I'm sure this has been done before....measuring the RPMs of a flywheel, but just looking for a sanity check.
   
  Lets say you have a hall sensor pickup on a flywheel that is giving you around 5000 pulses/sec  from the teeth.
   
  So thats 5000Hz or 200uS between edges.  A 4MHz PIC has an internal cycle time of 1uS so it can easily count these, but better yet is to use TMR0 and the prescaler so you can get a reasonable number using the 1:128 and get out 39 Hz when you use a 1 second interupt to read the TMR0 value.
   
  This is assuming the input signal is relativly clean as well.
   
  Comments?

 
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