No. On the other hand, you don't need to. Scan a tag. Send the data. The receiver time stamps the receipt of the tag, defining the start time. Scan a tag on the other end to record the end time for that tag.
This is how I had originally planned for the system to work but was concerned with latency issues from sending and receiving the data hence the idea to add a real time clock to the transmitter unit. For simplicity's sake would it be ok to assume that there is negligible delay from when the start gate is triggered and when the receiving Arduino is actually aware that it was triggered? At the very least would this delay be consistent for every rider throughout the day?
For simplicity's sake would it be ok to assume that there is negligible delay from when the start gate is triggered and when the receiving Arduino is actually aware that it was triggered?
Depends on how you actually write the code. The delay can be anywhere from a few hundred nanoseconds to days.
At the very least would this delay be consistent for every rider throughout the day?
Depends on how you actually write the code. The delay can be small enough to be considered insignificant. If the delay is on the order of microseconds or less, I doubt that the delay will be observable in the measured time with respect to the actual time. Certainly the displayed value of the measured time could have more variation (between the measured time and the displayed time) than the actual delay values.
I would like to be able to identify when a rider enters and leaves the course so that I know how long they are on course for. Each rider needs their own unique identity. Start and finish are significantly far apart to need some form of wireless communication. Will need to handle multiple riders on course at one time.
What sort of distance will there be between the start/end points?
I was considering an Xbee pro for the transmitter that has a theoretical outdoor line-of-sight range of a mile. These races take place on hillsides and often in quite dense woodland but the start is always at a much higher vertical elevation than the finish.
How tolerant will you be of false/missing results?
This is not for any regulatory body but I would rather avoid any if possible.
Does it need to be tamper-proof?
Not really, this is just for use between friends and clubs so I wouldn't expect any attempts to cheat or manipulate the system
Can you get away with simply banning overtaking?
No, but we could theoretically only allow one rider on course at any time. However this is not desirable as on a longer course (3 min for a fast rider or 5+ min for a slow rider) with many people each requiring 2 runs, you can quickly run out of time.
Is there anything stopping you having a human element involved in the normal operation of this?
It needs to be as automated as possible, I don't want someone writing down riders numbers as they finish for example.
Depends on how you actually write the code. The delay can be anywhere from a few hundred nanoseconds to days.
The delay can be small enough to be considered insignificant. If the delay is on the order of microseconds or less, I doubt that the delay will be observable in the measured time with respect to the actual time. Certainly the displayed value of the measured time could have more variation (between the measured time and the displayed time) than the actual delay values.
Thank you for confirming that for me, will hopefully make the project a little simpler to program and also cheaper.
Knowing what you do about the project, do you think at an Arduino FIO would be suitable to use for the start transmitter? Am I correct in assuming that I can connect the ID-12 and a photoswitch without issue or would it be more straightforward just to use an Uno board instead?