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Published byJonathan Howard Modified over 9 years ago
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David Meyers, Jared Santinelli, Phillip Robinson, Nazar Trilisky Georgia Institute of Technology School of Electrical and Computer Engineering October 23, 2008
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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
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Basic Layout Red- “Entrance/Exit Module” Green – “Room Module”
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ObjectiveImplementation Automated entry/exit and identification Phidget RFID readers triggering entry and exit modules Occupant trackingProvide 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 lightingPhotovoltaic switch to determine natural light conditions Electric door strikes for securityFail secure mode
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22.5 in 39.5 in 39 in
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Phidget RFID Reader (USB) EM4102 Passive Tags @ 125 kHz (Read Only) 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 6.8 cm 8.1 cm
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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
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Main door entering. Valid? Waiting for RFID tags to scan Room door entering. Valid? Main door exiting. Relock Open / Turn On Sleep Thread 1 Thread 2 Close/ Turn Off Yes No
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CY8C29466-24PXI 24 Digital General Purpose I/O Pins Maximum 80 mA combined I OH budget V OH = V dd – 1 V = 4 V Min. V OL =.75 V Max.
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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
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Motion Detector Op Amp Circuit RC Timer Circuit Isolation Op Amp Circuit To Transistors 100uF capacitor and 270kΩ resistor determine timing characteristic Created -12 VDC using 555 timer
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ProblemsSolutions Grounding IssuesRe-solder connections to circuit board and replace motion detector Unregulated 5V power sourceExternal 5V power supply C# coding restrictions (.NET compact framework) Adapted algorithms to use available libraries Pin 17 not functionalOther available pins Relay turn-off delaysComponents with higher tolerances Back EMF through transistorAddition of Snubber circuit
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Test 1: Invalid Tag Hallway 1 2 Room Door Main Door Main Door Remains Locked Test 2: Valid Tag Room 1 Main Door Unlocked Main Door Locks Lights On Room Door Unlocks Light On Test 3: Valid Tag Room 2 Lights On
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ItemExpectedActual Prototype Cost$451.97$688.90 Additional Room Modules Cost $155.41$275.34 Target Price of 50-Unit Building $38,600.00$43,270.00 5 Year Profit – 490 Units sold $1,090,119.00$1,008,498.26
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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
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