Hello everyone

Please some one can help me to know if is possible check the value of frequency on my analogue input

Cheers

Antonio :)

it would certainly be easier to do it on a digital pin...however it is possible.

You would need to determine what is a high state and low state in software(set thresholds) and then create a timer to measure the time between two high to low transitions or two low to high transitions.

I think it may be difficult to find the actual frequency by time-domain of the signal is having big noise or high level harmonics.

One thing I can suggest to do is convert the signal to frequency-domain. Following page may help you.
You can get the frequency information from its peak. The resolution/accuracy depends on how much samples you can use for the FFT and its window-function.

http://mbed.org/users/jcobb/notebook/audio-fft/

Is a signal coming from a MDU radar module  that change frequency however some one  is closer to  or farther from the device

http://www.microwave-solutions.com/shop.htm