I am new in the community, and as part of my studies I have to reset a speedometer.
For this I use an optical sensor fetch, and a lcd screen to display the speed.
I realized the program below, thanks to the library “freq counter” I determine the frequency of rotation then I use a basic physical formula to find the speed, but this does not give the desired result.
Do you see a major mistake?

Programme final.ino (2.15 KB)

Have you tried googling arduino tacho

Tom... :slight_smile: