How to store and use the date and time

[Michael-pi-projects]

Hi !!
I am new here .First thanks for this Rtc library and etc , I am using it ( more specific the with the DS3231 module and with the example DS3231 simple ) in a project of mine and i want to know if is there any way to get the time and date and store it to a variable or how else to store and use it for other perpose , for example to store it on an sd every 3 seconds.
I am new to arduino , I only have used it and code about 3 to 4 months with basic and simple projects and basic senros.
thanks!!!

[Makuna]

The current date time returned from the RTC is a RtcDateTime object.

The easiest way to store this is to call Epoch32Time() which returns a 32bit value that you can store.
Then you retrieve that stored value and pass to InitWithEpoch32Time(uint32_t time) to create an RtcDateTime object again.

Epoch time is a standard, the RtcDateTime object supports both 32 bit and 64 bit versions.

[Michael-pi-projects]

thanks o lot !! But is it posible to give an example of the code how to do it because i am not to familiar with objects on arduino ;
Or if you want i can show mine code here to get a better understanding .

[Michael-pi-projects]

//Here is the code and I want in the void loop to store the date and time
//Icomented the temperature because I dont want to use it

#include <Wire.h> // must be included here so that Arduino library object file references work
#include <RtcDS3231.h>

RtcDS3231 Rtc(Wire);

void DATE_TIME_YEAR(){
{
if (!Rtc.IsDateTimeValid())
{
if (Rtc.LastError() != 0)
{
// we have a communications error
// see https://www.arduino.cc/en/Reference/WireEndTransmission for
// what the number means
Serial.print("RTC communications error = ");
Serial.println(Rtc.LastError());
}
else
{
// Common Causes:
// 1) the battery on the device is low or even missing and the power line was disconnected
Serial.println("RTC lost confidence in the DateTime!");
}
}

RtcDateTime now = Rtc.GetDateTime();
printDateTime(now);
Serial.println();   


/*RtcTemperature temp = Rtc.GetTemperature();
temp.Print(Serial);
// you may also get the temperature as a float and print it

// Serial.print(temp.AsFloatDegC());
Serial.println("C");

delay(10000); ten seconds*/
//return(now);
}
}
#define countof(a) (sizeof(a) / sizeof(a[0]))

void printDateTime(const RtcDateTime& dt){
char datestring[20];

snprintf_P(datestring, 
        countof(datestring),
        PSTR("%02u/%02u/%04u,%02u:%02u:%02u"),
        dt.Month(),
        dt.Day(),
        dt.Year(),
        dt.Hour(),
        dt.Minute(),
        dt.Second() );
Serial.print(datestring);Serial.print(" ");

}

void setup() {
Serial.begin(115200);
Serial.print("compiled: ");
Serial.print(DATE);
Serial.println(TIME);

//--------RTC SETUP ------------
// if you are using ESP-01 then uncomment the line below to reset the pins to
// the available pins for SDA, SCL
// Wire.begin(0, 2); // due to limited pins, use pin 0 and 2 for SDA, SCL

Rtc.Begin();

RtcDateTime compiled = RtcDateTime(__DATE__, __TIME__);
printDateTime(compiled);
Serial.println();

if (!Rtc.IsDateTimeValid()) 
{
    if (Rtc.LastError() != 0)
    {
        // we have a communications error
        // see https://www.arduino.cc/en/Reference/WireEndTransmission for 
        // what the number means
        Serial.print("RTC communications error = ");
        Serial.println(Rtc.LastError());
    }
    else
    {
        // Common Causes:
        //    1) first time you ran and the device wasn't running yet
        //    2) the battery on the device is low or even missing

        Serial.println("RTC lost confidence in the DateTime!");

        // following line sets the RTC to the date & time this sketch was compiled
        // it will also reset the valid flag internally unless the Rtc device is
        // having an issue

        Rtc.SetDateTime(compiled);
    }
}

if (!Rtc.GetIsRunning())
{
    Serial.println("RTC was not actively running, starting now");
    Rtc.SetIsRunning(true);
}

RtcDateTime now = Rtc.GetDateTime();
if (now < compiled) 
{
    Serial.println("RTC is older than compile time!  (Updating DateTime)");
    Rtc.SetDateTime(compiled);
}
else if (now > compiled) 
{
    Serial.println("RTC is newer than compile time. (this is expected)");
}
else if (now == compiled) 
{
    Serial.println("RTC is the same as compile time! (not expected but all is fine)");
}

// never assume the Rtc was last configured by you, so
// just clear them to your needed state
Rtc.Enable32kHzPin(false);
Rtc.SetSquareWavePin(DS3231SquareWavePin_ModeNone); 

}

void loop() {
DATE_TIME_YEAR();
delay(3000);
}

[Makuna]

You need to work out how to store and retrieve the uint32_t, but here is the snippits of code to work with the RtcDateTime

to get a uint32_t from RTC module...

RtcDateTime now = Rtc.GetDateTime();  // reteives the current time from the module
uint32_t epochTime = now.Epoch32Time(); // converts the time stored in 'now' to uint32_t epoch time standard value of 32 bits
// now just store epochTime however you want

to get a RtcDateTime from uint32_t is just...

uint32_t epochTime = // however your set or retrieve it
RtcDateTime time;

time.InitWithEpoch32Time( epochTime );
// now do what ever you want with time.

[Michael-pi-projects]

you meen i ca use time variable as i want ?

one more question : what type of data does the time return ? and what type of data does the epochTime return ?

[Makuna]

search internet for the specific term "epoch time", it's a standard, its seconds since a specific date and time.