Added a Sunfounder DS3231 RTC to my Raspberry Pi 3 running weewx.

The following helped me with understanding how to

https://github.com/weewx/weewx/wiki/Raspberry-Pi

https://github.com/weewx/weewx/wiki/pi-RTC-with-raspbian-jessie

After a reboot before step 9 in the following, I then completed the rest of the steps through 14 and get the following:

pi@raspberrypi:~ $ timedatectl status
Local time: Sun 2016-10-30 14:44:09 MST
Universal time: Sun 2016-10-30 21:44:09 UTC
RTC time: Sun 2016-10-30 21:44:09
Time zone: US/Arizona (MST, -0700)
NTP enabled: yes
NTP synchronized: yes
RTC in local TZ: no
DST active: n/a

I have not disconnected it from the network yet to see if it’s really working, though. Will have to reconfigure my setup to have a console connection rather than an SSH.