16F877@4Mhz calculate Pulsin to RPM

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  1. - 22nd April 2004, 23:53 #17
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    lwindridge Guest

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    Yet another question.

    I've been using a variation on ccpx2.bas to find the pulse length in uS and working the math back from there.
    BUT, I don't seem to get a very reliable figure from this (eg. I have a 29hz input which is roughly 870rpm but it seems to equate to something wildly out eg. 255??).

    I've attached my current code and if someone can suggest a better way of taking the rpm reading, processing it, reading the 2 adc ports and telling a timer to delay the incoming signal on an output port (eg. 44us for a 2 degree delay at 7500rpm) and display some values on an LCD then I'd be more than welcome for the additional input.

    Fingers crossed it's just my maths playing up!!

    Leigh
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