In order that I could use the time more productively by thinking about my next project, or trying to figure out why my last project didn't work, I decided to build an electronic lap counter.
It keeps track of the number of laps, the time on the current lap, time on the previous lap, and total elapsed time.
A Little More DetailThe project is based on the Arduino microcontroller. I built the digits using LED Light Bars that I got from Sparkfun Electronics. I'm near-sighted so I wanted them big enough so that I could read them without my glasses. As noted above the timer keeps track of laps, current lap time, previous lap time, and total time, but I can control which of those values is displayed via the toggle switches that can be seen on the left side of the device in the picture above. It cycles through whichever values are selected for display by the toggle switches, showing each for about two seconds.
The trigger switch is build from a piece of aluminum bar, bent at a 90 degree angle, and then covered with closed-cell foam. I wanted to be able to activate it by either pushing horizontally on the part that sticks down into the pool or vertically by pushing down from the top. The switch triggers an interrupt on the Arduino so it is very dependable.
I experimented with RFID tags as triggers. I thought it would be good if my wife and I could both use it and it would know who was swimming and thus, maybe, keep track of workouts over time for both of us -- that sort of thing. The inexpensive RFID tags only have a range of a few inches, however, and so the touch-point needed to be so precise it just didn't seem practical. Thus, for now, it doesn't keep track of any information from workout to workout.
At the end of the day, however, I consider the project a complete success. While I would never confuse swimming laps with having fun, when I'm doing it I am using my mind for something more productive than counting.