ECE 477 Design Review Team 3 – Spring 2010

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

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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

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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

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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

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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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