sparkfun RV-1805 Hook-Up Manual page 13

Alphanumeric GPS Wall Clock
This is a GPS controlled clock - a clock you truly never
have to set! Using GPS and some formulas, we figure
out what day of the week and if we are in or out of
daylight savings time.
DeadOn RTC Breakout Hookup Guide
An introduction to the DS3234 real-time clock (RTC),
example wiring diagrams, and an Arduino library!
Or check out some of these blog posts for ideas:
Enginursday: Battle of the RTC
OCTOBER 6, 2016
DIY Sunrise Alarm
Real Time Clock Module Hookup Guide
A quick introduction to the DS1307 RTC module and a
hookup guide for the SparkFun Breakout.
Hardware Hump Day: Earth Day Hacking
APRIL 19, 2017
Nixie LED Clock