Kedar Hiremath Andrew Floren Josh Armstrong Matt deWet

Overview of Presentation Introduce the Configurable Laser Tag System Design and Implementation Problems Encountered Cost and Other Considerations Conclusion and Recommendations Questions?

Standard Laser Tag Simulated gun combat using infrared beams Problems: Limited Strategy Limited Teamwork Repetitive Low Replay Value

Solution: Add Configurability! Ability to customize the game Create different gametypes & objectives Modify behavior of game devices Improvements: -Objective-Based Gameplay -Complex Tactical Strategy -Teamwork Required -High Replay Value Screenshot from Halo – Capture The Flag

System Needs Basic laser tag functionality Wireless communication across devices Game scripting system Ability to script game Intuitive drag-and-drop GUI Robust compiler & linker Remotely initialize all game devices

System Needs Ability to play indoors & outdoors Minimal power usage (max battery life) Low consumer costs Low prototyping costs

Commercial Laser TagConfigurable Laser Tag Simulated gun combat Score Aggregation Objective-Based Play Configurable Devices Scriptable Gametypes Feature Comparison

Design Overview Two devices necessary for basic laser tag Tagger Necessary for tagging other players Transmits IR data Pack Necessary for sensing when a player is tagged Receives IR data

Design Overview In order to meet design objectives we need two additional devices Central Computer Keeps track of game state Enforces rules Communicates via RF Pylon Need stationary devices for players to interact with Functionality dependent on gametype

Scale of Project Four completely separate devices IR communication RF communication USB communication Scripting language Complex software running on all devices

System Communication

IR Communications Hardware Chose matching lens diameter and focal length Protocol Designed 23 bit IR packet Error Handling Added 6 bit hamming code for error correction TEAM IDPLAYER ID EVENT ID 40KHz Wave TSOP4840 IR Receiver TSAL6100 IR LED WPN DMG

RF Communication Hardware Using ONE-NET schematics Protocol Using ONE-NET protocol Allows multiple devices to share a single channel Uses acknowledgment packets to guarantee delivery

Scripting System Making scripting easy Think LabVIEW or Lego Mindstorms Basic structure Triggers & Primitives Basic logic How do we accomplish this? Internal representation? Interpreter?

Scripting System Example Example C code Equivalent Syntax Tree void takeDamage(int amount, int shooterId) { if(!isDead) { if (HP > amount) HP = HP - amount; else { HP = 0; die(shooterId); }

Scripting System Example Example Syntax Tree XML Representation

Implementing Scripting Have a back-end representation This must run on microcontrollers Need to convert XML to executable code

Implementing Scripting Drag-and-Drop GUI Abstract Syntax Tree (XML) XML Parser Compiler Linker Code Generation

Compiler & Linker Tasks Lexical Analysis / Parsing Preprocessing Semantic Analysis Linking within scripts Linking between multiple scripts Code generation Fix for microcontrollers Compiling is messy

Compiler & Linker Huge amount of work lines of code Written in C++ Used only XML parsing library Completed!

Interpreter GUI: User-drawn nodes  XML script Compiler: XML script  Data structures Interpreter: Run data structures

Interpreter GUI: User-drawn nodes  XML script Compiler: XML script  Data structures Interpreter: Run data structures Low level code to run on microcontrollers Control devices based on script Primitives & Triggers Event infrastructure

Interpreter GUI: User-drawn nodes  XML script Compiler: XML script  Data structures Interpreter: Run data structures Programmer/Flasher?

Remote Programming Need to load scripts onto microcontroller via RF Central computer listens for new devices Send initialization data Keep list of active devices Interrupts must be disable while flashing Created packet request mechanism

Major Changes Changed wireless module to XBee Modules pre-built Protocol nearly identical to ONE-NET Switched from crystal oscillator to timer circuit Timer circuit far more reliable Switched microcontrollers twice First to consolidate to a single type of microcontroller Second to increase RAM and IO pins

Device Design – Central Computer

Device Design - Tagger

Device Design - Pack

Device Design - Pylon

Device Casing

Work Completed IR communication Protocol, software, and hardware RF communication Software and Hardware PCBs Pack Tagger Pylon Central Computer

Work Completed LCD interface High level scripting language Parser, compiler, and linker Ability to flash compiled script Script interpreter Remote procedural calls

Work Remaining System integration IR and timer code Power circuit Script gametypes GUI for admin and scripting front end

Problems Encountered BDM Programmer PCB Problems Vdd and Vss Footprints Power circuit Via sizes

Hardware Testing System testing Incomplete hardware Module testing Pack, Tagger, Central Computer, and Pylon Component testing ICs and passives

Demo Milestone Protoboard Demo Tagger Pack Central Computer RF, IR, LCD All working

Compiler Testing

Project Scale Project was huge 12 hours per week to start 48 hours per week for last 5 weeks Plus other classes!

Past Costs ItemCost LCD, 10 IR Leds, 4 IR recievers$25.80 RF Parts$12.59 PCBs over the summer$85.00 Breakout Board$12.49 PVC$12.24 USB controller$18.00 IR mounting$88.95 Crystals for IR$13.00 Shipping costs$17.14 TOTAL$285.21

New Costs ItemCost Final order from Digikey$ Wires and connectors from pololu.com $ Jameco - IR circuit & various parts$30.62 Final ordered PCBs$ Final order from Mouser$ Final order of LCDs$39.42 RadioShack Purchases$40.78 TOTAL$595.20

Cost to Others Oscilloscopes Power supplies Countless parts checked out Resistors Capacitors Programmer Soldering Iron Breakout boards

Safety and Ethics IR safety Low power RF safety Low power FCC approved bands Entertainment device Failure is not dangerous

What We Learned USB communication and bus-power Send/receive encoded IR signals Send/receive encoded RF packets Design a language, XML parser, compiler and linker

What We Learned Solder SMT prototypes Efficiently design and layout circuits Conserve space Effective teamwork

Recommendations Do not tear down – make continual progress If possible, get components that run on the same voltage Do not try to re- invent the wheel

Recommendations Compromise between low prototype cost and low product cost Remember: it is a prototype, not the end product Prioritize the essential parts Do not leave the power system until the end

Conclusion The Configurable Laser Tag System Introduces customizable objective-based gameplay Is a complex integration of Configurable devices Communication protocols Game scripting software

Conclusion If any one subsystem is not functioning, the system as a whole will fail to operate Despite the problems we encountered, we learned a lot, worked hard, and completed a significant portion of the work