DS3231 RTC Driver for esp-idf

I forked from here.

git clone https://github.com/nopnop2002/esp-idf-ds3231
cd esp-idf-ds3231
idf.py menuconfig
idf.py flash

(*1) You can change using menuconfig.

This mode set RTC initial value using NTP time Server.
You have to set these config value using menuconfig.

You have to set gpio & NTP Server using menuconfig.

This mode take out the time from a RTC clock.
You have to change mode using menuconfig.

This mode get time over NTP, and take out the time from a RTC clock.
Calculate time difference of NTP and RTC.
You have to change mode using menuconfig.

https://github.com/nopnop2002/esp-idf-ds1302

https://github.com/nopnop2002/esp-idf-ds1307

https://github.com/nopnop2002/esp-idf-pcf8563