Purdue ECE Senior Design Semester Report
Course Number and Title
Semester / Year
Advisors
Team Number
Project Title
ECE 477 Digital Systems Senior Design Project
Fall 2004
Prof. Meyer and Prof. Johnson
9
CRU
Senior Design Students – Team Composition
Name
Major
Mohnish Rathi
EE
Pranav Kabra
CmpE
Sumit Mehra
CmpE
Brandon Fane
EE
Area(s) of Expertise
Utilized in Project
Power supply design,
Hardware, Embedded
Systems
Software Design,
Embedded Systems
Software Design,
Embedded Systems
Power supply design,
Hardware, Embedded
Systems
Expected
Graduation Date
12/19/2004
12/19/2004
12/19/2004
12/19/2004
Project Description: Provide a brief (one or two page) technical description of the design
project, as outlined below:
(a) Summary of the project, including customer, purpose, specifications, and a summary of the
approach.
Our aim was to build a stand alone wireless digital audio receiver. The CRU (Cru Radiation
Universe) will receive mp3 songs from computers connected to its wireless network via 802.11b
wireless protocol and relay the audio through a regular stereo output. The mp3 files will be
stored on an xD card. The CRU will also contain an LCD display which will display the song
details based on the ID3 tag of the song. The software on the device will ascertain the order of
the songs, and once played they will be released from the drive. The motivation of this project is
to provide apartments with multiple computers, and hence, multiple audio collections to have a
single place to output their music, often in another part of the residence. This can also be used as
a portable device to be taken to a friend’s residence for use there. A 12 volt D.C. “wall-wart”
will be used as a power supply.
(b) Description of how the project built upon the knowledge and skills acquired in earlier ECE
coursework.
This project was built upon all kinds of previous knowledge acquired in ECE classes. ECE
362 came into play the most. Knowledge of registers, assembly code and I/O in embedded
systems learned in 362 came in handy in many occasions when software was being written.
Since most of the programming could be done in a form of C, ECE 264 was useful for those who
had taken it. Many C functions were available in the form of C used and knowledge of the
programming language proved very useful. ECE 201 and 255 came into play when power
supply constraints were considered for the final power supply design.
(c) Description of what new technical knowledge and skills, if any, were acquired in doing the
project.
More than one new technical skill was learned doing this project. The fist of which is
overall system design. Never before had any of us really conceptualized a product, designed it,
and built it with this much complexity in mind. More specifically, documentation (i.e. user
manual, materials list, and detailed packaging drawings) was never undertaken like it had for this
particular project. Also, PCB layout, design and soldering were new skills we acquired over the
course of implementing our design.
(d) Description of how the engineering design process was incorporated into the project.
Reference must be made to the following fundamental steps of the design process:
establishment of objectives and criteria, analysis, synthesis, construction, testing, and
evaluation.
Success Criteria:
We needed to describe five Project Specific Success Criteria that we needed to meet to
receive a passing grade. Those PSSC s are as follows:
1. An ability to decode/play an MP3 file.
2. An ability to control mode of operation via keypad.
3. An ability to display song information on an LCD display.
4. An ability to save/load MP3 file to/from xD memory card.
5. An ability to transfer MP3 files via wireless 802.11b link (from a remote host).
Analysis was done through a series of design constraint analyses, and component selection
rationale.
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This involved choosing all the main components of our design based on the success
criteria we had already established. This was done in a homework in which we laid out our
choices for components and why we had chosen them.
Once that was accomplished, we began buying our parts and testing each individual
component of the design on breadboards. We tested software on a development board made
for our processor. We used wire-wrap to connect the bread boards with the development
board to test each individual part of the design. While doing that, we designed our PCB and
sent it off to the board house.
Once the PCB returned, we began populating the board and testing the individual parts on
the PCB. Once we had this accomplished, we built our packaging and put the components in
place.
Once the parts were all connected and placed in the packaging, we set out to integrate all
parts of the design into one piece of software. This was accomplished by including the
individual pieces of software written during testing as separate libraries for our final code.
Integration was considered successful when the PSSC’s were all tested and video taped
as working correctly. Once all five criteria were met, we considered the task of integration
complete and demonstrated the device on a video.
(e) Summary of how realistic design constraints were incorporated into the project
(consideration of most of the following is required: economic, environmental, ethical, health
& safety, social, political, sustainability, and manufacturability constraints).
As per the home works that we were assigned, we had to take into account the economic,
environmental, ethical, health and safety, and sustainability of our device. We determined the
final cost of manufacturing our design on a large-scale to be about $200. For environmental
concerns, we decided that the device should be made of recyclable plastic and had to outline the
ways to dispose the device in the user manual. For health and safety, we had to outline a
FMECA worksheet. For sustainability, we had to determine the mean time to failure for all the
major components. We had determined the first parts would begin to fail after about 111,000
hours. Since the device is a low power one and does not emit any harmful radiation, there were
few failures that could cause harm to the user. All possible failures have been identified in a
FMECA worksheet included in the reliability homework and our final report.
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(f) Description of the multidisciplinary nature of the project.
This project required some very heavy knowledge of software design; however, there are
some other skills that were necessary to its success. Knowledge of power supply constraints,
picking out correct connectors and other hardware concerns were necessary to choose the correct
voltage regulators to give the three appropriate voltages we needed as well as to make sure the
right types of devices were communicating in the correct way.
Also some elements of
manufacturing were necessary to create our packaging and mounting all our parts in the package
correctly. When everything is considered, this design made use of the expertise our group had in
hardware and software as well as some manufacturing skills none of us had going into the
project.
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