I am working on a project where I am reading High/Low changes from an XBand Motion sensor from Parallax (32213). While the software solution works fine it is a resource problem as I have other sensors to read from the Micro Processor in it's scanning loop. Someone recommended looking at using an LM2917 FtoV converter so I can simply read the voltage on an analog input to the MP (I think the max is 3.3v).

Does anyone have experience with the LM2917 that can suggest a circuit to use for this? I can handle the software end, my hardware skills are a bit rusty.

 

The LM2917 is a pretty simple circuit. Used it once, a very long time ago and the chip did its job without any problems. Have a look at the example circuit in the upper-left hand corner of the document at the URL below. All you would need to do is scale the parts for your particular desired frequency range.

http://www.freeimagehosting.net/prauh

 

I'll probably have to write some software to figure out the frequency range when motion is detected. Not sure of the range. Thanks for the link!