Public Transportation Display


[Adrian] and [Obelix] wanted to have an easy way to know when to expect the public transportation, so they hacked an LED dot matrix display to show arrival times for stops near their dorm.

They found the display on Ebay with a defective controller which they replaced with an ATmega328p. They connected the display to the internet by adding a small TP-Link MR3020 router and connecting it to the ATmega328p via a serial line. Their local transportation office’s web page is polled to gather wait times for the stops of interest. All rendering of the final image to display to the dot matrix display is done on their PC, which then gets pushed through to the MR3020, which in turn pushes it out to the ATmega328p for final display.

[Adrian] and [Obelix] warn about setting proper watchdog timers on the display driver to make sure bugs in the controller don’t fry the dot matrix elements. Their ATmega328p dot matrix driver code can be found on [Adrian]‘s GitHub page.

Check out a video of the display in action after the jump.


  1. einballimwasser says:

    Sup fellow Karlsruher students!

  2. For a second there I forgot what public transportation was (I catch it everyday) and it took me about 3 reads of that first paragraph before I realised it was talking about bus/train arrivals and not time travellers/terminators. I think I need more coffee.

  3. 4ndreas says:

    I was working on the exact same thing (even the same bus tour) … paused during exam period.
    Great work!

  4. wretch says:

    [Adrian] and [Obelix]? Surely it’s [Asterix] and [Obelix]?


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