DS3231 as a calendar reminder

Projects General Guidance
1

Is it possible to create something like a calendar reminder using an Arduino Uno and DS3231 RTC? I've scoured the internet and so far I've only seen alarm clocks (for time) . How do I make something that would trigger an alarm at a certain date that I can set myself?

2

you can create a calendar reminder system using an Arduino Uno and a DS3231 RTC module! The DS3231 has date-tracking capabilities (day, month, and year), so you can set specific date-based reminders instead of just time-based alarms. Save the reminder dates (DD/MM/YYYY & time) in the Arduino’s EEPROM or SD card (if available).
Continuously read the current date/time from the DS3231 and check if it matches a stored reminder.

3

You can certainly set the alarm and have it interrupt or wake up the Arduino when the alarm time is reached. But remember that the DS3231 alarms only go up to the day of the month. They don't let you include the month or year in the alarm setting. So to go more than a month into the future, you would need a series of monthly interrupts until you get to the right month and year.

4

Thanks! Is the code for this similar to howo a "normal" alarm clock would have? I'm not really that good with coding and only rely on github, or forums in general, mostly; so I was thinking of just tweaking some codes that are already available.

5

I didn't know that, thanks. Fortunately I only needed to set the date for a few weeks.

6

with the DS3231 you can trigger on whatever you want, like an Alarmclock on minute and hour but also for a longterm timer on date, month, year or all of them together. For example if you want an Alarm on August 25th 2028 at 07:23AM then built an "if / then" statement which includes all of these data read from the DS3231. In order to trigger only once include the second as well and include a delay(1000); in the if true condition. May look like this:

#include <DS3231.h>
// #include other stuff

DS3231 Clock;
int trigYear = 2028;
int trigMonth = 8;
int trigDate = 25;
int trigHour = 7;
int trigMinute = 23;

void setup() {
// other setup code...

}

void loop() {
/* your code...
.............
*/

if(Clock.getYear() == trigYear && Clock.getMonth() == trigMonth && 
   Clock.getDate() == trigDate && Clock.getHour() == trigHour &&
   Clock.getMinute() == trigMinute && Clock.getSecond() == 0) 
   {
    // *** alarm is triggered ***
    // *** do whatever you want ***
    delay(1000);
   }
}

I don´t know if programming experts now throw unsound tomatos at me but this is the way I use alarm conditions in my clock projects.

7

Is that alarm interrupt driven?

8

I built a couple of " birthday clocks" using the ds3231, arduino pro mini and a 1602 i2c lcd, couple of LEDs and pushbuttons.
Code in here somewhere....see if I can find it.

Have a peek here....

9

As others have said, definitely Yes.

The Uno project I made a year or so ago used a DFR Player as well as DS3231 RTC and LCD. One button delivers my spoken report on current/max/min indoor & outdoor temps, sunrise & sunset. But the button relevant to your post triggers announcement of my 'imminent events'. Birthdays, anniversaries, public holidays, scheduled meetings, etc. All within a user-settable period; I mainly used 28 days.

Central to that part is an array of about 50 elements. It contains both the file number of my recorded MP3 about that event, and the day of the year on which the event occurs. General idea shown in this extract:

struct NotableEvent
{
  int fileNumber; // Imminent.xlsx col F
  int dayOfYear; // Imminent.xlsx col D
};

NotableEvent notableEvents[] =
{
  {192, 60}, // Leap Year Day
  {140, 64}, // Terry Mon 4 Mar
  {193, 65}, // EGWAS Mar 5
  {145, 68}, // Andrew Fri 8 Mar
  {146, 76}, // Wendy Sat 16Mar
  {77, 89}, // EasterMonday 29 Mar
  {99, 89}, // OurAnniv (two events same date)
  {165, 91}, // Summer Time starts Sun 31/3 (+ 1 hr)
  etc

BTW, if anyone develops anything similar, don't make the mistake I did of not including a YEAR component!