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Wireless Key Locator:

Wireless Key Locator:. Jian Zhang Francisco Lao ECE 445: Senior Design. Objectives:. To keep track of one’s possessions such that one will never lose/misplace important items, such as keys, wallets, PDAs, etc. Similar Available Products. “Remote Control” Finder

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Wireless Key Locator:

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  1. Wireless Key Locator: Jian Zhang Francisco Lao ECE 445: Senior Design

  2. Objectives: • To keep track of one’s possessions such that one will never lose/misplace important items, such as keys, wallets, PDAs, etc.

  3. Similar Available Products • “Remote Control” Finder • Radio frequency remote controller locators • Sound induced remote controller locators

  4. Problems • Radio Frequency Finder • Uses one remote to find another • High power consumption • Sound-induced Finder • Environmentally limited • Very limited range

  5. Our Solution • RFid • Radio Frequency IDentification • RFID couples data into the RF portion of the electromagnetic spectrum • An RFID system consists of • Transponder • Transceiver • Antenna

  6. RFID Pros and Cons: • Pros • Power efficient • Very portable • Cheap • Long lifetime • Cons • Many different protocol standards • Operative range proportional to tag size and reader power • Operation range affected by environment

  7. Applications of RFid Today: • Inventory control • Product tracking through manufacturing and assembly • ID badges and assess control • Parking lot assess and control

  8. Our Design Goals • Low Power Consumption • Cheap • Portable • ~6 ft. Range

  9. Block Diagram

  10. Power Regulator • Goals: • Step down from 6V to 5V efficiently • Provide stable output independent of load • Results: • From Scope 

  11. Regulator Schematic

  12. Transceiver • Goals: • Low Power Consumption • ~ 6 ft. operation range • Small • Resolution: • TI-S6700 Transceiver IC • Small • Cheap ($10 per IC) • Low power consumption • 50 uA Idle-Oscillator off • 15 mA Idle-Oscillator On • High power transmission • 200 mA

  13. Transceiver Schematic Transceiver Design from TI-S6700 Manuel

  14. Microcontroller • Goals: • Provides appropriate inputs to the transceiver and the LEDs • Decodes transceiver outputs • Resolution: • PIC16F877

  15. Flow Chart of Microcontroller:

  16. Transponders: • Goals • Cheap • Portable • No External Power Source • Resolutions • Ti Tag-It Transponders

  17. Success and Failure • Success • Power Regulator Works Properly • Current drawn under no-load condition ~ 0.001 A • Voltage Output: 5.054 V, ripple 8.44 mV • Microcontroller Outputs and decodes properly • Transceiver Outputs Properly • Failure • Tag will not respond properly to Transceiver

  18. Experimental Results: Transceiver • Output Data of Transceiver using Tag-It

  19. Experimental Result: Tag + Transceiver • Transceiver with Tag • Transceiver without Tag

  20. Power Consumption • Direct Mode: • PIC + Transceiver Transmit mode  198 mA PIC  23 mA Transceiver  175 mA • PIC + Transceiver Idle mode  52 mA PIC  23 mA Transceiver  29 mA PIC + Transceiver Idle mode + Regulator  ~56 mA

  21. Power Consumption • Tag-it Mode • PIC + Transceiver Transmit mode  215 mA PIC  29 mA Transceiver  186 mA • PIC + Transceiver Idle mode  59 mA PIC  29 mA Transceiver  30 mA PIC + Transceiver Idle mode + Regulator  ~65 mA

  22. Power Consumption: • Idle state oscillator OFF: (NO XTAL) • Direct Mode: • PIC + Transceiver Transmit mode  35 mA PIC  23 mA Transceiver  ~12 mA • Tag-It Mode: • PIC + Transceiver Transmit mode  39 mA PIC  28 mA Transceiver  ~11 mA

  23. Problem Areas: • Incorrect RFid tag response • Power consumption not suitable for battery use

  24. Our Explanations: • Tag Response: • Incorrect CRC of transmission sequence • Frequency mismatch • Power Consumption: • Increased LOAD due to passive components

  25. Future Works • Smaller, more power efficient microcontroller • Small, stable, rechargeable source • Long range tags that respond to multiple transmission protocols • Design high-performance planar antenna on transceiver circuit

  26. Q & A:

  27. Acknowledgements • Jim Wehmer and the Part Shop people • Richard Cantzler • Chirantan Mukophadyay • Tech. Support at TI

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