Denny Esterline wrote :

> my point was that my original software algorithm spent a
> different amount of time in the interrupt routine depending 
> on which column it was working on.
> Just make sure your interrupt always takes the same amount of 
> cycles and it'll be fine.

Or, if that's not possible (not an unlikely case), update the LEDs
at the *start* of the ISR and then calculate the values for the
*next* column of LEDs in the rest of the ISR (and save those values
until the next interrupt). Then it doesn't matter how long that
calculation takes, as long as it isn't longer then the interrupt intervall
(in which case you will get flicker due to missed interrupts and
you have a bigger design problem :-) ).

Regards,
Jan-Erik



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