Efficient and Portable Refreshable Braille Display

University

Shawnee State University

Major

Computer Engineering Technology

Student Type

Undergraduate Student

Presentation Types

Oral Group Presentation (Live)

Keywords:

Refreshable Braille Display, Assistive Technology, Accessibility, Embedded Systems

Abstract

This project details the design and implementation of an efficient, portable refreshable braille display aimed at improving accessibility in public spaces, such as restaurant menus or informational kiosks. Addressing the logistical and financial limitations of traditional paper braille, the device features a streamlined, display-only architecture powered by an STM32 microcontroller and twenty custom-fabricated braille cells. The system integrates a custom printed circuit board (PCB) with mechanical components produced via masked Stereolithography (mSLA) printing. Hardware challenges, including the lack of an external high-speed clock for USB connectivity and logic flaws in the display decoder circuit, were resolved by adapting the communication protocol to USART using a USB-to-TTL serial cable and manually modifying PCB traces to ensure precise, individual cell actuation. The device firmware, developed in C, utilizes a state machine architecture to manage data storage and retrieval. A critical feat involved resolving issues within the system's interrupt handling by implementing volatile flags and critical sections, ensuring the device captures rapid user inputs without data corruption. Complementing the embedded system, a C# host application was developed to convert standard text into a custom hierarchical byte structure, achieving 100% accuracy in data encoding, packet transmission, and device navigation. While the electronic and software systems functioned as designed, the mechanical actuation faced persistent challenges. After fabricating electromagnetic solenoids, excessive friction initially prevented cam rotation. Although manual adjustments reduced this friction, the cams exhibited unstable stuttering behavior rather than locking into position; the root cause of this instability could not be isolated within the project timeline. Despite this, the final prototype demonstrates that a robust, battery-operated solution capable of over eight hours of continuous use can effectively bridge the gap between cost and accessibility, given further refinement of the electromagnetic actuators.

Human and Animal Subjects

no

IRB or IACUC Approval

no

Faculty Mentor Name

J.T. Ok

Faculty Mentor Title

Assistant Professor

Faculty Mentor Department

Engineering Technologies

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Efficient and Portable Refreshable Braille Display

This project details the design and implementation of an efficient, portable refreshable braille display aimed at improving accessibility in public spaces, such as restaurant menus or informational kiosks. Addressing the logistical and financial limitations of traditional paper braille, the device features a streamlined, display-only architecture powered by an STM32 microcontroller and twenty custom-fabricated braille cells. The system integrates a custom printed circuit board (PCB) with mechanical components produced via masked Stereolithography (mSLA) printing. Hardware challenges, including the lack of an external high-speed clock for USB connectivity and logic flaws in the display decoder circuit, were resolved by adapting the communication protocol to USART using a USB-to-TTL serial cable and manually modifying PCB traces to ensure precise, individual cell actuation. The device firmware, developed in C, utilizes a state machine architecture to manage data storage and retrieval. A critical feat involved resolving issues within the system's interrupt handling by implementing volatile flags and critical sections, ensuring the device captures rapid user inputs without data corruption. Complementing the embedded system, a C# host application was developed to convert standard text into a custom hierarchical byte structure, achieving 100% accuracy in data encoding, packet transmission, and device navigation. While the electronic and software systems functioned as designed, the mechanical actuation faced persistent challenges. After fabricating electromagnetic solenoids, excessive friction initially prevented cam rotation. Although manual adjustments reduced this friction, the cams exhibited unstable stuttering behavior rather than locking into position; the root cause of this instability could not be isolated within the project timeline. Despite this, the final prototype demonstrates that a robust, battery-operated solution capable of over eight hours of continuous use can effectively bridge the gap between cost and accessibility, given further refinement of the electromagnetic actuators.