WaitLess Bus Tracking
Display
Matthew Brooks
Chris Chidi
Josh Mauldin
Daniel Nadeau
Georgia Institute of Technology
ECE 4007 Senior Design
Preliminary Design Review
March 12th, 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
System Functional Diagram
Solar Charger
12V Battery
12Và5V
Regulator
12V
5Và3V
Regulator
WiFi Module
Processor
Serial
5V
I2C
LED
Display
Power Source
 Lead-Acid Battery, 12V, 7Ah
 Solar Battery Maintainer, 12V, 5.5W
• Provides 450mA During Daylight Hours
 Texas Instruments® Switching Voltage
Regulator (12Và5V)
System Functional Diagram
Solar Charger
12V Battery
12Và5V
Regulator
12V
5Và3V
Regulator
WiFi Module
Processor
Serial
5V
I2C
LED
Display
Wi-Fi Module
 ConnectOne wireless module
is used to connect to the
NextBus.com server and
receive GPS data.
 Uses WEP security with
GTWireless.
 Information is obtained every
10 seconds by sending a
specific URL to receive the
GPS location of all buses on a
particular route via XML.
GPS Data
 Using a specific URL provided by NextBus.com,
locations of buses on each route are saved every
10 seconds.
 URL provides XML data feed.
System Functional Diagram
Solar Charger
12V Battery
12Và5V
Regulator
12V
5Và3V
Regulator
WiFi Module
Processor
Serial
5V
I2C
LED
Display
Micro-processor
 Arduino development board
utilizes an Atmel ATMega168
micro-processor, 16MHz.
 16KB Program ROM, 1KB RAM
• Large arrays are saved in ROM
 Arduino provides I2C and
serial libraries for use with
the ATMega168.
Serial – TX, RX, Ground
 Used to communicate
with the Wi-Fi module
I2C – SCL, SDA, 5 V
 Used to communicate
with 7 LED drivers
System Functional Diagram
Solar Charger
12V Battery
12Và5V
Regulator
12V
5Và3V
Regulator
WiFi Module
Processor
Serial
5V
I2C
LED
Display
Lighting the LEDs
 CAT Semi CAT9552
 Common Anode RGB LED
• 16 channel I2C-bus LED
• Any combination of Red,
drivers
Green, or Blue color
• 7 drivers are used to
• 4000 mcd brightness
address 42 LEDs
• 20mA current draw
LED Locations on Map
Display/Board Design
Photoshop used to create map
graphic and calculate the LEDs XY
coordinates
KiCad used to create the schematic
and the PCB layout
Google Maps used to determine the
LEDs GPS locations
Project Schedule
Demonstration Plan
Daytime operation using solar
charger
Video to show night time operation
Live demonstration of a minimum of
two routes displayed
Current Status
Writing code for the Wi-Fi adapter
Debugging code to generate LED
commands
PCB is complete
Case is complete
Questions?