Vehical speed measurement using microcontroller

is just the number of bigticks between consecutive two pulses at speed of 1Km/hr. If you know the circumference of your driven wheel (1639.3 mm for my car) and the number of pulses it generates for each revolution (pulses per turn – 4.5 for me), then I think the calibration factor can be calculated easily. It is simple mathematics where first we find how much the car travels in duration of one pulse (my car travels 36.4 cm between two pulses). Next we calculate how much time it takes (in micro Seconds) for this distance at speed of 1Km/hr (1311439 micro seconds). Divide the microseconds by 32 to convert time into bigticks (40982) and here you go, your very own calibration factor is ready to be poked in c-source file in place

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