ECE445 Senior Design Group

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ECE445 Senior DesignGroup 4RFID Parking
Meter System

• Kyle Cline
• Wes McClain
• Rich Walther

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Introduction

• Over the course of 4 (or 5) years at the U of I,
  weve received many tickets as a result of not
  having change to feed the parking meter
• Why not have a system that automates the city
  parking process?
• More convenient
• Cost effective for the consumer and the city

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Objectives

• Create a parking system that
• -Utilizes the RFID concept
• -Requires very little input from the
  consumer
• -Requires very little work by attendants
• -Minimize Cost

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Design

• Hub Unit
• Collects and stores parking meter data
• Can be connected to a central database
• Parking Meter Unit
• Preliminary design to complement existing meters
  (would be mounted on same pole)
• RFID Transponder
• Contains a unique identifier to route parking
  time to a user account

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Original Design Components

• IPASS RFID Transponder
• Texas Instruments TRF6903 RF Transceiver
• PIC mProcesser

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Block Diagram
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Original Design
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Issues

• Legal (and red tape) issues with IPASS
• Technical
• Encrypted data
• Unnecessarily high bit rate (500kbps)
• Complexity of TI TRF6903
• Low cost transceiver, but requires a significant
  number of components to operate
• Many potential error sources
• Crystal discriminator, capacitances, inductances,
  control word accuracy

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Final Design Components

• Homemade RF Transponder
• Linx HP-3 Transmitter/Receiver Chips
• PIC mProcesser

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Challenges

• Avoid eliminate interference between multiple
  parking meters, hubs, and transponders
• Timing (Very difficult)
• Hardware consistency
• Programming glitches

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Design Facts

• Modular
• Each unit consists of
• Linx HP-3 Transmitter Receiver
• PIC mProcesser
• Software programming and some I/O differentiates
  each unit

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Final Design Operation

• Utilize all available channels on Linx HP-3s
• 1 common channel, 7 unique channels
• Each meter has its own unique channel
• When the button on the meter is pushed, the meter
  sends its unique channel via the common channel
• The new transponder receives this data and sets
  its RX/TX channel to match the meter

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Final Design Operation

• Hub unit sends poll signal sequentially on each
  individual channel
• Each transponder responds to poll signal on
  individual respective channel by sending serial
  number to the parking meter unit
• When hub unit polls the meter, the unit sends
  status word transponder info to the hub

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Testing Procedures

• Transponder
• Made mock TX files
• Checked status flags (LEDs, LCD)

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Testing Procedures

• Meter-Transponder
• Tested reception of meter signal (LCD, Scope)
• Tested frequency hopping
• Tested Transponder response (frequency and data
  content)
• Timing (Most difficult part)

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Testing Procedures

• Hub
• Hub-Transponder communication (LEDs)
• Transponder-Meter reception after Hub poll sent
• Hub-Meter Poll
• Overall Integration (Difficult)

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Testing Procedures

• Hardware Issues
• Added 47 µF Capacitors (Noise rejection)
• Checked continuity on every PCB connection
• Found consistent boards/programs to find faulty
  parts

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Plots
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Hub Frequency Hopping Demonstration
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Communication Protocol

• ltsynchgtltstartgtlttypegtltdatagtltparitygtltendgt
• lttypegt defines what type of data the packet is
  carrying
• TransponderID lt0xC1gt
• ParkTime lt0xC4gt
• Status lt0xC6gt

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Successes

• Meter able to detect transponder and change
  frequency channel consistently
• Hub able to communicate with meter and
  transponder
• Hub able to tell if car has left

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Future

• Utilize RFID windshield
• sticker tags
• Develop Bluetooth / WiFi
• interface for hubs to wirelessly connect
• Directional antennas for Parking Meter to
  Transponder communication
• Antenna switching circuit to eliminate 2nd
  omni-directional antenna
• Web interface so people can look online and see
  if parking spaces are available
• Increasing availability of web-enabled mobile
  phones

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Recommendations

• Compare cost vs. ease of use in design stage
• Use directional antennas to simplify logic
• Cheaper TX/RX chip
• Optimize power consumption

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Questions ?