The plan was that laser would hit 5V solar panels. The Arduino reads the solar panel output through it’s analog port. The firmware compares the analog value at startup to the current value. If the value drops below a some value (80% of original seemed to work well during testing), the beam has been broken by the player and a penalty must be indicated and recorded.
When the massive green button is pushed by the person running the game, a 3-second countdown begins followed by a long beep indicates the timer has began. The goal of the game, besides just having fun, is to press the massive red button at the end of the course as fast as possible. If a beam is broken, an “angry” beep sounds and 5 seconds added to the timer. There is also a “tick” sound every second. A red Adafruit 1.2″ 4-Digit 7-Segment Display w/I2C Backpack was used for time display. A Teensy 2.0 ran the show. The 2.0’s 5V I/Os made it easy to work with the display.
I must say that this system only worked well in controlled environments. Fog machines, used so the laser beams could be seen, and varying lighting conditions made the solar panel output readings very noisy. But I am sharing the information anyway in case it may serve as a good starting point for others.
Code is on Gist.