Monday, February 29, 2016

Hockey scoreboard

What's missing from this picture (of a backyard hockey rink)?

You got it (probably the post title helped too): a scoreboard.
For those not familiar, a traditional one looks like in the photo below (click on it to see it bigger).

It may look simple, but it provides a lot of functionality:
  • display 2-digit home score;
  • display 2-digit visitor score;
  • countdown timer, with the starting time configurable/settable; timer displays mostly minutes and seconds, but under 1 minute, it displays seconds and tenths of a second;
  • stop/resume the countdown;
  • display round/period; number of periods is configurable/user-settable;
  • buzzer sounding at the end of the round, game or on demand;
  • penalty timers for up to four players (that also stop/resume with the main timer);
  • functions as a clock when not used in a game.
The control for the hockey scoreboard is pretty complex too. The control console is usually wired to the scoreboard. Sometimes the console is detachable (brought in to the booth by the score keeper), connected to a cable that plugs in.

An easy and quick way to build a home-made hockey scoreboard is to re-program a dual-display (16 x 64 pixels) Wise Clock 4. The scoreboard should be controlled wirelessly, from a distance of at least 10 meters (which disqualifies infrared remotes and also the most common Bluetooth, "class 2"). Potential solutions for the scoreboard remote control are:
  1. XBee
    • good distance range;
    • not cheap;
    • reliable communication;
    • requires building and programming a remote control device;
    • already hardware-supported by Wise Clock 4 board;
  2. RFM-12
    • good distance range;
    • cheap;
    • reliability probably ok for short messages;
    • requires building and programming a remote control device;
    • uses SPI interface, requiring some hardware hacking;
  3. RF 4-button key fob
    • cheap
    • easy to integrate
    • does not require any software support;
    • reliability at distance greater than 10m (?);
    • no need to build the remote control;
    • unfortunately limited to only 4 buttons;
  4. WiFi
    • cheap (ESP8266)
    • works as access point; user connects from smart phone or tablet, to access HTML form pages to type/input commands;
    • requires extra coding;
    • no need for extra remote control device (since using phone or tablet);
For the user, the easiest way to control the scoreboard would be by pressing physical buttons (the other, less-friendly, way would be by entering/selecting messages, e.g. "STOP", or "resume").

If using buttons, at least 4 are required to cover the minimum functionality:
  • reset scoreboard - D0;
  • start/stop/resume countdown timer - D1;
  • increment home score - D3;
  • increment visitor score - D2 (available) or D22 (re-routed)
which makes the 3rd solution above (RF 4-button key fob) an easy pick.

This is how the prototype scoreboard works on my desk:

The software is a branch-out of the Wise Clock 4 main software (using the same libraries, classes and functions, but in a separate .ino file). I created a new font (file fontFull.h) for the score digits, defined in a 8x16 matrix.
To add extra features ("clock mode", "chrono mode", message scrolling etc), more buttons/commands would be required on the remote control. Which means that the RF 4-button key fob is barely enough for now, and another solution must be implemented. My next favourite is the RFM-12, a topic for a future post.


  1. Oh sweet! I'm thinking the same thing when I go to soccer games.

    1. It's been years (decades?) since I went to a soccer game. In those times, only the referee knew the time and the score was changed manually, using boards with numbers :)
      I'm actually not kidding.

  2. What about something like this (there is the display only and down on the comments you can find as well the power stage with MOSFETs):

    1. Catalin,
      Really crafty display, also great instructable.
      I'll probably never attempt to build it, since it exceeds my abilities (and time, money and space I would need to allocate for it).
      From the instructable (and the comments) I understand that you need a way to control it? Software or hardware? Do you need a Wise Clock 4 board? (I could send you one as gift.)

    2. Yes, indeed building it was not so simple as I thought in the beginning, now I can do it in a different simpler way. The idea behind was to have such display for some local sport competitions organized by the club I am part of it (amateur sport events). Therefore here are some requirements: have count down (time limit sport events) and count up options, show clock and temperature, have a way to setup and control the display (these days I am working with a ESP8266-07). I'll be happy to get more details about the Wise Clock 4, thank you :)