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ECE 477 Design Review Team 3 – Spring 2010. Sean Ma. Jacob Champion. Kelli Hacker. George Hadley. Outline. Project overview Project-specific success criteria Block diagram Component selection rationale Packaging design Schematic and theory of operation PCB layout - PowerPoint PPT Presentation
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ECE 477 Design ReviewTeam 3 – Spring 2010
11Sean Ma Jacob Champion Kelli Hacker George Hadley
Outline Project overview Project overview Project-specific success criteriaProject-specific success criteria Block diagramBlock diagram Component selection rationaleComponent selection rationale Packaging designPackaging design Schematic and theory of operationSchematic and theory of operation PCB layoutPCB layout Software design/development statusSoftware design/development status Project completion timelineProject completion timeline Questions / discussionQuestions / discussion
22
Project Overview
Arm-wearable device for snowsports enthusiastsArm-wearable device for snowsports enthusiasts Provides real-time information: current downhill Provides real-time information: current downhill
velocity, temperature, altitude, and airtime - via velocity, temperature, altitude, and airtime - via headphone audioheadphone audio
““Emergency mode" uses GPS to navigate the Emergency mode" uses GPS to navigate the user back to a programmable safe locationuser back to a programmable safe location
Li-polymer battery is monitored and recharged Li-polymer battery is monitored and recharged in-circuitin-circuit
Target battery life of ten hours Target battery life of ten hours Operational in subfreezing temperatures Operational in subfreezing temperatures
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Project-Specific Success Criteria
An ability to communicate sensor data via audio An ability to communicate sensor data via audio to the user to the user
An ability to recharge and monitor an on-board An ability to recharge and monitor an on-board battery battery
An ability to determine current location via GPS An ability to determine current location via GPS An ability to direct the user to a "safe" waypoint An ability to direct the user to a "safe" waypoint An ability to save acquired data to persistent An ability to save acquired data to persistent
storage storage
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Block Diagram
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Component Selection Rationale
Major components to be selected:Major components to be selected:Audio InterfaceAudio InterfaceAccelerometerAccelerometerMicrocontrollerMicrocontrollerGPS ModuleGPS ModuleAltimeterAltimeterCharacter LCDCharacter LCD
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Component Selection Rationale
Audio Interface: VLSI Audio Interface: VLSI VS-1011eVS-1011e
Streaming WAV and Streaming WAV and MP3 decoderMP3 decoder
50 mA active / 30 mA 50 mA active / 30 mA inactiveinactive
SPI interface (512-byte SPI interface (512-byte packets)packets)
Headphone driverHeadphone driver
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Accelerometer: Analog Accelerometer: Analog ADXL345ADXL345
40 uA active draw40 uA active draw SPI interfaceSPI interface +/-16g maximum+/-16g maximum Free-fall and motion Free-fall and motion
interrupt supportinterrupt support Breakout board availableBreakout board available
Component Selection Rationale
Microcontroller: Microchip Microcontroller: Microchip PIC24FJ256PIC24FJ256
Flexible clock and low Flexible clock and low power drawpower draw
Floating-point library Floating-point library supportsupport
Very few external Very few external peripherals neededperipherals needed
Large amount of on-chip Large amount of on-chip Flash and remappable Flash and remappable pins for flexibilitypins for flexibility
GPS Module: Polstar GPS Module: Polstar PMB-648PMB-648
Excellent fix timesExcellent fix times Low power consumption Low power consumption
and configurable update and configurable update ratesrates
Two-wire TTL serial Two-wire TTL serial communicationcommunication
Team members have Team members have previous experienceprevious experience
88
Component Selection Rationale
Altimeter: VTI Altimeter: VTI SCP1000-D01SCP1000-D01
Incredibly low power Incredibly low power draw (25 uA at 3.3V)draw (25 uA at 3.3V)
Up to 9 cm resolution in Up to 9 cm resolution in ideal conditionsideal conditions
Onboard thermometer Onboard thermometer saves circuit spacesaves circuit space
Breakout board Breakout board availableavailable
SPI interface operationSPI interface operation
Character LCD: Newhaven Character LCD: Newhaven NHD-C0216CiZNHD-C0216CiZ
Small, light chip-on-glass Small, light chip-on-glass solutionsolution
16 x 2 characters16 x 2 characters Operates on 3.3VOperates on 3.3V Bright backlight takes Bright backlight takes
only 20 mAonly 20 mA
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Packaging Design Device needs to be wearableDevice needs to be wearable
LightweightLightweight SmallSmall
Device intended to be worn for Device intended to be worn for outdoor sportsoutdoor sports DurableDurable
Package Choice: OKW Ergo-Package Choice: OKW Ergo-CaseCase Fits above criteriaFits above criteria ErgonomicErgonomic Designed to be worn on the forearmDesigned to be worn on the forearm Free SamplesFree Samples Multiple SizesMultiple Sizes Armband includedArmband included
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Packaging Design
LCD
Headphone JackDC Power In
Pushbuttons
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Schematic/Theory of Operation: Power
Component Current Consumption (mA)
Microcontroller 24mA
Accelerometer 40µA
Altimeter 10µA
GPS Module 65mA
LCD Display 20mA backlight, 0.5mA supply
MicroSD Card ~75mA active
MP3 Decoder 50mA active, 30mA inactive
Total: 234mA (worst case)
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Schematic/Theory of Operation: Power
3.3V power rail 3.3V power rail provided by LTC3440 provided by LTC3440 buck/boost converterbuck/boost converter
On/off slider switch On/off slider switch disconnects regulator disconnects regulator from circuitfrom circuit
Analog comparator Analog comparator prevents battery prevents battery undervoltage undervoltage conditions, shutting conditions, shutting down regulator at down regulator at LiPo's minimum 2.75VLiPo's minimum 2.75V
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Schematic/Theory of Operation: Battery
Battery is charged by a Battery is charged by a 5V wall wart connected 5V wall wart connected to an MCP73811T to an MCP73811T charge controllercharge controller
0.1Ω sense resistor 0.1Ω sense resistor provides voltage for provides voltage for LTC4150 fuel gaugeLTC4150 fuel gauge
Battery voltage Battery voltage connected to uC's connected to uC's ADC for absolute ADC for absolute measurementmeasurement
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Schematic/Theory of Operation: Audio
VS1011EDecodes MP3 files and drives an audio jack
Manufacturer recommended circuit
“Native Mode” – recommended for new projects and easier to implement
Internal oscillator
Separate digital and analog grounds
+3.3 V tied to analog and digital VDD
Audio Circuit
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ESD protection at audio jack
SPI connection to PIC24
SCI for control
SDI to receive data
xDCS chip select for SDI pulled up – use xCS for both SCI and SDI
xReset and DREQ also connected to PIC24
Schematic/Theory of Operation: Audio
Audio Circuit
Schematic/Theory of Operation:Accelerometer
Analog Devices ADXL345 Analog Devices ADXL345 Accelerometer deviceAccelerometer device
Utilizes SPI interface Utilizes SPI interface (shared with Altimeter (shared with Altimeter module)module)
Useful features: freefall Useful features: freefall detection, interrupt detection, interrupt detection, 13-bit detection, 13-bit resolution, ±16g rangeresolution, ±16g range
Acceleration data provided Acceleration data provided used to determine velocityused to determine velocity
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Schematic/Theory of Operation:Altimeter
VTI Technologies SCP1000 VTI Technologies SCP1000 altimeter devicealtimeter device
Utilizes SPI interface (shared Utilizes SPI interface (shared with Accelerometer module)with Accelerometer module)
Useful features: resolution, Useful features: resolution, 18cm accuracy, integrated 18cm accuracy, integrated thermometerthermometer
Derivative of altimeter data Derivative of altimeter data provides Z velocity provides Z velocity measurement (used for slope measurement (used for slope detection, velocity detection, velocity calculations)calculations)
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Schematic/Theory of Operation:GPS Module
Polstar PMB-648 GPS Polstar PMB-648 GPS modulemodule
Utilizes 2-wire TTL Serial Utilizes 2-wire TTL Serial Communication (9600 baud)Communication (9600 baud)
Useful features: track up to Useful features: track up to 20 satellites, enhanced 20 satellites, enhanced performance in performance in canyon/foliage environmentscanyon/foliage environments
Provides XYZ position Provides XYZ position information as well as time, information as well as time, velocity information used in velocity information used in slope calculationsslope calculations
1919
Schematic/Theory of Operation:Microcontroller
PIC24FJ256GA106 microcontrollerPIC24FJ256GA106 microcontroller Central control for Gauntlet deviceCentral control for Gauntlet device 2020
Schematic/Theory of Operation:Microcontroller
Performs Performs position/velocity/acceleratiposition/velocity/acceleration/time formatting and on/time formatting and calculationscalculations
Displays results to user Displays results to user interfaceinterface
Monitors power supply to Monitors power supply to check for low-battery check for low-battery conditionsconditions
External 8 MHz oscillator External 8 MHz oscillator crystal will be used for crystal will be used for increased UART accuracy increased UART accuracy w/ GPSw/ GPS
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Schematic/Theory of Operation:Microcontroller
Microcontroller Interfaces:Microcontroller Interfaces: UART: 2-wire TTL 9600 baud serial to GPSUART: 2-wire TTL 9600 baud serial to GPS I2C: 400kHz interface to LCD displayI2C: 400kHz interface to LCD display GPIO:GPIO:
Battery MonitorBattery Monitor Battery ChargerBattery Charger Pushbuttons/User InterfacePushbuttons/User Interface
SPI (x3):SPI (x3): 500kHz for shared accelerometer/altimeter interface500kHz for shared accelerometer/altimeter interface 3Mhz interface to MP3 Decoder Chip3Mhz interface to MP3 Decoder Chip 4MHz interface to SD Card (subject to change)4MHz interface to SD Card (subject to change)
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Schematic/Theory of Operation: Storage
Will be using a microSD card for memoryWill be using a microSD card for memoryCheap, readily available, persistent memory Cheap, readily available, persistent memory
for prototypingfor prototypingCan interface with other devicesCan interface with other devicesSmaller than normal SD card, so conserves Smaller than normal SD card, so conserves
spacespaceWill use PIC library for FAT32 File I/O systemWill use PIC library for FAT32 File I/O system
Connect to microcontroller via SPI busConnect to microcontroller via SPI busNo need for pull-ups, according to several No need for pull-ups, according to several
sourcessources
Schematic/Theory of Operation: User Interface
User Input:User Input:Pushbuttons (Use Generic I/O)Pushbuttons (Use Generic I/O)Menu SystemMenu System
Audio:Audio:The VS1101E MP3 Decoder has built-in audio The VS1101E MP3 Decoder has built-in audio
driverdriverCommunicates with microcontroller using SPICommunicates with microcontroller using SPI
LCD:LCD:Character LCDCharacter LCDCommunicates via I2CCommunicates via I2C
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PCB Layout
2626
PCB Layout: Power
Buck-boost circuit Buck-boost circuit layout is crucial to layout is crucial to proper performanceproper performance
Inductor traces Inductor traces must be wide to must be wide to support high support high currentcurrent
Must be isolated Must be isolated from other digital from other digital circuitrycircuitry
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PCB Layout: Battery
PCB must act as PCB must act as heatsink for linear heatsink for linear charge regulatorcharge regulator
Sense resistor Sense resistor should be as close should be as close to fuel gauge as to fuel gauge as possiblepossible
Power traces Power traces should be kept should be kept wide and short for wide and short for minimal lossesminimal losses
PCB Layout: Audio
Analog and digital ground Analog and digital ground need to be tied close to need to be tied close to VS1011EVS1011E
Decoupling capacitors Decoupling capacitors placed as near as possibleplaced as near as possible
Header connection for SPI Header connection for SPI and microcontroller signalsand microcontroller signals
Audio jack must be on Audio jack must be on right edge of PCB for user right edge of PCB for user accessaccess
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PCB Layout: Sensors Accelerometer must be by Accelerometer must be by
mounting point to avoid circuit mounting point to avoid circuit resonanceresonance
Breakout boards for Breakout boards for accelerometer and altimeter accelerometer and altimeter placed on edge of circuit to placed on edge of circuit to conserve spaceconserve space
Accelerometer and altimeter Accelerometer and altimeter placed close to one another – placed close to one another – share an SPI busshare an SPI bus
Header for ribbon cable to Header for ribbon cable to GPSGPS
Header for access to SPI bus Header for access to SPI bus and chip selects and chip selects
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PCB Layout: Microcontroller
64-pin QFP package64-pin QFP package Contains 3 digital Contains 3 digital
power/ground pairs, 1 power/ground pairs, 1 analog power/ground analog power/ground pair, Vddcore and pair, Vddcore and Vddcap pinsVddcap pins
Require .01µF Require .01µF decoupling capacitors decoupling capacitors (locate near (locate near microcontroller)microcontroller)
Requires 8MHz external Requires 8MHz external crystal (locate near crystal (locate near MCU)MCU)
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Software Design/Development Status
Components verified for correct functionalityComponents verified for correct functionality Primarily timer-based – allows for low power consumptionPrimarily timer-based – allows for low power consumption At set intervals:At set intervals:
Poll accelerometer for jump dataPoll accelerometer for jump data Poll GPS and altimeter for velocity and positionPoll GPS and altimeter for velocity and position Poll altimeter for temperaturePoll altimeter for temperature Poll battery for absolute voltagePoll battery for absolute voltage Poll pushbuttons for user inputPoll pushbuttons for user input
Act on readings byAct on readings by Calculating downhill velocityCalculating downhill velocity Notifying user via audio (user-set intervals)Notifying user via audio (user-set intervals) Saving GPS/altitude waypoints as neededSaving GPS/altitude waypoints as needed Activating modes of operation based on user inputActivating modes of operation based on user input
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Project Completion Timeline Week 8 Week 9
Week 10
Week 11
Week 12
Week 13
Week 14
Week 15
1-Mar 8-Mar 22-Mar 29-Mar 5-Apr 12-Apr 19-Apr 26-Apr
Design Review
Start Software
Proof-of-Parts
Final Schematic
Final PCB
Software Design Narrative
All sensor interfaces working in software
Patent Liability Analysis
Put power circuitry on PCB
Reliability and Safety Analysis
Software basically finished
Battery and micro on PCB
Ethical and Enviro Impact Analysis
Software debugging
SD card and sensors on PCB
User Manual
PCB and software finalized
Cut packaging
PSSC Presentation 3232
Questions?
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