I'm planning to count the RPM of a RC Car which is controlled with a PI B+.
But while planning the question occurs, how to count the RPM. My Idea is via a Sensor, which gives a Pulse every Round, and to count that via Software.
My Problem right now is, that I didn't find reliable Information, about how fast I can count GPIO Changes and I don't know hot to do that efficiently.
Right now I would like to use Python with RPI.GPIO, since most of the stuff you find is made like this.
According to this Answer, it is possible to get up to 1 MHz (which should be 1M RPS, which I shouldn't reach).
Others state a max of 9 kHz (9k RPS) which is a completely other Dimension, and I think I've also read lower values while researching...
My Idea of Code yet is to add an event callback to a function, which simply counts up a counter and in the main thread I read and reset that counter about every .5 seconds (and measure the time). Furthermore I would keep the last three values and calculate an average.
So I hope Someone can give me advice, how to get the RPM the best way, and about how many Pulses per Second I can count max/for sure