#include "user_i2c.h"

Thanks for posting your work.
Just wonder where to find this
#include "user_i2c.h" ?
Yes I am new here and finding it may be obvious but not for me. I can find it..
I am looking for how to Set the alarm for waking up an esp32 unit.

Sorry if this breaks any rules...

[tuupola]

You need to provide the i2c functions by yourself. If you are using ESP32 you could use these:

https://github.com/tuupola/esp_i2c_helper

You can find example usage at:

https://github.com/tuupola/esp_m5stick