timing from spark signals

[Steve Stegmann <stegmann@domain.elided>]

I forgot to mention that the rpm comes from watching the timing between 
the *same* plug firing.  They know how many cylinders there are.

Steve

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Steven A. Stegmann
     _/_/_/    _/      _/_/_/ "No free man shall ever be debarred the use
   _/    _/   _/_/   _/    _/  of arms.  The strongest reason for the 
   _/        _/ _/   _/        people to retain the right to keep and bear
    _/_/    _/  _/    _/_/     arms is, as a last resort, to protect 
       _/  _/_/_//       _/    themselves against tyranny in government"
 _/    _/ _/    _/ _/    _/    
 _/_/_/  _/     _/ _/_/_/         Thomas Jefferson, June 1776
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