ECE 477
Digital Systems Senior Design Project
Rev 8/11
Homework 3: Design Constraint Analysis and Component Selection Rationale
Team Code Name: __GNMS______________________________________ Group No.
__6___
Team Member Completing This Homework: _Larry Price___________________________
E-mail Address of Team Member: __lrprice_____ @ purdue.edu
NOTE: This is the first in a series of four “professional component” homework assignments,
each of which is to be completed by one team member. The body of the report should be 3-5
pages, not including this cover page, references, attachments or appendices.
Evaluation:
SCORE
DESCRIPTION
Excellent – among the best papers submitted for this assignment. Very few
10
corrections needed for version submitted in Final Report.
Very good – all requirements aptly met. Minor additions/corrections needed for
9
version submitted in Final Report.
Good – all requirements considered and addressed. Several noteworthy
8
additions/corrections needed for version submitted in Final Report.
Average – all requirements basically met, but some revisions in content should be
7
made for the version submitted in the Final Report.
Marginal – all requirements met at a nominal level. Significant revisions in content
6
should be made for the version submitted in the Final Report.
Below the passing threshold – major revisions required to meet report requirements
*
at a nominal level. Revise and resubmit.
* Resubmissions are due within one week of the date of return, and will be awarded a score of
“6” provided all report requirements have been met at a nominal level.
Comments:
Grader: Jacob Pfister
Score:8/10
See comments below. Technical content was mostly good. Formatting and grammar need a little
work. Please do not change any of the formatting (i.e. changing the page layout to Landscape,
eliminating the spacing between sections to hide going over the page limit).
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ECE 477
1.
Digital Systems Senior Design Project
Rev 8/11
1.0 Introduction
GNMS is a multi-touch-capable surface designed for use with games and other media. The
surface will be approximately table-sized for an immersive computing experience.
Project-Specific Success Criteria:
1. An ability to interpret and track touch signals using Frustrated Total Internal Reflection
2.
3.
4.
5.
(FTIR) from the motherboard..
An ability to control power to the projector using internal IR signals as from a remote
control. (PCB)
An ability to monitor temperature and control fans for cooling when necessary (PCB).
An ability to run applications and display them appropriately on the screen.
An ability to perform system actions such as loading a new application, cycling overall
power, and adjusting screen brightness using a non-touch interface. (PCB)
For updated Block Diagram, see Appendix B.
2.0 Design Constraint Analysis
The design constraints in this report are computation requirements, interface
requirements, on-chip and off-chip peripherals, power constraints, packaging constraints and cost
constraints. The GNMS Touch Surface is inspired by the Microsoft Touch Surface but designed
to be similar to a touch-enabled home desktop computer. The Microsoft Touch Surface is a very
advanced piece of hardware with a high price tag. The GNMS Touch Surface is more affordable
and designed to give the average person the opportunity to experience touch-enabled personal
computing on a larger scale. The on-chip and off-chip peripherals are included to deal with
internal system control such as power and temperature monitoring. The microcontroller uses
buttons and rotary pulse encoders to interface with the user when touch is not an available
option. As the device is similar to a computer, it will need a constant AC power supply. The
device package has been designed to be the height of a foosball table (around 36 inches), and the
screen itself is designed to be 32” x 24” in size to conform to the projector’s 4:3 aspect ratio.
2.1 Computation Requirements
The system’s computing is divided between a microcontroller and a main motherboard.
The computational tasks provided by the microcontroller are intercepting button pushes,
analyzing potentiometer/rotary encoder turns, monitoring system temperature, adjusting fan
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ECE 477
Digital Systems Senior Design Project
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speed to ventilate air based on the measured system temperature, and sending infrared signals to
the projector. The clock speed will need to be higher than the frequency at which the signals
need to be sent to the projector. This speed is estimated to be 38kHz, which was determined to be
the frequency of approximately 90% of infrared remotes according to [1]. Button presses are
assumed to be infrequent and will not affect clock speed. System temperature measurement and
ventilation fan control need only be updated at a frequency on the order of 1 Hz.
For the main motherboard, the project relies on capturing infrared data from a screen
using a USB camera. The project will also allow the user to connect a USB flash drive to run
their own applications. Therefore, the motherboard must have at least 2 USB ports. The
motherboard must be able to run embedded Linux to run the software associated with capturing
and interpreting infrared data. The motherboard must have a VGA port to allow video output to a
projector.
2.2 Interface Requirements
A GPIO port will be used by the microcontroller to activate power to other parts of the
system. Eight GPIO ports will be used with two separate rotary pulse encoders to control
brightness of the projector and volume of the speakers. USB communication will be needed from
the microcontroller to the motherboard. This communication route is so that the software on the
motherboard can adjust the brightness/volume as necessary.
2.3 On-Chip Peripheral Requirements
The cooling fan will require 3 channels of 10-bit ATD for temperature sensing. The
device requires 2 channels of PWM for fan control and one channel for control of the infrared
LED.
2.4 Off-Chip Peripheral Requirements
An infrared LED will be controlled from the microcontroller to power on/off the
projector by mimicking the remote control which comes with the projector. The device will need
at least 2 temperature sensors and 2 ventilation fans. The device will also need an off-chip USB
housing to connect to the motherboard.
2.5 Power Constraints
The device will be A.C. powered only due to the number of separate peripherals in need
of power. The projector is likely the peripheral which will consume the most power, requiring
246 W of power while running according to [2]. The motherboard consumes approximately 24.2
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Digital Systems Senior Design Project
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W with a 5V power supply according to [3]. Power consumed by the microcontroller will be
relatively small compared to the larger devices. Devices which generate excessive heat do not
need to be placed in close proximity to each other due to the large size of the operating
environment.
2.6 Packaging Constraints
The packaging for the GNMS Touch Surface is based heavily on the throw distance of
the used projector and the desired screen size. The desired screen size is approximately 32”x24”.
With the height of the projector as 3.5” according to [2], the dimensions of the top and bottom of
the project will be approximately 36”x28”. The height of the box is designed to be the same
height as an average American foosball table, which is 36”. This height is chosen because it is a
comfortable height from which to both stand and sit while using the surface. To reach this height
restriction, the projector will be mounted facing down so the display is reflected off a mirror on
the bottom of the box to accommodate for the high throw distance of the chosen projector. The
camera can be placed by the mirror on the bottom of the box. The microcontroller and
motherboard can be located in any of the empty space available in the box. Due to the high heat
production of the projector and the atom board, we will be mounting one fan on the side of the
box blowing inward, and another fan on the back of the box blowing outward.
2.7 Cost Constraints
Competition for the GNMS Touch Surface includes the Microsoft Surface 1.0 ($12,500
MSRP according to [4]), Microsoft Surface 2.0 ($7,600 MSRP according to [5]), and the
EXOdesk ($1,299 MSRP according to [6]). However, technology inside these competitors’
machines is more advanced than the GNMS Touch Surface prototype and the software provides
a much better user experience, so the cost for the GNMS Touch Surface will be much lower to
account for the technology difference.
3.0 Component Selection Rationale
Many different microcontrollers fit the needs of this project. Two such products are the
Atmel AT32UC3B164 found at [7] and the Pic PIC32MX220F032D found at [8]. The Pic is a
32-bit 40 MHz processor with 5 PWMs and 13 ATDs of 10-bit resolution. It also has 33 I/O pins,
32KB of Flash, and 8KB of RAM. The Atmel is a 32-bit 60MHz processor with 13 PWMs, 6
ATDs of 10-bit resolution, 28 pins of I/O, 64KB of Flash, and 16KB of SRAM. The Atmel is a
more powerful processor. Looking at the integrated development environments [IDE] provided
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ECE 477
Digital Systems Senior Design Project
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by Atmel and Pic, the Atmel IDE appears to be more modern. Based on these specifications, we
have decided to go with the Atmel processor.
The design requires a motherboard with more than 2 USB ports, a VGA output, and the
ability to run embedded Linux. Two motherboards looked at were the Intel Atom D525MW at
[3] and the Beagleboard at [9]. The Beagleboard uses an ARM processor and has all the ports we
need, but runs at the price of $149. The Atom board in question uses an Intel Atom processor and
has more than what we need, but can be found for around $80. Due to the price and a build-up of
trust with Intel, the group decided to go with the Atom board.
The motherboard will also need an external power supply. Two power supplies
considered were the Raidmax RX-380K found at [17] and the Logisys PS480D2 found at [18].
These two power supplies are very similar and both fit the design constraints for the
motherboard. The group decided to go with the Raidmax due to better reviews on the vendor
website.
The design only requires a small amount of RAM on the motherboard to keep things
running smoothly. The Patriot PSD32G13332S 2GB DDR3 RAM found in [10] and the Crucial
CT25664BF1339 2GB DDR3 RAM found in [11] are similar choices as each is a 204-pin 1333
2GB DDR3 RAM made for laptop memory. The Patriot RAM can be found slightly cheaper, and
reviews were found that confirmed compatibility with Atom boards.
The design requires a USB camera which detects only infrared light. As true infrared
cameras are expensive, a standard webcam will be purchased and modified to sense only infrared
signals. The two cameras considered are the Logitech HD Pro Webcam C910 found at [12] and
the Sony Playstation Eye found at [13]. The Playstation Eye is less expensive and has many
tutorials online for modifying it to only receive infrared signals. The Logitech C910 is newer and
has a better resolution. Eventually, we decided to go with the Playstation Eye for half the price of
the C910 in case we destroy the camera in the process of modifying it.
The design requires a projector with moderately high resolutions and a low price point.
The only new projector available for under $100 was the Discovery Expedition Entertainment
Projector at [14]. However, this projector received very poor reviews and didn’t seem to have the
resolution necessary for this project. Fortunately, a family member of one of the group members
was interested in parting with an Epson EX30 as seen at [2]. This projector was high-end in
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ECE 477
Digital Systems Senior Design Project
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2008, had a great resolution, came relatively customizable, and had a price point of $50. The
group went with the Epson model.
The design requires cooling fans. The group found that there are many cooling fans
available, but the smaller fans are more expensive and take more rotations to create the same
effect. The Rexus Rexflo250mm Case Fan found at [15] is a 250 mm in diameter fan with a
noise level below 25 dBA. The Cooler Master Hyper 212 Plus found at [16] is a 120 mm in
diameter fan with a noise level below 32 dBA. The Rexus fan is less expensive but has a heavier
weight than the Cooler Master fan. The Cooler Master runs between 600 and 2000 rotations per
minute [RPM] while the Rexflo runs between 760 and 840 RPM. The group decided to purchase
the Rexus Rexflo250mm fan due to cost and quietness.
4.0 Summary
The information in this reports outlined the requirements to design a low-cost touch table.
Many parts were identified to fit the project specifications, and an analysis of several of these
parts is included in section 3. The list of parts found in Appendix A is an exhaustive list of all the
electronics necessary for building this design, with several components doubled in case of
emergencies. The final price in Appendix A does not relay the amount needed to build the screen
and external packaging for the end product.
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ECE 477
Digital Systems Senior Design Project
Rev 8/11
List of References
[1] Wikipedia (2012, Jan. 29). Consumer IR [Online]. Available:
http://en.wikipedia.org/wiki/Consumer_IR
[2] Epson (2008, October 12). EX30 Media Projector [Online]. Available:
http://www.epson.com/cmc_upload/0/000/119/949/EX30_ProdPrev.pdf
[3] Intel Corporation (2010, July). Intel Desktop Board D525MW and Intel Desktop Board
D525MWV Technical Product Specification [Online]. Available:
http://downloadmirror.intel.com/19123/eng/D525MW_D525MWV_TechProdSpec.pdf
[4] Wikipedia (2012, Jan. 29). Microsoft Surface [Online]. Available:
http://en.wikipedia.org/wiki/Microsoft_surface#Overview
[5] Foley, Mary Jo (2011, Jan. 6). CES: New Microsoft Surface to be Priced at $7,600 [Online].
Available: http://www.zdnet.com/blog/microsoft/ces-new-microsoft-surface-to-be-priced-at7600/8368
[6]Windows Era (2011, Nov. 21). EXOdesk A Smart Alternative To Microsoft Surface [Online].
Available: http://windowsera.com/exodesk-a-smart-alternative-to-microsoft-surface
[7] Digi-Key. “AT32UC3B164” [Online]. Available:
http://search.digikey.com/us/en/products/AT32UC3B164-AUT/AT32UC3B164-AUT-ND/1769702
[8] Microchip (2011, Nov. 2). “PIC32MX220F032D” [Online]. Available:
http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en556010
[9] Beagleboard. Beagleboard System Reference Manual [Online]. Available:
http://beagleboard.org/static/BBSRM_latest.pdf
[10] Newegg. “Patriot Signature 2GB 204-Pin DDR3 SO-DIMM DDR3 1333 (PC3 10600)
Laptop Memory Model PSD32G13332S” [Online]. Available:
http://www.newegg.com/Product/Product.aspx?Item=N82E16820220424&Tpk=PSD32G13332S
[11] Newegg. “Crucial 2GB 204-Pin DDR3 SO-DIMM DDR3 1333 (PC3 10600) Laptop
Memory Model CT25664BF1339”
[Online]. Available: http://www.newegg.com/Product/Product.aspx?Item=N82E16820148490
[12] Newegg. “Logitech C910 USB 2.0 1080p HD Pro Webcam” [Online]. Available:
http://www.newegg.com/Product/Product.aspx?Item=N82E16826104385
[13] Amazon. “Playstation Eye” [Online]. Available: http://www.amazon.com/PlayStation-Eye3/dp/B000VTQ3LU
[14] Amazon. “Discovery Expedition Entertainment Projector” [Online]. Available:
http://www.amazon.com/Discovery-1625075-Expedition-EntertainmentProjector/dp/B002AKHHHM/ref=sr_1_1?ie=UTF8&qid=1327872564&sr=8-1
[15] Newegg. “Rexus Rexflo250mm 250mm Case Fan” [Online]. Available:
http://www.newegg.com/Product/Product.aspx?Item=N82E16835705056
[16] Newegg. “COOLER MASTER Hyper 212 Plus RR-B10-212P-G1 “heatpipe Direct
Contact” Long Life Sleeve 120mm CPU Cooler Compatible Intel Core i5 & Intel Core i7”
[Online]. Available: http://www.newegg.com/Product/Product.aspx?Item=N82E16835103065
[17] Newegg. “RAIDMAX RX-380K 380W ATX12V Power Supply” [Online]. Available:
http://www.newegg.com/Product/Product.aspx?Item=N82E16817152019
[18] Newegg. “LOGISYS Computer PS480D2 480W ATX12V Power Supply” [Online].
Available: http://www.newegg.com/Product/Product.aspx?Item=N82E16817170016
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Digital Systems Senior Design Project
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ECE 477
Digital Systems Senior Design Project
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Appendix A: Parts List Spreadsheet
Vendor
Digi-Key
Manufactu
rer
Atmel
Deal
Extreme
Amazon
None
Galactics
Newegg
DealExtrem
e
Newegg
Newegg
Rexus
RaidMax
TOTAL
Sony
Epson
Intel
Patriot
Part No.
AT32UC3B1
64
Description
32-bit
microcontroller
IR 5 mm LED Kit
100 Pcs
Playstation Eye
Projector
motherboard
2 GB DDR3 RAM
EX30
D525MW
PSD32G1333
2S
Rexflo250mm 250 mm Fan
RX-380K
380W ATX12V
Power Supply
$???. $269.80
??
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Unit Q Total
Cost
Cost
7.04 2 14.08
2.93 1
0
22.48 1
50 1
76.99 1
9.99 2
29.3
22.48
50
76.99
19.98
19.99 2
16.99 1
39.98
16.99
ECE 477
Digital Systems Senior Design Project
Appendix B: Updated Block Diagram
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