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Multidisciplinary Engineering Senior Design 6510 Interface Project Preliminary Design Review 11/19/05 Project Participants Sponsor: Mr. David Perlman Coordinator: Professor George Slack Team Members: Eric Bohannon (CE), Michael Winslow (EE), Scott Urban (ID) Project Mission Create a cost effective card reader that wirelessly transmits the data to a listening host computer to perform a computer instruction Platform independent Audience of 10 to adult Card containing bar code created on credit card size piece of cardboard Feasibility Project mission is attainable Innovation Creative way to convert cardboard ink to electronic signal Photo-Diode Creative way to design “card reader” Interfacing Keeping bits from bar code stored PIC Wireless Communication between host computer and card reader Customer Requirements Entire product is low cost Card reader is compact Card reader is battery powered Card produced on inkjet or laser printer Customer Requirements Card produced on cardboard Card Dimensions (credit card) Platform independent Wireless transmission End software has media capability Block Diagram Bar code reading circuitry Card Reader Power Supply Wireless transmission circuitry Card containing bar code Wireless Receiver circuitry Host PC reception Host PC software (media app) Core Design Modules Card Reader (physical structure, dimensions, look and feel) Card containing bar code Power supply Bar code reading circuitry Core Design Modules Wireless transmission circuitry Wireless receiver circuitry Host PC wireless reception Host PC end software Card Design Credit Card Size Card Stock Black Bar = “1” White Bar =“0” Card Reader Self Contained (power supply, bar code circuitry, wireless transmission circuitry, and card holder) Slot for obvious insertion of card Withstand falling Reader Design Aesthetics (board/party game) Appeal to young teenagers without distancing adult market (target: 10-up) Reader Design Power Supply Standard (Duracell/Energizer) 9V batteries LM2937 5V linear regulator Save Power Sleep Mode (PIC) Disable Wireless Transmission Low Battery Detect Low Battery Warning Voltage Divider with Comparator Bar Code Reading Circuitry Eight detectors will be used to detect the black (no light) and white (light) lines on the card. Comparators CMOS Levels IS489 Light Detector Eight IS489 devices will read the data bits off the card. Light No Light IS489 Light Detector IS489 Light Detector 0 volt output To PIC 5 volt output To PIC PIC16F627 Microcontroller Controls photo-detectors and wireless circuitry SLEEP mode 16 Input/Output pins RISC CPU, each instruction takes 1us @ 4 MHz (except program branches) Power Up Initialize Registers and I/O pins Wake up Interrupt (card entered) SLEEP mode Read Data off Card TX Data to IR Transceiver Wait for “OK” signal coming back from computer Check Low Battery Pin Flash LED to Indicate Problem Yes Signal Received No Signal not Received Wireless Circuitry Agilent HSDL-3000 IR Transceiver One at card reader and another at computer end. Typical link distance > 1.5 m Low shutdown current (10 nA typical) Agilent HSDL-3000 USB Interface FTDI FT232BM Receives data from IR transceiver and sends it to the computer via USB port. Virtual com port drivers available DLP-TXRX End Software Java program listening to USB Receive each bar code from USB Filter “noise” Execute instruction Virus scan Mail check Special Media options Query USB Thread Bar Code Received? No Yes Update Spreadsheet Media file? User Request Thread Yes, user queue? Handle User Requests Yes, place in queue Create Card Change Bar Code If user queue, Check Media Availability Maximize Window If free, execute next media in queue No, Execute File Physical Level Realization PIC16F627A Card Reader (plastic) Battery (Duracell) IR transceiver IR transceiver PC/ MAC/ Laptop USB connection 5V USB power PIC16F627A Human User Card Reader User Scan (power enabled) Card entry recognition Cards Black = 1 End Result Printer (inkjet or laser) Photodetector Reflection White = 0 Amplify, Digitize signals PIC bit reception IR reception IR transmission USB Communica tion Java software bit reception Media Application Update Interface Enter Waiting Queue PIC bit recognition Cost Assessment Power Supply ~ $4 Photo-Detector Circuit ~ $7 Microcontroller ~ $5 IR Transceivers ~ $7 USB Interface ~ $7 Total ~ $30 Testing Battery Life Card Reader Dimensions Card Size Dimensions Bar code dimensions Distance between photo-detectors Testing Wireless transmission error rate User error Photo-detection error Wireless distance Mac/Windows capability Technical Concerns: Power Saving (ability to keep card reader off when idle) Wireless signal distance (how far away will card reader be from computer) Photo-Detector saturation levels (how differently will black ink and a white background saturate a transistor) Questions ?