DS3231 best library to manage alarm

Other Hardware Sensors
1

Hi,
I'am making an alarm clock with Arduino UNO and DS3231 component.
Can you suggest me an update Library for DS3231 I2C to work with date/time/alarm?

Thanks in advance.

2

Using the words "Library for DS3231 I2C" entered into my favortire internet engine provided me with a list of libraries to choose from. After that it is a matter of looking through the libraries for things such as last updated and methods listed. Pick a few and give them a test to see if the libraries meet your requirements.

3

Check out the DS3232RTC library by J Christensen.

On that page there's also a link to an 'alarm-primer' that he wrote.

Don

4

Thank you Floresta fou your suggested library.
The problem that I have got is: I can't disabled alarm on my DS3231.

I set the alarm1 for example.
The alarm is triggered at the right time but then I can't disabled it to prevent next triggered.

Can you suggest my something or post an example sketch please?

5

I haven't worked with the DS3231 alarms in a few years and when I did I didn't use a library. If you are comfortable with dealing with the clock registers directly here is some of what I found in my archives:

// ======================== DS3231 RTC related code ======================
void setAlarmRTC()
{
  Wire.begin(); // enable I2C communications  
  clearAlarms(); // get rid of any old Alarm settings
  setAlarm2EveryMinute(); // set Alarm 2
  
  // enable interrupt from Alarm 2 and turn clock oscillator on
  //    enable interrupt from Alarm 2
  //    enable interrupts from the clock
  //    make sure the clock is running

/*      DS3231 Control Register
        0 0 0 0 0 1 1 0 
        | | | | | | | |_____ (A1IE)  - disable Alarm 1 interrupt
        | | | | | | |_______ (A2IE)  - enable Alarm 2 interrupt
        | | | | | |_________ (INTCN) - enable interrupts from alarms
        | | | | |___________ (RS1)   - 1 Hz square wave (if enabled)
        | | | |_____________ (RS2)   - 
        | | |_______________ (CONV)  - do not read chip temperature
        | |_________________ (BBSQW) - disable square wave output
        |___________________ (EOSC)  - enable oscillator (low turns clock on)
*/
  Wire.beginTransmission(addr_DS3231); // access RTC
  Wire.write(0x0E); // point to Control register
  Wire.write(0b00000110); // write bitmap to register
  Wire.endTransmission(); 
  
  clearA2F(); // clear the Alarm 2 flag   
 }

// .......................................................................
void clearAlarms()
{
  // clear Alarm 1 
  Wire.beginTransmission(addr_DS3231);
  Wire.write(uint8_t(0x07)); // lowest Alarm 1 register
  
  Wire.write(uint8_t(0b00000000));
  Wire.write(uint8_t(0b00000000));
  Wire.write(uint8_t(0b00000000));
  Wire.write(uint8_t(0b00000000));
  Wire.endTransmission();
  
  // clear Alarm 2 
  Wire.beginTransmission(addr_DS3231);
  Wire.write(uint8_t(0x0b)); // lowest Alarm 2 register
  
  Wire.write(uint8_t(0b00000000));
  Wire.write(uint8_t(0b00000000));
  Wire.write(uint8_t(0b00000000));
  Wire.endTransmission();
}  

// .......................................................................
void setAlarm2EveryMinute()
{
  // set Alarm 2 to generate an alarm (interrupt) every minute
  Wire.beginTransmission(addr_DS3231);
  Wire.write(uint8_t(0x0b)); // lowest Alarm 2 register
  
  // Alarm once per minute (00 seconds of every minute)
  Wire.write(uint8_t(0b10000000));   // A2M2 set --> ignore minutes bits
  Wire.write(uint8_t(0b10000000));   // A2M3 set --> ignore hours bits
  Wire.write(uint8_t(0b10000000));   // A2M4 set --> ignore day/date bits
  Wire.endTransmission();
}

// .......................................................................
//clear A2F
void clearA2F()
{
  Wire.beginTransmission(addr_DS3231);
  Wire.write(0x0F); // Status register
  Wire.requestFrom(addr_DS3231, 1); // get one byte
  while(Wire.available())
  {
    byte tmp = Wire.read(); // get current status
    bitClear(tmp, 1); // clear the Alarm 2 Flag
    Wire.write(tmp); // write new status
  }
  Wire.endTransmission();
}

Don

6

Hello. Sorry for my intrusion, but can you explain why use this routine:

//clear A2F
void clearA2F()
{
  Wire.beginTransmission(addr_DS3231);
  Wire.write(0x0F); // Status register
  Wire.requestFrom(addr_DS3231, 1); // get one byte
  while(Wire.available())
  {
    byte tmp = Wire.read(); // get current status
    bitClear(tmp, 1); // clear the Alarm 2 Flag
    Wire.write(tmp); // write new status
  }
  Wire.endTransmission();
}

Couldn't be like void clearAlarms()?

void clearA2F()
{
  Wire.beginTransmission(addr_DS3231);
  Wire.write(uint8_t(0x0F)); // Status register
  Wire.write(uint8_t(0b00000000));
  Wire.endTransmission();
}

Thanks in advance!

7

yago4xd:
Hello. Sorry for my intrusion, but can you explain why use this routine:
. . .

Sorry - I wrote that several years ago and I really don't remember.

Actually I don't even remember what I had for breakfast yesterday - it gets worse as you get older.

Don

1 Like
8

Hahaha don't worry. I'll see more references about.

Thanks!

9

There is a pair of libraries TIME and TIME ALARMS. The latter needs the former. I haven't used them for years but they seemed to do everything.