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  • #3276

    Dave
    Participant

    OK. So I want to use a crumble to do some simple timing.

    The idea is that a model car goes over a contact to set ‘A’ high then after going down a slope, sets ‘A’ low. In between then, the crumble just does a loop and counts very fast. I figure that if it counts say 700 times a second (I’d time it against a watch to calibrate) then if the car goes down with a count of 6600, its 6600/700 seconds.

    In this little prog, the sparkle goes green to show its ‘timing’. Then red for 2 seconds to show its stopped timing. As variables are only integers, the bit at the end just gives seconds and tenths, converting from just timing in ‘tenths’

    Two problems:
    1) It only works at all when connected to computer by usb! Minor issue if the slope is near the computerCrumble . I know you could have pupils pressing switches, but they might as well use a stopwatch in that case! Is there a way of storing a variable when ‘headless’ and getting it back again?
    2) SOMETIMES it seems to stop timing immediately – switch bounce! Any idea how to trap that?

    Thanks

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    #3538

    Mike
    Participant

    Don’t put the crumble in the car. Have it connected to two ‘gates’ one at the top and one at the bottom of the slope. This will be far more accurate than using a stopwatch and they can focus on the car build for speed or whatever.

    If you really want it in the car, go super cute and make the car trace out the shape of the number (like a turtle) after it stops timing 🙂

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