LED Dot Matrix Smart Notice Board

Project Overview

The LED Dot Matrix Smart Notice Board is a versatile digital signage solution that transforms traditional static bulletin boards into dynamic, remotely-manageable display systems. Using a cascaded array of 8x8 LED dot matrix modules controlled via WiFi, this project enables real-time message updates from anywhere in the world through a custom mobile application or web interface. The system supports scrolling text, animations, multiple fonts, adjustable brightness, and scheduling features that allow messages to change automatically at predetermined times. Perfect for schools, offices, retail stores, transportation hubs, or anywhere information needs to be displayed and updated frequently without physical access to the board. This project demonstrates practical IoT applications in information dissemination while maintaining low cost and easy deployment.

Problem Statement

Traditional notice boards using paper, whiteboards, or static digital displays present numerous challenges: updating content requires physical access; information becomes outdated quickly; creating visually appealing displays is time-consuming; multiple messages can't be rotated efficiently; emergency announcements can't be pushed instantly; and there's no way to manage content remotely or schedule automated updates. In educational institutions, offices, and public spaces where timely information dissemination is critical, these limitations create inefficiencies and missed communication opportunities. Existing commercial LED displays are often expensive, require specialized software, lack wireless connectivity, or don't provide user-friendly interfaces for non-technical users. The need exists for an affordable, easy-to-use, remotely-accessible digital signage solution that anyone can deploy and manage without technical expertise or ongoing subscription costs.

Solution & Approach

Our solution employs a modular LED matrix display built from MAX7219-based 8x8 dot matrix modules, cascaded to create larger display areas (typically 32x8 or 64x8 pixels). The NodeMCU ESP8266 microcontroller manages the display while providing WiFi connectivity for remote access. The system architecture includes three components: the display hardware, ESP8266 firmware running a web server, and client applications (mobile app and web interface). Users send messages through the app using HTTP POST requests; the ESP8266 receives, stores, and displays the content with smooth scrolling animations. The firmware implements message queuing allowing multiple messages to cycle automatically, brightness control for different ambient lighting conditions, and scheduling functionality for time-based content changes. The mobile app, developed using MIT App Inventor, features an intuitive interface with text input, emoji/symbol selection, speed adjustment, brightness control, and saved message templates for quick access. A web dashboard provides advanced features including message scheduling, display preview, statistics on message views, and multi-device management for controlling several boards simultaneously. Power management supports both AC adapter and battery operation with automatic brightness adjustment based on ambient light sensors to conserve power.

Technologies Used

The display uses four or eight MAX7219-driven 8x8 LED dot matrix modules connected via SPI communication, providing high refresh rates and individual LED control. NodeMCU ESP8266 serves as the controller and WiFi interface, programmed in C++ using Arduino IDE with MD_MAX72XX and MD_Parola libraries for advanced display control including text scrolling, sprites, and animations. The libraries support various fonts, alignment options, and transition effects. Network communication uses ESP8266WiFi and ESP8266WebServer libraries implementing RESTful API endpoints for message submission, status queries, and configuration changes. The Android app was created in MIT App Inventor 2 with HTTP client components for sending data and JSON parsing for receiving board status. The web interface uses HTML5, CSS3, and JavaScript with AJAX for asynchronous updates. For scheduling, we implemented a real-time clock (DS3231 module) with battery backup ensuring accurate timekeeping even during power outages. Message storage uses SPIFFS (SPI Flash File System) on the ESP8266, allowing permanent storage of multiple messages and configuration settings. Optional features include a light-dependent resistor (LDR) for automatic brightness adjustment and a buzzer for audio notifications. The enclosure is laser-cut acrylic with 3D-printed mounting brackets, creating a professional appearance suitable for public spaces.

Challenges & Learnings

Display refresh rate and text scrolling smoothness required careful timing optimization—initial implementations showed flickering and jerky movement until we implemented hardware SPI and optimized the refresh loops. Long messages exceeded ESP8266 memory, so we developed streaming algorithms that process text in chunks without loading entire messages into RAM. WiFi stability in public spaces with multiple networks presented connectivity challenges; we implemented smart connection algorithms with SSID priority lists and automatic channel selection. Character encoding for special characters and emojis required custom sprite definitions since standard ASCII doesn't include these symbols. Power consumption management was critical for battery-operated deployments; we implemented sleep modes between display updates and optimized LED usage patterns to minimize power draw. User interface design for the mobile app went through multiple iterations based on feedback—early versions had too many options that confused users, so we simplified to essential features with an advanced settings section. Network security was important since the board is accessible over WiFi; we implemented password-protected access, HTTPS support for secure communication, and rate limiting to prevent spam or denial-of-service attacks. Brightness control needed calibration for different viewing angles and ambient light conditions. We learned the importance of providing immediate visual feedback in the app when messages are sent, implementing confirmation screens and error handling for network timeouts.

Results & Impact

The LED Matrix Notice Board has been successfully deployed in several locations including our university robotics lab, a local small business, and a community center, demonstrating practical viability across different use cases. The system reliably operates 24/7 with minimal maintenance, displaying scheduled announcements, event information, and real-time updates. Message update latency averages under 2 seconds from app submission to display, enabling truly real-time communication. The board supports messages up to 500 characters with smooth scrolling at adjustable speeds from 15 to 100 pixels per second. Power consumption runs approximately 5W for a 64x8 display at medium brightness, making solar-powered operation feasible. User feedback has been overwhelmingly positive—administrators appreciate the convenience of remote updates, eliminating trips to physically change displays, and the scheduling feature ensures timely information delivery without manual intervention. The project cost approximately $40-50 in materials, representing significant savings compared to commercial LED displays costing hundreds of dollars. Educational impact includes using the project in workshops to teach students about IoT, display multiplexing, web servers, and mobile app development. The open-source code repository on GitHub has been forked multiple times with community contributions adding features like multi-language support, animated GIF playback, and integration with smart home systems. This project demonstrates that sophisticated digital signage solutions are accessible to schools, small businesses, and community organizations without requiring large budgets or technical expertise.

• Designed and developed a remote-controlled notice board using an LED dot matrix display.
• Enabled real-time message updates via wireless communication (e.g., Bluetooth/Wi-Fi).
• Implemented an intuitive interface for dynamic content management from mobile or web platforms.