Fwd: Re: Timing of events in an ISR

[gregory.menke at gsfc.nasa.gov]

Mark VanderVoord writes:
 > 
 > Is the ISR calling dependent on the
 > MICROSECONDS_PER_TICK setting in some way?  I am
 > operating at 125usec/tick.  If I raise this to
 > 500usec/tick, it appears to increase the delay we
 > have been discussing substantially.  I am unable to
 > find a value that will actually run that is smaller
 > than 125usec/tick, so I am unable to determine if this
 > would fix my issue or not.
 >  
 > Mark S VanderVoord
 > Self-Guided Systems, LLC
 > 

Could the problem be your interrupt source is asserts its irq, which
is inadvertently being masked somewhere such that no interrupt occurs,
then the next time the timer tick comes along the vectoring code sees
the asserted irq and then handles it- essentially 1 timer tick late?

Gregm