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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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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.


Block Diagram

Future I/O Expansion

P/S 2 Input


Display Driver

I/O Controller


Display Driver



Frame Buffer and

Character Lookup Table

Pin Grid



50 MHz

GCC programmable

Power supply





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


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


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.






0.02” to 0.05”


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










Analog design m m mux memory
Analog Design : M&M (MUX Memory)


  • More complex then High-Z DeMUX design

  • Memory will allow pins to remain elevated

  • Eliminates possible problems with surrounding pins








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



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