[ntp:questions] Linux 11-minute mode (RTC update)

Martin Burnicki martin.burnicki at meinberg.de
Tue Apr 15 08:48:14 UTC 2008


Serge,

Serge Bets wrote:
>  On Thursday, April 10, 2008 at 18:02:38 +0100, Maciej W. Rozycki wrote:
> 
>>> This holds the clock for up to a second
>> I am not sure what you mean
> 
> Anyway I experimented a little: This doesn't seem to work as I hoped.
> And it can even lock the clock, requiring a oscillator reset. :-(
> 
> The idea was about the RTC_SET flag (bit #7 of register B). It suspends
> clock updates, without any effect on the oscillator nor PIE. I was
> hoping it would delay next updates by as long as it was asserted. But
> no: the next update is either skipped, or happens at the usual time.

About 20 years ago I worked with the same same RTC type which was controlled
by a microcontroller. 

IIRC we changed the clock rate of the counter chain to the highest rate for
a certain interval in order to compensate the 500 ms offset which was
introduced when the RTC was set to a new time.

Martin
-- 
Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont
Germany




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