Build a multi-monitor ANSI Art scrolling display. For example, here are 4 monitors connected to 4 Raspberry Pis:
On each Raspberry Pi, you'll need to run the following:
# Install Docker
curl -fsSL https://get.docker.com | sh
sudo usermod -aG docker pi
# Log out/log in again to pick up the new group
# On the server:
docker run --restart always --privileged --network host -dt ghcr.io/asm/ansi_scroller_server:latest
# On all clients:
# On older RPI models, you may have to switch to the legacy GL driver (use raspi-config, advanced options) if you see errors when launching the client
# Be sure to set the LCD_NUMBER to something between 0 (inclusive) and the number of screens - 1
# where LCD_NUMBER=0 is located at the bottom of the stack:
export LCD_NUMBER=xxx
docker run --restart always --privileged --network host --env LCD_NUMBER -dt ghcr.io/asm/ansi_scroller_client:latest--restart always will run the Docker containers at boot, perfect for art installations. The clients will auto-discover the server via SSDP so there's no config necessary (other than setting the screen number) as long as they're on the same network. Running a client and server on the same node is supported. You might consider setting the screen number in /etc/profile to make it permanent.
You can power down/up your screens on a schedule using cron and vcgencmd (RPi only). For example, to power down at 10pm and up again at 8am (be sure to check your timezone), simply run crontab -e and append:
0 22 * * * vcgencmd display_power 0
0 08 * * * vcgencmd display_power 1
SD cards are notorious for corrupting filesystems, usually due to excessive or dirty writes (ie during power loss). To prevent these issues, it's possible to run everything on OverlayFS.
sudo apt install -y fuse-overlayfs
# This will overwrite your docker config, be sure to check if this file exists
echo '{
"storage-driver": "fuse-overlayfs"
}' | sudo tee /etc/docker/daemon.json
# Restart docker to pick up the changes
sudo service docker restart
# Start the client (if you haven't already)
docker run --restart always --privileged --network host --env LCD_NUMBER -dt ghcr.io/asm/ansi_scroller_client:latest
# Now the important part: Stop docker and remove a directory it attempts to rename on boot. OverlayFS doesn't support renaming.
sudo service docker stop
sudo rm -rf /var/lib/docker/runtimes
# Run raspi-config and enable overlayfs and read only /boot in "Performance Options", then reboot
sudo raspi-configAt this point, no file changes will survive a reboot. To make changes, just run raspi-config again and disable overlayfs. More details on getting Docker working on OverlayFS can be found here.
The server loads a list of ANSI artworks to display from a JSON list via a URL. You can change that URL here. You'll note the files are in the .bin format (not .ans). This format is far easier to read and you can use PabloDraw to convert artwork. Someday, I'll write the code necessary to read .ans files.
Checkout the code to build and run the docker images yourself by running:
sudo apt install -y git
git clone https://github.com/asm/ansi_scroller.git
cd ansi_scroller
# On the server:
docker build -f Dockerfile.server . -t ansi_scroller_server
docker run --privileged --network host -dt ansi_scroller_server
# On clients:
docker build -f Dockerfile.client . -t ansi_scroller_client
export LCD_NUMBER=xxx
docker run --privileged --network host --env LCD_NUMBER -dt ansi_scroller_clientTo ease development, there is a Docker compose file that will run on Linux and Chrome OS. It launches a server and four displays, each in its own window. To start it, run:
xhost +local:root
docker-compose up --build- Support
.ansfiles.
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