[lm-sensors] w83792d watchdog

dezheng shen dzshen at Winbond.com.tw
Thu Mar 30 03:37:45 CEST 2006


I will forward to the responsible engineer anyway but I have to consult 
him if he is willing to communicate with you directly.

thanks,

dezheng

> Hello all,
>
> I begun to work on the watchdog support for w83792d. I have several 
> questions about the watchdog device in w83792d. Please can
> yuou forward them to responsible person?
>
> I'm using ver 1.0 of datasheet
>
> There are 4 watchdog regs:
>
> CR01 handles the unlock codes
> CR02 "Watch Dog Enable" -> this should be more likely called "Watch 
> Dog Enable Status" - because this regs are RO only
> CR03 is quite mystery for me
>      the "WDT stage" is not described in datasheet at all, I assume 
> this has someting to do with hard mode of watchdog
>
>
> the HARD_TO and SOFT_TO have following commnents:
>
> HARD_TO: 1: a hard timeout occurs. This bit will be cleared while 
> reading.
>
> What I know:
>
> 1) this bit is not cleared on reading
> 2) I think the sentece should be: "a hard timeoud had occured"
>     because this is set when there was a timeout/reset it seems
>
> This is so far to datasheet, now to real funcs:
>
> 1) What will happen if I enable hard and soft watchdog same time? (i'm 
> disabling the hard watchdog timer in first place so
> it should not be an issue but you never know)
> 2) I tried many ways to reset the watchdog timer but only seems to 
> work is to write 0xAA to CR1 and then 0x55 to re-enable it.
>     This seems bit strange because the computer can fail just in 
> between of this two writes Yes I know this is not probable, but
>     the best method is just to re-write the timeout value or rewrite 
> the enable (0x55) - as others might do. Were there
>     some strange reason for this design?
>
> And last thing, It seems that the device registers survive system 
> power cycle. Maybe I was just too fast and the caps powered
> the chip. I will investigate...
>
> I hope you can understand my thought because I'm quite tired now.
>
> regards
> Rudolf
>
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