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ECE 477 Design Review Team 14  Spring 2008

ECE 477 Design Review Team 14  Spring 2008. Shiv. Robert. Yukeun. Donghan. Outline. Project overview Project-specific success criteria Block diagram Component selection rationale Packaging design Schematic and theory of operation PCB layout Software design/development status

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ECE 477 Design Review Team 14  Spring 2008

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  1. ECE 477 Design Review Team 14  Spring 2008 Shiv Robert Yukeun Donghan

  2. Outline • 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

  3. Project Overview • HID for touch-based control • Move mouse cursor, other applications • Wearable glove • Three fingers – touch sensors/accelerometers • Bluetooth communication • UART interface • Battery powered • Rechargeable through USB connector

  4. Project-Specific Success Criteria • Communicate “mouse commands” wirelessly via a Bluetooth interface. • Move cursor using motion of a single finger. • Encode and decode gestures • Distinguish among cursor movement, mouse clicks, and gestures via finger-tip sensors. • Charge battery and manage battery power

  5. Component Selection Rationale • Microcontroller

  6. Component Selection Rationale • Bluetooth Module

  7. Component Selection Rationale • Battery/Battery Charger IC • MAX1555 • Manufacturer: MAXIM • Designed to charge Lithium polymer batteries • Input range: • USB: 3.7V to 6V 100mA charge • AC adapter: 3.7V to 7V 350mA charge • Can charge with either USB and/or AC adapter • Cheap and small

  8. Component Selection Rationale • Accelerometer

  9. Component Selection Rationale • Touch Sensor • FlexiForce • Manufacturer: Tekscan • Sensitivity: 1 lb/25lb/100lb • Slim and easy to interface • Acts as a variable resistor

  10. Packaging Design • OKW Ergonomic Enclosure • 150mm x 100mm x 40mm Main PCB Breakout-boards/Sensors

  11. Block Diagram Force Sensor Force Sensor Force Sensor Computer Main PCB Microcontroller PIC18F4550 ATD ATD ATD Bluetooth Receiver Bluetooth Module 2 Battery Charger USB ATD ATD ATD 2 2 2 Battery X-Y Accelerometer X-Y Accelerometer X-Y Accelerometer Breakout Board 1 Breakout Board 2 Breakout Board 3

  12. Schematic/Theory of Operation Battery Charger LED Bluetooth Touch Sensors Crystal Oscillator ICD 2 Accelerometer Sensors Microcontroller

  13. Schematic/Theory of Operation • Breakout Board (Accelerometers) • Three breakout boards for accelerometers • Main purpose of this is to reduce noise • Cx and Cy determine the bandwidth • 0.1uF will be used • Bandwidth = 50 Hz • Noise = 17.91mV which is 0.35% of maximum output voltage

  14. Schematic/Theory of Operation • Input impedance should be lower than 2.5Kohm • Voltage Follower circuit • To reduce input impedance • 5VRail-to-rail • Single supply Accelerometers

  15. Schematic/Theory of Operation • Without load, Rs is 1Mohm • An inverting operational amplifier • Different voltage levels – different resistance values • RF = 300Kohm • Vout = -5 * ( 300Kohm / Rs ) To ATD Touch Sensor

  16. Schematic/Theory of Operation • Touch Sensor • DC voltage inverter • Vout = -5 * ( 300Kohm / Rs ) • To generate positive voltage output Generate -5V

  17. Schematic/Theory of Operation • Battery Charger USB Detection Schottky diode USB POWER Battery Charge Status Battery LED DC POWER

  18. Schematic/Theory of Operation • Switch

  19. PCB Layout Analog MICRO USB Bluetooth Charging Power

  20. PCB Layout

  21. PCB Top Layer

  22. PCB Bottom Layer

  23. Software Design/Development Status • Microcontroller • Bluetooth • Accelerometer • Touch Sensor • Windows Driver

  24. Upcoming Schedule • Week 9 – Finish PCB layout, Accelerometer code • Week 10 to 11 – Bluetooth, Force Sensor code, Windows Driver • Week 12 – Windows Driver, Soldering • Week 13 – Packaging, integration • Week 14 – Testing / Documentation • Week 15 to 16 – Testing / Wrap up / Documentation

  25. Project Completion Timeline

  26. Questions / Discussion

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