Before getting lost in the stormy code, I have a doubt that you will surely know how to solve immediately.
In adapting your code to my application, I am using the DS1307new library that does not have the possibility of attaching other pins to 20 and 21.
On the other hand, I want to use a PCF8745, which, in my case, should be with pins 18 and 19.
However, you change the pins, is there any reason why you change the pins ?, in other words, can I use the RTC with pins 20 and 21 and PCF8575 with pins 18 and 19 ?.
Thanks for your time and attention,