re electronic odometers was used bmw qu just a few comments about the feasability of zipping up a bunch of miles on your electronic odometer with an oscillator i wouldn t expect to be able to do this not because the engineers at bmw are putting in anti fraud logic but just because an automobile is a noisy hostile environment for electronics and i would expect the software to be conservative if i were to design a microprocessor based odometer speedometer program it would have the following features just off the top of my head debouncing deglitching is this a real pulse or just a glitch smoothing the rate of change of speed cannot be too high this is a car not an electron top speed limit anything above mph is ridiculous must be electrical noise or contact bounce as for getting in and presetting the pins if this is the circuit board out of a bmw dashboard i seem to remember a single big chip with lotsa pins in the middle of the card good luck getting at the counter i wouldn t expect a high input frequency to damage the meter remember it s probably damped so it can t move too fast and is probably protected after all a car is an extremely hostile place for delicate electronics there used to be an app note in the national semiconductor linear databook that went into this in good detail jerry kaidor tr jerry dragoman com jkaidor synoptics com jerry kaidor
