Hi, thank for you soon reply!
I've got the library yet, but it's a little bit to understand to me how to use it to time a function. I'm trying to keep hard an eye on to understand it.
The interrupt I would try to set is only for the timed function. I.e.: pushing a key on the keyboard cause the start of a measurement (for a certain and yet set sensor); pushing another button cause the stop of the measurement. During the function I would like Arduino will get values from the sensor and send value to the serial port (simply using Serial.print(....)) using a set time period (for example one serial printing every two second). After every printing Arduino should search the serial port for the "stop key", used as interrupt. I would like to use the sensor data to plot a graph on Processing. Thank you very much!