Transcript Multidisciplinary Engineering Senior Design Project 06509

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
Design Process
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Needs Assessment
Concept Development
Feasibility Assessment
Needs Assessment
Deliverables
RFID Garage Door Opener
Needs to interface with
standard garage door
opener (24VDC)
Range of 30 feet
Shall store at least one tag.
May store more.
Tag shall be battery
operated and portable
System Shall Use RFID
Surface Mountable
Shall have one 120V power
connection (hot, neutral,
ground)
Mass Production cost of
less than $100
Tag shall have battery life
span of at least one year
System will not interfere
with existing factory setup
Shall have disabling device
on reader. May have one
on tag
System shall be easy to
install
Unit shall interface with all
hardwired controls
Project Overview
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RFID Background
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What is RFID?
Types of RFID tags
Passive
 Semi-Passive
 Active
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Encoding Options
Garage Door Background
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Pushbuttons and Safety
Pushbutton Schematic
Wall Pushbutton
Garage
Door
Inputs
Garage Door Opener
Unmodified Garage
Control Setup
Concept Development
Design of a RFID Garage Door Entry System
Concept
Concept
Reader
Tag
Existing
Garage Door
System
+
RFID Garage Door Entry
System
=
RFID System
Communication
Communication
>30'
In Car
In Garage
RFID Tag
RFID Reader
In Garage
Hardwired Connection
Garage Door
Opener
Wireless 433 MHz
Transmit/Response
Rate
Reader
I/O
Reader
Reader
Manual Override
rfPIC
Microcontroller &
Transmitter
I/O
Garage Door
Motor Control
I/O
RF Receiver
I/O
Garage Door
Buttons
Existing System
Optional CO detector
I/O
I/O
I/O
Memory
Tag
Tag
Tag
rfPIC
Microcontroller &
Transmitter
I/O
RF Receiver
Automatic control of Door
Key Requirements & Critical
Parameters (Concept Development)
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RFID Reader
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RFID Tag
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433MHz Communication
120VAC 60Hz
1 Year Battery Life
Communication Protocol
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Minimal Power Drain
ASK
Devices (Concept Development)
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rfPIC12F675F Transmitter
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ASK
14 mA transmit current draw
.1 µA standby current draw
rfRXD0420 Receiver
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ASK
8.2 mA receive current draw
<100 nA standby current draw
Detailed Software Design Flow
Initialize:
Door is closed.
Write variable
Status = Closed
Car is not present.
Software Design
Start
Call
Module
1
1
Module 1?
Tag in range.
Status = Open;
Door_Signal();
Point A
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
0
Tag out of range.
Status = Closed;
enable switch state.
Point B
5 min wait
Car is present.
Status = Open;
Timer Done?
Call
Module
1
Module 1?
0
Door_Signal();
Status = Closed;
Call
Module
1
Module 1?
1
1
Door_Signal();
Status = Closed;
Sleep();
Status = Closed;
Door Signal();
Start();
Wait 60 seconds
1
Timer Done?
0
0
Software Design Flow (Interrupts)
Push Button Interrupt
Timer Interrupt
Push Button Interrupt-Highest Priority Level
Standard Timed Interrupt-2nd Highest Priority Level
Current
Process
(run/
sleep)
Load/Start Timer0
INT pin
Current
Process
(run/
sleep)
1
Door_Signal();
Status =
not(Status);
Timer0 done?
0
1
Current
Process ==
Run?
0
GPIO1
1
Return to point A
0
Return to Point B
Mode = Run
Mode = Sleep
Transistor Relay Circuit
Wall Pushbutton
Garage
Door
Inputs
Wall Pushbutton
Garage Door Opener
INT Pin on
Microcontroller
Unmodified Garage
Control Setup
VDD
(+5VDC)
VDD
(+5VDC)
Relay
Garage
Door
Inputs
No Connection
Relay Coil
Coil Voltage: 5VDC
Coil Res: 167Ω
Garage Door Opener
GPIO0 Pin on
Microcontroller
RFID Reader
Modified Garage
Control Setup
Rx
29.4kΩ
Transistor Relay Simulation
•Desired Ic ≈ 30mA
•Ic = β*Ib
•β =205
Security
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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)
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Key Features
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ASK
Tag ID
Pseudo Random Key
Security Function (Password
Generation)
Feasibility Analysis
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Power Equation
365 min
1hour
1hour
(8.2mA  14mA)  525235 min 
(.0001mA  100nA)  137mAh
60 min
60 min
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
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rfPIC12F675F Transmitter
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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
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433 MHz
8.2 mA to <100 nA current draw
ASK
BOM & Costs
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
RadioShack……………………$9.28
Project Enclosures
Crystek…………………………$2.36
Crystals
muRata…………………………$0.50
HF Ceramic Filter
EPCOS…………………………$0.93
HF SAW Filter
rfPIC12F675F
Mouser…………………………$2.92
DC Power Jack
IRC Resistor
NPN Transistor
Total Cost:
$42.74
Anticipated Design Challenges

Antenna Design
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Tag
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Range
Interference
Power Output
Power Consumption
Programming
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Complexity
SD II Project Plan
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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