Midway Design Review Advisor: Professor Russell Tessier Team: Michael Shusta Lucas Root Brandon 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 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

Development Approach Weekly PowerPoints to update progress –Discuss and plan design of hardware and software components –Group insight into individual problems –Motivate progress Team account Subversion for code and group documents, repository of resources

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

System Elements

Server: IDB

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 TX RN-4116F688

Powering Bluetag Bluetooth Module and Microcontroller –Rn-41: 30 mA connected, 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 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 Powering Bluetag

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

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 UI Window One: Input username and password Window Two: Item ID entry Window Four: Continue Shopping Yes Window Three: Item info & confirm purchase YesNo

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 HelloWorld Wrote UI w/ Java Sample GUI GUI (JavaUI  BlackBerry GUI) HelloWorld LabelField RichTextField Sample GUI HorizontalFieldManager VerticaltalFieldManager BitmapField Bitmap LabelField BasicEditField EditField 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

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