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

Card Reader

Power Supply

Wireless transmission circuitry

Bar code reading circuitry

Wireless Receiver circuitry

Host PC reception

Host PC software (media app)Card

containing bar code

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.

IS489 Light Detector

Light 0 volt output

To PIC

IS489 Light Detector

No Light

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

SLEEP mode

Wake up Interrupt (card

entered)

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

YesSignal

Received

NoSignal 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

User Request Thread

Bar Code Received? No

Yes

Update Spreadsheet

No, Execute File

Media file?

Yes, user queue?

Handle User Requests

Yes, place in queue

Create Card

Maximize Window

Change Bar Code

If user queue, Check Media Availability

If free, execute next media in queue

Physical Level Realization

Card Reader (plastic)

Battery (Duracell)

PIC16F627A

IR transceiver

PIC16F627A

IR transceiver

USB connection

PC/ MAC/ Laptop

5V USB power

End Result

Human User

Cards

Card Reader

Printer (inkjet or laser)

User Scan (power enabled)

Card entry recognition

Photo-detectorReflection

IR transmission

PIC bit recognition

Amplify, Digitize signals

Media Application

Java software bit reception

USB Communication

PIC bit reception

IR reception

Enter Waiting Queue

Update Interface

White = 0

Black = 1

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 ?