[RFD] divecomputer time/date synchronization while downloading dives

[Jef Driesen]

On 2017-07-20 10:08, Jef Driesen wrote:
> On 19-07-17 22:08, Linus Torvalds wrote:
>> Anyway, what this all builds up to is that I'd actually like to just
>> set the time automatically when I connect the dive computer to my
>> laptop (or my cellphone, for that matter - usually those end up being
>> synchronized to the local time quite nicely).
>> 
>> And I just wrote the code for that for the Suunto EON Steel. Patch to
>> libdivecomputer attached in case anybody cares (and I was happy to
>> realize that it actually uses milliseconds for synchronization, but
>> then noticed that it may be just a protocol thing, and the extra
>> precision may get thrown away).
>> 
>> But I suspect people will hate that patch because it does that time
>> sync thing *unconditionally*. It would be good to have a check-box and
>> some way to actually set the "sync time" flag. But for that to happen,
>> we'd need not just the UI side, we'd need to have the libdivecomputer
>> interface too.
>> 
>> And yes, I know about "configure dive computer" and the "sync time"
>> hack there. But it's really an ostc-specific hack, not something that
>> can be used in general to synchronize the clock.
>> 
>> Thus the "request for discussion". I'd love to be able to pass in
>> flags like this to dc_device_open() or add a sane
>> "dc_device_set_feature()" interface or something..
> 
> How about turning the ostc specific clock sync function into a
> standard function that is part of the dc_device_t interface? Then
> every backend that supports setting the time can easily implement it.
> I'm pretty sure there are more dive computers where the protocol
> supports this (e.g. the oceanic software has a time sync setting), so
> I see no reason not to support this as a standard feature.
> 
> dc_status_t
> dc_device_clock (dc_device_t *device, const dc_datetime_t *datetime);
> 
> And then it's up to the application to call this function or not.
> Doing this kind of stuff automatically from within libdivecomputer is
> probably a bad idea (host clock can be wrong, set to a different time
> zone, etc).

This feature is now available in the master branch! At the moment, the 
new dc_device_timesync() function is implemented for the Heinrichs 
Weikamp backends.

Jef