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Hello value 1 - So for an interrupt service routine (ISR), the general rule is to keep them as short as possible. They should not contain parameters or routines, such as, "displayTime". It is also recommended that shared variables between the main progrm and ISR are declared as volatile. More information on interrupts can be found here: www.arduino.cc/reference/en/language/functions/external-interrupts/attachinterrupt/ and here: gammon.com.au/interrupts

Hi Aubrey - This should be relatively easy. In the Arduino IDE program, you will need to go to "Tools" and then scrool down and select the Arduino Mega you have from the list of options. That should be all you need to do, unless you are using a different Mega pin to monitor the SQW output. If so, you need to change the SQWinput pin in the sketch to match the Mega pin you are using. Make sure it is an interrupt capable pin (2, 3, 18, 19, 20 or 21).

Interesting. I have not tried running the the RTC on the coin celll alone. The DS3231 datasheet mentions a 0.1uF decoupling capacitor should be placed in parallel with the coin cell if it is the primaty power source. I would need to investigate this further.

It's complicated. I tried this yesterday and failed. First RTC is not powered by a coin cell, where there is power on VCC. When you disconnect that power putting it for example on arduino output pin and setting it low, it instantly triggers interrupt cause SQW/INT pin goes from high to high impedance. Then there's a chance that RTC may be powered via data pins.And when I measured current with SDA and SCL disconnect, it was 600uA, whereas with connection to Arduiono, it draws something like 90uA. It's not horrible. Also note there's a BBSQW enable bit in either config or status register (battery backed square wave).

Hello Sukhbir Singh - You can remove the LED connected to the SDA pin with no problems. It is not required. If I am understanding your other question about pin 12, you should be able to drive a second LED with it as long as you use a 220 or 330 Ohm resistor. It sounds like you want to light this LED every second?

@Cedric Lessard - The transistors are N-Channel enhancement FETs, part number ZVN4206A. Have fun!

Hello @Denisa Muhut - I think you're looking for a Fritzing drawing showing parts placements. I attempted to draw one but the components are so close together that it's hard to see what is attached where. I will attempt to draw the wiring diagram a different way and post it when ready.

@@DuranioLabs thank you for replying, I made some kind of sketch in Tinkercad and managed to understand your circuit

@Denisa Muhut - Sounds good. I also created a drawing using Fritzing and placed a PNG file in GitHub, called "Dice Roll Wiring 4-17-22(2).png" and placed it in GitHub at this location: github.com/DuranioMakes/ArduinoDice

Thank you for sharing!

Good question! I have not tried that. It would be easy to experiment with making that change in the program to see what happens. If no errors are reported, it probably works.

@@DuranioLabs Thank you, I tried it and seems to have worked. I use SQWinput to trigger the alarm, but otherwise works fine.

@mihaisor Glad that worked!

Very intersting! I checked out your channel and also found further information on GitHub.

Great! I'm glad you found this video useful. Stay curious and keep experimenting!

Hi, can you share pictures?

I created a drawing using Fritzing and placed a PNG file in GitHub, called "Dice Roll Wiring 4-17-22(2).png" and placed it in GitHub at this location: github.com/DuranioMakes/ArduinoDice

Glad it was helpful!

DEC is for decimal and instructs the Arduino to print the value in decimal (base 10) format. I found that it is redundant and you could just leave it out. For example: Serial.print(now.second(), DEC); can be changed to: Serial.print(now.second()); and it will still work as expected. You can change the DEC to HEX which displays the value in hexidecimal (base 16) just to see what happens. Have Fun!

@@DuranioLabs thank you so much for replying! I been trying to understand this part for a while, thank you!

@Vitaliy Reznikov - Great! I'm glad you found this video usefull. Happy programming!

The slowest frequency setting available for the SQW pin is 1Hz but you can accomplish what you want a different way. If your project still requires a real time clock, you can test the state of minutes and seconds and change the state of an Arduino pin when minutes and seconds both equal 00. For example you can add the following lines to the Arduino sketch. 1) At the beginning of the sketch, assign an Arduino pin for the new output signal. const int PIN = 3; // Arduino pin 3 called "PIN". You can rename it if you'd like 2) Within setup, "void setup ()" add the following lines: pinMode(PIN, OUTPUT); //Set the new Arduino pin (pin 3) as an output digitalWrite(PIN, HIGH); //Set the initial output state of PIN as HIGH 3) Within "void displayTime ()" add the following: if (now.minute() == 00 && now.second() == 00){ digitalWrite(PIN, LOW); //If minutes are 00 and seconds are 00, it's the top of the hour so set PIN low } if (now.minute() == 00 && now.second() == 30){ digitalWrite(PIN, HIGH); //After 30 seconds, set PIN high } You can add an LED and 220 Ohm resistor to the output to test the changes. Good luck!

*calculate = set

Good question. The DS3231 does not have resolution below seconds, but a counter could be written in the software to provide counts down to the millisecond, while still being reset every 1,000msec by the 1Hz squarewave.

@@DuranioLabs could u provide the tutorial or the steps? I really have no idea. This is for my final project on university:( i'll be thankful for the tutorial

@DONNY ALI SANJAYA - So I think an even better way to count down to milliseconds with an Arduino is to use the millis() function. The millis() function returns the number in milliseconds since the board began running its program. A description of millis() is here: www.arduino.cc/reference/en/language/functions/time/millis/ And a detailed description of it use can be found here: th-cam.com/video/qn8SP93L3iQ/w-d-xo.html Anyway, I'm not sure if you're building a real time clock or something more like a stopwatch with Arduino. If you need time expressed down to the millisecond, then the millis() function is where you should start.

@@DuranioLabs Got it! I'll try with milliseconds. Thx for the explanation sir! Really apreciate it!

Sure! I just posted the sketch on GitHub along with a copy of the breadboard layout as JPEG and Fritzing files. Here is the link: github.com/DuranioMakes/DS3231_RTC_SQW_1Hz_Interrupt Thanks for watching!