IrtcTimeValid() checks whether the RTC time is trustworthy.

bool IrtcTimeValid(bool& valid)

void setup() {
  Serial.begin(115200);
  if (!IrtcBegin()) return;  // Check the DS3231 RTC connection and begin operation.
 
  bool valid = false;
  if (IrtcTimeValid(valid) && !valid) {  // Check whether the RTC time is reliable.
    IrtcSet(2026, 9, 7, 9, 0, 0);  // Set the RTC date and time.
    IrtcClearOscillatorStopFlag();  // Clear the oscillator-stop flag.
  }
}
 
void loop() {
  IrtcDateTime now;
  uint32_t unixTime = 0;
  float rtcTemperature = 0.0F;
  if (IrtcRead(now) && IrtcUnixTime(unixTime) && IrtcGetTemperature(rtcTemperature)) {  // Return the RTC's internal temperature. / Return the current time as Unix time. / Read the RTC date and time.
    Serial.print(unixTime); Serial.print(','); Serial.println(rtcTemperature, 2);
  }
  delay(1000);
}

Run each device's corresponding Begin command first. Check I²C addresses and pin sharing; if the bool return value is false, inspect wiring and power.

← Built-in Command List