Transcript RFID Smart Home System

David Meyers, Jared Santinelli, Phillip Robinson,
Nazar Trilisky
Georgia Institute of Technology
School of Electrical and Computer Engineering
October 23, 2008

Goal: Prototype of an RFID-based access control system
featuring adaptive lighting

Target Customer: Builders and developers of Multiple
Dwelling Units (MDUs)

Motivation: Increase security and convenience while
saving money
 ~44% reduction in electricity

Target Prototype Cost: < $500
 Actual Cost: $688.90

Basic Layout
 Red- “Entrance/Exit Module”
 Green – “Room Module”
Objective
Implementation
Automated entry/exit and
identification
Phidget RFID readers triggering
entry and exit modules
Occupant tracking
Provide and update a log file and
GUI
Hallway light automation
entry/exit
Entry lighting controlled by eBox.
Exit lighting controlled by timing
circuit
Need based foyer lighting
Photovoltaic switch to determine
natural light conditions
Electric door strikes for security
Fail secure mode
22.5 in
39 in
39.5 in
Phidget RFID Reader (USB)
 EM4102 Passive Tags @ 125 kHz
(Read Only)
6.8 cm
 Min Distance Between Readers: 1 m
▪ Actual: 18-24 in
 Read Range
▪ Vertical: 0.5 in to 4 in
▪ Lateral: 0.5 in to 2 in
8.1 cm


eBox-2300
Available Interfaces
 3 USB ports – For RFID Reader Communication
 1 RS-232 port – For Microcontroller Communication
▪ Straight through serial cable - TxD Pin #3
 1 Ethernet
 1 Monitor Connection

OS/Application languages
 Windows CE 6.0
 C# - Modified sample code
Waiting for RFID tags to scan
Main door
entering. Valid?
Yes
No
Relock
Room door
entering. Valid?
Main door
exiting.
Yes
Open / Turn On
Sleep
Thread 1
Close/ Turn Off
Thread 2

CY8C29466-24PXI
 24 Digital General Purpose I/O Pins
 Maximum 80 mA combined IOH budget
 VOH = Vdd – 1 V = 4 V Min.
 VOL = .75 V Max.

Door Strike (SD-995C)
 Triggered with 7.3 V differential
 Fail-safe or Fail-secure modes

12 V Relays
 Operate at 80-100% of specification voltage
 DP-DT increases scalability

Photovoltaic Switch

Three Position Switch
Motion
Detector
Op Amp
Circuit
RC Timer
Circuit
•100uF capacitor and 270kΩ resistor
determine timing characteristic
•Created -12 VDC using 555 timer
Isolation
Op Amp
Circuit
To Transistors
Problems
Solutions
Grounding Issues
Re-solder connections to
circuit board and replace
motion detector
Unregulated 5V power source
External 5V power supply
C# coding restrictions (.NET
compact framework)
Adapted algorithms to use
available libraries
Pin 17 not functional
Other available pins
Relay turn-off delays
Components with higher
tolerances
Back EMF through transistor
Addition of Snubber circuit
Room Door
Unlocks
Light On
1
Test 1: Invalid Tag
Test 2: Valid Tag
Room 1
Test 3: Valid Tag
Room 2
Room Door
Hallway
Lights On
Lights On
2
Main
Door
Main Door
Main Door
Remains
Unlocked
Locks
Locked
Item
Expected
Actual
Prototype Cost
$451.97
$688.90
Additional Room Modules
Cost
$155.41
$275.34
$38,600.00
$43,270.00
$1,090,119.00
$1,008,498.26
Target Price of 50-Unit
Building
5 Year Profit – 490 Units
sold

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Alternative communication between readers and ebox
 Ethernet, Wireless
Integration of additional systems
 Security, AV Equipment
Regulated DC created from AC power
Integration of circuit components into a single DIP
Processing power required for expanded system