PCF8523 with Alarm

I'm wanting to implement alarms on the PCF8523 RTC module that will occasionally (every 20m or so) wake up my MCU. The standard RTCLib does not support this feature on the PCF.

I've searched around, but I haven't found any real examples of this feature working on Arduino, but the posts are fairly old. I was hoping I could just post here and maybe see if someone has a working example. Thanks so much!

It may not support it directly with function calls, but the alarm pin is the same as the SQW pin but you have to program the chip to use it as an alarm vs. generating a square wave. You will just have to use some lower level calls to read/write some of the chip's registers to set it up.

Yeah. I may end up using a low power mode on chip (not lowest unfortunately) with an internal wake up. I’ve tried a few things to get the alarm working but nothing seems to work. I’m sure it can be done, but I was hoping to find a simple working example.

You might find this tutorial helpful.

Perfect! Thanks!