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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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slide1

µBITS

Chris Page

Peter Gimeno

Christina Williams

Greg Weatherford

Christopher Howard

bits pictures for the blind
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.
bits overview presentation outline
µBITS Overview – Presentation Outline
  • Product Overview
  • Initial Requirements
  • Block Diagram
  • Digital Design Process
  • Analog Design Process
  • Project Flowchart
  • Problems and Cost
  • Questions, Comments?
bits product overview a tactile display board
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
initial requirements environmental standards
Operation at standard room temperatures.

Safe for end user operation.

Compliant with FCC standards.

Safe for pacemaker users.

Initial Requirements – Environmental Standards
initial requirements performance standards
Initial Requirements - Performance Standards
  • CPU Capable of image/video decoding.
  • 2Mb of frame backing/character lookup memory.
  • 4Mb of CPU memory.
initial requirements interface standards
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.
slide8

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

digital design process
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.
analog design process
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

analog design layout of pin board lpb
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.
analog design lpb initial pin board design
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.)

analog design ideas for pin elevation
Analog Design : Ideas for Pin Elevation
  • Magnetic Elevation (ME)
  • NIST ‘Pins’ down (NIST)
  • Temperature Sensitive Metals (TSM)
analog design magnetic elevation
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.
analog design me pin elevation
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.
analog design me the pin
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 .
analog design nist pins down
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

analog design tsm
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

analog design ideas for implementation
Analog Design : Ideas for Implementation
  • Pin Addressing
    • High Z MUX Decoder
    • M&M (MUX Memory)
  • PWM (for 3D)
analog design high z demux decoder
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

analog design m m mux memory
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

analog display driver pwm for 3d
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)

analog design first prototype
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.
analog design prototype checklist
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.
analog design next steps prototype and beyond
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
potential problems
Potential Problems
  • Software problems
    • IDE learning curve
    • FPGA/CPU communication
    • USB debugging interface problems
  • Hardware Problems
    • Current limitations
    • Display refresh problems
    • Interface issues
cost estimate
Cost Estimate
  • FPGA development board: $250
  • Computer PCB: $250
  • Each 2x3 pin grid module: $5
  • Digital-Analog Components: $100
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