Re: [avr-gcc-list] preserve state during watchdog reset

[Simon Han]

On Tuesday, February 3, 2004, at 12:43 PM, Gavin Jackson wrote:

> -----Original Message-----
> From: Simon Han [mailto:address@hidden
> Sent: Wednesday, 4 February 2004 9:30 a.m.
> To: address@hidden
> Subject: [avr-gcc-list] preserve state during watchdog reset
>
>
> Hi all,
>         Does anyone figure out a way to preserve state during watchdog
> reset?
>         I am using watchdog to monitor for some of my functions.  Before and
>
> after function calls, I do a watchdog reset.  Now the problem is how I
> can figure out which function caused the watchdog timeout.  I was
> thinking to store this information in EEPROM, but the delay of doing
> this is way too high.  Will it be possible to assume certain registers
> are not reset?
>
> Any suggestions?
> Simon
>
> -----------------------------------------------------------------------
>
> Hi Simon
>
> Store whatever it is you want to remember in the SRAM.
>
> Just remember to either place it in the .noinit section as below:
>
> static int KeepTrack __attribute__ ((section (".noinit")));
>
> so that it's not set to 0x00 at startup or you can declare a 'normal'
> static variable and check it's value before the startup code runs
> that clears all static variables to 0x00.
>
> To .noinit option is the easiest to do.
>
> Regards
> Gavin

Hi Gavin,
Thank you for the help!
One more question.  How can I tell between a cold start and a watchdog 
reset?
Placing KeepTrack in .noinit will make KeepTrack arbitrary value when I 
use it in main().
AVR datasheet suggests using MCUCSR to tell between them.
Now my question is that will avr-libc change this register during 
initialization?

Thank you again,
Simon