teste sketch

// CONNECTIONS:
// DS3231 SDA --> SDA
// DS3231 SCL --> SCL
// DS3231 VCC --> 3.3v or 5v
// DS3231 GND --> GND

/* for software wire use below
#include <SoftwareWire.h>  // must be included here so that Arduino library object file references work
#include <RtcDS3231.h>

SoftwareWire myWire(SDA, SCL);
RtcDS3231<SoftwareWire> Rtc(myWire);
 for software wire use above */

/* for normal hardware wire use below */
#include <Wire.h> // must be included here so that Arduino library object file references work
#include <RtcDS3231.h>
RtcDS3231<TwoWire> Rtc(Wire);
/* for normal hardware wire use above */
long n;

#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);
}

void resetAlarm(RtcDateTime time) {
  RtcDateTime alarm =(time + 30);

  DS3231AlarmOne alarm1(
      alarm.Day(),
      alarm.Hour(),
      alarm.Minute(),
      alarm.Second(),
      DS3231AlarmOneControl_MinutesSecondsMatch);
  Serial.println("RTC to trigger at : ");
  printDateTime(alarm);
  Rtc.SetAlarmOne(alarm1);
  delay(500);
  Rtc.LatchAlarmsTriggeredFlags();
  Serial.println("----");
}

void setup ()
{
    Serial.begin(9600);

    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())
    {
        // Common Cuases:
        //    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_ModeAlarmOne);

    n = millis();
}

int count = 0;
void loop ()
{

    if (count >= 10) {
      resetAlarm(Rtc.GetDateTime());
    }

    if (!Rtc.IsDateTimeValid())
    {
        // Common Cuases:
        //    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();
    Serial.print(temp.AsFloatDegC());
    Serial.println("C");

    delay(1000); // ten seconds



    count++;
}