Injector Pulse Width Resolution 16 bit or 8 bit

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    Subj:   Injector Pulse Width Resolution 16 bit or 8 bit
    Date:   96-02-23 12:43:52 EST
    From:   early at finite.nrl.navy.mil (Derrick Early)


 >  How many bits should be stored in the lookup table for a injector pulse
 >  width map?  Should I use 8 bits or 16 bits?  I know 16 is better, but
 >  is it necessary?

    What is your expected maximum injector opening time?  Divide that
    figure by 255, and if that is enough resolution for you, use 8 bits....

    An example is a 4 stoke engine with a torque peak about 3000 RPM.  If
    the injector is on through most of the full 720 degrees of crank
    rotation at 3000 RPM, that is about 40 mSec.  Divide 40 mSec by 255 and
you
    get 156 uSec.  Is that enough resolution?  If it is, now you have to
    clock your injector timer reg at that 156 uSec rate  (6375 Hz)......

    Scot Sealander      FIScot at aol.com