Yeah, Henrik, I think the problem is exactly what you said, because I´ve just implemented the code to use ad raw data in comparision (to skip the math) and the result is the same!

The best result I got is with 190ms, which is the minimum pause that will not cause a false trigger. But it is still too high for a 15 second period of logging.

The filter is a good idea but I´ve also thought about using a higher adc sample time (ADC_SAMPLEUS 500 or something like that..) do you think that it would work?

Anyway, I think it´s a good idea to start thinking about a filter...

Thanks a lot!