> It can be just a few Hz, I don't need 500 Hz. Tldr: understood that you think you don’t need 500 Hz, but there is a technological limitation why you need tha

> It can be just a few Hz, I don't need 500 Hz. Tldr: understood that you think you don’t need 500 Hz, but there is a technological limitation why you need that frequency for these systems to work. The reason these measurements need to be so fast is because the measurement is not absolute but periodic. Meaning that when you measure something it can’t tell you how large it is in absolute terms just how much larger it is than the closest integer period. In mathematical notation you can measure x where the whole distance is k*period+x, where k is an unknown integer, and period is a design parameter. It can’t natively tell you what is the value of k. So to figure out the whole measurement you need to calculate k. And you can do that by keeping track of it. You know it is zero when they zero out the caliper, and you know that it just increased by one every time there was a falling discontinuity of x. (Meaning that every time x approaches the period and then suddenly drops to a low number it just crossed over one of these period boundaries.) Similarly you decrease k every time x had a positive discontinuity. And you can only do that trick if the sampling rate is much higher than the speed the caliper is moved. If you sample too slow suddenly the caliper might move multiple whole periods between two samples and the code would loose track of the value of k.