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POV LED Display Machine Design - Innovative Features for User Interaction

This project involves creating a Persistence of Vision (POV) machine with rotating LEDs to display patterns, track beacons, and update images in real-time. The success criteria include directional control, beacon tracking, and user input acceptance. The detailed design involves component selection rationale, block diagrams, schematics, PCB layout, and software development. The packaging design ensures efficient power transfer and noise control. The theory of operation covers power supplies, slip ring mechanisms, microcontroller functions, infrared and LED operations, RF communication, and user location detection. PCB layouts are segmented for different functions. Software development focuses on menu navigation, data reading, pixel generation, and communication between microcontrollers. Project completion timeline and discussion on project progress are also included.

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POV LED Display Machine Design - Innovative Features for User Interaction

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  1. ECE 477 Design Review Team 07  Fall 2009 Eric Glover Shaun Greene Steve Andre Russell Willmot POV Machine

  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 • Persistence of Vision (POV) machine that will control a single column of rotating LEDs to project a pattern to the user • 96x32 pixel 3-bit color output • Display in 360° with 10° resolution • Track an RF beacon • Example output patterns are a clock and thermometer, a small image, or other text

  4. Project-Specific Success Criteria • The ability to display a pattern with rotating LEDs • The ability to control the direction in which a pattern is projected • The ability to track the angle of arrival of an RF beacon • The ability to update a projected image while the machine is in operation • The ability to accept user-generated input to change display

  5. Block Diagram Lower Board

  6. Block Diagram Upper Board

  7. Assumed: 1800 RPM speed 15 cm radius disc (center to LED post) 180° display 96x32 RGB pixel display RF transceiver is 1Mbps (SPI) Minimum voltage difference of phase detector = 0.014 V for a 10° angle change Results 33 ms per revolution 174 μs per column (96 bits per column) Image data rate = 552 kbps (SPI) 92.6 μs = 1° of rotation Image = 9216 bits Time to transfer image = 10ms (ideal) 3.3V ATD resolution min = 8 bit (0.013 V resolution) Component Selection Rationale

  8. Micro #2 SPI (2 channel) 552 kbps & 1Mbps 16 I/O External Interrupt Timer Pulse Accumulator 8 KB of Flash 6 KB of SRAM 3.3 V preferred Component Selection Rationale Micro #1 • A/D (3 channels), at least 8 bit • SPI (1 channel) 1 Mbps • At least 21 I/O pins • 36 KB of SRAM • 36 KB of Flash to store images • 3.3 V preferred

  9. Component Selection Rationale Micro #1 Micro #2 • PIC24FJ32GA002 Microcontroller • 32 MHz Clock w/PLL • 16-bit Architecture • 8 MHz SPI (2 channels) • 21 I/O pins available • 32 KB of Flash • 8 KB of SRAM • 3.3 Volt supply • 28 pin SOIC • C Compiler Optimized Instruction Set • Extra Features: • Not a whole lot ARM Cortex M3 LM3S8962 Microcontroller • 50 MHz Clock w/PLL • 32-bit Architecture • 4 A/D channels (10 bit) • 24 MHz SPI • 37 I/O pins available • 256 KB of Flash • 64 KB of SRAM • 3.3 Volt supply • 100 pin LQFP Extra Features: • Integrated support for graphic OLED screen • Programmable with LabVIEW for ARM • Integrated Micro SD card drivers and hardware • Direct connection to Ethernet port • Free!!!

  10. Packaging Design

  11. Packaging Design

  12. Packaging Design

  13. Packaging Design

  14. Schematic/Theory of Operation • Main Power Supplies • Lower Board To Slip Ring 3.3V LDO 5V Buck converter Rectifier & Filter

  15. Schematic/Theory of Operation • Slip Ring – Power transfer from stationary PCB to rotating PCB • Uses carbon brushes against rotating brass rings to transmit power • 2.8 Vrms noise @ 30 Hz worst case • 0.7 Vrms noise @ 30 Hz best case

  16. Schematic/Theory of Operation • Main Power Supplies • Upper Board Power Input & Filter 5 V 3.0 Amp buck converter 3.3V LDO

  17. Schematic/Theory of Operation • Upper Board Microcontroller (PIC24F)

  18. Schematic/Theory of Operation • Infrared Red Emitter/Detector

  19. Schematic/Theory of Operation • LED Driver and LED connections

  20. Schematic/Theory of Operation

  21. Schematic/Theory of Operation • RF Transceivers: • Wireless communication • 2.4 GHz band • SPI Interface • 1 Mbps data rate

  22. Schematic/Theory of Operation • User Location Detection: Amplifier 1.2 GHz Oscillator Handheld Transmitter

  23. Schematic/Theory of Operation • User Location Detection:

  24. Schematic/Theory of Operation • User Location Detection: RF Connector Phase Detector/Comparator 1.2 GHz Bandpass Filter

  25. PCB Layout • Four PCB Segments • Lower Board (motor power circuitry, 1.2 GHz RF circuit, power supply) • Upper Board (power circuitry, PIC microcontroller) • LED Post (RGB LEDs and LED drivers) • Transmitter (oscillator, antenna)

  26. PCB Layout • Lower Board 4.7”x4.7”

  27. PCB Layout • Upper Board 3.7”x3.0”

  28. PCB Layout • LED Post 5.3”x2.0”

  29. PCB Layout • Transmitter 2.0”x2.0”

  30. Software Design/Development Status • Stationary Micro Software Functions • Control OLED screen and accept input from pushbuttons • Allow user to navigate a menu and select options • Read analog phase detection and temperature data • Generate new pixel maps • Send pixel map data to upper micro

  31. Software Design/Development Status • Upper Micro Software Functions • Use external interrupt to determine “0°” • Use IR pulses and timer to calculate rotational speed and stability • Read and store data from RF transceiver • Shift data out to the LED drivers at precise times

  32. Software Design/Development Status • Lower Microcontroller • User interface started and minimally working • The rest is in progress • Upper Microcontroller • Have PIC24F development board and all software in progress • No milestones yet

  33. Project Completion Timeline • Week 9 – Finish final schematic PCB and proof of parts • Week 10 – Finish software architecture and flow • Week 11 – Test software, build packaging and start soldering • Week 12 – Continue soldering and testing PCB • Week 13 – Complete software, start packaging & debugging • Week 14 – Continue construction and debugging • Week 15 - Finish debugging and add final tweaks • Week 16 – Demonstrate a complete working project

  34. Questions / Discussion

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