This repository contains a python driver for interfacing the Mobitec FlipDot Displays that we have at CRF via simple MQTT messages. The idea is to use the displays for displaying various data and messages, for example the status of our 3D-printers.
The displays communicate over a serial link at 4800 baud using RS-485. Each one have a different address (as indicated in the configuration file) selectable by on-board dip switches. The displays are powered using +20-24 volts, and only use any current while flipping the dots.
First clone this repository and enter the newly created directory
git clone https://github.com/ChalmersRobotics/mqtt-flipdot-driver
cd mqtt-flipdot-driverThe project uses pipenv to manage all dependencies. Make sure you have pipenv installed before proceding. If not, you can install it using
pip install pipenvYou may need to run the command as sudo and/or using
python -m pip install pipenv
and run the following comand:
pipenv installThis will install all required dependencies.
If pipenv somehow didn't work (happens on Raspberry Pi because Python 3.7.0 is not yet available for it as of this writing) or is not available, use the following command to install the required dependencies manually.
pip install PyYAML paho-mqtt pyserialAfter installing the required dependencies, rename or copy the file config.example.yaml to config.yaml. The file contains configuration parameters specifying what MQTT broker to use, what base topic to listen on and a list of all available displays together with their name and size.
After modifying the configuration to your liking, the driver is ready to accept MQTT messages on the specified base topic. The topic defines what display to write to and what action to perform and is of the form {BASE TOPIC}/{DISPLAY NAME}/{ACTION}. The driver expects the payload to be JSON formatted text with values depending on the specified action.
Currently, the only action available is text and expects an array of objects, each with the following keys:
font- a string representing what font to use, defaults to "SMALL_F"xandy- numbers defining the position of the text on the display, defaults to 0text- the string of text to write to the display, defaults to "?"
As an example, here is the payload for displaying the text "Hello World" on two lines using the F5 font with a small margin to the left:
[
{"font": "F5", "x": 5, "y": 0, "text": "Hello"},
{"font": "F5", "x": 5, "y": 7, "text": "World"}
]Note: If you only want a single line of text, you still have to include the brackets ( [] ) around the single object to create an array of length 1.
Since the displays support a bitmap-like font, there is the possibility of adding an action to write a simple binary bitmap to the display. For now though, the text action is more than enough for our needs. Feel free to create a PR if you have any suggestions of changes and/or new features!
Here are some links that we found useful while developing this project. They contain more information about the hardware used and some reverse enginered protocol detatils.
- Building an Android-controlled Flip-Disc Display
- Adventures with Flippy the Flip-dot Display
- Svenska ElektronikForumet: Mobitec flipdot RS-485 protokoll
- Brose Vollmatrix
- GitHub: mobitec rs485 flip-dot display example
- GitHub: Controller software for the flipdot displays
- Matrix hardware reverse engineered setup