Wearable LED Emoji Toy

Technologies and Libraries: KiCad (PCB Design), Arduino (Optional Programming), Charlieplexing (LED Control Technique)

Project Overview:

This project involved designing an interactive toy to teach schoolchildren fundamental electronics and programming concepts. The goal was to create a customizable and engaging product within budget constraints (<$15 per unit) for use in school workshops.

Project Goals and Challenges:

• Hands-on Learning: Develop a toy that facilitates hands-on exploration of electronics and programming principles.

• Budget-Friendly Design: Maintain a cost per unit below $15 for large-scale adoption in educational settings.

• Customization and Appeal: Create a product that appeals to students of various age groups with customization options.

Design Inspiration and Solution:

• Reference Design: The Lite-Brite toy served as inspiration for utilizing an LED array with user-configurable components.

• Customizable LED Array: Taking inspiration from Lite-Brite, I designed an LED array where LEDs could be:

  • Manually plugged into a mini breadboard for basic interaction.

  • Programmed to light up in specific configurations using an optional microcontroller.

• Doubled LED Density: The mini breadboard's limitations (10 LEDs per row) were overcome using Charlieplexing, a technique that enables controlling twice the number of LEDs within budget constraints.

Technical Implementation:

• Charlieplexing Integration: By strategically placing two LEDs on the same columns with opposite orientations, a microcontroller can switch states rapidly, making both LEDs appear lit simultaneously.

• Microcontroller Programming: An ATtiny85 microcontroller (optional) facilitates LED control and pattern programming.

• PCB Design: KiCad software was used to create the final product as a printed circuit board (PCB) for improved reliability and production efficiency.

Project Outcome and Learnings:

• Successful Design: This project resulted in a unique and cost-effective solution that meets all project requirements.

• Technical Expertise Displayed: The project showcases skills in:

  • Hardware Design: Adapting an existing concept (Lite-Brite) for a new application.

  • Electronics Integration: Integrating LEDs, microcontrollers, and breadboards.

  • Programming: Utilizing Charlieplexing technique and optional microcontroller programming.

  • PCB Design: Designing the final product as a PCB using KiCad software.

• Problem-Solving: Successfully doubled the LED density within budget constraints using Charlieplexing.