LED Matrix Display

Project Overview

The LED Matrix Display is a cascaded 8x32 LED panel driven by four MAX7219 ICs connected in a daisy-chain SPI configuration with an Arduino UNO. It scrolls custom text messages, displays animations, and can receive new messages wirelessly via a connected HC-05 Bluetooth module — making it a versatile display unit for announcements, scoreboards, or decorative signage.

Key Features & Implementation

• Cascaded MAX7219 Drivers: Four MAX7219 ICs are daisy-chained over SPI, allowing the Arduino to control all 256 LEDs with just 3 data pins and minimal CPU overhead.
• Custom Font Rendering: A 5x7 pixel font library is stored in Arduino's program flash memory (PROGMEM), enabling crisp character rendering for all ASCII characters including special symbols.
• Wireless Message Updates: A paired HC-05 Bluetooth module allows new scrolling messages to be sent from a smartphone app without physically accessing the device.

Challenges Solved

Smooth scrolling at higher speeds caused visible flicker due to SPI transfer delays. By pre-rendering the next frame into a shadow buffer and performing atomic SPI burst transfers, flicker was eliminated and scroll speed was increased by 3× compared to the naive single-LED update approach.