Hi Gerhard
I did the same thing in both my interrupt handlers.  (so much from learning
from my past mistakes)
The low one was easy to spot because when I halted the program it was in the
always in  the ISR just like you would expect it to be.
Now the high level ISR had strange behavior. 
It appeared to work for the most part but every once in a while the ultoa
function would return a value that not that was garbage or out side the
range of the value being passed.
Every thing else appeared to work just fine.
I could not imagine and that there was something wrong with the ultoa
function and of course there wasn't.
So I reckoned that I had a corrupt stack or had run out of stack space
causing the undefined/weird behavior.   

 
Phillip
Things should be as simple as possible but no simpler
 
 
 
Phillip Coiner
CTO, GPS Source, Inc.
 
 
Your source for quality GNSS Networking Solutions and Design Services, Now!
-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of
Gerhard Fiedler
Sent: Wednesday, June 28, 2006 6:40 PM
To: piclist@mit.edu
Subject: Re: [PIC] C18 resource remaining metric/test

Wouter van Ooijen wrote:

>> The data sheet says that interrupt flag bits must be cleared in software
>> to avoid recursive interrupts. 
> 
> are you sure? can you give URL and page?

Not exactly recursive interrupts, but successive ones. Many if not most
interrupt flags must be cleared in software. No URL and page, but some bit
names: EEIF, INT0IF, RBIF, TMR0IF, TMR3IF, ...

What happens when you forget to do that (and don't for some reason clear
the enable bit) is that your program gets stuck in an infinite loop through
the interrupt handler -- and that's the same no matter the language used :)
(except possibly for some Basic interpreter that takes care of this behind
the scenes).

Gerhard

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist