Midway Design Review

1. Midway Design Review Team BeepachU November 26, 2013

2. Team 7 Members Eric Wagner EE Mark Wagner EE Quanquan Han EE David Zeifman CSE

3. This Presentation: Overview • Review: What is BeepachU? • Block Diagram: Old and New • Demos: TX/RX and working Audio • CDR deliverables, Team Responsibilites, and Schedule

4. Review

5. Review: What is BeepachU? • Problem: Lost items • Solution: Cheap tracking tag that makes sounds to lead you to your item • Key Fob transmits to tag  tag makes sound for user Where’s my Wallet?

6. Review: BeepachU Specifications • Range: 100m (outdoor line of sight) • Battery life: 6 months for both Keyfob and Tag • Weight: Keyfob < .5 lb, Tag < .5 Ib • Response time: under 2 seconds • Size: • Keyfob < 4 square inches • Tag < 3 square inches • Robust • Tag will not be set off by interference signal • Cheap: Each unit < $30 when mass produced

7. Block Diagram

8. Previous Block Diagram

9. Redesigned Block Diagram

11. Block Diagram: ANT SoC Block • Contains the nRF51422 “ultra low power” ANT SoC • ANT, like bluetooth, is a network protocol • ANT is pre-implemented in software on the chip • Programmed in C

12. Block Diagram: Network Diagram (using ANT protocol) • ANT Protocol uses time-division multiplexing to separate channels • Master and Slave devices are preset only to connect with eachother

14. Block Diagram: Speaker System • LM 386 audio amplifier- $0.34 • CDM-10008 8 Ohm speaker- $0.79 • 2.9mm height, 10mm diameter

16. Block Diagram: UserInterface

18. Block Diagram: Power Supply • 3V CR-2032/VP Energizer coin cell battery • 225mAh lifespan • 0.79” diameter x 0.13” height • $0.40 per battery • One battery per keyfob, two per tag

20. Block Diagram: Antenna + PCB • Same PCB used for keyfob and tag (reduces cost) • PCB = 1.2 x 1.5 inches • “Inverted F” antenna integrated into PCB • Isotropic, often used in cell phones • Can be tuned manually by scraping copper off its end

21. Demonstrations

22. Review of Proposed MDR Deliverables • Demonstration of working TX/RX • TX and RX recognize each other and work at close distance • TX and RX hardware not necessarily contained in small package (may be on a breadboard or Development Kit Module) • Not yet battery powered • Working speakers driven by TX/RX hardware • Small audio system will be operational • Same transceiver SoC that drives TX/RX must be able to drive audio system. • Not yet battery Powered

23. Demonstration • Transmit/Receive Demo • Audio Demo • Enjoy

24. CDR Deliverables, Team Responsibilities, and Schedule

25. Proposed CDR Deliverables • Fully functional system • Doesn’t necessarily meet specs, but works • Powered by battery • Implemented on custom PCB not development board • Hot cold feature implemented • Beep will work and will be audible

26. Individual Responsibilities DaveZeifman • Produce finalized & power efficient BeepachU TX/RX code Eric Wagner • Order and Test PCB module with integrated Antenna • Tune Antenna for optimal performance Mark Wagner • Produce finalized audio driving code Quanquan Han • Produce packaging + integrate packaging with PCB

27. Schedule

28. Thank You Questions?

29. Power Specifications (with 3.3V source) • Keyfob (on) • Sleep mode = 8.25uW (or 2.5uA) • Transmitting as master device = 8.58mW (or 2.6mA) • Transmitting + LED on = 16.8mW (or 5.1mA) • Battery indication LED = 8.25mW (2.5mA) • RX (always on) • RX sleep/search mode (10% duty cycle) = 262.2mW (or 79.5uA) • Paired as slave device = 8.58mW (or 2.6mA) • Paired as slave + beep and blink= 640.2mW (or 194mA)

30. Power Usage Estimations • Keyfob (TX) is on for about 2 minutes per use • Transmitting + LED on (for Hot/cold): 120s • Battery indication LED: 120s • Total = 912 mAs = 0.2533 mAh (888 uses) • Tag (RX) is used for 2 minutes per use • Hot/Cold active (connected) : 115s • Beep & LEDs active: 5s • Total = 1269mAs = 0.3525mAh (297 uses) • Tag (RX) is on sleep/search mode for the rest of the time

31. Preliminary Cost Analysis • “Each unit < $30 when mass produced”

32. Multiple Tags for a Single Keyfob? • ANT allows for “star networks” with one master (keyfob) and multiple slaves (tags) • Tags must be paired with masters during initial programming  multiple tags will have to be bought alongside the keyfob

33. ANT Network Security • Can use Single Channel Encryption • 128-bit AES-CTR (symmetric algorithm – single shared key) • Supports multiple slaves per master on single channel, but only one channel per master

34. Responsibilities : Dave Zeifman • Keyfob Programming • Keyfob must initiate connection with tag when hot/cold is active • Must display RSSI in accurate manner using LED • Must be power efficient • Tag Programming • Tag must constantly search for Keyfob • Tag must know when to connect and when to beep • Must be power efficient

35. Responsibilities : Mark Wagner Sound Driver • Store “Beep” sound bite in chip • Write audio driving code for receiver • Generate pleasant and audible beeping sound • Acceptable power consumption

36. Responsibilities : Eric Wagner • PCB • Must be able to support all buttons/LEDs/speakers on UI • Must fit size specifications • Must be cheap enough to produce on BeepachU budget • Antenna • Must be nearly isotropic in tag, can be directional in keyfob • Must have high enough efficiency to meet range requirements • Must be tunable

37. Responsibilities: Quanquan Han • UI/Packaging • Must fabricate packaging • Fabrication should be within BeepachU budget • Buttons, LEDs and Speakers must be integrated into package • Package must not muffle tag beeps • Package must not interfere with antenna