@snehasg96 Can you try the same thing with utime.sleep() instead? I haven't tried it myself yet, but I plan to do so.

@seb So my code was not the full text, but the part with which i made my mearusement... i tried your Period_timer()-class and now with the mean value from some measurements its really close to the expected value. Thats great. So obviously my code was very bad i think. But i still have this "wrong" values like the one in the middle (0.01154399 0.06744957). Any idea where they coud come from? At the moment i filter them by a minimum value. With 305 - 310 measurements, i got ~ 5-10 wrong Values. All close below to 1.5 ms. I tried to change my electrical circuit for better Voltages 0,15 V and 3.3 V instead of 0,4 V and 2,9 V. After i solved this i tried to run the same code. My wrong Values increased to ~ 286 from 586 measurements and the wrong values are close to 2,5 ms. I can´t set my minimum value to that, because my signal coud change to this period of time. This ist the new Signal: [image: 1518701859712-scr10-resized.png] The time span for my testing is still always the same(12,50 ms). Coud be the two little peaks at the very first beginnig a problem? Zoomes into the Signalstart at 0 s: [image: 1518702094347-scr11-resized.png] You don´t get wrong values, just to short? Andy