Midway Design Review

1. Midway Design Review Advisor: Professor Russell Tessier Team: Michael Shusta Lucas Root Brandon Thorpe Gilbert T. Kim

2. Outline • MDR Deliverables and PDR Concerns • Development Approach • Design Decisions and Progress • Current and Projected Costs • Patenting and Competition • Meeting MDR Goals • CDR Goals

3. MDR Deliverables PDR Concerns For 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

4. 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

5. System Overview Server Locked Item Client Store Inventory Bluetag Database Department of Electrical & Computer Engineering

6. System Elements

7. Server:IDB

8. 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

9. 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.

10. SolidWorks View • 3D printed using ABS plastic/photopolymer resin • Assemblies can be verified/animated before fabrication

11. AIRcable Update • Purchased chip and hand-soldered to DIP connector • Ran simple routines on the AIRcable, met MDR goal • Unstable system • Discontinued product line

12. 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

13. TX RX RN-41 16F688 RX TX 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

14. 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)

15. Powering Bluetag • Battery Life Estimate • Assumption: • 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

16. Battery Life Estimate β is the total energy capacity of the battery system in Joules ∆t is the duration of time the solenoid is energized u is the number of hours between recharging τ 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

17. Powering Bluetag • 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

18. Programming the BlackBerry • Decided on BlackBerry JDE Plug-in for Eclipse • Involved configuration but familiar environment • Use of Simulators • Enabled real-time phone monitoring

19. Basic Flow of the Graphical UI Window One: Input username and password Window Two: Item ID entry Window Three: Item info & confirm purchase Yes No Window Four: Continue Shopping Yes EXIT No

20. 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

21. User Interface Progress • Simple UIs using BlackBerry simulators • Formatted and installed UIs on BlackBerry

22. Progress Block Diagram HelloWorld LabelField RichTextField Sample GUI HorizontalFieldManager VerticaltalFieldManager BitmapField Bitmap LabelField BasicEditField EditField Accomplished Processing

23. 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

24. 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

25. MDR and CDR Goals • All MDR goals met • IDB • AIRcable • Lock Design • BlackBerry Programming • CDR Goals • UI completed • Full SolidWorks • PCB • Embedded Programming