Integrate GPS sensor

[patricktokeeffe]

Integrate the Ultimate GPS v3 breakout board as a GPS sensor/real-time clock (RTC) module:

• [x] document wiring
  • [ ] investigate adding PPS for microsecond support
  • [ ] possibly swap with K30 for Pi's hardware uart (to avoid USB errors during boot)
  • [ ] add light pipe or secondary LED to for external status indicator?
• [ ] enable as RTC
  • [ ] make Pi use for hardware clock (reason to use hardware UART?)
  • [ ] tie into ntpd systemd service
  • [ ] verify battery back-up operational
  • [ ] enable ntp statistics
• GPS data outputs
  • [ ] locally republish NMEA0183 data using kplex? gpsd?
  • [ ] log all NMEA0183 sentences to disk? with rotation limits?
  • [ ] add position logging to AQ data service
  • [ ] report current status (and possibly statistics) to local RPi Monitor instance