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by elliottbolzan
Tue May 07, 2013 8:23 pm
Forum: Automation, sensing and robotics
Topic: Timer: Photocell or Distance Sensor ?
Replies: 13
Views: 6758

Re: Timer: Photocell or Distance Sensor ?

Thanks geekinthesticks, that's pretty much what I'm trying to implement (except all the timestamping will take place on one device, to minimize error). Concerning Linux freezing up for a tenth of a second, I should be able to minimize the issue by running nothing else on the board. And I guess, wors...
by elliottbolzan
Tue May 07, 2013 7:44 pm
Forum: Automation, sensing and robotics
Topic: Timer: Photocell or Distance Sensor ?
Replies: 13
Views: 6758

Re: Timer: Photocell or Distance Sensor ?

Ah, I understand your point. Well, in the case of wireless transmissions, this won't be a problem: the time taken for the software to interface with the hardware will be included in the average travel time. However, I can see how this could be an issue with the sensing at the finish line. The good n...
by elliottbolzan
Tue May 07, 2013 7:09 pm
Forum: Automation, sensing and robotics
Topic: Timer: Photocell or Distance Sensor ?
Replies: 13
Views: 6758

Re: Timer: Photocell or Distance Sensor ?

Pi sends 100 packets of data to Arduino, and waits for responses. Calculates the average one-way travel time between both devices. User presses button on Arduino to arm timer. Pi is notified. Pi (after a delay), sends the command to the Arduino to play a sound through a Piezo. The time at which this...
by elliottbolzan
Tue May 07, 2013 6:53 pm
Forum: Automation, sensing and robotics
Topic: Timer: Photocell or Distance Sensor ?
Replies: 13
Views: 6758

Re: Timer: Photocell or Distance Sensor ?

I've decided to go the wireless way, with two Pi's or a Pi and an Arduino. I imagine I could have communication between both devices before the run, and calculate the average transfer time; I could then just subtract this from the final speed. Thanks for suggesting a semiconductor light sensor as we...
by elliottbolzan
Sun May 05, 2013 6:21 pm
Forum: Automation, sensing and robotics
Topic: Timer: Photocell or Distance Sensor ?
Replies: 13
Views: 6758

Re: Timer: Photocell or Distance Sensor ?

Thanks for the suggestion. It sounds great, but I'm afraid I won't be able to use WiFi, or have any other connection to Internet. Any other ideas ?
by elliottbolzan
Sun May 05, 2013 3:20 pm
Forum: Automation, sensing and robotics
Topic: Timer: Photocell or Distance Sensor ?
Replies: 13
Views: 6758

Timer: Photocell or Distance Sensor ?

I'm trying to create a system that will precisely time sprints on a track (100M probably the main distance being timed). The Raspberry Pi will emit a sound, and 100M later, a sensor will be set off by the runner. The difference in time between both of these events will then be recorded. However, the...

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