Wouter van Ooijen wrote:
>> Another part of this low end with which I'm not familiar..
>> If interrupts are disabled when one *would have* been delivered,
>> is it lost?
>
>> (to some stack-limited number, no doubt)?
>
> no

I think this needs some clarification.  Interrupt conditions are not stacked
anywhere in a PIC as Wouter says.  For each interrupt condition, the PIC has
a flag that indicates whether that condition is asserted or not.  These are
called the xxxIF bits.  The hardware sets these, and software action resets
them.  If another event occurs for a interrupt condition that is already
set, nothing more happens.

For example if a INT0 edge occurs but this interrupt is disabled for
whatever reason, then the INT0 interrupt flag bit gets set and no interrupt
occurs.  If the INT0 interrupt flag bit remains untouched and the INT0
interrupt is enabled, a interrupt will occur immediately.  If in the mean
time another INT0 event comes along, no state will be changed.  The number
of multiple INT0 events is not remembered, only that at least one has
occurred.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist