Oooopss, wrote that one too early in the morning. You are of course correct,
WDT is generated from internal RC oscillator, hence, it's use to reset
devices from sleep and it's variations with temperature. Not sure about PIC,
but I've seen the Scenix WDT specced with up to 30% innacuracy in extreme
cases. You can also control the WDT period by assigning the TMR0 prescaler
to it (TMR0 prescaler = 1:1), but yes the actual value is inaccesible.


BTW: Very nice use of WDT by Jason.
Tom.
----- Original Message -----
From: Dr. Imre Bartfai <root@PROF.PMMF.HU>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, October 25, 1999 8:58 PM
Subject: Re: WDT (was: PIC Wierdness)


> Hi,
>
> sorry, but the text below contains parts which are simply not true. The
> correction:
>
> In fact, WDT is an independent timer has a nominal 18msec timeout. It has
> nothing to do with instructions or whatever, e. g. WDT runs even in sleep
> mode. The prescaler multiplies that 18msec, so the longest WDT timeout is
> nominally 2.304 sec. I say nominally as it runs an independent RC
> oscillator with a fairly tolerance and temperature dependence. The
> programmer has no access to the WDT counter except he can clear it by
> means of CLR WDT instruction.
>
> Please consider this when interpreting the otherwise correct text below.
>
> Regards,
>
> Imre