User Guide: Hybrid LED Video Display System

Welcome to your custom LED video display system. This guide will walk you through the setup and operation. The display is a powerful hybrid system capable of showing a live video feed from its companion computer, playing video files from a microSD card, and displaying custom text message overlays.

What You'll Need

  • The main LED Display unit with the attached microcontroller.
  • The companion computer unit with its Wi-Fi adapter and power supply.
  • A main 5V power supply for the LED display.
  • An RC controller (transmitter).
  • You must provide: A microSD Card (32GB or smaller is recommended).

Step-by-Step Setup

Part A: Prepare Your Content (The microSD Card)

This is the most important step to ensure your custom content plays correctly.

  1. Format the Card: Your microSD card must be formatted as FAT32.
  2. Prepare Video Files:
    • The display plays video files with an .avi extension.
    • Videos must be in the MJPEG format, sized to 128x64 pixels, and encoded at 25 frames per second.
    • Copy your finished .avi files to the main (root) directory of the SD card. They will be played in alphabetical order, so we recommend naming them like 01_intro.avi, 02_main.avi, etc.
    • For advanced users: The correct format can be created using a tool called ffmpeg with the following command: ffmpeg -i input.mp4 -vf "fps=25,scale=128:64:force_original_aspect_ratio=increase:flags=lanczos,crop=128:64,unsharp=5:5:0.5" -c:v mjpeg -q:v 1 -an output.avi
    • Image files are not currently supported - convert an image to a looping video with ffmpeg -loop 1 -framerate 25 -i input.jpg -c:v mjpeg -q:v 1 -t 5 -an output.avi
  3. Prepare Text Files:
    • The system can load multiple text messages from plain .txt files. Name your files alphabetically to set their channel order (e.g., 01_hello.txt, 02_alert.txt).
    • Each message requires two lines in the file:
      • Line 1: The exact text you want to display.
      • Line 2: The 7-character hex color code for the text, including the '#' symbol (e.g., #FF0000 for red).
    • The display mode is chosen automatically based on the file's content:
      • Static Text: If the text is narrower than the screen, it will be centered and static.
      • Scrolling Text: If the text is wider than the screen, it will automatically scroll.
      • Flashing Text: If you add multiple pairs of text and color lines to the file, the display will cycle through each one, creating a flashing effect.
    • Text support is only for standard ASCII characters (no unicode, no characters with accents)

Part B: Connect the Hardware

  1. Gently insert your prepared microSD card into the slot on the microcontroller.
  2. Connect the main 5V power supply to the LED display unit.
  3. Power on your companion computer and your RC controller.

Operating Your Display

The display is controlled with the two channels on your RC controller.

  • Changing the Video: One stick controls the main video. Push the designated channel up or down to cycle through the available video channels.
  • Changing the Text Overlay: The other channel controls the text messages. Push this stick up or down to cycle through your text files.
  • Important: To change a channel again, you must let the stick return to the middle (neutral) position first. This is a feature to ensure each "flick" of the stick results in only one channel change.
  • Adjusting the Brightness: A third control, typically a knob or a side lever, is used to adjust the overall brightness of the display.
  • ⚠️ IMPORTANT WARNING: Dangers of Excessive Brightness
    • Setting the brightness too high can draw a very large amount of power. This can cause the power supply to struggle, leading to some LED panels showing incorrect colors (like a brownish or reddish tint) instead of pure white due to insufficient voltage.
    • Excessive brightness also generates significant heat, which can damage the LED panels or even create a fire hazard over time.
    • For a consistently positive and safe viewing experience, we strongly recommend you err on the side of a lower brightness setting.

Understanding the Channels

Video Channels

  • Channel 0: Live video feed from the companion computer.
  • Channel 1: A blank, black screen.
  • Channel 2 and higher: Plays your .avi video files from the SD card.

Text Channels

  • Channel 0: Text Off.
  • Channel 1 and higher: Shows your .txt message files from the SD card.

Simple Troubleshooting

  • The screen is solid red when I turn it on.
    • This means no .avi video files were found on the SD card. Check that the card is inserted correctly and your video files are in the main directory.
  • A video from my SD card is a blank screen or freezes.
    • The video file is likely in the wrong format. Please ensure it is a 128x64 MJPEG .avi file. If a file is corrupted, the system will attempt to automatically skip to the next channel.
  • The Live Video feed (Channel 0) is frozen or black.
    • Ensure the companion computer and its Wi-Fi adapter are powered on. The system is designed to recover from a broken feed, but it may take a moment. If it persists, try restarting the companion computer.

Video Transmitter Notes

The video transmitter is a small computer that reads the HDMI input, scales it to 128 by 64 pixels, and transmits it over the wifi adapter connected to it. The wifi adapter is using a well-known open source project to convert it to a generic radio.

Important Notes:

  • The mapping of USB ports matters
    • HDMI input goes to the bottom blue (USB 3.0) USB port
    • Wifi adapter goes to the top blue (USB 3.0) port
  • The most likely issue is underpowering the wifi adapter - a longer USB cable can introduce a problem
    • The fix here would be to feed additional 5v power to the wifi adapter, but importantly, that 5v of additional power should be a parallel connection to the 5v coming into the computer’s USB-C port (do not use two separate power supplies, this risks damaging the board). This can be done by wiring in parallel to the USB-C port, or you can use the computer’s header pins for 5v power supply.
  • An output monitor is required.
    • If no monitor is detected, video will not transmit
    • The monitor is necessary because it’s an indicator that video is transmitting. Generally, as long as the monitor has output video, the system is transmitting.
  • Video signal is transmitted at 2.4 GHz frequency - existing antenna could be swapped out for a directional / patch antenna, amplifier can be added, etc (but ensure it’s a 2.4 GHz antenna)
  • If anything is wrong, power cycling will generally resolve the problem.