Hi,
I have a 7Hz 5Vpp square wave signal, you give me an advice on an easy way, to turn that signal into the corresponding DC voltage, so I can read it through the microprocessor's ADC converter?

Thank you.

 

Is this a square wave of constant frequency and voltage?
Or a rectangular wave of varying frequency, mark to space ratio, voltage?
And how fast do you need a responce to it?
You may well just need to feed it to a 10uF tantalum cap through a 10K resistor to get a reasonable "DC" to read.

 

the request is:
take a square wave signal with a fixed width of 0-5V and a variable frequency (3Hz to 10Hz, approximately) and convert it into a continuous signal ...
I hope I was clear...

 

Is this a school/college problem?

 

sounds like frequency to voltage converter. There might dedicated chips for it.
http://www.ti.com/lit/ds/symlink/lm2907-n.pdf

 

So the 3Hz~10 Hz equal to 0~5V?

 

I think if you have been given this as a project, you need the professor to state the project correctly. As you may notice from some of the questions, the way you have stated the problem does not make complete sense.

 

the request is:
take a square wave signal with a fixed width of 0-5V and a variable frequency (3Hz to 10Hz, approximately) and convert it into a continuous signal ...
I hope I was clear...

Yes, you were clear, but you did not tell us what you want to know about the signal.
Presence, frequency, amplitude, combination of the preceding or some other characteristic?

 

And you probably mean 5V height or amplitude, not width.

 

Take a sheet of graph paper (checkered paper) and draw a square wave on it.
Now write down all of the dimensional features of what you have drawn that make your square wave a square wave.
How many features were required to describe the square wave?
Now, which one of those features do you wish to be converted into a DC voltage?