[time-nuts] June 30 2015 leap second
d0ct0r
time at patoka.org
Fri Jan 9 16:58:06 UTC 2015
Reading about "leap seconds" for the past two days, I found that common
solution for it - just encode "leap second event" proactively and wait
for it.
Of course that possible only if device has that option. For example,
BC637PCI has a menu item "7. Program Leap Event Seconds". Which I did.
Now, if I do the request for time settings, its shows me following:
Time Settings:
Mode : GPS
Time Format : Binary
Year : 2015
Local Offset : 0.0
Propagation Delay : 0
Current Leap Seconds : 16
Scheduled Leap Event Time : 1435708799
Scheduled Leap Event Flag : Insertion
GPS Time Format : UTC Format
IEEE Daylight Savings Flag : Enable
"Scheduled Leap Event Time" - is so-called UNIX time. However, I am not
sure where its take number "16" (Current Leap Seconds). Its definitely
was not programmed there by me.
Concerning of my clock project, I am thinking about best approach how to
set up leap second procedure. I mean which time exactly I'll need to do
correction for my clock (set time on RTC module). There is two options,
I think. One: to reset RTC at July 1, 00:00:00 and set it back to June
30, 23:59:00. Or, at July 1, 00:00:01, set RTC back to July 1 00:00:00
and then at July 1 00:00:01 reset RTC with occurrance of raising edge of
1PPS. I would prefer to play with July 1, because in this case I don't
need to do much calculations to transfer RTC time to number of seconds,
decrement it by 1 second, transfer it back to BCD format and write it
back to RTC. Instead, I'll need just read/write RTC register which keeps
number of seconds inside.
Regards,
Vlad
> Just because you observe one tz update from Debian does not imply that
> all "Linux systems" on planet earth (or in space) magically know about
> leap seconds. There must be millions (billions?) of embedded or
> isolated systems -- from web servers to desktops to military systems
> to gadgets to Raspberry Pi's to mobile phones, that have not, and will
> not ever receive this update.
--
WBW,
V.P.
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