Multidisciplinary Engineering Senior Design

Project 06509 RFID Garage Door Entry SystemPreliminary Design Review2.24.2006

Team Members: Kenneth Williams, Michael Cummins,Thomas Cervino, Michael Flannery

Kate Gleason College of EngineeringRochester Institute of Technology

Design Process

Needs Assessment Concept Development Feasibility Assessment

Needs Assessment

RFID Garage Door Opener

Needs to interface with standard garage door

opener (24VDC)

Tag shall have battery life span of at least one year

Range of 30 feetSystem will not interfere

with existing factory setupSurface Mountable

Shall store at least one tag. May store more.

Shall have disabling device on reader. May have one

on tag

Mass Production cost of less than $100

System Shall Use RFIDSystem shall be easy to

installUnit shall interface with all

hardwired controls

Shall have one 120V power connection (hot, neutral,

ground)

Tag shall be battery operated and portable

Deliverables

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

Garage Door Opener

Garage Door Inputs

Wall Pushbutton

Unmodified Garage Control Setup

Concept Development

Design of a RFID Garage Door Entry SystemT

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Existing Garage Door

SystemRFID System+ =

RFID Tag RFID ReaderGarage Door

Opener

Reader

rfPICMicrocontroller &

Transmitter

Optional CO detector

RF Receiver

Garage Door Motor Control

Garage Door Buttons

Memory

Manual Override

I/O

I/O

I/O

I/O

I/O

I/O

RFID Garage Door Entry System

In Car In Garage In Garage

Reader

>30'

Wireless 433 MHz Transmit/Response

Rate

Hardwired Connection

Existing SystemAutomatic control of Door

I/O

Tag

Tag

rfPICMicrocontroller &

TransmitterI/O RF Receiver

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.

Initialize:Door is closed.Write variable

Status = ClosedCar is not present.

Start

Call Module

1

Module 1?

Tag in range.Status = Open;Door_Signal();

Tag out of range. Status = Closed;

Timer Done?

5 min wait

1 0

0 1

Call Module

1

Module 1?

Door_Signal();Status = Closed;

Door_Signal();Status = Closed;

Point A

Sleep();

Car is present. Status = Open;

Call Module

1

Module 1?

Wait 60 seconds

Point B

Timer Done?

Status = Closed;Door Signal();

Start();

1 0

1 0

Software Design Flow (Interrupts)

Current Process

(run/sleep)

INT pin

Door_Signal();Status =

not(Status);

Push Button Interrupt-- Highest Priority Level

1

Current Process ==

Run?

Return to point A Return to Point B

0

Push Button Interrupt

Load/Start Timer0

Timer0 done?

GPIO1

Mode = SleepMode = Run

Current Process

(run/sleep)

1 0

0

1

Standard Timed Interrupt-- 2nd Highest Priority Level

Timer Interrupt

Transistor Relay Circuit

Garage Door Opener

Relay

No Connection

Garage Door

Inputs

Rx29.4kΩ

GPIO0 Pin on Microcontroller

VDD (+5VDC)

Relay CoilCoil Voltage: 5VDCCoil Res: 167Ω

RFID Reader

Wall Pushbutton

INT Pin on Microcontroller

Modified Garage Control Setup

VDD (+5VDC)

Garage Door Opener

Garage Door

Inputs

Wall Pushbutton

Unmodified Garage Control Setup

Transistor Relay Simulation

•Desired Ic ≈ 30mA

•Ic = β*Ib

•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 day8.2 mA receive draw, 14 mA transmit draw

mAhnAmAhour

mAmAhour

137)1000001(.min60

1min525235)142.8(

min60

1min365

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

rfPIC12F675FMouser…………………………$2.92

DC Power Jack

IRC Resistor

NPN Transistor

RadioShack……………………$9.28

Project Enclosures

Crystek…………………………$2.36

CrystalsmuRata…………………………$0.50

HF Ceramic FilterEPCOS…………………………$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

Antenna Length Calculation:

λ=c/f where c is the speed of light and f is the

transmission frequency

Backup Slides and References

R8 is a variable resistance that changes the RF output power