GN

D

100n

GN

D

+5V

100n

+5V

GN

D

1u

+5V

AT

ME

GA

16U

2-M

U

3x2

M

+5V

GN

D

GN

D

GN

D

BLM

21

CG0603MLC-05E

CG0603MLC-05E

CS

TC

E16M

0V

53-R

0 1

6M

HZ

GND

1M

1k

1k

1k

1k

10K

10K

10K10K

10K

10K

10K

10K

1k

1k

1k

1k

22R

22R

22R

22R

TS

42031-1

60R

-TR

-7260

1M

GN

D

16MHz

22p 22p

GND

2x2M - NM

LM

V358ID

GK

R

LM

V358ID

GK

R

CD1206-S01575

18x2

F-H

8.5

+5V GND

10x1

F-H

8.5

8x1

F-H

8.5

CD1206-S01575

ICS

P1

23

45

6

1 2 3 4 5 6 7 8

PW

ML

PC

1P

C2

ON

D1

11

22

33

1

IN3

OU

T42

IC1

C3

C6

C2

1 2 3 4 5 6 7 8

AD

CL

1 2 3 4 5 6 7 8

CO

MM

UN

ICA

TIO

N

GN

DG

ND

GN

D

VC

CV

CC

VC

C

(A8

)PC

05

3(A

9)P

C1

54

(A1

0)P

C2

55

(A11

)PC

35

6(A

12

)PC

45

7(A

13

)PC

55

8(A

14

)PC

65

9(A

15

)PC

76

0

(AD

0)P

A0

78

(AD

1)P

A1

77

(AD

2)P

A2

76

(AD

3)P

A3

75

(AD

4)P

A4

74

(AD

5)P

A5

73

(AD

6)P

A6

72

(AD

7)P

A7

71

(AD

C0

)PF

09

7(A

DC

1)P

F1

96

(AD

C2

)PF

29

5(A

DC

3)P

F3

94

(AD

C4

/TC

K)P

F4

93

(AD

C5

/TM

S)P

F5

92

(AD

C6

/TD

O)P

F6

91

(AD

C7

/TD

I)PF

79

0

(AL

E)P

G2

70

(CL

KO

/ICP

3/IN

T7

)PE

79

(ICP

1)P

D4

47

(MIS

O/P

CIN

T3

)PB

32

2

(MO

SI/P

CIN

T2

)PB

22

1

(OC

0A

/OC

1C

/PC

INT

7)P

B7

26

(OC

0B

)PG

51

(OC

1A

/PC

INT

5)P

B5

24

(OC

1B

/PC

INT

6)P

B6

25

(OC

2A

/PC

INT

4)P

B4

23

(OC

3A

/AIN

1)P

E3

5(O

C3

B/IN

T4

)PE

46

(OC

3C

/INT

5)P

E5

7

(RD

)PG

15

2

(RX

D0

/PC

IN8

)PE

02

(RX

D1

/INT

2)P

D2

45

(SC

K/P

CIN

T1

)PB

12

0

(SC

L/IN

T0

)PD

04

3(S

DA

/INT

1)P

D1

44

(SS

/PC

INT

0)P

B0

19

(T0

)PD

75

0

(T1

)PD

64

9

(T3

/INT

6)P

E6

8

(TO

SC

1)P

G4

29

(TO

SC

2)P

G3

28

(TX

D0

)PE

13

(TX

D1

/INT

3)P

D3

46

(WR

)PG

05

1

(XC

K0

/AIN

0)P

E2

4

(XC

K1

)PD

54

8

AG

ND

99

AR

EF

98

AV

CC

10

0

GN

D113

26

28

1

PH

0(R

XD

2)

12

PH

1(T

XD

2)

13

PH

2(X

CK

2)

14

PH

3(O

C4

A)

15

PH

4(O

C4

B)

16

PH

5(O

C4

C)

17

PH

6(O

C2

B)

18

PH

7(T

4)

27

PJ0

(RX

D3

/PC

INT

9)

63

PJ1

(TX

D3

/PC

INT

10

)6

4P

J2(X

CK

3/P

CIN

T11

)6

5P

J3(P

CIN

T1

2)

66

PJ4

(PC

INT

13

)6

7P

J5(P

CIN

T1

4)

68

PJ6

(PC

INT

15

)6

9P

J77

9

PK

0(A

DC

8/P

CIN

T1

6)

89

PK

1(A

DC

9/P

CIN

T1

7)

88

PK

2(A

DC

10

/PC

INT

18

)8

7P

K3

(AD

C11

/PC

INT

19

)8

6P

K4

(AD

C1

2/P

CIN

T2

0)

85

PK

5(A

DC

13

/PC

INT

21

)8

4P

K6

(AD

C1

4/P

CIN

T2

2)

83

PK

7(A

DC

15

/PC

INT

23

)8

2

PL

0(IC

P4

)3

5P

L1

(ICP

5)

36

PL

2(T

5)

37

PL

3(O

C5

A)

38

PL

4(O

C5

B)

39

PL

5(O

C5

C)

40

PL

64

1P

L7

42

RE

SE

T3

0

VC

C1

03

16

18

0

XTA

L1

34

XTA

L2

33

IC3

C5

C4

1 2 3 4 5 6 7 8

AD

CH

C1

C8

C13

RX

TX

X2

1234

P$1P$1

P$2P$2

F1

C9

L

C7

T1

C12

C11

21RE

SE

T-E

N

C10

IC4

(AIN

0/IN

T1

)PD

17

(AIN

2/P

CIN

T11

)PC

25

(CT

S/H

WB

/AIN

6/T

O/IN

T7

)PD

71

3

(INT

4/IC

P1

/CL

K0

)PC

72

2

(INT

5/A

IN3

)PD

41

0

(OC

0B

/INT

0)P

D0

6

(OC

1A

/PC

INT

8)P

C6

23

(PC

INT

5)P

B5

19

(PC

INT

6)P

B6

20

(PC

INT

7/O

C0

A/O

C1

C)P

B7

21

(PC

INT

9/O

C1

B)P

C5

25

(PC

INT

10

)PC

42

6

(PD

0/M

ISO

/PC

INT

3)P

B3

17

(PD

I/MO

SI/P

CIN

T2

)PB

21

6

(RT

S/A

IN5

/INT

6)P

D6

12

(RX

D1

/AIN

1/IN

T2

)PD

28

(SC

LK

/PC

INT

1)P

B1

15

(SS

/PC

INT

0)P

B0

14

(T1

/PC

INT

4)P

B4

18

(TX

D1

/INT

3)P

D3

9

(XC

K/A

IN4

/PC

INT

12

)PD

511

AV

CC

32

D+

29

D-

30

GN

D3

PA

D3

3

RE

SE

T(P

C1

/DW

)2

4

UC

AP

27

UG

ND

28

UV

CC

31

VC

C4

XTA

L1

1

XTA

L2

(PC

0)

2

ICS

P1

12

34

56

L1

Z1

Z2

21GR

OU

ND

Y1

R1

RN

4A

18

RN

4B

27

RN

4C

36

RN

4D

45

RN5A

1 8

RN5B27

RN5C

3 6

RN5D

4 5

RN

1A

18

RN1B

2 7

RN1C

3 6

RN

1D

45

RN

3A

18

RN

3B2

7

36

RN

3C

4 5

RN3D

RN

2A1

8

RN

2B

27

RN

2C

36

RN

2D4

5

RE

SE

T

1 23 4

5

R2

IN1

ON

/OF

F3

NC

/FB

4

OU

T5

GN

D2

Y2

2 1

C14 C15

JP5

1 23 4

IC7A

2 31

IC7B

6 57

84

D3

XIO

12

34

56

78

91

011

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

JP

61234567891

0

12345678

PO

WE

R

D2

+5V

+5V

GN

DA

RE

F

AR

EF

AR

EF

RE

SE

T

RE

SE

T

RE

SE

T

RE

SE

T

RE

SE

T

VIN

VIN

VIN

M8R

XD

M8R

XD

M8T

XD

M8T

XD

PW

RIN

AD

C0

AD

C2

AD

C1

AD

C3

AD

C4

AD

C5

AD

C6

AD

C7

+3V

3

+3V3

+3V

3

SD

A

SD

A

SD

A

SC

L

SC

L

SC

L

AD

C9

AD

C8

AD

C10

AD

C11

AD

C12

AD

C13

AD

C14

AD

C15

PB

3

PB

3

PB

3

PB

2

PB

2

PB

2

PB

1

PB

1

PB

1

PB

5P

B4

PE

5

PE

5P

E4

PE

4P

E3

PE

3

PE

1P

E1

PE

1

PE

0P

E0

PE

0

DT

R

US

BV

CC

US

BV

CC

US

BV

CC

GA

TE

_C

MD

CM

P

PB

6

PH

3

PH

3

PH

4

PH

4

PH

5

PH

5

PH

6

PH

6

PG

5

PG

5 RX

D1

TX

D1

RX

D2

RX

D2

RX

D3

RX

D3

TX

D2

TX

D2

TX

D3

TX

D3

PC

0

PC

0

PC

1

PC

1

PC

2

PC

2

PC

3

PC

3

PC

4

PC

4

PC

5

PC

5

PC

6

PC

6

PC

7

PC

7

PB

0

PB

0

PG

0

PG

0

PG

1

PG

1

PG

2

PG

2

PD

7P

D7

PA

0

PA

0

PA

1

PA

1

PA

2

PA

2

PA

3

PA

3

PA

4

PA

4

PA

5

PA

5

PA

6

PA

6

PA

7

PA

7P

L0

PL0

PL1

PL1

PL2

PL2

PL3

PL3

PL4

PL4

PL5

PL5

PL6

PL6

PL7

PL7

PB

7

VU

CA

P

RD

-

RD

-

RD

+

RD

+

RE

SE

T2

RE

SE

T2

MIS

O2

MIS

O2

MO

SI2

MO

SI2

SC

K2

SC

K2

XV

CC

RX

LT

XL

D-

D+

UGND

UG

ND

USHIELD

XTA

L2

XTA

L1

XTA

L1

XT

2

XT

1

8PB78PB6

8PB58PB4

L13

+

+

X1

PO

WE

RS

UP

PLY

_D

C21M

MX

USB

0 1 2 3 4 5 6 7

8 9 10

11 12

13

Ard

uin

o M

EG

A 2

560

15

16

17

18

19

20

21

14

(SC

K)

(MIS

O)

(MO

SI)

pw

mpw

mpw

mpw

m

pw

mpw

mpw

m

pw

mpw

mpw

mpw

mpw

m

pw

mpw

mpw

m

(TX

0)

(RX

0)

51

52

53

pw

mpw

m

pw

m

pw

mpw

m

(MIS

O)

(SC

K)

(MO

SI)

(SS

)(M

OS

I)(S

CK

)(M

ISO

)

22

23

24

25

26

27

28

29

30

32

34

36

31

33

35

37

49

47

45

43

41

39

50

48

46

44

42

40

38

pw

mpw

mpw

m

USB boot En

TM

Refe

rence D

esig

ns A

RE

PR

OV

IDE

D "A

S IS

" AN

D "W

ITH

ALL F

AU

LTS

. Ard

uin

o D

ISC

LA

IMS

ALL O

TH

ER

WA

RR

AN

TIE

S, E

XP

RE

SS

OR

IMP

LIE

D,

Ard

uin

o m

ay m

ake c

hang

es to

specific

atio

ns a

nd p

roduct d

escrip

tions a

t any tim

e, w

ithout n

otic

e. T

he C

usto

mer m

ust n

ot

RE

GA

RD

ING

PR

OD

UC

TS

, INC

LU

DIN

G B

UT

NO

T L

IMIT

ED

TO

, AN

Y IM

PLIE

D W

AR

RA

NT

IES

OF

ME

RC

HA

NTA

BIL

ITY

OR

FIT

NE

SS

FO

R A

PA

RT

ICU

LA

R P

UR

PO

SE

rely o

n th

e a

bsence o

r chara

cte

ristic

s o

f any fe

atu

res o

r instru

ctio

ns m

ark

ed "re

serve

d" o

r "undefin

ed." A

rduin

o re

serve

sth

ese fo

r futu

re d

efin

ition a

nd s

hall h

ave

no re

sponsib

ility whats

oeve

r for c

onflic

ts o

r incom

patib

ilities a

risin

g fro

m fu

ture

chang

es to

them

.T

he p

roduct in

form

atio

n o

n th

e W

eb S

ite o

r Mate

rials

is s

ubje

ct to

chang

e w

ithout n

otic

e. D

o n

ot fin

alize

a d

esig

n w

ith th

is in

form

atio

n.

AR

DU

INO

is a

reg

iste

red

trad

em

ark

.

Figure B.2: Arduino Mega Schematic

49

Appendix

C Appendix - Enclosure Dimen-sions

252,00

162,00

R5,00

59,30 30,00

90,00

135,00162,00

225,00252,00

R5,00

R3,00

18,40223,00245,00

74,00114,00154,00190,50212,00238,00

117,00155,00

40,0075,00128,00130,00136,00

128,60

75,00

A

A

B

B

Unterteil Innenansicht

Base part inside view

7,00 74,70

1,20

3,404,00

15,008,00

A-A

0,401,30

4,507,75

4,00

B-B

220,00242,00

114,00152,00

Oberteil Innenansicht

Top part inside view

224,65

134,65

R3,00

FolientastaturM

embrane keyboard

+0

+0

220,50

152,50

212,00

128,00

4,20

R10,50

147,00

115,00

243,00

Platine U

nterteilP

CB

base part

M 1:1.5

152,50128,00

147,00

220,50212,00

4,20R10,50

Montageplatte

Mounting plate

2.5mm

dickthickness 2.5m

m

ML

87654321

ML

KJ

HG

FE

DC

BA

KJ

HG

FE

DC

BA

87654321

ENTWICKLUNG

Technische Änderungen vorbehalten. Irrtümer oder Druckfehlerbegründen keinen Anspruch auf Schadenersatz. W

ichtige Ein-baumaße bitte direkt mit dem aktuellen Produkt abstimmen.Subject to technical modification without prior notice. Typogra-phical and other errors do not justify any claim for damages. Alldimensions should be verified using an actual moulded part.Sous reserve de modifications techniques. Toute erreur ou fauted'impression ne justife aucune demande d'indemnisation. Nousprions les clients de verifer les dimensions des composants avecles boitiers avant le montage.

Informationskopie

wird nicht aktualisiert

Copy for Inform

ationw

ill not be updated

1:1

DIN 6 Teil 2

M00013957Dateinam

e:

Status:

KUNDEZeichnungsart:

Toleranzen:

Volumen:

DIN 16901 T13001.08.2012

01 D. Hasselbach

252 x 162 x 90C702508*

IN-BOX

Erst. von:

Freig. von:

Erst. am:

Freig. am:

Revision:

not be reproduced or copied and not be used or incorporated in any product.and is tendered subject to the conditions that the inform

ation be retained in confidence

Für dieses Dokument behalten wir uns alle Urheberrechte vor. Es darf auch auszugs-

weise weder vervielfältigt noch Dritten in irgendeiner Form zugänglich gem

acht werden.

This document contains proprietary inform

ation of OKW

Gehäusesystem

e Gm

bH

D

1

C

Figure C.3: Enclosure Dimensions

50

Appendix

D Appendix - Peripherals Pin As-signment Table

0 GND GND GND Button1(S/S) Pin341 5V MISO 50 GND2 20kPot SCK 52 Button2(Reset) Pin363 Pin32 MOSI 51 GND4 GND CS 535 Pin30 5V 5V Buzzer Pin36 - 3V3 3V3 GND7 - GND -8 - DigitalPinsUsed 4 VoltReadout Pin19 - AnalogPinsUsed 0 Control Pin3810 Pin28 PWMPinsUsed 011 Pin26 GND GND12 Pin24 Echo Pin713 Pin22 Trig Pin3814 5V 5V 5V15 GND DigitalPinsUsed 4

DigitalPinsUsed 6 AnalogPinsUsed 1AnalogPinsUsed 0 PWMPinsUsed 1PWMPinsUsed 0

PeripheralsPinAssignmentTable

ExternalPowerPinAssignment

BuzzerPinAssignment

SensorPinAssignment

LCDPinAssignment SDCardPinAssignment ButtonPinAssignment

Figure D.4: Peripherals Pin Assignment Table

51

University of Manitoba Department of Electrical & Computer...

Documents

Transcript of University of Manitoba Department of Electrical & Computer...