sync date to an RTC without hwclock

James Hughes james at virtualjames.com
Wed May 29 02:00:06 CEST 2019


Sorry...  prematurely sent.

The link in the previous email is to the permanent installation at Western
Washington University in Bellingham, WA. One of the pointers always points
at the moon, and other always points at the sun. They run 24/7/365. There
is one pi per pointer and the comprise the pointer control system. They are
interfacing with some encoders, stepper drivers and doing some light
interpolation on data points in a giant pre-computed lookup table (40 years
of data stored on disk). These pieces are supposed to have a 30 year
lifespan, so we couldn't depend on a service (or even internet). They do
have wifi to keep the clocks in sync, but they don't depend on it.

On Tue, May 28, 2019 at 4:32 PM James Hughes <james at virtualjames.com> wrote:

>
>
> On Tue, May 28, 2019 at 4:07 AM Ronny Nilsson <
> rln-nard at arbetsmyra.dyndns.org> wrote:
>
>>
>> Hi James
>> A quick workaround for you might be to use and old mobile phone as a WiFi
>> accesspoint. Share Internet access for the Pi via tethering.
>
>
> Yeah, it seems like this might be the best option. Unfortunately, the
> piece is being exhibited in Gwangju, South Korea, so setting up mobile
> phone is a bit more complicated. Perhaps, we can just get it set up on wifi
> locally and hope the battery on the RTC can survive the shipping process.
>
>
>> Otherwise, can
>> you provide additional technical information? What RTC model have you
>> added
>> and how is it connected? By what pins? I suspect you may need to define
>> your
>> setup via Device Tree to inform the OS. If you are unsure of what Nard
>> version you are running; check the "/etc/release" file   in the target.
>>
>
> I think all I did to get this going was to set the /boot/config.txt like
> this:
> # use the real-time clock
> dtoverlay=i2c-rtc,ds3231
>
> I don't recall what pins I used.
>
> It's running:
> Nard Linux SDK v1.00
>
>
>> Cool thing with an art installation. Is there any photos of the project?
>> What
>> are the Pi doing?
>>
>
> https://www.rebeccacummins.com/work#/public-comissions/
>
> Scroll down to the 5th pic ("Detail of mechatronic sun and moon pointers")
>


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