Re: [Sdcc-user] Problem with interrupts.

[Raphael N. <rn...@we...>]

Hi,

> One sidenote. IIRC you cannot access the stack on the pic16f devices.
> This is only possible on pic18f devices. There is a wonderfull appnote
> about that on microhcip website.

You are right, but ...
I was talking about the pseudo stack that is used by the compiler to pass  
arguments to subroutines. This "stack" is placed into the "sharebank"  
available on (most?) PIC14 devices to be available in all memory banks and  
thus avoid banksel's upon access. For the 16f877, the region 0x70..0x7f is  
mapped to all 4 banks (memory at 0x70..0x7f equals mem at 0xf0..0xff  
equals mem at 0x170..0x17f equals mem at 0x1f0..0x1ff).
The problem at hand can ignore the hardware stack which is used to store  
return addresses during calls to subroutines as long as this hw stack does  
not overflow (which would likely result in a different error scenario,  
although... 8 levels of call stack is not *that* much ... ==> should  
investigate; unfortunately, there is no  
reset-on-stack-overflow-indication/reset available) as we employ no  
"thread switch" but only need to protect memory/registers shared between  
interrupt handlers and "regular" code from being modified behind the  
application's back.

Best regards,
Raphael