1. Department of Electrical and Computer Engineering Team BeepachU March 3, 2014 Comprehensive Design Review

2. Department of Electrical and Computer Engineering Team 7 Members Eric Wagner EE David Zeifman CSE Mark Wagner EE Quanquan Han EE

3. 3 Department of Electrical and Computer Engineering This Presentation: Overview  Review: What is BeepachU?  Preview of Demonstration  Demonstration  FPR Goals/Deliverables  Questions

4. 4 Department of Electrical and Computer Engineering Review

5. 5 Department of Electrical and Computer Engineering 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. 6 Department of Electrical and Computer Engineering 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. 7 Department of Electrical and Computer Engineering Block Diagram

8. 8 Department of Electrical and Computer Engineering Block Diagram

9. 9 Department of Electrical and Computer Engineering ANT SoC Block

10. 10 Department of Electrical and Computer Engineering Block Diagram: ANT SoC  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

11. 11 Department of Electrical and Computer Engineering Audio

12. 12 Department of Electrical and Computer Engineering Block Diagram: Speaker System  LM 386 audio amplifier- $0.34  CU-115 8 Ohm speaker- $1.01  2.9mm height, 15mm diameter

13. 13 Department of Electrical and Computer Engineering Packaging/UI

14. 14 Department of Electrical and Computer Engineering Block Diagram: User Interface

15. 15 Department of Electrical and Computer Engineering Power

16. 16 Department of Electrical and Computer Engineering Block Diagram: Power Supply  3V CR-2032/VP Energizer coin cell battery  225mAh lifespan  0.79” diameter x 0.13” height  $0.20 per battery  One battery per keyfob, two per tag

17. 17 Department of Electrical and Computer Engineering Antenna

18. 18 Department of Electrical and Computer Engineering Block Diagram: Antenna + PCB  Planar Inverted F Antenna (PIFA) integrated into PCB Isotropic, often used in cell phones Can be tuned manually by scraping copper off its end  Same PCB used for keyfob and tag (reduces cost)  PCB = 1.2 x 1.5 inches

19. 19 Department of Electrical and Computer Engineering Demonstration (Preview)

20. 20 Department of Electrical and Computer Engineering Review of 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

21. 21 Department of Electrical and Computer Engineering Demonstration  A tour of the BeepachU PCB  Item location using “Beep” feature  Item location using “Hot/Cold” Enjoy

22. 22 Department of Electrical and Computer Engineering

23. 23 Department of Electrical and Computer Engineering FPR Deliverables, Team Responsibilities

24. 24 Department of Electrical and Computer Engineering Proposed FPR Deliverables  Fully functional system System works and meets specs System fits into packaging and has professional- looking UI  Multiple tags on a single fob Because we know you want it

25. 25 Department of Electrical and Computer Engineering Individual Responsibilities Dave Zeifman  Polish current “Beep” and “Hot/Cold” code  Implement power-efficiency into TX/RX functions  Write code for multiple tags per keyfob Quanquan Han  Produce and integrate final BeepachU packaging

26. 26 Department of Electrical and Computer Engineering Individual Responsibilities Mark Wagner  Conduct power-efficiency measurements  Polish audio driving code/speaker Eric Wagner  Measure TX/RX range  Tune antenna if possible

27. Department of Electrical and Computer Engineering Questions? Thank You

28. 28 Department of Electrical and Computer Engineering 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 = 54.45mW (or 16.5mA) 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)

29. 29 Department of Electrical and Computer Engineering Power Usage Estimations  Keyfob (TX) is on for about 2 minutes per use Transmitting + LED on (for Hot/cold): 60s Working mode (for Beep): 10ms Battery indication LED: 120s Total = 1290.02615mAs = 0.359 mAh  Tag (RX) is used for 2 minutes per use Hot/Cold active : 60s Beep & LEDs active: 5s Sleep/search mode = 55s Total = 1130.3725mAs = 0.314mAh  Tag (RX) is on sleep/search mode for the rest of the time

30. 30 Department of Electrical and Computer Engineering Antenna Efficiency Measurements  Band of Operation: 2.4 - 2.5 GHz  S11 = measure of power not radiated by antenna  Max return loss within band = -15dB ≈ 3.1%

31. 31 Department of Electrical and Computer Engineering Preliminary Cost Analysis  “Each unit < $30 when “mass produced”  Mass production = 5000 units or more made  NOTES: -Each Beepachu unit requires 2 PCB’s -only the Tag requires a speaker  Total Price Tag = $13.47 Fob = $14.01 Total = $27.48

32. 32 Department of Electrical and Computer Engineering 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. 33 Department of Electrical and Computer Engineering 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. 34 Department of Electrical and Computer Engineering 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