WaitLess Bus TrackingDisplay

Matthew BrooksChristopher Chidi

Daniel NadeauJosh Mauldin

Georgia Institute of Technology ECE 4007 Senior Design

Final Project PresentationApril 24th, 2009

Project Overview What: A display showing GPS locations of Georgia Tech

campus buses using LEDs arranged along a map placed at campus bus stops.

Why: 96% of surveyed students are dissatisfied with current text based bus prediction systems which are limited to only a few bus stops.

Who: Assists campus pedestrians in deciding whether to wait for the bus or just walk.

Cost: Estimated prototype development cost of $6700. Per unit cost production will be ~ $600.

Design Objectives Low Power

Solar panel with battery Low power micro-processor

Internet Access Wi-Fi module Use existing GPS data available via

NextBus.com (XML feed)

Self-Sustaining/Easy to Deploy No wires/low maintenance No energy cost Weather proof case

Low Cost Per unit cost ~ $600

Design Overview12Và 5V

Regulator

5V

I2C

5V

5Và 3VRegulator

12V BatterySolar Charger

Processor

LED Display

WiFi Module

5Và 3VVoltage Divider

3Và 5VLevel Shifter

Serial

Obstacles and ModificationsObstacles Solutions

Found that LED leads were not as specified on spec sheet, hence flawing PCB design

Soldered jumper wires on the PCB to correct the layout error

RN-111b WiFly module did not support HTTP and therefore could not poll NextBus server

Implemented the Nano WiReach module which has support for HTTP and XML data

The serial pin header on the Nano WiReach module was too small to solder wires to

Ordered the Molex pin header connector mate and soldered the pins to a breakout board

Obstacles and ModificationsObstacles Solutions

Nano WiReach module failed for unknown reasons

Had on hand a spare module, Secure Socket iWiFi, which operates similar to WiReach

ATMega168 processor lacked sufficient onboard memory (16KB) and RAM (1KB)

Upgraded to the ATMega328 which has 32KB of memory and 2KB of RAM

Processor uses 5V TTL for serial communication whereas the Wi-Fi module uses 3V, hence could not communicate via serial link

Implemented a 5V – 3V voltage divider from the processor to module, and a 3V – 5V level shifter from module back to the processor

PCB Board Design Verification PCB board testing and verification

− Corrected LED lead assignments − Performed diagnostics testing by lighting all LEDs using I2C

commands from the Arduino processor

Troubleshooting Visual Display and Aesthetics

Tested LED visibility after assembly of display box− Decided to use heat shrink wrap to funnel LED illumination

Serial to Wi-Fi Module Configuration Wi-Fi module network connectivity and XML data collecting

− Utilized RealTerm Serial / Telnet software for module configuration and AT+i serial code debugging

Arduino Processor Programming / Debugging

Microprocessor programming and debugging− Utilized Arduino C

programming platform to code and debug data communications and parsing algorithms.

Power Supply Testing Tested solar panel power supply and battery supply

− Found that the solar panel provides ~450 mA of current in daylight conditions

− Original battery supply was faulty, obtained a new battery

Acceptance Testing Compared WaitLess display with the NextBus Live Map Performed final testing with system as standalone

− Assembled final product with battery and solar panel attached and positioned system at an actual bus stop

Results Product is capable of tracking all buses on all four

routes of the Georgia Tech transportation service Current draw of the device at peak operating

conditions is ~200 mA which is well below the 450 mA provided by solar panel

Connecting to GTwireless requires external device authentication through PC− New WPA security features of GT LAWN network

will ease module connectivity Wi-Fi module sometimes becomes unresponsive

after 5-10 minutes of operation− Needs a firmware update

Project Demonstration Requirements

Display the tracking of all buses on at least two routes of the campus bus service

Demonstrate the sustainability of the product i.e. solar powered

Demonstrate low current draw / power Demonstrate standalone operation running solely

on battery and solar power Exhibit wireless connectivity and weather resistance

Market / Cost AnalysisComponent

Labor Hours Labor Cost Equip Cost Total Cost

Arduino Duelmilanove/ ATmega328/V

150 $5,250.00 $34.95 $5284.95

I2C LED Controllers 2 $70.00 $16.00 $86.00

Red, Green, Blue LEDs 10 $350.00 $33.99 $383.99

Serial to Wi-Fi Module 1 $35.00 $62.90 $97.90

Solar Panel 1 $35.00 $49.95 $84.95

Battery 1 $35 $18.21 $53.21

Switching Voltage Regulator 2 $70.00 $22.00 $92.00

Custom PCB 10 $350.00 $100.00 $450.00

External Weather-Proof case 3 $105.00 $50.00 $155.00

TOTAL LABOR 180 $6,300

TOTAL PARTS $388.00

PROJECT TOTAL $6,688.00

Market / Cost AnalysisTotal Project Cost: $6,688.00

Physical Value of Product:

$388.00

# of Units Capable of being sold:

42 for each bus stop on the GT campus

Estimated Market Value of Product to

Break Even:$600.00

Future Enhancements and Modifications Reduce the depth of the display box

− Implement a smaller, more efficient battery− Solder all electronic components to one PCB

design− Investigate surface mount LED technology

Place the vinyl map decal inside of transparent casing to protect it

Implement WPA security login for easier module connectivity

Expand the design to be used for other transportation services

Add an LED array panel below the map display to output text-based arrival time estimations for each stop

Questions?