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µ BITS

µ BITS. Chris Page Peter Gimeno Christina Williams Greg Weatherford Christopher Howard. µ BITS - Pictures for the Blind. Designed to provide a tactile display allowing the blind to interact with computers, text, and possibly three dimensional images.

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µ BITS

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  1. µBITS Chris Page Peter Gimeno Christina Williams Greg Weatherford Christopher Howard

  2. µBITS - Pictures for the Blind • Designed to provide a tactile display allowing the blind to interact with computers, text, and possibly three dimensional images. • Can allow for communication between physically disabled people across the world.

  3. µBITS Overview – Presentation Outline • Product Overview • Initial Requirements • Block Diagram • Digital Design Process • Analog Design Process • Project Flowchart • Problems and Cost • Questions, Comments?

  4. µBITS Product Overview –A Tactile Display Board • Designed for use by the blind. • Capable outputting multiple character sets • Flexible I/O interface • Integrated Keyboard Support (USB or PS/2) • Software designed to support up to a 320x240x8 pin display. • Compact

  5. Operation at standard room temperatures. Safe for end user operation. Compliant with FCC standards. Safe for pacemaker users. Initial Requirements – Environmental Standards

  6. Initial Requirements - Performance Standards • CPU Capable of image/video decoding. • 2Mb of frame backing/character lookup memory. • 4Mb of CPU memory.

  7. Initial Requirements – Interface Standards • P/S 2 keyboard input • Pin Grid Output • 2 General purpose I/O inputs • Capable of supporting USB, IDE, Digital Cameras, serial, and many other popular input methods.

  8. Block Diagram Future I/O Expansion P/S 2 Input FPGA Display Driver I/O Controller Analog Display Driver Memory 2 Mb SRAM Frame Buffer and Character Lookup Table Pin Grid Processor CY7C67200 50 MHz GCC programmable Power supply DC –DC converters Memory 4Mb SRAM Future Expansion

  9. Digital Design Process • Determine Specification Details • Block Diagrams • Part selection • Schematic Capture • Schematic Review • Layout • Board Manufacturing (if possible) • Interface / Test / Debug • Implementing additional features.

  10. Analog Design Process Analog Display Driver • Layout of Pin Board (LPB) • Ideas for Pin Elevation (PE) • Ideas for Implementation • MUX Decoder • Current Amplifier • PWM • First Prototype Board • First Prototype Analysis Checklist • Next Steps (Prototype and Beyond) Pin Grid Power supply overall

  11. Analog Design: Layout of Pin Board (LPB) • Initially, we will work towards a 2D board similar to the board seen in the picture on the left. • Hopefully, for 3D contour, we will need to be able to elevate the pins to a greater height for higher 3D resolution.

  12. Analog Design (LPB): Initial Pin Board Design • We have chosen to start with a board that works with Braille characters. • We are looking to modularize each 2x3 section. • The pins will meet Braille specifications. 11” 11” 0.2” 0.1” 0.2” 0.02” to 0.05” 0.1” Distance between each Braille module = 0.15”(hor.) and 0.2”(ver.)

  13. Analog Design : Ideas for Pin Elevation • Magnetic Elevation (ME) • NIST ‘Pins’ down (NIST) • Temperature Sensitive Metals (TSM)

  14. Analog Design : Magnetic Elevation • Permanent magnets are many times stronger than the field created by current loops. • Use Neodymium Iron Boron (NdFeB) pins wrapped in current carrying coil. • Current in coil creates opposing magnetic field, which sends the pin up the tube.

  15. Analog Design (ME): Pin Elevation • Each solenoid needs around 80 wraps. To save space we put the coils on different levels. • Can control the height of elevation using PWM.

  16. Analog Design (ME): The Pin • Diameter of each pin would be approximately 1/10” to 2/10”. • Top of pin is steel (black) • Pin rod is plastic (red) • Permanent magnet (gray) is below, reacting to the current through the coil .

  17. Analog Design : NIST ‘Pins’ Down • Our hope is to be able to meet with – and – to discuss how their pin board is designed. • If there idea is to expensive or to complex, we will see what other ideas they would have. NIST Researchers John Roberts and Oliver Slattery

  18. Analog Design (TSM) : • Bimetallic strip • As strip is heated, bends with highest deformation in the center. • Will cool and maintain height of pin. Max Cohen, Hamza Aziz, Michael Amiet, Tora Unuvar, Hirotaka Fujita : Duke University : Department of Electrical and Computer Engineering

  19. Analog Design : Ideas for Implementation • Pin Addressing • High Z MUX Decoder • M&M (MUX Memory) • PWM (for 3D)

  20. Analog Design : High-Z DeMUX Decoder • Source Decoder • On is High Voltage • Off is High Impedance • Drain Decoder • On is Low Voltage • Off is High Impedance • This design allows only the desired pins to activate • Simplest solution, but may not work • Decoder will consist of a DeMUX, Memory and Current Source Outputs FPGA Decoder 1 Z Decoder Z 0 Z

  21. Analog Design : M&M (MUX Memory) Outputs • More complex then High-Z DeMUX design • Memory will allow pins to remain elevated • Eliminates possible problems with surrounding pins FPGA Clock DEMUX Memory Reset Current Driver Pin Grid

  22. Analog Display Driver: PWM (for 3D) • PWM to provide capabilities of hovering pins • PWM needed because providing constant current causes pin to rise to up most position. • A transistor is our first choice for the CCVS and VCCS CCVS VCCS PWM (UC3525)

  23. Analog Design : First Prototype • Will be a 2x3 board. (one Braille character) • Need to test board dimensions. • Will use magnetic elevation (ME). • Need to know wrapping to current ratio. • Size of pins needed. • Will use one of the pin addressing designs. • Depends on if High Z MUX will perform as expected within a reasonable cost. • Will not be connected to FPGA, will simulate FPGA output.

  24. Analog Design : Prototype Checklist • Pin has to elevate to correct height. • Record winding to current ration for correct height. • Pin has to stay elevated at correct height for specific amount of time. • Touching our display will not cause harm to the person. • Measure current and voltage on each pin to help with interfacing of pin bed to FPGA. • Calculate magnetic field.

  25. Analog Design : Next Steps (Prototype and Beyond) • Layout Board • Record list of manufactures and stores needed. • Wrapping solenoids. • Begin tests of layout board • Looking specifically at: • Scrolling • Pin addressing • Current Contacts to work with us • Lisa Pao - CU • NIST Researches of Tactile Board • John Roberts • Oliver Slattery

  26. Potential Problems • Software problems • IDE learning curve • FPGA/CPU communication • USB debugging interface problems • Hardware Problems • Current limitations • Display refresh problems • Interface issues

  27. Cost Estimate • FPGA development board: $250 • Computer PCB: $250 • Each 2x3 pin grid module: $5 • Digital-Analog Components: $100

  28. Questions, Comments?

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