ECE 477 Design Review Team 1002 Spring 2010

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

Outline

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

Project Overview

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

Project-Specific Success Criteria

Block Diagram (Portable)

Block Diagram (Base)

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

Component Selection Rationale

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

Microcontroller: dsPIC30F4011

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

RF: Linx 418MHz Transceiver

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

IR: Vishay TSOP 56kHz & TSAL

Packaging Design (Portable)

Vest Four Sensor Pods Status LEDs Heavy-Duty Fabric

Gun PCB Housing IR Transmitter LCD Screen

Packaging Design (Base)

RF Ground Plane Durable LCD Screen Keypad

Base Station◦ Microcontroller◦ Keypad encoder◦ Keypad

Allow user input◦ Shift Register◦ LCD Screen

Displays game stats◦ RF Transceiver

Communicates with gun/vest pairs

Theory of OperationBase Microcontroller External Device Function Pin #Programming Header PGC clock input 1 PGD - data input/output 44 /MCLR - Master Reset 18 VDD 40 VSS 39Shift Register SDO1 - SPI Data out 44 SCK1 43LCD Screen RE5 - LCD Enable 8 RF0 - Register Select 5Key Encoder RE4 - output enable 9 RE3 - Data out D 10 RE2 - Data out C 11 RE1 - Data out B 14 RE0 - Data out A 15 IC7 - Data Available 23RF Transceiver AN3 - RSSI 22 RB0 - Data 19 RB1 - T/R Select 20 RB2 -Power down 21

Base Station Schematic

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

Keypad Encoder and Header

• MM74C922 16-Key Encoder

• Key bounce elimination with capacitor

• Low power consumption

• On-chip row pull-ups

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

Portable Gun and VestGun

• 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

Vest and Gun SchematicPortable Microcontroller External Device Function Pin #Programming Header PGC clock input 1

PGD - data input/output 44

/MCLR - Master Reset 18 VDD 40 VSS 39Shift Register SDO1 - SPI Data out 44 SCK1 43LCD Screen RE5 - LCD Enable 8 RF0 - Register Select 5RF Transceiver AN3 - RSSI 22 RB0 - Data 19 RB1 - T/R Select 20 RB2 -Power down 21Trigger RF1 - trigger input 4IR LED PWM1H 14Laser LED RE2 - Gen I/O 11Color LED Set 1 RC14 - Gen I/O 35Color LED Set 2 RE8 - Gen I/O 36Photo Transistor Set 1 IC1 - input capture 42Photo Transistor Set 2 IC2 - input capture 37Photo Transistor Set 3 IC8 - input capture 24Photo Transistor Set 4 IC7 - input capture 23

Trigger circuit and IR/LaserTrigger 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

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

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

Considerations:◦ RF ground plane◦ No traces under transceiver◦ Centrally placed microcontroller◦ Noise reduction

PCB Layout

PCB Layout (Base)

3” x 5”

PCB Layout (Portable)

3” x 5”

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

Software Design/Development Status

Project Completion TimelineWeek Projected Tasks

8 Revise Schematic, Revise PCB, Learn MPLab IDE and Debugger

9 Finalize PCB, Ensure all parts are on hand and fit PCB10 Spring Break11 RF and IR software communication stacks and protocol12 Game software and remaining software13 PCB Assembly14 Software and hardware debugging15 Final testing, user manual, demo preparation16 Final demonstration

Questions / Discussion