I'm working on a data acquisition system for byke/car engine. I'm trying to figure out which would be the best way to count RPM and I've thought to two different ways:1- using an interrupt routine attached to a digital input to count, say, 10 revolution and then look how much time passed between the first and the tenth to figure out ho many would they be in a minute. 2- using an IC to transform frequency to voltage and then read it from an analog input.
I think that solution 2 is better and cleaner but I'd like to keep everything on the same board. On the other side I don't know if the solution 1 would be accurate enough.
Max value would be 18000rpm that is 600hz for a 4 cylinder, 4 stroke engine...pretty low for most MCU. It'd be ok to have a resolution of100rpm (3HZ).