DS3231 Alarm interupt

I hate to ask this question, because based on my previous searches, it has been asked a 1000 times. So please forgive me as I'm new at this.

So like everyone else, I am trying to have my DS3231 wake up my Arduino Pro Mini from deep sleep using the RocketScream low power library when an alarm is triggered running on batteries...

I have been through a ton of forums including here, and I can't find a circuit diagram that explains what I need to do, because based on my reading, there are actual hardware changes needed / register changes.

I have been able to get it to work when connected to the VCC on the pro mini and one time when i have it connected to a digital pin and use that pin to power the RTC (because it starts on), however once I turn it off and rely on the battery with the interrupt, as you know, it doesn't work natively.

If anyone could point me to a circuit diagram or a good tutorial or anything even close, I would really appreciate it.


Here are some of the links I have read for days...

this one seemed promising: https://publiclab.org/notes/kinasmith/06-07-2016/one-way-of-using-the-rtc-alarms-to-schedule-logging-on-the-riffle

The DS3231 *INT/SQW output is open drain, so to wake an Arduino up from sleep , you need a pullup resistor from that output to the Arduino supply voltage, and program the Arduino input to wake on falling edge.

A 1 Meg resistor should work as a pullup, but you could try going higher to minimize power drain during sleep.

Note that some of the cheap eBay DS3231 modules already have low value pullup resistors on the 32kHz and *INT outputs, and thus ridiculous power drain. I remove those as described here Using a $1 DS3231 Real-time Clock Module with Arduino | Underwater Arduino Data Loggers