Weather Balloon Instrumentation Data Recorder
Christopher Jensen
Scott Aguilar
Kevin Grant
04 May 2012
____________________________________________________________________
Instructor Approval
Dr. Don Cripps
Department of Electrical Engineering
Utah State University
____________________________________________________________________
Sponsor Approval
Garrett Wheeler
Physics Master Student
Utah State University
Acknowledgements
We would like to thank Garrett Wheeler and Shane Larsen for working so close
with us on this project. Ensure potential physics students with an opportunity to conduct
real world atmospheric experiments.
We would like to thank Badger Screen Printing for using their screen printer to
make our design more professional.
We would also like to thank Dr. Cripps for giving us this opportunity to stretch
ourselves. To expand our knowledge of working with microcontrollers, configuring SD
cards, and the opportunity to expand our horizons.
i
Abstract
This report outlines the design of a data logger for a weather balloon. The data
recorder provides power to the various sensors as well as record the data on an SD
card that is inserted into the data logger. The readings can then be pulled off of the
card onto a computer for analysis and calculation.
This will be a tool for the physics department to conduct atmospheric
experiments and encourage potential physicists into the physics department at Utah
State University.
ii
Table of Contents
1
2
3
4
5
6
7
Introduction or Background ................................................................................................. 1
Review of Conceptual and Preliminary Design .................................................................... 2
2.1
Problem Analysis ......................................................................................................... 2
2.2
Decision Analysis ......................................................................................................... 4
Basic Solution Description .................................................................................................. 5
Design of System Components and Performance Optimization .......................................... 6
4.1
Description of components and their component-level specifications ........................... 6
4.2
Design criteria used ..................................................................................................... 7
4.3
Discussion of the technical approach used .................................................................. 8
4.4
Discussion of design details ......................................................................................... 9
4.5
Presentation and discussion of engineering drawings and schematics .......................10
4.6
Fabrication, construction, or production instructions and specifications.......................13
4.7
Summary of the final design results ............................................................................13
4.8
Performance evaluation ..............................................................................................13
Project Implementation/Operation and Assessment ...........................................................14
5.1
Details of implementation ............................................................................................14
5.2
Operational test results ...............................................................................................14
5.3
Evaluation of results relative to design criteria ............................................................15
5.4
What changes are suggested by design results ..........................................................15
Final Scope of Work Statement..........................................................................................15
6.1
Summarize what has been done .................................................................................15
6.2
Lessons learned and suggestions for future activities .................................................16
6.3
Describe any special details of the design that only you would know ..........................16
Other Issues ......................................................................................................................17
7.1
Material selection ........................................................................................................17
7.1.1
Microcontroller Selection ......................................................................................17
7.1.2
PCB .....................................................................................................................19
7.1.3
Voltage Regulators ..............................................................................................19
7.1.4
BOX .....................................................................................................................20
7.2
Safety .........................................................................................................................20
7.3
Reliability ....................................................................................................................20
7.4
Environmental Concerns .............................................................................................20
7.5
Impact .........................................................................................................................20
7.5.1
Global ..................................................................................................................21
7.5.2
Economic .............................................................................................................21
7.5.3
Society .................................................................................................................21
7.6
Maintenance ...............................................................................................................21
7.7
Ownership ..................................................................................................................21
7.8
Support .......................................................................................................................22
7.9
Training.......................................................................................................................22
7.10 Operating Procedures .................................................................................................22
7.10.1 Connecting to the Data Logger ............................................................................22
7.10.2 Turning Off Retrieval Alarm..................................................................................23
iii
7.10.3 Retrieving Data ....................................................................................................24
7.11 Inspection ...................................................................................................................24
7.12 Decommissioning........................................................................................................24
7.13 Quality assurance .......................................................................................................24
8 Costs .................................................................................................................................25
8.1
Hours ..........................................................................................................................26
8.2
Operating costs...........................................................................................................26
9 Project Management Summary ..........................................................................................26
9.1
Personnel ...................................................................................................................26
10
Conclusion .....................................................................................................................27
iv
List of Tables
Table 4-1: Component Description and Part Number
Table 7.1.1: Software Options
Table 8-1: Parts, Suppliers, Cost
v
List of Figures
Figure 4-2: System Overview
Figure 4-4: Block diagram of the software
Figure 4-5a: Power Distribution
Figure 4-5b: Upper Set of Pins
Figure 4-5c: Lower Set of Pins
Figure 4-5d: PCB Schematic
Figure 9-1: GANTT Chart
vi
1 Introduction
This document outlines the purpose of the project, the way it was designed, and
what was implemented after finishing the design. The problem arose from a co-worker,
Garrett Wheeler, who needed a lightweight, easy to use data-logger to be used for a
weather balloon. Garrett helps with a program at Utah State University that uses
Weather Balloon Experiments as a means of recruiting students to the physics program.
The objective was to meet these design requirements while implementing a
specific microcontroller and a real time operating system (RTOS). The RTOS would
ensure stability and the specific microcontroller would satisfy the team’s learning
objective for their individual classes.
A top down system design approach was used. This meant looking at the whole
system, focusing on the smaller objects as needed while keeping in mind the big picture
of the whole project. Each subsection was built and then assembled and tested each
section as part of the whole design.
The completed design met the expectations of the design team, and provided a
good starting point for the physics department to use. The product is enclosed in a
black plastic box, that has a button to start the launch, and a slot to insert a Secure
Digital (SD) card; moreover, it has 15 inputs for analog sensors. The redesigned
payload enables the physics team to connect other devices, allowing for more flexibility
in their experiments, and more efficient balloon launches.
This report is organized into sections to enable easy navigation. Preceding these
pages is an index including Acknowledgements, Abstract of the project, Table of
Contents, and lists of Tables and Figures. Including this section, the main body will
1
introduce the project, explain the problem, the preliminary solution, what things were
changed from that solution and finish with the logistics that were involved to bring to
pass the solution. Attached at the end is an Appendix of design files for reference.
2 Review of Conceptual and Preliminary Design
The project posed a number of problems, as well as specific requirements that
were given from the team’s course and from the physics department. This section will
cover the problem that was posed and the preliminary research that was done to make
the decision.
2.1 Problem Analysis
In the past, the physics team has used an off shelf data recording device to record
the data from their sensors. The problem has been that they needed one data
recording device per sensor, thus increasing weight and cost. The increase in weight
would necessitate in a larger balloon. The larger balloon would then need to be
reported to the FAA, as well as increase the cost of the project. The subsequent
increase in cost tightens their budget, which leaves little money for the actual
experiments. The goal was to provide a data recording device that can connect to
multiple sensors, which eliminates the need for multiple data recorders. This reduces
the weight and cost.
Another problem faced in the past is the fact that many sensors require different
voltage inputs. If the wrong voltage is applied to a sensor, it will either not respond, or it
will burn up. The physics team has used multiple batteries in the past, which in turn
2
raises the weight of the payload. The plan was to provide the necessary voltages using
an 18 volt power supply by two 9 volt batteries. Then using one central power source, it
would effectively minimize the payload weight while allowing the 18 volts to be stepped
down using voltage regulators.
The specifications for this project came from the physics department, and some
of the classes that the team was involved in. The first three requirements were from the
physics department and the remaining were from the class’s rubrics:
●
Keeping the payload under 12 pounds
●
Provide voltages of 12, 9, 5 and 3 volts for the sensors
●
Provide an easy way to record sensor data on the weather balloon from
the sensors
●
Incorporate a real time operating system
●
Use an ARM microprocessor
●
Provide alert sound to ensure easy recovery
The project complied with all of the previous specifications except the voltage.
After talking to the physics department, it was decided that most sensors use 5 volts or
3 volts. The 12 volt and 9 volt power supply would be unnecessary to the design. This
also benefited the power consumption. Voltage could be run at 9 volts instead of the 18
volts that was proposed.
Some of the main features of the design problem are the power supply, the
software, the electrical hardware, the sound subsystem, and the enclosure. Each of
these are crucial to meeting the specifications for this project.
3
The approach being used, as discussed before, is a top down approach for the
whole system, but then using a bottom up approach for each subsystem. This means
that the basic design concept for the weather balloon was made knowing that the
microcontroller, STM32F4DISCOVERY, would be used with an SD card to log the data.
The whole design was to be housed in an enclosure to ensure proper operation. What
was described was the top down approach. Then each subsystem was built from the
bottom up. This meant the details of the subsystems were viewed, tested, and then
formed together into the final design.
A few options for each subsystem were compared to ensure the best practice
was used and that it was a good fit for the individual subsystem. A few different
microcontrollers were compared. Any microcontroller with an analog to digital converter
would fulfill the requirement to read from the sensors. Anything that could store this
data from the sensors was feasible. Voltage regulation was another consideration,
which in the end was handled outside of the microcontroller. Each of these areas
admitted different solutions to choose from.
2.2 Decision Analysis
The decision for the hardware was made among devices that were familiar, or
that had been previously used by members of the team. One alternative would have
been to put pre-built measurement devices, like a digital thermometer, on the balloon
and had a camera take pictures of the devices screen output. This would not have
been a hard design, but would have been heavy, and not allowed the team to practice
design skills. The approach that was taken involved using a microcontroller, however
that introduced options that needed to be decided on in the development software.
4
The effectiveness criteria that was used were not so much as to quantifiable
results as they were qualitative arguments. The microcontroller that was chosen
needed to support ADC. The software needed a way to manage the 15 different sensor
inputs and write them to a disk. This had to be done in a small time frame (about 1
second), as well as minimize the power consumption of the device.
The 8051 microcontroller was used in a previous class, and projects were
programmed sequentially. This would be a very easy way to program, but would make
it hard to manage the parts of the microcontroller including; use of the ports, the analog
to digital converter, the SD card and most any other feature on the microcontroller. A
real time operating system was chosen for programming. This took a little longer to
learn how to program, but allowed for flexibility in the design by allowing for multiple
processes to appear to the user to run simultaneously. There are a multitude of real
time operating systems (RTOS). The desire was to minimize cost, while still having the
features that allowed the ability to write to the SD card, and interface to our
microcontroller.
In the end, it was decided to use the chibiOS for the RTOS and the
STMF4DISCOVERY for the microcontroller. By so doing, this allowed for low power
and low cost, but high functionality. This will be discussed more in depth in section 4.
3 Basic Solution Description
The objective of this project was to solve the problems that were posed above,
namely reducing the weight the balloon will need to carry and reducing the cost by
implementing a new design. A data recorder was built that incorporates the features as
stated above. This effectively replaced the multiple data recorders that have been in
5
use. Using this newly designed data recorder gives more ability for customization and
reduces costs all while improving the product
While accomplishing the previous, this project serves the purpose for learning. The
team has worked to better understand the Advanced RISC Machines (ARM)
microcontroller architecture, embedded programming, and collaboration in a team
environment.
The finished project was completed in a timely manner. This gave the weather
balloon team in the Physics Department ample time to launch their weather balloon, as
well as doing it in a manner that provides ease of use for them and be a robust design.
The physics team has received a working microcontroller platform with sufficient
connectivity for multiple sensors and multiple voltages, while keeping the weight below
twelve pounds.
4 Design of System Components and Performance
Optimization
This section covers the details of the design, the components used, schematics,
implementation and performance of the system.
4.1 Description of components and their component-level
specifications
The following table includes a list of the parts used in the project. Data sheets are
included in Appendix A.
Table 4-1: Component Description and Part Number
#
Description
Part Number
Quantity
6
1
Batteries
N/A
2
2
100 nF Capacitor
399-3676-1-ND
6
3
MAX3232E
296-19850-1-ND
1
4
PUSHBUTTONNO
N/A
1
5
4.7KΩ Resistor
RMCF1206JT4K70CT-ND
5
6
220KΩ Resistor
311-220KERCT-ND
2
7
220Ω Resistor
RMCF1206JT220RCT-ND
7
8
RS232_HEADER
9
Terminal block
1
Molex-39357-0015
3
10 2pos_connect
WM7877-ND
1
11 SD Card
PRT-10117
1
12 DIGITAL BAROMETRIC
BMP085
1
13 3.0V Voltage regulator
ZSR300GTA
1
14 5.3V Voltage regulator
LD1086D2T33TR
2
15 Soundboard
RK-92001A
1
16 Speaker 8Ω 0.25W
TXF 8Ω 0.25W
1
17 ARM processor
STM32F4DISCOVERY
1
18 50_hole connector
XG4H-5031-ND
1
19 Blue LED
276-0316
1
20 LED HOLDER
276-0080
1
21 DC PWR Jack
274-1563
1
22 DC PWR COAX Plug
274-1569
1
PRESSURE SNSR
4.2 Design criteria used
The following is the design criteria for the system. The system needed:
7
●
To be easy to interface with multiple sensors of various types
●
To provide voltage regulation for the power to the sensors
●
To store sensor data
●
Low power consumption
●
To be lightweight
●
To sound an alarm upon landing to aid in finding the instruments
A system level view of the criteria is seen below.
Figure 4-2: System Overview
4.3 Discussion of the technical approach used
The following discusses why parts and programs were chosen:
The STM32F4DISCOVERY Microcontroller was chosen because:
●
Two were readily available at no extra cost
●
It has fifteen ADCs available
8
●
It is powerful enough to run the ChibiOS real time operating system
After prototyping was complete, a Printed Circuit Board, or PCB, was designed
and ordered. The PCB was used because:
●
It provided ease of interfacing with the microcontroller board
●
It provided a central location to handle the analog voltage regulation
needs
●
It provided a more finished product
Linear voltage regulators were used because they provide the most reliable
linear voltage, which gives the best readings on the sensor data.
ChibiOS was used because it is a powerful real time operating system that allows
for better control of the microcontroller and lower power consumption.
4.4 Discussion of design details
The design includes the STM32F4DISCOVERY ARM processor as the central
part of the design. It acts as a processor of information that is collected from various
sensors. Once the data is collected, it will be stored on a Secure Digital flash card,
more commonly referred to as an SD card. The processor will continually collect data
until the balloon reaches a certain altitude at which point it will pop, and the data
recorder will fall to the ground via a parachute. Once the data recorder reaches the
ground, it will begin to play a distress call. This makes it easier to locate the
instrumentation once the flight is finished.
To determine when the device has reached the ground, a reset button will be
pushed before the launch and current altitude and barometric pressure will be recorded.
A count down timer will start, allowing time for the balloon to leave the range of altitude
9
and barometric pressure expected upon landing. From that point, the data will be
continuously logged as it launches. As the balloon rises, the microcontroller will sample
at a certain interval as determined by the physics team. The data will continue to be
recorded until no motion is sensed and altitude and barometric pressure have been
detected, as well as the delay time from the launch. After this point, it will be
determined that the balloon has hit the ground and the alarm will sound. This can be
seen in the software flow diagram shown below in Figure 4-4.
Figure 4-4: Block diagram of the software
Below are pictures of the hardware used:
4.5 Presentation and discussion of engineering drawings and
schematics
Below is the schematic of the power distribution for the PCB design. The
schematic shows:
●
The power supply in
●
How it is distributed to the system for the electronics
10
●
How power is supplied to the terminal blocks for the sensors
Figure 4-5a: Power Distribution
Figure 4-5b shows the connections to the upper set of pins on the microcontroller
development kit.
11
Figure 4-5b: Upper Set of Pins
Figure 4-5c shows the connections to the lower set of pins on the microcontroller
development kit.
Figure 4-5c: Lower Set of Pins
The following figure is the schematic for the PCB.
12
Figure 4-5d: PCB Schematic
4.6 Fabrication, construction, or production instructions and
specifications
The PCB contains all of the connections needed to the STM32F4DISCOVERY
development kit, except for the connections to the soundboard. The soundboard will
connect directly to the pins of the STM32F4DISCOVERY. The PCB dimensions are set
to fit inside of the box that was purchased.
The modifications to the box that were needed:
●
Cut a slot for the SD card
●
Drill a hole for the push button
●
Drill a hole for the wires carrying the power from the 9 volt batteries
●
Cut slots in the lid for the sensor terminal block connections
This design makes it easy to replace any one part.
4.7 Summary of the final design results
The final design consists of a simple box containing:
●
The voltage regulation
●
The data recording circuits with input wires for the power-in
●
Terminal connections for 15 sensors, 5 3V sensors, and 10 5V sensors
●
Push button to begin the data logging
●
An SD card slot to store and transfer the data to other devices
●
Wires out for the speaker
4.8 Performance evaluation
13
The device accomplishes all of the original goals, in that it is light weight, low
power, low cost, easy to use and interface with. The one exception is that it does not
provide 12 and 9 volt supply and sensor support. It would have been possible to
provide support, however, the possible loss of accuracy by scaling the voltages down
was deemed unacceptable and it was decided to use voltages that are supported by the
ADCs on the STM32F4DISCOVERY.
5 Project Implementation/Operation and Assessment
This section covers implementation details, test results, evaluation of test results
and suggested changes.
5.1 Details of implementation
The following was used to implement the design:
●
STM32F4DISCOVERY ARM microprocessor
●
PCB with the necessary circuitry to interface with all other components
●
The ChibiOS real time operating system
The different parts of the system were prototyped before the PCB was designed
and ordered to ensure proper functionality.
5.2 Operational test results
Accelerometers have been tested and data output to computer screen. SD card
communication has been tested and is functioning as needed. Temperature sensors
have also been read and successfully output to computer screen. Power consumption
found. It was found to meet the lower power requirements. The battery will last 4 hours
with all of the devices running.
14
5.3 Evaluation of results relative to design criteria
All tests have met the design criteria needed for the system.
5.4 What changes are suggested by design results
The greatest area for improvement would be a processor that would allow an
external reference voltage on its ADC. This would allow for more accuracy and for
other voltage ranges for the sensors as originally desired.
6 Final Scope of Work Statement
Section 6.0 covers:
●
A summary of the work completed
●
The work that still needs to be accomplished
●
What was learned
●
Suggestions for future activities
●
Special details
●
Project management
●
Life cycle
6.1 Summarize what has been done
This document has detailed the design of the Weather Balloon data logger
device and the functionality tests that have been completed on it. The physical
construction and software implementation has also been covered.
6.2 Summarize what still needs to be done
The remaining test that still needs to be completed is an onboard weather
balloon test.
15
6.2 Lessons learned and suggestions for future activities
The lessons learned from the project are:
●
Set tool chain up sooner to avoid missing its free and open time period.
(Because it was not a simple executable file to install, this created extra
work in installing the tool chain. Many separate tools needed to be
installed to work together)
●
Before ordering, be more careful with design to avoid higher cost
●
Look more carefully at other hardware options when ordering
●
To avoid higher costs associated with rush ordering, place PCB order
earlier
6.3 Describe any special details of the design that only you would
know
A PCB can be ordered at a reduced price for student projects. Normal price is
around $180. A company was found that would manufacture the PCB for around $30 if
the order is placed online and shipped to the school.
6.5 Related project management issues
Complete work earlier to avoid the mad dash at the end while fighting endless
paperwork
6.6 Address complete system life-cycle issues
This design was made to be easily repaired. Each individual part can be ordered
for a relatively low cost if needed. It should provide a reliable data recording device for
the Physics Department for many years to come. The device could also be updated to
include a microcontroller that would allow for an external reference voltage when it is
replaced.
16
7 Other Issues
Some of the other issues that needed to be covered are as follows:
•
Materials selected and why.
•
Safety
•
Reliability
•
Environmental concerns
•
Impact
•
How to:
o
maintain the data logger
o operate the data logger
o Inspect the data logger
o obtain support for the data logger
o train others on the use of the data logger
•
Ownership
•
Inspection
•
Decommissioning
•
Quality assurance
7.1 Material selection
The materials that were used and the reason they were used.
7.1.1 Microcontroller Selection
The STM32DISCOVERY was the best microcontroller that was
found for meeting the following criteria.
•
ARM controller required
17
•
Low-power/cost
•
Sufficient inputs for conversion
•
Weight
The following figure, Figure 7.1.1, is an image of the STM32DISCOVERY.
Figure 7.1.1: The STM32DISCOVERY
18
There were several RTOS’ to use, as seen in Table 7.1.1. The ChibiOS
was chosen due to its compatibility with the materials being used.
Table 7.1.1: Software Options
7.1.2 PCB
The PCB was designed and ordered from Advanced Circuits. It was designed
with the software Dip Trace. An image of the design is shown in Figure 7.1.2.
Figure 7.1.2: PCB circuit design
7.1.3 Voltage Regulators
19
The voltage regulators were ordered from digikey. The voltage regulator
selected had the ability to run with up to 1A of current, in order to provide enough power
to the sensors and the microcontroller.
7.1.4 BOX
The box was ordered from Jameco. It was screen printed at Badger Screen
Printing. The box was cut to make room for such items as the power supply, the SD
card, the light indicator, the sensor connections and the button.
7.2 Safety
Use caution when wiring sensors into the unit. The batteries can produce up to
500 mA. When used with care, electrocution is a very unlikely incident.
Do not open the case. There are sharp objects and exposed wires that can harm
and possibly electrocute the user.
7.3 Reliability
The Data Logger is reliable for the normal operating conditions of the weather
balloon. It is rated for operation in up to -40 C, with no errors in low pressure
environments. It is susceptible to water damage and must be kept in a relatively dry
environment.
7.4 Environmental Concerns
If thrown away, the packaging would take years to decompose. As long as the
unit is running and operational, the environmental impact should be negligible.
7.5 Impact
20
7.5.1 Global
If this product is successful, it may improve the interaction of Physics
students with engineers. Inspiring other Physics programs to work with their
Electrical and Computer Engineering program to benefit all of the Universities.
7.5.2 Economic
This product will improve the economic situation of the physics
department. Now when they wish to add an instrument to their weather balloon,
they no longer need to buy a separate data recorder for it. This will allow the
Physics Department and the Universities to spend the money on more important
projects.
7.5.3 Society
This will get more people excited about physics and engineering. With
more physicists and engineers, technology will advance, changing everyday life
and making the world a better place to live.
7.6 Maintenance
In order to maintain the system, the Physics Department will be given the
specifications as well as this paper. If a fault occurs in the system, the Physics
Department will have the documentation and with the help of a trained technician in
Computer or Electrical Engineering, will be able to repair the fault.
7.7 Ownership
The Physics Department shall retain ownership of the data recorder, the designs
and all other property associated with this project. It shall only be used for academic
purposes and not for any commercial use.
21
7.8 Support
Support for the device is not be provided by the documentation. The
documentation is detailed enough such that any error that occurs in the system will be
able to be fixed by anyone with the qualification in either electrical or computer
engineering.
7.9 Training
Training for the device will initially be provided by our team. Eventually when the
Physics Department becomes familiar with the method, they will be able to train others
to use the instrumentation.
In addition a training document will be provided for use of the product.
7.10 Operating Procedures
A serial port is used for communication and set up of the device. This can be
accessed via a terminal such as PuTTY.
(see: http://www.chiark.greenend.org.uk/~sgtatham/putty/.)
The following instructions show a step by step process to operate data recorder.
7.10.1 Connecting to the Data Logger
1. Connect a serial cable to the Data Logger.
2. Connect the cable to a computer.
3. Provide power to the Data Logger.
4. Using serial communication software, such as PuTTY, open a
communication session with the microcontroller.
a. Using a rate of 38400.
b. Using 8-bits with no parity bit.
22
5. This will open up a command prompt allowing several functions to be run.
a. Help
•
Once in the terminal, type "help". This shows the available
commands.
b. Setting up Sensors
•
From the Data Logger’s Terminal, run the command “Sensor
Settings”. This will bring up a display showing which sensor
are being used and which ones aren’t by placing an “x” by
the sensor ports currently selected.
•
To change sensor settings, type “change”. This prompts for
a sensor number and to select or deselect it.
•
To exit to the main menu type “exit”.
c. Live Reading
•
To view live reading, type “live” from the main menu. This
will give the current readings coming from the sensors.
d. Activating Data Recorder
•
To activate the data recorder, type “run” in the main menu of
the terminal. This will start the data recording immediately.
•
If not launched within the hour, the Retrieval Alarm will
sound and data recording will be stopped.
7.10.2 Turning Off Retrieval Alarm
1. Once the Retrieval Alarm has triggered, only pressing the reset button will
stop the alarm.
23
a. Note: The data will still be stored on the SD card even though no
more readings will be taken.
b.
7.10.3 Retrieving Data
1. The data is retrieved using the SD card
a. Connect SD card to a computer
b. Using MATLAB, read in the file and convert it the appropriate data.
7.11 Inspection
Using the live reading, an inspection can be done. Also a dead reading can be
taken by starting the program on the ground and wait the requisite hour taking reading
and sounding the alarm.
7.12 Decommissioning
This product will be decommissioned gradually as parts start to fail. The most
integral parts that may fail are the microcontroller itself, the ADC on board, the serial
port and the power unit. Indications that a specific part is failing or has failed may be:
•
Microcontroller: faulty output from the serial port.
•
Serial Port: doesn’t output any feedback or the output is extremely faulty.
•
ADC: the ADC will fail when it is too far off from the control test.
•
Power Unit: the system doesn’t power up, or has erratic power. This may be
determined by either observation or by measurement using instrumentation
including, but not limited to, a voltmeter and oscilloscope or a logic analyzer.
7.13 Quality assurance
24
There will be a control test to measure the accuracy of the sensors using known
temperature, pressures, etc. In order to accomplish this, the ability to view live reading
will be built into the software. This will allow calibration of the sensors.
8 Costs
Table 8-1 is a breakdown of the suppliers used, the quantity of parts that were
purchased and how much the parts cost.
Table 8-1: Parts, Suppliers, Cost
Supplier
Quantity
Part Number
Description
Price/Each
Total Price
Jameco
2
216427
9V With lead wires 150mm
$0.75
$1.5
Jameco
1
18893
Jameco 3.5"x6" case
$4.95
$4.95
DigiKey
1
828-1005-1-ND
DIGITAL BAROMETRIC PRESSURE SNSR
$7.89
$7.89
SparkFun
1
SEN-09418
Digital Temperature Sensor Breakout - TMP102
$5.95
$5.95
SparkFun
1
PRT-10117
SD/MMC Socket - Tall (4UCON)
$3.95
$3.95
Digi-Key
3
WM7871-ND
CONN TERMINAL BLOCK 15POS 3.5MM
$5.34
$16.02
Digi-Key
2
497-8341-1-ND
"3V PMIC - Voltage Regulators - Linear (LDO)
$1.14
$2.28
Digi-Key
5
497-1180-1-ND
5V PMIC - Voltage Regulators - Linear (LDO)
$0.53
$2.65
Digi-Key
5
497-7272-1-ND
9V PMIC - Voltage Regulators - Linear (LDO)
$0.59
$2.95
Digi-Key
5
497-7767-1-ND
12V PMIC - Voltage Regulators - Linear (LDO)
$0.55
$2.75
Digi-Key
2
ZSR300GCT-ND
-55°C ~ 125°C 3v 200mA(max)
$1.31
$2.62
Digi-Key
5
497-1170-1-ND
-40°C ~ 125°C 5v1.5A
$0.87
$4.35
Digi-Key
5
425-2638-1-ND
-40°C ~ 85°C 9V 1A
$0.63
$3.15
25
Digi-Key
5
497-6037-1-ND
-40°C ~ 125°C 12v 1.5A
$1.02
$5.10
Digi-Key
2
296-19752-1-ND
IC RS3232 LINE DVR/RCVR 16-SOIC
$2.23
$4.46
8.1 Hours
The total of 1000 man hours of work at $30/hours = $30,000
8.2 Operating costs
$2 batteries
Any additional costs of purchasing sensors.
9 Project Management Summary
Our progress is shown in the Gantt chart in Figure 9-1. This shows a breakdown
of when we accomplished our tasks and the time table for finishing them.
Figure 9 - 1: GANTT Chart
9.1 Personnel
● Christopher Jensen
○ Interfacing with the Microcontroller
○ System Design
○ Hardware to software interface
○ Prototyping
● Kevin Grant
26
○ Power Management
○ Notification Alarm
● Paul Aguilar
○ Team Lead/Organizer
○ Software Design
● All
○ Parts Selection and Ordering
○ Administerial Duties for Reports, Proposal, etc...
10Conclusion
The Weather Balloon data logger that was produced was meant to be easy to use,
while increasing functionality of the previous design. Although there are other options
for data loggers out there, few have the ability to measure 15 different analog sensors
simultaneously. This project doesn’t have to be simply relegated to Weather Balloons, it
can be used for anything that is in need of multiple analog sensors.
For the physics department at Utah State University, this project impacts their
ability to recruit prospective students, as well as collect data to help prove hypotheses
and test theories of the physical world.
In its current form, the Weather Balloon data logger is very beneficial to the
physics department, but could always be improved. After finishing the project, it was
apparent that adding custom formulas for calculation would be helpful. As well as
renaming sensors in the software. Currently there is no over current, or voltage
27
protection on the input pins of the system. This could pose a risk to the microcontroller
if connected to an outside voltage source.
Christopher Jensen
[email protected]
Kevin Grant
[email protected]
Robert Paul Scott Aguilar
[email protected]
28
Appendix A
See attached documents.