>-----Original Message-----
>From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] 
>Sent: 26 April 2005 13:44
>To: Microcontroller discussion list - Public.
>Subject: [PIC] HiTech C and Local Variables
>
>
>I'm wondering if anyone else has come across strange behaviour 
>sometimes when using local function variables with HiTech's 
>PIC C compiler (latest version - 8.05PL2, and also 8.03PL3)?
>
>The contents of temporary local variables in some of my 
>functions are getting overwritten without reason. By changing 
>them to static it fixes the problem.
>
>I'm having to allocate a lot of the other variables in 3 of 
>the banks, so I'm wondering if that is a cause? I've turned 
>off all optimization and it still happens. At no point does 
>any of my code write to an address in RAM except via a pointer 
>to a variable, so I can't see how these variables are getting 
>overwritten.
>

I think that statement might be a little optimistic.  Even if you only
use pointers to access all your variables (which in itself seems
unlikely), then you still have to initialise the pointer which will be
stored in RAM.

>What makes it so much harder to track down is that it doesn't 
>happen in the MPLAB similuator but only when I program the 
>PIC, of course! ;) So I'm debugging with a scope and some 
>diagnostic pin output...

If it dosen't happen in MPLAB then either you aren't simulating enough
states/inputs or you are hitting a silicon bug in the real part.
However, as the 16F876A is now quite a mature part I would think that
the former is more likely.

>
>I've been using this compiler for a couple of years without 
>this trouble before, but with this code it's happening all 
>over the place. I've never targeted this PIC (16F876A) before, 
>but I doubbt that's central to it.
>
>I could raise this on HiTech's forum but that gets little 
>traffic. I'm really looking for any experiences from people 
>here that could backup or otherwise what I think I'm seeing! 
>Many thanks.
>

I would email support@htsoft.com with an example of code that displays
the problem.  They tend to resolve problems very quickly if you go
through this route.  They don't always look at the forum on a regular
basis so bug reports on there take longer.

Regards

Mike

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