I’m trying to build a system that will provide timing for autocross events. I’ve got two arduinos with xbees, one pair each for the start and finish lines, connecting to a web service via connectPort. So far, so good.
What I’m missing is the trip mechanism. I’ve been testing infrared, but have not found any emitters / receivers that are strong enough to cross the road (No chicken jokes, please). So first question, could someone recommend a emitter / received pair for the job?
But even if I get an infrared beam across the road as a timing trigger, I’d need, I believe, two arduinos at each timing gate: one to modulate the IR on one side of the road, and one to receive it and transmit via xbee on the other side of the road. (I see I could use a timing circuit to modulate, but I think thats beyond my skills.) So, could there be a way to set up a trigger mechanism that only uses one arduino? For instance, could the IR emitter be so powerful that the car passing it would reflect the light back into the same arduino receiver? (I feel foolish asking this, but seeing as how my home stereo remote IR bounces all over the room, I thought it might be possible).
Lastly, I wish there were some device I could attach to the cars that would identify the car as it made it around the course. Right now, if for some reason either the start or finish gate does not register a time, and because the times are not tied in any way to a specific car, a missed trigger or errant trigger will cascade through the service and is difficult to correct without lots of re-runs. But, if I could tie each trigger to a specific vehicle, it would be easy to see if a vehicle was missing a start or finish trigger. So, would there be a practical and inexpensive way to “tag” the cars? (Typically there are ~50 cars participating)
I appreciate any input!