1. ECE 477 Design Review Team 3 – Spring 2010 1 Sean MaJacob ChampionKelli HackerGeorge Hadley

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

3. Project Overview Arm-wearable device for snowsports enthusiasts Arm-wearable device for snowsports enthusiasts Provides real-time information: current downhill velocity, temperature, altitude, and airtime - via headphone audio Provides real-time information: current downhill velocity, temperature, altitude, and airtime - via headphone audio “Emergency mode" uses GPS to navigate the user back to a programmable safe location “Emergency mode" uses GPS to navigate the user back to a programmable safe location Li-polymer battery is monitored and recharged in-circuit Li-polymer battery is monitored and recharged in-circuit Target battery life of ten hours Target battery life of ten hours Operational in subfreezing temperatures Operational in subfreezing temperatures 3

4. Project-Specific Success Criteria An ability to communicate sensor data via audio to the user An ability to communicate sensor data via audio to the user An ability to recharge and monitor an on-board battery An ability to recharge and monitor an on-board 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 storage An ability to save acquired data to persistent storage 4

5. Block Diagram 5

6. Component Selection Rationale Major components to be selected: Major components to be selected: Audio Interface Audio Interface Accelerometer Accelerometer Microcontroller Microcontroller GPS Module GPS Module Altimeter Altimeter Character LCD Character LCD 6

7. Component Selection Rationale Audio Interface: VLSI VS-1011e Streaming WAV and MP3 decoder Streaming WAV and MP3 decoder 50 mA active / 30 mA inactive 50 mA active / 30 mA inactive SPI interface (512-byte packets) SPI interface (512-byte packets) Headphone driver Headphone driver 7 Accelerometer: Analog ADXL345 40 uA active draw 40 uA active draw SPI interface SPI interface +/-16g maximum +/-16g maximum Free-fall and motion interrupt support Free-fall and motion interrupt support Breakout board available Breakout board available

8. Component Selection Rationale Microcontroller: Microchip PIC24FJ256 Flexible clock and low power draw Flexible clock and low power draw Floating-point library support Floating-point library support Very few external peripherals needed Very few external peripherals needed Large amount of on-chip Flash and remappable pins for flexibility Large amount of on-chip Flash and remappable pins for flexibility GPS Module: Polstar PMB-648 Excellent fix times Excellent fix times Low power consumption and configurable update rates Low power consumption and configurable update rates Two-wire TTL serial communication Two-wire TTL serial communication Team members have previous experience Team members have previous experience 8

9. Component Selection Rationale Altimeter: VTI SCP1000-D01 Incredibly low power draw (25 uA at 3.3V) Incredibly low power draw (25 uA at 3.3V) Up to 9 cm resolution in ideal conditions Up to 9 cm resolution in ideal conditions Onboard thermometer saves circuit space Onboard thermometer saves circuit space Breakout board available Breakout board available SPI interface operation SPI interface operation Character LCD: Newhaven NHD-C0216CiZ Small, light chip-on-glass solution Small, light chip-on-glass solution 16 x 2 characters 16 x 2 characters Operates on 3.3V Operates on 3.3V Bright backlight takes only 20 mA Bright backlight takes only 20 mA 9

10. Packaging Design Device needs to be wearable Device needs to be wearable Lightweight Lightweight Small Small Device intended to be worn for outdoor sports Device intended to be worn for outdoor sports Durable Durable Package Choice: OKW Ergo- Case Package Choice: OKW Ergo- Case Fits above criteria Fits above criteria Ergonomic Ergonomic Designed to be worn on the forearm Designed to be worn on the forearm Free Samples Free Samples Multiple Sizes Multiple Sizes Armband included Armband included 10

11. 11 Packaging Design LCD Headphone Jack DC Power In Pushbuttons

12. 12 Schematic/Theory of Operation: Power ComponentCurrent Consumption (mA) Microcontroller24mA Accelerometer40µA Altimeter10µA GPS Module65mA LCD Display20mA backlight, 0.5mA supply MicroSD Card~75mA active MP3 Decoder50mA active, 30mA inactive Total:234mA (worst case)

13. 13 Schematic/Theory of Operation: Power 3.3V power rail provided by LTC3440 buck/boost converter 3.3V power rail provided by LTC3440 buck/boost converter On/off slider switch disconnects regulator from circuit On/off slider switch disconnects regulator from circuit Analog comparator prevents battery undervoltage conditions, shutting down regulator at LiPo's minimum 2.75V Analog comparator prevents battery undervoltage conditions, shutting down regulator at LiPo's minimum 2.75V

14. 14 Schematic/Theory of Operation: Battery Battery is charged by a 5V wall wart connected to an MCP73811T charge controller Battery is charged by a 5V wall wart connected to an MCP73811T charge controller 0.1Ω sense resistor provides voltage for LTC4150 fuel gauge 0.1Ω sense resistor provides voltage for LTC4150 fuel gauge Battery voltage connected to uC's ADC for absolute measurement Battery voltage connected to uC's ADC for absolute measurement

15. 15 Schematic/Theory of Operation: Audio VS1011E Decodes 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 V DD Audio Circuit

16. 16 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

17. Schematic/Theory of Operation: Accelerometer Analog Devices ADXL345 Accelerometer device Analog Devices ADXL345 Accelerometer device Utilizes SPI interface (shared with Altimeter module) Utilizes SPI interface (shared with Altimeter module) Useful features: freefall detection, interrupt detection, 13-bit resolution, ±16g range Useful features: freefall detection, interrupt detection, 13-bit resolution, ±16g range Acceleration data provided used to determine velocity Acceleration data provided used to determine velocity 17

18. Schematic/Theory of Operation: Altimeter VTI Technologies SCP1000 altimeter device VTI Technologies SCP1000 altimeter device Utilizes SPI interface (shared with Accelerometer module) Utilizes SPI interface (shared with Accelerometer module) Useful features: resolution, 18cm accuracy, integrated thermometer Useful features: resolution, 18cm accuracy, integrated thermometer Derivative of altimeter data provides Z velocity measurement (used for slope detection, velocity calculations) Derivative of altimeter data provides Z velocity measurement (used for slope detection, velocity calculations) 18

19. Schematic/Theory of Operation: GPS Module Polstar PMB-648 GPS module Polstar PMB-648 GPS module Utilizes 2-wire TTL Serial Communication (9600 baud) Utilizes 2-wire TTL Serial Communication (9600 baud) Useful features: track up to 20 satellites, enhanced performance in canyon/foliage environments Useful features: track up to 20 satellites, enhanced performance in canyon/foliage environments Provides XYZ position information as well as time, velocity information used in slope calculations Provides XYZ position information as well as time, velocity information used in slope calculations 19

20. Schematic/Theory of Operation: Microcontroller PIC24FJ256GA106 microcontroller PIC24FJ256GA106 microcontroller Central control for Gauntlet device Central control for Gauntlet device 20

21. Schematic/Theory of Operation: Microcontroller Performs position/velocity/acceler ation/time formatting and calculations Performs position/velocity/acceler ation/time formatting and calculations Displays results to user interface Displays results to user interface Monitors power supply to check for low-battery conditions Monitors power supply to check for low-battery conditions External 8 MHz oscillator crystal will be used for increased UART accuracy w/ GPS External 8 MHz oscillator crystal will be used for increased UART accuracy w/ GPS 21

22. Schematic/Theory of Operation: Microcontroller Microcontroller Interfaces: UART: 2-wire TTL 9600 baud serial to GPS UART: 2-wire TTL 9600 baud serial to GPS I2C: 400kHz interface to LCD display I2C: 400kHz interface to LCD display GPIO: GPIO: Battery Monitor Battery Monitor Battery Charger Battery Charger Pushbuttons/User Interface Pushbuttons/User Interface SPI (x3): SPI (x3): 500kHz for shared accelerometer/altimeter interface 500kHz for shared accelerometer/altimeter interface 3Mhz interface to MP3 Decoder Chip 3Mhz interface to MP3 Decoder Chip 4MHz interface to SD Card (subject to change) 4MHz interface to SD Card (subject to change) 22

23. 23 Schematic/Theory of Operation: Storage Will be using a microSD card for memory Will be using a microSD card for memory Cheap, readily available, persistent memory for prototyping Cheap, readily available, persistent memory for prototyping Can interface with other devices Can interface with other devices Smaller than normal SD card, so conserves space Smaller than normal SD card, so conserves space Will use PIC library for FAT32 File I/O system Will use PIC library for FAT32 File I/O system Connect to microcontroller via SPI bus Connect to microcontroller via SPI bus No need for pull-ups, according to several sources No need for pull-ups, according to several sources

24. Schematic/Theory of Operation: User Interface User Input: User Input: Pushbuttons (Use Generic I/O) Pushbuttons (Use Generic I/O) Menu System Menu System Audio: Audio: The VS1101E MP3 Decoder has built-in audio driver The VS1101E MP3 Decoder has built-in audio driver Communicates with microcontroller using SPI Communicates with microcontroller using SPI LCD: LCD: Character LCD Character LCD Communicates via I2C Communicates via I2C 24

25. 25 PCB Layout

26. 26 PCB Layout: Power Buck-boost circuit layout is crucial to proper performance Buck-boost circuit layout is crucial to proper performance Inductor traces must be wide to support high current Inductor traces must be wide to support high current Must be isolated from other digital circuitry Must be isolated from other digital circuitry

27. 27 PCB Layout: Battery PCB must act as heatsink for linear charge regulator PCB must act as heatsink for linear charge regulator Sense resistor should be as close to fuel gauge as possible Sense resistor should be as close to fuel gauge as possible Power traces should be kept wide and short for minimal losses Power traces should be kept wide and short for minimal losses

28. PCB Layout: Audio Analog and digital ground need to be tied close to VS1011E Analog and digital ground need to be tied close to VS1011E Decoupling capacitors placed as near as possible Decoupling capacitors placed as near as possible Header connection for SPI and microcontroller signals Header connection for SPI and microcontroller signals Audio jack must be on right edge of PCB for user access Audio jack must be on right edge of PCB for user access 28

29. PCB Layout: Sensors Accelerometer must be by mounting point to avoid circuit resonance Accelerometer must be by mounting point to avoid circuit resonance Breakout boards for accelerometer and altimeter placed on edge of circuit to conserve space Breakout boards for accelerometer and altimeter placed on edge of circuit to conserve space Accelerometer and altimeter placed close to one another – share an SPI bus Accelerometer and altimeter placed close to one another – share an SPI bus Header for ribbon cable to GPS Header for ribbon cable to GPS Header for access to SPI bus and chip selects Header for access to SPI bus and chip selects 29

30. PCB Layout: Microcontroller 64-pin QFP package 64-pin QFP package Contains 3 digital power/ground pairs, 1 analog power/ground pair, Vddcore and Vddcap pins Contains 3 digital power/ground pairs, 1 analog power/ground pair, Vddcore and Vddcap pins Require.01µF decoupling capacitors (locate near microcontroller) Require.01µF decoupling capacitors (locate near microcontroller) Requires 8MHz external crystal (locate near MCU) Requires 8MHz external crystal (locate near MCU) 30

31. Software Design/Development Status Components verified for correct functionality Components verified for correct functionality Primarily timer-based – allows for low power consumption Primarily timer-based – allows for low power consumption At set intervals: At set intervals: Poll accelerometer for jump data Poll accelerometer for jump data Poll GPS and altimeter for velocity and position Poll GPS and altimeter for velocity and position Poll altimeter for temperature Poll altimeter for temperature Poll battery for absolute voltage Poll battery for absolute voltage Poll pushbuttons for user input Poll pushbuttons for user input Act on readings by Act on readings by Calculating downhill velocity Calculating downhill velocity Notifying user via audio (user-set intervals) Notifying user via audio (user-set intervals) Saving GPS/altitude waypoints as needed Saving GPS/altitude waypoints as needed Activating modes of operation based on user input Activating modes of operation based on user input 31

32. Project Completion Timeline Week 8Week 9 Week 10 Week 11 Week 12 Week 13 Week 14 Week 15 1-Mar8-Mar22-Mar29-Mar5-Apr12-Apr19-Apr26-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 32

33. Questions? 33