Re: [avr-libc-dev] XMega Watchdog clock domains not synchronized?

[Bob Paddock]

On Tue, Oct 11, 2011 at 2:08 PM, Bob Paddock <address@hidden> wrote:
> Trying to find out why my XMega 128A1 keeps resetting I noticed this
> in the XMega Manual:
>
> 11.7.3 STATUS – Watchdog Status Register
>
> Bit 0 - SYNCBUSY
> When writing to the CTRL or WINCTRL registers, the WDT needs to be
> synchronized to the
> other clock domains. During synchronization the SYNCBUSY bit will be
> read as one. This bit is
> automatically cleared after the synchronization is finished.
> Synchronization will only take place
> when the ENABLE bit for the Watchdog Timer is set.
>
> I do not see where this clock domain synchronization is accounted for
> in avr/wdt.h wdt_enable().
> Am I missing something?
>
> App Note AVR1321 for the RTC32 explains the cross clock domain  issue,
> however it doesn't really say what happens in the Watchdog or the RTC
> case if things are not in sync.
>
> Seems like this would cause the watchdog to not be enabled at random
> times when wdt_enable() is used in the XMega parts.