ECE 477 Design Review Team 100 2  Spring 2010

1. ECE 477 Design Review Team 1002 Spring 2010

2. Outline • Project overview • Project-specific success criteria • Block diagram • Component selection rationale • Packaging design • Schematic and theory of operation • PCB layout • Software design/development status • Project completion timeline • Questions / discussion

3. Project Overview • Laser tag game system with a few bonuses: • RF Communication • Designed for outdoor use • Multiple firing modes • Video game style power-ups/shields • Challenges include: • Long distance IR communication • RF collision and communication protocol • Battery power (especially for high current LED drive) • Packaging to withstand high adrenaline gameplay • Innovative bonus features

4. Project-Specific Success Criteria • An ability to wirelessly transmit a shot and receive a hit via Infrared • An ability to remotely enable and disable the gun/vest pair • An ability to control game operation using base station keypad • An ability to wirelessly communicate game statistics to base station via RF • An ability to provide user with local display of game information

5. Block Diagram (Portable)

6. Block Diagram (Base)

7. Component Selection Rationale • Microcontroller • Free samples, contains all desired peripherals, well documented, many GPIO pins • Radio Frequency • Extremely well documented, phone support, example prototyping boards, complete solution kit • Infrared • Based on proven TV remote control technology, sample schematics available online, inexpensive • Keypad • Standard, inexpensive 4x4 key array • LCD • Inexpensive, backlight, low power, wide 2.7-5.5V range

8. Microcontroller: dsPIC30F4011 • In Circuit Serial Programmable • 48kB Program Memory, 2kB RAM • Internal Oscillator 7.37 MHz • 6x PWM for IR transmission • 1x SPI for Shift Register/LCD display • 4x Input Capture for Keypad and IR detectors • 10 bit, 1Msps ATD for RF Signal Strength • 2.5 to 5V operating range • 72mA max at 3.3V and 20MIPS

9. RF: Linx 418MHz Transceiver • Development kit with example PCBs, application notes, phone support, and multiple transceivers and antennas • Receive and transmit within one package • Serial bi-directional communication • Zero configuration • 2.6 to 3.6V operating range • Typical supply current: 6-12mA

10. IR: Vishay TSOP 56kHz & TSAL • Same proven technology from home entertainment device remotes • TSOP detector filters external sources of IR by only triggering on 56kHz • Designed for long distance communication • TSAL IR LED rated for 100mA continuous

11. Packaging Design (Portable) • Vest • Four Sensor Pods • Status LEDs • Heavy-Duty Fabric • Gun • PCB Housing • IR Transmitter • LCD Screen

12. Packaging Design (Base) • RF Ground Plane • Durable • LCD Screen • Keypad

13. Theory of Operation • Base Station • Microcontroller • Keypad encoder • Keypad • Allow user input • Shift Register • LCD Screen • Displays game stats • RF Transceiver • Communicates with gun/vest pairs

14. Base Station Schematic

15. Shift Register and LCD Screen • MM74HC164 Shift Register • 8-Bit Serial-in/Parallel-out • Typical operating frequency: 50MHz • Typical propagation delay: 19ns (clock to Q) • NHD‐0224BZ‐FL‐GBW LCD Screen • 2 lines x 24 characters • Transflective • Yellow/Green LED backlight • Potentiometer allows for change in contrast of screen

16. Keypad Encoder and Header • MM74C922 16-Key Encoder • Key bounce elimination with capacitor • Low power consumption • On-chip row pull-ups

17. RF Transceiver • Pin 4 – Receive Signal Strength Indicator • Pin 7 – Data line will output received data when in receive mode and will be a data input when in transmit mode • Pin 8 – Transmit and receive select • Pin 9 – Power down when low

18. Portable Gun and Vest • Gun • Microcontroller • Shift Register • LCD Screen • Displays game stats • RF Transceiver • Communicates with base station • IR LED • Pulses IR signal as a shot • Laser Diode • Visual cue to aim • Trigger • Batteries • Vest • Color LEDs • Simulates the status of the player and distinguishes between teams • IR Receiver • Receives signal of IR pulse and sends to gun microcontroller

19. Vest and Gun Schematic

20. Trigger circuit and IR/Laser • Trigger Circuit • Pin is pulled up in static state • When button is pressed, switch pulls pin to ground • Pin is never floating in this configuration • IR LED and laser connected to PWM to allow for set frequency pulsing • NPN transistor as pull-down • Transistor base connected to Micro to pulse to allow for larger drive current • Pull up resistor to supply voltage

21. Vest color LEDs • NPN transistor as pull-down • Transistor base connected to microcontroller to pulse to allow for larger drive current • Pull up resistor to supply voltage

22. IR Detector Modules • Asserts low when 56kHz square wave pulse is detected; high otherwise • Goes to input capture and triggers a software interrupt on an edge • Parallel detectors for wider detection angles

23. PCB Layout • Considerations: • RFground plane • No traces under transceiver • Centrally placed microcontroller • Noise reduction

24. PCB Layout (Base) 3” x 5”

25. PCB Layout (Portable) 3” x 5”

26. Software Design/Development Status • RF communication protocol: Listen before transmit with random retry • IR protocol: Simple ID number transmission like television remote • Practicing with MPLab IDE by Microchip to create interrupts, run simple programs, and set up peripheral units • Using MPLab simulator to test chip functionality before PCB is assembled

27. Project Completion Timeline

28. Questions / Discussion