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Wirelessly Powered Sensor Network

Team Tesla. Wirelessly Powered Sensor Network. Damian Manda Leo Ascarrunz. Brian Fairburn Sarah McNamara. Review: Project Description. Power Transmitter. Wireless Sensor. Wireless Sensor. Wireless Sensor. Wireless Sensor. Wireless Sensor. Wireless Sensor. Extended. Internet. GUI.

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Wirelessly Powered Sensor Network

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  1. Team Tesla Wirelessly Powered Sensor Network Damian Manda Leo Ascarrunz Brian Fairburn Sarah McNamara

  2. Review: Project Description Power Transmitter Wireless Sensor Wireless Sensor Wireless Sensor Wireless Sensor Wireless Sensor Wireless Sensor Extended Internet GUI Base Station

  3. System Block Diagram Sensor Module Web-based Interface Analog & Digital Lines Power / Processing Board ANT (2.45 GHz RF) REST 5.8 GHz RF Computer USB Base Station Power Transmitter

  4. Power System Block Diagram Power Source Selection Rectenna Processor Transceiver Sensors DC-DC Converter Battery Charging

  5. Power Receiving Antenna • Dual polarized microstrip patch rectenna • 5.8GHz 3.8cm 3.8cm

  6. Rectenna Peak Power • Antenna power output is dependent on: • Incident power density (here in μW/cm2) • Load resistance • Optimal load resistance for peak power collection is mostly independent of incident power density

  7. Emulated Resistance • Desired Emulated Resistance: 1.2kΩ – 1.5kΩ • Want to be on the right side of the curve

  8. Power System Block Diagram Power Source Selection Rectenna Processor Transceiver Sensors DC-DC Converter Battery Charging

  9. Boost Converter • Operates in pulsed fixed frequency discontinuous conduction mode

  10. Boost Converter

  11. Boost Converter Problems • Resistance seen by the input varies with the output voltage

  12. Buck-Boost Converter • Also operates in pulsed fixed frequency discontinuous conduction mode • Requires a floating input voltage source to allow non-inverted output

  13. Buck-Boost Converter

  14. Buck-Boost Converter • Choice of parameter settings based on: • expected input power level • desired emulated resistance • Expected input power: 50 μW – 200 μW • Emulated resistance: 1.2kΩ – 1.5kΩ

  15. Spice Simulation Results • Output Voltage between 3.3 and 2.6 V • Input power independent of output

  16. Spice Simulation Details 30ms Active Time 150 uf Storage

  17. Power System Block Diagram Power Source Selection Rectenna Processor Transceiver Sensors DC-DC Converter Battery Charging

  18. Power Source Selection • Processor is able to switch to the backup battery by outputting the Batt_Backup signal • If battery backup is needed, Batt_Backup is set to high, and the input power source is changed to the backup battery

  19. Power Source Selection • Using Si151DL • Complementary 20-V (D-S) Low-Threshold MOSFET

  20. Power System Block Diagram Power Source Selection Rectenna Processor Transceiver Sensors DC-DC Converter Battery Charging

  21. Battery Charging • As long as the output voltage from the buck-boost converter is above a set level, we want the battery to be charging • If the converter output drops below that set level, the battery stops charging

  22. Battery Charging • Using ISL88001 • Ultra Low Power 3 Ld Voltage Supervisors • Fixed-voltage options allow precise monitoring of +1.8V, +2.5V, +3.0V, +3.3V and +5.0V power inputs • 160nA supply current

  23. Power Source Selection Schematic View Battery Charging System

  24. Sensors & Transmission Data Collection & Dissemination

  25. Sensor Board Diagram Universal Header Connection Sensor IC Sensor ID Micro Pitch Connector Samtec LSHM–120–01–L–DH–A–S–K–TR Power / Processor Board

  26. Circuit Diagrams – Sensor Board • Accelerometer • CMA3000 • Temperature • TMP36 • LM94022 • Humidity • Ambient Light • Occupancy • Pressure • Force

  27. Transceiver: nRF24AP2

  28. Transmission Operation Using asynchronous communication mode w/ modules as masters Connection Configuration [UART] Data Packet

  29. Data Transmission Antenna • Antenna Factor ANT-2.4-CHP-T • Omni-directional radiation pattern • 50Ω impedance – no external matching • 0.5dBi Gain

  30. Processor Pinout MSP430F2616

  31. Software Flowchart

  32. Programming • Setup • Get Data • Process Data • Transmit Data • Sleep

  33. Setup • Lock all Unused Pins • Set to Input with pull down/up Resistor active • Set on Used Pins • Built in UART enabled • 9600 baud • Built in A/D enabled • Watchdog and Interrupts configured • Set voltage supervisor trip point

  34. Get Data • Temperature and Accelerometer • Both are analog devices • Use the Built in 12 bit A/D convertor. • Sample and Hold • Possible use of the on board DMA controller to transfer data

  35. Process Data • Determine if data is needed to be sent. • New? • Important? • Format Data into a useful format to send. • Inputs: Data from A/D • Outputs: Data sent to Transmitter

  36. Transmit Data • Use Built in UART to communicate with our transceiver. • Asynchronous communication at currently 9600 Baud • Input: Data from Process Data • Output: UART communication

  37. Sleep • Low Power Mode 3 • CPU Disabled • MCLK/SMCLK Disabled • DCO's dc generator Disabled • ACLK still active • Interrupt to deal with data. • DMA

  38. Computer Software • GUI Programmed in C# • Native USB Libraries • Easy to display output • Knowledge of developer • Web interface • Communication to a REST PHP based server • Output to flash charts / PHP dynamic pages

  39. Parts List

  40. Schedule & Planning

  41. Full Schedule

  42. Update on CDR Goals Original Progress Circuit diagrams complete Revision in development by grad students PCB created, but have since revised converter design Various sample code run, basic setup code created • Sensor testing boards • Initial antenna design • First power supply boards done & testing begun • Development board learning

  43. Forward Schedule Summary • Milestone 1 • Sensor boards physically constructed • Final antenna design • Power supply optimization • Milestone 2 • Full sensor reading & data transmission • Full PCB w/ all parts integrated • Computer interface developed • Expo • Documentation • Final board revisions

  44. Ongoing Risks & Solutions • Boost Converter Needs 2.2V to start switching • Can use S-882Z charge pump to pre-charge output capacitor to 2.2V • Use a battery as storage element

  45. Division of Labor

  46. Questions? Team Tesla In order of presentation: Sarah McNamara Leo Ascarrunz Damian Manda Brian Fairburn

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