Arduino Uno deep sleep wake-up with DS3231: from once an hour to several times

[J-M-L]

RTClibExtended.H is a fork of the Adafruit library extended for DS3231 only and supporting the alarms.

The adafruit library implements the DateTime class so you would do aDateTime now = rtc.now(); // instead of rtc.read( tm ); when you are woken up and now.minute() would be the equivalent to tm.Minute

See this example in the adafruit lib to understand how to access current time