Bus- und Bahn-Anzeige (bus and train display)

This is the code to send information to the station display that is hanging in the hallway of CCCHH.

Documentation

The docs directory contains a number of documents about the device, all in German.

Development Environment

Use Poetry to manage a local environment:

poetry install

Local Development

You can run the server without having a physical display attached. The server will open HTTP port 3000 on localhost, and show an emulated display.

Deployment

The server is deployed as a Docker image and run with Docker Compose. See below for the configuration.

You will need to allow access to the serial port. For example, in compose.yaml:

services:
  buba:
    image: buba
    environment:
      BUBA_SERIAL: /dev/ttyUSB0
    devices:
      - /dev/ttyUSB0

Configuration

Buba is configured completely through environment variables:

Name	Default	Description
BUBA_LISTEN	127.0.0.1:3000	IP and port to listen on.
BUBA_SERIAL	/dev/ttyUSB0	Serial port the display is connected to.
DEBUG	false	Set to any value except false to enable debug output.

Creating Animation Plugins

Buba instantiates objects of type BubaAnimation and runs through them in a loop. Each animation must implement the show() method, which should send data to the display. The animation is run in its own thread, therefore, the animation should sleep an appropriate time to let users take in the information. See the existing animations in buba/animations for inspiration.

To implement your own animation, subclass BubaAnimation.

In the __init__() method, you will want to set self.title, and configure your data source.

Implement update() to fetch any data and fill in self.rows (list of rows). Each row in self.rows is a list of values for the columns in the layout.

The default layout has a wide, left-aligned column for text, and a short, right-aligned column for a time period or a value. You can define your own layout if necessary.

If you do not want to show tabular data, you can override show() and implement sending text to the display yourself.

Character Set

The display uses Code Page 437, with a few exceptions. Due to the limited resolution of the segments, the display can deviate significantly.

Note that the Python codecs for CP437 do not map all special characters correctly.

Code	CP437	Geavision Spaltenschrift
0xb4	┤ u2524	Vehicle end left
0xb5	╡ u2561	Vehicle end right
0xb6	╢ u2562	Track
0xff	u00a0	Three full segments

In other displays, the vehicle ends can be used together with other special characters to show carriage information; this set seems to be missing those extra characters.