Multidisciplinary Engineering Senior Design Project RFID Garage Door Entry System Preliminary Design Review Team Members: Kenneth Williams, Michael Cummins, Thomas Cervino, Michael Flannery Kate Gleason College of Engineering Rochester Institute of Technology

Design Process  Needs Assessment  Concept Development  Feasibility Assessment

Needs Assessment

Project Overview  RFID Background What is RFID? Types of RFID tags  Passive  Semi-Passive  Active Encoding Options  Garage Door Background Pushbuttons and Safety

Pushbutton Schematic

Concept Development

Key Requirements & Critical Parameters (Concept Development)  RFID Reader 433MHz Communication 120VAC 60Hz  RFID Tag 1 Year Battery Life  Communication Protocol Minimal Power Drain ASK

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

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.

Software Design Flow (Interrupts)

Transistor Relay Circuit

Transistor Relay Simulation Desired I c ≈ 30mA I c = β*I b β =205

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

Security (continued)  Key Features ASK Tag ID Pseudo Random Key Security Function (Password Generation)

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

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

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

Anticipated Design Challenges  Antenna Design Range Interference  Tag Power Output Power Consumption  Programming Complexity

SD II Project Plan  Build Prototype  Test Software  Determine Range  Test Complete Functionality

Questions

Backup Slides and References