Tennis Court Status Updater

Tennis court staff flip a switch on a small box and an update is posted to a web page for players to check before they call or leave home.

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Outdoor tennis courts, especially clay courts, are subject to the whims of the weather; when it rains the courts are closed, despite what the girls in the photo think. When the weather is iffy, players call to check the status of the courts. This is annoying to the players and to the staff at the courts. This gadget helps both groups.

It is very simple. A small box has a tennis ball light and is placed on the counter where the tennis players come in. The light shows the current status of the courts, green for open and red for closed. When the status changes, the tennis staff toggles the switch which changes the color of the light and posts an update to a web page.

Players can check the web page to see the current status of the courts before they leave home.

The tennis court staff like this because it saves them answering the phone to say Yes or No. Players like it because they can check the status in just a few seconds and don't have to hassle the staff.

8-13-14 This project is brand new and probably too late for the Hackaday Prize, but whatever...

It is based on an Electric Imp (  that very easily connects a sensor or switch to the Internet. This is the type of project where if you know how an Electric Imp works you immediately know how to do it, and if you are not a techy (like my tennis player buddies) it is MAGIC. I've explained what I'm doing and they have no idea how it might work but they do know how to check a web page (most of them, anyway). They are psyched and have started pestering me about getting it done.

I like this project because it has a high ratio of Utility to Effort, which is somewhat unusual in my experience.

So, technical details. Based on an Electric Imp with an April Development board (Amazon Prime, of course). Also has a toggle switch and a RGB LED and either a battery holder or a connector to a small power supply brick.

The plan is to put the RGB LED in one of two tennis ball lights I've found and ordered ($4 and $7 respectively). If this looks too dorky I'll just have the light on the box. The picture here is a terrible mock-up of  what it might look like, but hopefully you get the idea.

The light will help the staff know they have the status set correctly and will let players know the status of the courts when they walk in the front door and want to know if the courts are open (again a constant source of  (minor) annoyance to the staff).

I do a little web site development so that side of things is simple. I have a temporary web page now that I'm using. I registered and will use that eventually.

Still not sure how to power this. There probably is no problem using a small brick power supply but the best place to put this might not be near a wall outlet. Since the RGB LED is on all of the time it likely will take a fair amount of power. I won't know until I see how hard I have to drive the LED to make it visible inside the tennis ball light.

More to come...

  • 1 × Electric Imp Module to connect to Internet
  • 1 × April board for Electric Imp Breakout board for Electric Imp
  • 1 × RGB LED Status LED
  • 1 × Toggle Switch TBD
  • 1 × Plastic Housing TBD

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  • Electric Imp Code Posted

    Don Gettner08/20/2014 at 15:06 0 comments

    8-20-14 Posted the Electric Imp Agent and Device code to the support page for this project. Like all code it will be tweaked and modified over the next few weeks, but this version works so feel free to take a look.

    I realized the existing code will keep the RGB LED on 24/7 even though the tennis courts are not open all of the time. This has to be fixed. There are several options. Could have a hardware On-Off switch so the staff can turn it on in the morning when they arrive and turn it off when they leave, but one main feature of this design is that the staff doesn't have to do much so I doubt I'll do this. Could have a photodetector to turn off the unit when it is dark, but this would need a way to set the threshold and some rooms are never completely dark so this might be a problem.  The electric imp knows what time it is (or can find it out easily) so I will probably add an option to set the starting time and ending time on the web page and then use those times to control the RGB LED. We can have default values of 6:00 AM and 10:PM (we have lights on the courts and this probably is common) which probably would work for most. Not sure how to do this in the code but that is how this project has developed; find something I want to add and then figure out how to do it.

  • Web Site Snag

    Don Gettner08/19/2014 at 22:22 0 comments

    Got the prototype hardware working nicely and then ran into a snag with the web site code I need. I've been learning a bit about Javascript and JQuery and got enough done to have a working page, shown below.

    The Electric Imp Agent code sends a "Open" or "Closed" message to my web page which is shown on the screen, along with the time and the battery voltage. That works great.

    I've been learning about how to trap the Open or Closed message and then do more with it (like have the background color be green if the courts are open) but it isn't as simple as I expected (or I just haven't figured it out yet).

    Oh well, if it were easy it wouldn't be any fun.

  • Intro Video

    Don Gettner08/15/2014 at 15:58 0 comments

    Made and posted an intro video for this project. I was supposed to play tennis, but got rained out. Karma, I guess.

  • Prototype Breadboard

    Don Gettner08/14/2014 at 21:44 0 comments

    Made a prototype breadboard today. It is essentially two of the sample projects from the Sparkfun Tutorials on Electric Imp mashed together (Example 2 & 3).

    Here is the breadboard:

    Here is the schematic

    When S1 is closed then LED1 will be set to 'Green' and a status update will be sent to the server to be posted on a web page saying the tennis courts are open. If it starts raining then the staff will flip the S1 switch to open, the LED1 will be set to 'Red' and a status update will be sent to the server.

    I have ordered parts for the engineering prototype, which primarily are two tennis ball lights, one of which I hope I can make work for this project. The rest of the parts I have here hiding in old projects.

    Next I will get the software working, which shouldn't be bad since like the hardware will be based on existing working examples (I know, famous last words).

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