RTC DS3231

#include <DS3231.h>


RTC	RTCLib	GPIO RTC Pgmmng	DS1302 & DS1307 ClassRef
DS3231 setTim()	DS3231.cpp	DS3231.h	DS3231 DataSheet
Northern Wiget DS3231.h	Wire	DateTime Ref	DateTime.cpp
Examples	DS3231 RTCLib Ref	DS3231_RTC.cpp	ESP32 Register Map
ds3231.cpp

Note: the DS3231 also contains a Non-Volatile Ram, ATMEL732 24C32 flash memory.
The RTC's I2C address is 0X68, the NvRam's address is 0X57.
Vcc: 3.3 - 5Volts.

DS3231

DS3231 uses an I2C interface

ESP32 Registers

Address	Bit 7 MSB	Bit 6	Bit 5	Bit 4	Bit 3	Bit 2	Bit 1	Bit 0 LSB	Funcion	Range
00h	0	10 Secs			Secs				Seconds	00-59
01h	0	10 MIns			Mins				Minutes	00-59
02h	0	12,*24	*AM, PM	10 Hour	Hour				Hours	1-12 + *AM,PM 0-23
03h	0	0	0	0	0	Day O Week			Day	1-7
04h	0	0	10 Date		Date				Date	01-31
05h	Century	0	0	10 Month	Month				Month/Century	01-12 Century
06h	10 Year				Year				Year	00-99
07h	A1M1	10 Seconds			Seconds				Alarm 1 Secs	00-59
08h	A1M2	10 Minutes			Minutes				Alarm1 Mins	0-59
09h	A1M3	12, *24	*AM,PM	10 Hour	Hour				Alarm 1 Hours	1-12 + *AM,PM
09h	A1M3	12, *24	20 Hour	10 Hour	Hour				Alarm 1 Hours	0-23
0Ah	A1M4	Dy,Dt	10 Date		Day				Alarm 1 Day	1-7
0Ah	A1M4	Dy,Dt	10 Date		Date				Alarm 1 Date	1-31
0Bh	A2M2	10 Minues			Minutes				Alarm2 Minutes	0-59
0Ch	A2M3	12,*24	*AM,PM	10 Hour	Hour				Alarm 2 Hours	1-12 + *AM,PM 00-23
0Ch	A2M3	12,*24	20 Hour	10 Hour	Hour				Alarm 2 Hours	1-12 + *AM,PM 00-23
0Dh	A2M4	12 *DT	10 Date		Day				Alarm 2 Day	1-7
0Dh	A2M4	12 *DT	10 Date		Date				Alarm 2 Date	1-31
0Eh	*EOSC	BBSQW	CONV	RS2	RS1	INTCN	A2IE	A1IE	Control	-
0Fh	OSF	0	0	0	EN32kHz	BSY	A2F	A1F	Control/Status	-
10h	SIGN	DATA	DATA	DATA	DATA	DATA	DATA	DATA	Aging Offset	-
11h	SIGN	DATA	DATA	DATA	DATA	DATA	DATA	DATA	MSB of Temp	-
12h	DATA	DATA	0	0	0	0	0	0	LSB of Temp	-