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Mobile Location Detection Device

Mobile Location Detection Device. Group 12 Peter Ling Michael Guh. Harness Technology to reduce frustration Harness technology in cheap practical ways Find lost wallets and keys more quickly Save time and energy, today’s most precious commodity

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Mobile Location Detection Device

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  1. Mobile Location Detection Device Group 12 Peter Ling Michael Guh

  2. Harness Technology to reduce frustration Harness technology in cheap practical ways Find lost wallets and keys more quickly Save time and energy, today’s most precious commodity Gain peace of mind knowing there is a reliable way to fine those essential items Introduction

  3. Objectives • Create circuit capable of locating a tagged item within a 50 foot radius • Give directionality and approximate distance indication • Powered by 9v battery • LED display to inform relative distance of tracked object

  4. Original Design Microcontroller (USER) Directional Antenna (RF Transmitter Omni-directional Antenna (Chip antenna) User XBee module (Object XBee module) Output to USER

  5. Original Design (continued) • Microcontroller • PIC16F877A • 5V power using LM7805 voltage regulator • Controls XBEE using RS232 by connecting RX/TX to Dout/Din respectably • Outputs LEDs

  6. Original Design (continued) • XBEE transceiver module • 2 Types • Frequency 2.4GHz • 1mW transmit power output • 2.8V-3.4V supply voltage using LM317

  7. Original Design (continued) Directional Antenna • UHF -> RPSMA, SMA or others. • Small sized directional Antenna (Patch)

  8. Design Modifications • Powering PIC16F877A • XBEE is capped at 3.4V supply. Powering the PIC16F877A at 5V would cause the XBEE to burn out. (Lesson learned). • PIC can be powered at 3.3V to solve this issue. • Directional Antenna • Directional antenna expensive and also quite large. • Other choices for directionality.

  9. Initialize Send “zzz” PIC Flow Chart Received ”zzz” ? YES Send “+++” Reset LEDs No “OK\r” received? Yes Send ATDB Read RSSI Output LEDs Send ATCN NO

  10. Reading XBEE Data • Interrupt Service to read 4 bytes at a time. • RS232 has data • Interrupt Service is called • KBHIT=1 or ½ second time out • If KBHIT=1 then read character • Repeat this 4 times

  11. PIC-XBEE Interface • Retrieving RSSI value. • Delay One second with no data sent • Print(“+++”) • Delay One second to receive “OK” and carriage return • Print(“ATDB”) and carriage return • Get RSSI values from XBEE

  12. Directional Antenna • Made from Omni-directional antenna with a grounded copper corner reflector 4.88” 2”

  13. Directional Antenna (continued) radiation pattern from past users of this corner reflector design Radiation pattern obtained from our corner reflector

  14. Lost Item Module

  15. Handheld Module

  16. Steel Chassis 6” 5.25” 9” Copper taping to completely seal edges of steel chassis Wire for grounding circuit and antenna

  17. Construction Handheld circuit in steel chassis 10 LED display

  18. Construction Omni directional antenna Corner reflector for directionality Assembled handheld unit Tagging module

  19. Functional Test Distance in Feet RSSI signal in DB Signal strength varies as square of distance

  20. Testing Xbee performance (line of sight) Percent transmitted successfully Distance in feet

  21. Testing Xbee performance (through cement wall) Percent transmitted successfully Distance in feet

  22. Power Supply • Draws power from a 9V battery • Provides stable +3.1 V and Ground to both Xbee module and PIC • Powers both handheld and lost item module Vout = 1.25V(1 + R2/R1) + Iadj(R2)

  23. Power Vmax: 3.1195 V Peak to Peak: 6.3mV Frequency: 5.93 MHz

  24. Battery Life • 500mAhr rated capacity for battery. • Xbee draws 45 mA of current in Receive/Transmit mode • Translates to approximately 11 hour of search time

  25. PCB/Protoboard • Created a PCB for the user board • Board errors • Time restrictions • Proper use of protoboards can reduce size of both modules.

  26. Success • Safe powering of XBEE and PIC • PIC Interface with XBEE • Data transfer between 2 XBEEs • Obtaining a relative distance of 50 feet

  27. Challenges • Obtaining exclusive directionality • Isolating antenna emissions • Minimizing power consumption • Understanding RS232 along with PIC

  28. Next Steps • Reduce size of both modules to increase efficiency for user • Look into using Zensys ZW0201 Zradios • Cheaper • Smaller • More power efficient • Continue investigation to increase effectiveness of directional antenna

  29. Recommendations • Work at your strong points • Know the tools and resources available • Keep your options open • If you get stuck, ask around. Someone might say something that will be useful. • Give the machine shop time • You wait for them

  30. Thank You • Our TA: Paul Rancuret • Professor Gary Swenson • Professor Jennifer T. Bernhard • Mark Smart

  31. Questions?

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