ECE 477 Design Review Team 02  Fall 2008

Outline Project overview - KProject overview - K Project-specific success criteria -KProject-specific success criteria -K Block diagram -KBlock diagram -K Component selection rationale -AComponent selection rationale -A Packaging design -APackaging design -A Schematic and theory of operation -MSchematic and theory of operation -M PCB layout -DPCB layout -D Software design/development status -KSoftware design/development status -K Project completion timeline -AProject completion timeline -A Questions / discussionQuestions / discussion

Project Overview Alleviate risks by providing a cushion between the player’s head and the worldAlleviate risks by providing a cushion between the player’s head and the world Real time monitoring of player impactsReal time monitoring of player impacts Hardware in high stress environmentHardware in high stress environment Keeping player happy while improving functionality of an old toolKeeping player happy while improving functionality of an old tool

Project-Specific Success Criteria An ability to recharge and monitor an integrated (lithium ion) battery.An ability to recharge and monitor an integrated (lithium ion) battery. An ability to sense impact data using 3-D accelerometers.An ability to sense impact data using 3-D accelerometers. An ability to alert sideline personel when a dangerous hit is received.An ability to alert sideline personel when a dangerous hit is received. An ability to log/timestamp impact data on a removable memory device (SD card).An ability to log/timestamp impact data on a removable memory device (SD card). An ability to remotely monitor real-time impact data and tune impact detection thresholds via an embedded web server.An ability to remotely monitor real-time impact data and tune impact detection thresholds via an embedded web server.

Block Diagram

Component Selection Rationale Microcontroller: PIC18F45K20Microcontroller: PIC18F45K20 32 Kbytes Program Memory32 Kbytes Program Memory 36 I/O pins36 I/O pins bit AtoD channels14 10-bit AtoD channels Up to 64MhzUp to 64Mhz 20Mhz

Component Selection Rationale Accelerometers: MMA1212 & MMA2301Accelerometers: MMA1212 & MMA2301 Limited choicesLimited choices +/- 250g sensitivity+/- 250g sensitivity 5V power source5V power source Single axisSingle axis

Component Selection Rationale Wi-Fi: MatchportWi-Fi: Matchport Limited choices on wireless protocol.Limited choices on wireless protocol. Flexible antennaFlexible antenna Embedded webserverEmbedded webserver

Packaging Design Weight…Weight… –Helmet: 8 lbs + circuit Safety…Safety… –Avoid cutting into helmet –Cut into padding Performance…Performance… –Antenna routed near surface –Multiple PCBs

Packaging Design PCB InterconnectsPCB Interconnects –100mil right angle pins –Twisted Pair Ethernet Wiring 4 twisted pair shielded

Packaging Design PCB PlacementPCB Placement –Avoid the front of the helmet –Exact PCB placement unknown Spread around accelerometer boardsSpread around accelerometer boards

Schematic/Theory of Operation Microchip MCP73838 Charge Manager USB or AC input Texas Instruments TPS75733 LDO 3.3V output, 5V input Up to 3A output current Linear Technology LT1303 Boost Operating voltage: volts 5V output Linear Technology LTC3440 Buck Boost Operating voltage: volts 3.3V output Maxim DS2740 Fuel Gauge Operating voltage: V Single-wire interface

Schematic/Theory of Operation PIC18F45K20 Microcontroller Use 9 channels of ATD conversion with 2 more used for reference voltage 1 SPI used for SD interfacing 2 TTL pins for RS232 interfacing Operating Voltage: 3.3V 8 MHz operating frequency mA

Schematic/Theory of Operation Accelerometers Freescale MMA1212 and MMA2301 Accelerometers  x-axis and z-axis Operating voltage: 5 V Operating Current: 3-6 mA Analog output between 0.5V and 4.5V Matchport b/g Wireless Adapter Operating voltage: 3.3 V Operating Current: mA Connected to microcontroller via RS232 Embedded web server

Schematic/Theory of Operation Microcontroller Schematic

Schematic/Theory of Operation Power Supply Schematic

Schematic/Theory of Operation Accelerometer Schematic This single schematic is replicated three times in the design

Schematic/Theory of Operation WiFi Schematic

Schematic/Theory of Operation microSD Schematic

PCB Layout 7 PCBs with 5 unique layouts7 PCBs with 5 unique layouts –Power –Microcontroller –SD Card –Wi-Fi –3x Accelerometer Trace widthTrace width –Mostly 12 mil –Up to 50 mil for power

PCB Layout Power ManagementPower Management Power PCB Micro PCB 3.3V 5V V SD PCB Accel PCB 5V 3.3V Battery DC LDO MatchPort 3.3V V Wall Wart 5V Accel PCB 1320mW 1144mW 90mW 660mW 66mW

SD PCB Fairly SimpleFairly Simple Header and micro SD holderHeader and micro SD holder

Accelerometer PCB Short data tracesShort data traces Data routes away from Power routesData routes away from Power routes Similar length data routesSimilar length data routes 1k Resistors1k Resistors Bypass capacitorsBypass capacitors

Power PCB Battery off boardBattery off board Zener diode switchZener diode switch

Wi-Fi PCB Mounting BracketsMounting Brackets Passive circuitry on bottomPassive circuitry on bottom Separate dedicated powerSeparate dedicated power Bulk CapacitorBulk Capacitor

Microcontroller PCB Power apart from DigitalPower apart from Digital Single source groundSingle source ground Ground planes under U28Ground planes under U28 Bypass capacitorsBypass capacitors Filter capacitorsFilter capacitors Bulk capacitorBulk capacitor Short data tracesShort data traces Micro clocked slower than max to reduce noiseMicro clocked slower than max to reduce noise

Software Design/Development Status Algorithm designAlgorithm design –Need an algorithm for computing the moment and rotational force of 3 vectors

Project Completion Timeline Villanova’s TimelineVillanova’s Timeline Parts in soon!Parts in soon! Coding to begin week of October 20thCoding to begin week of October 20th

Questions / Discussion