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Multidisciplinary Engineering Senior Design Project 06509 RFID Garage Door Entry System Preliminary Design Review 2.24.2006 Team Members: Kenneth Williams, Michael Cummins, Thomas Cervino, Michael Flannery Kate Gleason College of Engineering Rochester Institute of Technology
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Design Process Needs Assessment Concept Development Feasibility Assessment
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Needs Assessment
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Project Overview RFID Background What is RFID? Types of RFID tags Passive Semi-Passive Active Encoding Options Garage Door Background Pushbuttons and Safety
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Pushbutton Schematic
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Concept Development
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Key Requirements & Critical Parameters (Concept Development) RFID Reader 433MHz Communication 120VAC 60Hz RFID Tag 1 Year Battery Life Communication Protocol Minimal Power Drain ASK
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Devices (Concept Development) rfPIC12F675F Transmitter ASK 14 mA transmit current draw.1 µA standby current draw rfRXD0420 Receiver ASK 8.2 mA receive current draw <100 nA standby current draw
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Detailed Software Design Flow Software Design The controller possesses two independent timer modules which will be used in software timing and to generate a standard timed interrupt to detect changes in the enable switch state.
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Software Design Flow (Interrupts)
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Transistor Relay Circuit
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Transistor Relay Simulation Desired I c ≈ 30mA I c = β*I b β =205
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Security Phase 1 (Start signal) Reader -> Transmit Tag -> Receive Phase 2 (ID) Reader -> Receive Tag -> Transmit Phase 3 (Security Key) Reader -> Transmit Tag -> Receive Phase 4 (Password) Reader -> Receive Tag -> Transmit
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Security (continued) Key Features ASK Tag ID Pseudo Random Key Security Function (Password Generation)
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Feasibility Analysis Power Equation Battery = 220 Milliamp Hours 365 minutes = 30 seconds transmit/receive x 2 times a day 8.2 mA receive draw, 14 mA transmit draw
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Devices rfPIC12F675F Transmitter 433 MHz, 4800 Baud 1024 x 14 Flash Program Memory 128 x 8 EPROM Data Memory 100,000 Write Flash Endurance 6 I/O Pins 2 Timers ASK 14 mA to.1 µA current draw rfRXD0420 Receiver 433 MHz 8.2 mA to <100 nA current draw ASK
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BOM & Costs Total Cost: $42.74 Digi-Key………………………$21.46 Capacitors Resistors Lithium Cell Battery Coin Cell Battery Holder Pushbutton Switches Relay 120V to 5V Transformer Square Headers and Right Angle Posts Microchip……………………$5.29 rfRXD0420 rfPIC12F675F Mouser…………………………$2.92 DC Power Jack IRC Resistor NPN Transistor RadioShack……………………$9.28 Project Enclosures Crystek…………………………$2.36 Crystals muRata…………………………$0.50 HF Ceramic Filter EPCOS…………………………$0.93 HF SAW Filter
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Anticipated Design Challenges Antenna Design Range Interference Tag Power Output Power Consumption Programming Complexity
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SD II Project Plan Build Prototype Test Software Determine Range Test Complete Functionality
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Questions
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Backup Slides and References
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