Scanned the signal with osciloscope and it gives a fine AC wave.
I don t understand very weel interrupts an if it is possible to count a pulse of time between two low activations for example.
Are you sure it's an inductive sensor? Is there a magnet in your toothed wheel?
I believe you could feed your sensor output through a diode clamp, and into a comparator circuit to get a clean square wave, then feed this into a pin 2 interrupt. Then make a super-simple interrupt handler that counts interrupts. Finally, in your loop() you would sample the current count value and elapsed time, and calculate motor speed from that.
Peter,Many inductive sensors contain magnets, the toothed wheel simply gate's the flux which produces enough variation in flux density to induce voltage in a coil.
If all you need is to know the rpm, you don't need to adc the signal. Feed it to the mcu's counter / capture pin via a small resistor (like 1k - 10k).
Feed it to the mcu's counter / capture pin
QuoteFeed it to the mcu's counter / capture pinSincerely i don t know what pin in arduino as this capabilitie, or is some software that enable a analog pin to sense the signal?