I have been learning about micro-controllers mostly from a book "Język C dla mikrokontrolerów AVR" by Tomasz Francuz, but unfortunately I did not always had the same peripherals! (Back then I bought my stuff mostly from aliexpress, because components were cheap and delivery was free... The drawback was that it took a really long time to ship purchased items from china) So I had to improvise and use what I have got at my house (And a had a lot!) for me it was an educational experience because you could not just copy and paste working code from the book... So for this project I had to rewrite library for PCF8563 RTC to work with the DS3231 (You can still find it on my GitHub and I also used It on my engineer degree project!). Based on this I build simple clock with date project on a breadboard.