> Hello friends,
>      Suppose I initialize PortB (RB4) as interrupt on change, and I need to
> be interrupted on every rising edge only and during my high to low
> transition, I should not get interrupted.  I am using limit switch as an
> interrupt source.  But my program behaves erratically during emulation.
> What could be the reason.  MPLAB simulation is perfectly ok.
>
> thanks
> rams
>

Probably switch contact bounce. Switches do not open and close
like the text books say. Is your software behaving like it sees many
contact closures/openings instead of just one? Normal practice is
to write a software debounce routine that rejects rapid input
changes of less than say 20-30ms duration. Hardware debounce
circuits are also possible but it is usually preferable to do it in
software which is more flexible and does not require extra
components.


Brent Brown
Electronic Design Solutions
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Hamilton, New Zealand
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eMail:  brent.brown@clear.net.nz