GPS clock

There are two separate yet related goals here:

• Create a local timeserver for my network, based on a GPS time-source on a raspberry-pi.

 * Should use a 1PPS capable GPS module.
 * Doesn't really need a display, though it can have one.
 * Wired networking is fine
 * I think it can almost entirely be based on existing packages, like gpsd, ntpd, etc.

• Create a standalone clock, using a GPS source, based on a raspberry-pi

 - GPS can be a simple cheap, available one.
 - Doesn't really need super-accurate inter-second timing, we're only going to display
   to the nearest second anyway.
 - Absolutely needs a display of some sort
 - Should be able to work with no network at all.  If wireless is available, to do FW updates or something, bonus.
 - Power usage is somewhat of a concern, though could start out using wall-wart power
 - A big 5" or 7" touch display is way overkill, but could display sun location, etc, and use touch for setup
 - Use GPS co-ords to pick local timezone.
 - OLED screen and batteries?
 - Could we get away with solar power?
 - low-power mode is a goal to get us off the plug
 - any way we can have it turn the display off when its not light out?  or when I'm not looking at it? :)

Things to Display

• Date & Time in several formats:

 - UT1
 - UTC
 - Unix
 - Local
 - MST
 - AST

• Number of satellites used in fix
• Battery power left
• Day of week (text) and month of year (text) and week of year (numeric, ISO)
• Time to sunset/since sunrise
• Temp/humidity/pressure
• latitude/longitude
• local time-zone
• DST active

Things to Adjust

• Ideally nothing, other than date/time display preferences:

 - 12-hour/24-hour?
 - ISO formatting options?
 - which time choices (above) to display at all times

• Other localization settings & options

 - C/F for temp
 - Power-saving settings?

• Some way to initiate FW updates?

 - Would be cool if it would detect when my phone is making Wifi available, then:
    * connect to that
    * check git for FW updates (or somewhere)
    * check somewhere for OS and kernel updates
    * update itself if needed
    * reboot/restart app if needed

Anything else to make available?

• Maybe a calculator? phone or laptop is more convenient, probably
• Some sort of calendar mode? Again, for something like this, more than a glance, phone/laptop more convenient
• Something else I could see at a glance? Home status?