RTC ds3231 second-issue

Using Arduino Sensors
1

Hey!

I need to use a RTC in my project, so Ibought a ds3231 i2c-breakout. It's working and I was able to set the time, but the serial printed time is always incorrect. Specifically the seconds are jumping like 10:22:00 - 10:22:01 - 10:22:00 - 10:22:02 - 10:22:10 -10:22:11 -10:22:10 -10:22:20 (more or less) ...

I used the example code

/*
DS3231_test.pde
Eric Ayars
4/11

Test/demo of read routines for a DS3231 RTC.

Turn on the serial monitor after loading this to check if things are
working as they should.

*/

#include <DS3231.h>
#include <Wire.h>

DS3231 Clock;
bool Century=false;
bool h12;
bool PM;
byte ADay, AHour, AMinute, ASecond, ABits;
bool ADy, A12h, Apm;

void setup() {
	// Start the I2C interface
	Wire.begin();
	// Start the serial interface
	Serial.begin(9600);
}

void loop() {
	// send what's going on to the serial monitor.
	// Start with the year
	Serial.print("2");
	if (Century) {			// Won't need this for 89 years.
		Serial.print("1");
	} else {
		Serial.print("0");
	}
	Serial.print(Clock.getYear(), DEC);
	Serial.print(' ');
	// then the month
	Serial.print(Clock.getMonth(Century), DEC);
	Serial.print(' ');
	// then the date
	Serial.print(Clock.getDate(), DEC);
	Serial.print(' ');
	// and the day of the week
	Serial.print(Clock.getDoW(), DEC);
	Serial.print(' ');
	// Finally the hour, minute, and second
	Serial.print(Clock.getHour(h12, PM), DEC);
	Serial.print(' ');
	Serial.print(Clock.getMinute(), DEC);
	Serial.print(' ');
	Serial.print(Clock.getSecond(), DEC);
	// Add AM/PM indicator
	if (h12) {
		if (PM) {
			Serial.print(" PM ");
		} else {
			Serial.print(" AM ");
		}
	} else {
		Serial.print(" 24h ");
	}
	// Display the temperature
	Serial.print("T=");
	Serial.print(Clock.getTemperature(), 2);
	// Tell whether the time is (likely to be) valid
	if (Clock.oscillatorCheck()) {
		Serial.print(" O+");
	} else {
		Serial.print(" O-");
	}
	// Indicate whether an alarm went off
	if (Clock.checkIfAlarm(1)) {
		Serial.print(" A1!");
	}
	if (Clock.checkIfAlarm(2)) {
		Serial.print(" A2!");
	}
	// New line on display
	Serial.print('\n');
	// Display Alarm 1 information
	Serial.print("Alarm 1: ");
	Clock.getA1Time(ADay, AHour, AMinute, ASecond, ABits, ADy, A12h, Apm);
	Serial.print(ADay, DEC);
	if (ADy) {
		Serial.print(" DoW");
	} else {
		Serial.print(" Date");
	}
	Serial.print(' ');
	Serial.print(AHour, DEC);
	Serial.print(' ');
	Serial.print(AMinute, DEC);
	Serial.print(' ');
	Serial.print(ASecond, DEC);
	Serial.print(' ');
	if (A12h) {
		if (Apm) {
			Serial.print('pm ');
		} else {
			Serial.print('am ');
		}
	}
	if (Clock.checkAlarmEnabled(1)) {
		Serial.print("enabled");
	}
	Serial.print('\n');
	// Display Alarm 2 information
	Serial.print("Alarm 2: ");
	Clock.getA2Time(ADay, AHour, AMinute, ABits, ADy, A12h, Apm);
	Serial.print(ADay, DEC);
	if (ADy) {
		Serial.print(" DoW");
	} else {
		Serial.print(" Date");
	}
	Serial.print(' ');
	Serial.print(AHour, DEC);
	Serial.print(' ');
	Serial.print(AMinute, DEC);
	Serial.print(' ');
	if (A12h) {
		if (Apm) {
			Serial.print('pm');
		} else {
			Serial.print('am');
		}
	}
	if (Clock.checkAlarmEnabled(2)) {
		Serial.print("enabled");
	}
	// display alarm bits
	Serial.print('\nAlarm bits: ');
	Serial.print(ABits, BIN);

	Serial.print('\n');
	Serial.print('\n');
	delay(1000);
}

and tried also some other codes, always with the same result.

2

There is a delay of 1000mS at the end of that sketch , so the reading you get will sometimes be the same , sometimes jump 1or 2seconds, depending on when you exit the delay and read the clock.

While back now , but found the simple examples supplied with the library worked fine

This is example code just to illustrate the commands used and gets absolutely everything from the sensor , you probably won’t need that and it may also be holding stuff up by taking a significant time ( unlikely?).

Try writing a simple sketch to just read seconds and print to the serial monitor.

And .....

  • there are more upto date more suitable library’s ?? I would start with that provided by the supplier, and their examples.
    *Finally you are running it from 3.3v ...