AVR-Chat

At 03:23 PM 7/7/2005, arhodes19044 wrote:
>Well, no it was more the way I had said it.  The 1 hz interrupt
>currently does more than just set flags.  And it gives me angst.
>
>The idea is, as stated before, is cooperative multitasking.  THere
>is no absolute reason why interrupt code can not be pretty long and
>complex, just so it completes before it needs to execute again.

True, but you're pushing in the wrong direction.

>   As long as the ISR in question does not lock-out other vital interrupt
>processes while it is active

There's the key. Re-entrant interrupts are expensive to code, and god 
forbid you get into a deadly embrace with ISR2 waiting on something 
that almost happened in ISR 1 before it got interrupted by ISR2.


>So, I think I will be able to offload the heavy duty stuff from the
>ISR.  Just because "conventional wisdom" prefers it that way.

Long and hard experience behind that.

>My point in this thread was to point out WHY conventional wisdom
>says that ISRs should be SHORT, SHORTER or SHORTEST. but that the
>real limit is re-entrancy, and any length code is possible within
>the overall limits of the rest of the application andits demands.

Sure. As long as you can assure that this is ALWAYS true.