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ECE 477 Design Review Team 5  Spring 2009

ECE 477 Design Review Team 5  Spring 2009. Project Overview. Inertial based character recognition device Battery powered pen Wall/battery powered base station Wireless communication betwixt pen and base. L. Project-Specific Success Criteria.

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ECE 477 Design Review Team 5  Spring 2009

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  1. ECE 477 Design Review Team 5  Spring 2009

  2. Project Overview • Inertial based character recognition device • Battery powered pen • Wall/battery powered base station • Wireless communication betwixt pen and base L

  3. Project-Specific Success Criteria • An ability to initiate the drawing of a character. • An ability to match and display characters on an LCD screen. • An ability to monitor battery life and display status. • An ability to interpret data from accelerometers as characters. • An ability to transmit data wirelessly to a base device.

  4. Block Diagram Pen Base Station MRF24J40MA (Transceiver) MRF24J40MA (Transceiver) 7 7 ADXL330 (Accelerometer) PIC18F2320 (Microcontroller) ~3 dsPIC33FJ128GP204 (Microcontroller) HD44780U (LCD) 10 LTC4150 (Fuel Gauge) LTC4150 (Fuel Gauge) LTC4054-4.2 (Battery Charger)

  5. Overall Design Constraints • Pen • PCB small enough to fit on a pen • Low enough power consumption to run off batteries • Proper peripherals to interface with wireless transceiver (SPI in master mode) and accelerometers (3 ATD channels) • Base Station • Proper peripherals to interface with wireless transceiver (SPI in master mode) • Enough I/O pins to interface with LCD Display • Large FLASH memory

  6. Component Selection ADXL330 • ‘Usable’ package • LFCSP • Analog signal • 1.8-3.6V • 3-Axis • 4×4×1.45mm • Alternative: ADXL 213

  7. Component Selection MRF24J40MA Integration with microcontrollers Usable package Surface Mount All inclusive 2.4-3.6V 17.8 mm x 27.9 mm Alternative: Meshnetics MNZB-24-A2 using ATmega 1281v MCU

  8. Component Selection PIC18LF2320 • 1-SPI; 3-ATD; • Software stack for MiWi protocol • 3.3KB PMemory (8192B) • 200B Ram (512B) • 2-5.5V • 0.3 in x 1.4 in • Internal Oscillator • Well supported

  9. Component Selection dsPIC33FJ128Gp204 • 1 SPI • Software stack for MiWi protocol • 3-3.6V • 6 x 6 x 0.9 mm • 128KB program memory • Well supported • Alternative: dsPIC33FJ64GP306 • 64 GPIO pins • 64kB PMemory

  10. Power Consumption & Battery Life • Pen • Two Duracell Rechargeable NiMH AA batteries in series • 1800 mAh • 5.5 hours estimated battery life

  11. Power Consumption & Battery Life • Base Station • Ultralife Li-Ion Rechargeable battery • 1800 mAh • 8 hours of battery life

  12. Packaging Design

  13. Pen Power Management Battery Headers 3.3V Boost Fuel Gauge

  14. Pen Power Management 3.3V Possibly remove? 3V (2AA)

  15. Pen Power Management 3V (2AA)

  16. Pen PIC/Peripherals Axes Signals ICD2 Header Transmitter Header Microcontroller Accelerometer Transmitter Pen Tip

  17. Accelerometer

  18. Microcontroller

  19. Transceiver

  20. Base Station Power 5V Boost 4V DC LDO Fuel Gauge Battery Charger 3.3V Buck

  21. LDO, Fuel Gauge, Battery Charger

  22. 5V Boost and 3.3 V Buck

  23. Base Station PIC/Peripherals PIC Transceiver LCD Header

  24. PCB Layout – Constraints Base station: • No strict size limitation • Separate power management (analog) from microcontroller and transceiver (digital) for noise control • Transceiver needs to be on the edge of the board to limit interference • 3 power rails: 4 volt regulated, 5 V for LCD, 3.3V for the other digital components • Size: 1.75” x 4.1”

  25. PCB Layout – Base station LCD Header Charger chip Fuel gauge 3.3V Buck Transceiver Linear Regulator (4 V) dsPIC33 5V Boost ICD2 Header

  26. PCB Layout – Base station (T)

  27. PCB Layout – Base station (B)

  28. PCB Layout – Base station (ground) LCD Header Charger chip Fuel gauge 3.3V Buck Transceiver Linear Regulator (4 V) dsPIC33 5V Boost ICD2 Header

  29. PCB Layout – Base station (4 V) LCD Header Charger chip Fuel gauge 3.3V Buck Transceiver Linear Regulator (4 V) dsPIC33 5V Boost ICD2 Header

  30. PCB Layout – Base station (5 V) LCD Header Charger chip Fuel gauge 3.3V Buck Transceiver Linear Regulator (4 V) dsPIC33 5V Boost ICD2 Header

  31. PCB Layout – Base station (3.3 V) LCD Header Charger chip Fuel gauge 3.3V Buck Transceiver Linear Regulator (4 V) dsPIC33 5V Boost ICD2 Header

  32. PCB Layout – Base station (Power management) Charger chip Fuel gauge 3.3V Buck Linear Regulator (4 V) 5V Boost

  33. PCB Layout – Base station (dsPIC33) dsPIC33

  34. PCB Layout – Base station (Transceiver) Transceiver

  35. PCB Layout – Constraints Portable device (pen): • Tight size constraints • Keep analog traces from accelerometers as short as possible; accelerometers close to the tip of the pen • Transceiver needs to be on the edge of the board to limit interference (preferably on top) • Size: 1.3” x 4.2”

  36. PCB Layout – Portable device Accelerometer Header Transceiver PIC18 3.3V Boost Fuel gauge Acc SPI Header ICD2 Header

  37. PCB Layout – Portable device

  38. PCB Layout – Portable device

  39. PCB– Portable device (ground) Accelerometer Header Transceiver PIC18 3.3V Boost Fuel gauge Acc SPI Header ICD2 Header

  40. PCB– Portable device (3.3 V) Accelerometer Header Transceiver PIC18 3.3V Boost Fuel gauge Acc SPI Header ICD2 Header

  41. PCB– Portable device (Accelerometers) Acc

  42. PCB– Portable device (PIC18) PIC18

  43. PCB– Portable device (Power Management) 3.3V Boost Fuel gauge

  44. PCB– Portable device (Transceiver) Transceiver

  45. Software Design/Development Status Base Station Pen

  46. Project Completion Timeline

  47. Questions / Discussion

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