I need a circuitry to detect the falling and rising edges of voltage signals [square waves, probably PWM signals] ranging between 0.5V - 40V at a resolution of maybe 10us (10 micro seconds)
the data(voltage amplitude and on/off times) are to be fed to a micro-controller (probably from the Atmel Xmega family)

any guidelines about where i should start looking to design such a board ?
p.s. i guess its gonna be something like the circuitry of an oscilloscope

 

Is the gain adjustable, or does it have to work with any pulses between 0.5 and 40V without adjustment or gain switching.

Quantizing 40V with a 10bit AD would mean a resolution of 40/1024 = 39mV

 

for this, i will have to confirm with my instructor

 

Do you mean that a given square wave signal is going between a low value of 0.5V and a high value of 40V, or do you mean that your system needs to work today with a square wave that is 0.5V in amplitude and tomorrow with a square wave that is 40V in amplitude?

 

Are you trying to measure the slope of the rising and falling edges, or merely detect at what instants the edges occur, or pass a threshold voltage?

 

Do you mean that a given square wave signal is going between a low value of 0.5V and a high value of 40V, or do you mean that your system needs to work today with a square wave that is 0.5V in amplitude and tomorrow with a square wave that is 40V in amplitude?

I think its going to fluctuate between the values of 0.5V - 40V i mean it could be like 2V or 36V at different times

 

Are you trying to measure the slope of the rising and falling edges, or merely detect at what instants the edges occur, or pass a threshold voltage?

Its the second one, i have to detect the instants at which they occur

 

You might try using a peak detector to establish a reference for your upper level and then a voltage divider to establish the reference level for your comparator.

What is the frequency of this PWM signal? Is that fixed or can that vary, too? If so, over what range?