[En-Nut-Discussion] Watchdog problems with v4411 on SAM7X256-ek

Harald Kipp harald.kipp at egnite.de
Fri Aug 29 09:53:49 CEST 2008

ennut at thezachariasgroup.com wrote:
> I commented out the following code as shown:
>          /*
>           * The watchdog is enabled after processor reset. Disable it.
>           */
> /*
>          ldr     r1, =WDT_BASE
>          ldr     r0, =WDT_WDDIS
>          str     r0, [r1, #WDT_MR_OFF]
> */

Arrrgh! That was too obvious. I received several requests about non 
working watchdogs on the SAM, but never had enough time to evaluate this.

Indeed the problem is, that the watchdog on some CPUs is activated on 
reset. If disabled, it can't be enabled again. IMHO, this paranoid 
design is "krank" (http://dict.leo.org/).


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