Midway Design Review
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Transcript of Midway Design Review
Midway Design Review
Advisor: Professor Russell Tessier
Team:Michael Shusta
Lucas RootBrandon Thorpe
Gilbert T. Kim
Outline• MDR Deliverables and PDR Concerns
• Development Approach
• Design Decisions and Progress
• Current and Projected Costs
• Patenting and Competition
• Meeting MDR Goals
• CDR Goals
MDR Deliverables PDR ConcernsFor MDR:
– IDB finalized with preliminary implementation– Locking mechanism design and prototype– Simple routines on the AIRcable– BlackBerry “hello world”
PDR Concerns:– Current and power requirements– Power storage and delivery– Cost of device in pilot run– Competing technology
Development Approach
• Weekly PowerPoints to update progress– Discuss and plan design of hardware and
software components – Group insight into individual problems– Motivate progress
• Team email account
• Subversion for code and group documents, repository of resources
IDB• Can establish RSA secure XML based
channel with client software• Can connect to and query the Bluetag
database as well as a demo store database
• Currently handles client requests synchronously, multi-threading is incomplete
• MDR goals met
Lock• Mechanism View via Prototype Demo
– Linear, Pull-type, Spring-Loaded Solenoid– Rotating Latch Holds Clothing Pin– Coil Suppressor– Solid-State Relay Control– See MDR Design Report for in-depth
discussion of physics, parts selection, force diagrams, etc.
SolidWorks View
•3D printed using ABS plastic/photopolymer resin•Assemblies can be verified/animated before fabrication
AIRcable Update• Purchased chip and hand-soldered to DIP
connector
• Ran simple routines on the AIRcable, met MDR goal
• Unstable system
• Discontinued product
line
AIRcable Debugging• Ability to connect to and program AIRcable
sporadic• Troubleshooting steps:
– Installed and learned Linux Bluetooth support– Visual inspection, ohmmeter check– Pin voltage under different operating conditions– Continued dialog with development team
• What went wrong?– Damage while soldering– Faulty chip– Damaged during operation
Tag Bluetooth Redesign• Separate module and microcontroller with UART
communication
• Roving Networks RN-41:– Small, low power, configurable, DIP breakout, low
cost, UART, widely used
• PIC 16F688:– Small, low power, low cost, UART, DIP, advanced
development tools
TXRX
RXTX
RN-41 16F688
Powering Bluetag• Bluetooth Module and Microcontroller
– Rn-41: 30 mA connected, .25-2.5 mA deep sleep at 3.3 V
– 16F688: 640 uA normal operation, 11 uA deep sleep at 3.3V
• Solenoid– SS2EP: 7W at 100% duty cycle at ~3.3V
Important Specification: peak power delivery of battery system must be at least 7.101W (solenoid + transceiving)
Battery Life EstimateAssumption:•The idle mode dissipation (8.23mW) of the control circuitry dominates its power demands
Performance Metrics:•One: Assume an up-time and estimate the maximum number of purchases•Two: Assume a maximum number of purchases and estimate the up-time
Powering Bluetag
Battery Life Estimate
t7
u3600108.23- -3
β is the total energy capacity of the battery system in Joules∆t is the duration of time the solenoid is energizedu is the number of hours between rechargingτ is the number of purchases
Ex. Let u = 8 hours, ∆t = 5 seconds and a battery of 8 W-h is used: lock would last 816 cycles before fully exhausting its battery
Ex. Setting τ=5 for an 8 W-h battery with ∆t = 5 seconds gives an uptime of 966 hours, or about 40 days
31023.83600
t7-u
What do these metrics tell us?•Battery must deliver high transient power a few times per charge•Clothing pin should be spring-loaded to minimize power draw window•Lithium-ion battery is proper choice:
-highest energy density per unit weight of commercial chemistries-available rechargeable, cell voltage near 3.3V-see MDR Design Report for in-depth discussion
What don’t these metrics tells us?•Probabilistic model of battery life (purchasing is a Poisson process!)•Relationship between mass, volume and capacity of batteries•Battery terminal design techniques
Powering Bluetag
Programming the BlackBerry
• Decided on BlackBerry JDE Plug-in for Eclipse– Involved configuration but familiar
environment
• Use of Simulators
• Enabled real-time phone monitoring
Basic Flow of the Graphical UIWindow One:
Input username and password
Window Two:Item ID entry
Window Four:Continue Shopping
Yes
Window Three:Item info & confirm purchase
Yes No
No
The BlackBerry UI APIs• Screen components
- Standard screen layout - Default menu
• Field components- Standard UI element for options, check boxes, lists, text fields &
labels, and progress bar controls
• Layout managers- Horizontal- Vertical- Left-to-Right flow
User Interface Progress
• Simple UIs using BlackBerry simulators
• Formatted and installed UIs on BlackBerry
Progress Block Diagram
HelloWorldLabelFieldRichTextField
Sample GUIHorizontalFieldManagerVerticaltalFieldManagerBitmapFieldBitmapLabelFieldBasicEditFieldEditField
Accomplished
Processing
Current and Projected Costs• Prototype Cost: $193 - $243
– PIC 16F688: $2.31– Lithium Ion Battery: $10– Ledex 2EP Solenoid: $20– Crydom SRR: $1– 3D Printing: $75-$125– PCB Fabrication: $50– RN-41: $34.91
• Development Costs: $49.66– PIC Development Board: $15.95– PICKit 3: $33.71
Patenting and Competition
• Met with CVIP Director Nick DeCristofaro– Proceed after prototype– One year window after disclosure
• Potential Competition Includes:– Phone based barcode scanners– Resonant tags with data storage– DoCoMo cell phone purchasing