Alarm DS3231 doesn't work after 40 minutes

Projects Programming
1

Hi, I've use DS3231RTC Library. link of Library is here: https://github.com/JChristensen/DS3232RTC
I have a problem with my code:
my aim is to wake up Arduino from sleep every 20 minutes.
I set the alarm for every 20 minutes. It trigger the INT0 of Arduino at first time but in second time (2*20=40minutes later) it doesn't Trig the INT0 and my Arduino never wakes up until I reset the device.
here is my code:

#include "LowPower.h"
#include <DS3232RTC.h> 
#include "DHT.h"        
#include <SPI.h>       
#include <SD.h>        

const int wakeUpPin = 2;
#define DHTPIN 4  
#define DHTTYPE DHT11  
DHT dht(DHTPIN, DHTTYPE);
File myFile;
const int chipSelect = 10;
const int time_interval=20;// Sets the wakeup intervall in minutes

void wakeUp()
{
     detachInterrupt(0); 
}

void setup() {
  Serial.begin(9600);
  pinMode(LED_BUILTIN,OUTPUT);
  pinMode(wakeUpPin, INPUT_PULLUP); 
  digitalWrite(LED_BUILTIN,HIGH);
  
    RTC.setAlarm(ALM1_MATCH_DATE, 0, 0, 0, 1);
    RTC.setAlarm(ALM2_MATCH_DATE, 0, 0, 0, 1);
    RTC.alarm(ALARM_1);
    RTC.alarm(ALARM_2);
    RTC.alarmInterrupt(ALARM_1, false);
    RTC.alarmInterrupt(ALARM_2, false);
    RTC.squareWave(SQWAVE_NONE);
   
     time_t t; //create a temporary time variable so we can set the time and read the time from the RTC
    t=RTC.get();//Gets the current time of the RTC
    RTC.setAlarm(ALM1_MATCH_MINUTES , 0, minute(t)+time_interval, 0, 0);// Setting alarm 1 to go off 5 minutes from now
    // clear the alarm flag
    RTC.alarm(ALARM_1);
    // configure the INT/SQW pin for "interrupt" operation (disable square wave output)
    RTC.squareWave(SQWAVE_NONE);
    // enable interrupt output for Alarm 1
    RTC.alarmInterrupt(ALARM_1, true);
    
    dht.begin();//Start the DHT sensor
 
    Serial.print("Initializing SD card...");
    if (!SD.begin(chipSelect)) {
        Serial.println("initialization failed!");
        return;
    }
    Serial.println("initialization done.");
}

void loop() {
 delay(5000);
 Going_To_Sleep();
}

void Going_To_Sleep(){
   attachInterrupt(0, wakeUp, LOW);
    digitalWrite(LED_BUILTIN,LOW);          
    time_t t;                                             
    t=RTC.get();                                             
    Serial.println("Sleep  Time: "+String(hour(t))+":"+String(minute(t))+":"+String(second(t)));
    delay(1000);                                       
     LowPower.powerDown(SLEEP_FOREVER, ADC_OFF, BOD_OFF); 
    Serial.println("just woke up!");
    digitalWrite(LED_BUILTIN,HIGH);
    temp_Humi();
    t=RTC.get();
    Serial.println("WakeUp Time: "+String(hour(t))+":"+String(minute(t))+":"+String(second(t)));

    RTC.setAlarm(ALM1_MATCH_MINUTES , 0, minute(t)+time_interval, 0, 0);
  
  RTC.alarm(ALARM_1);
  }


void temp_Humi(){

  float h = dht.readHumidity();
  float t = dht.readTemperature();
  float f = dht.readTemperature(true);
  writeData(h,t,f);
  Serial.print("Humidity: ");
  Serial.print(h);
  Serial.print(" %\t");
  Serial.print("Temperature: ");
  Serial.print(t);
  Serial.print(" *C ");
  Serial.print(f);
  Serial.print(" *F\t");
}

  void writeData(float h,float t,float f){
  time_t p;
  p=RTC.get();
  String file_Name=String(day(p))+monthShortStr(month(p))+String(year(p))+".txt";
  myFile = SD.open(file_Name, FILE_WRITE);
  if (myFile) {
    Serial.print("Writing to "+ file_Name);
    myFile.println(String(hour(p))+":"+String(minute(p))+" Hum: "+String(h)+"% C: "+String(t)+" F: "+String(f));
    myFile.close();
    Serial.println("done.");
  } else {
    Serial.println("error opening "+ file_Name);
  }
  myFile = SD.open(file_Name);
  if (myFile) {
    Serial.println(file_Name);
    while (myFile.available()) {
      Serial.write(myFile.read());
    }
    myFile.close();
  } else {
    Serial.println("error opening"+ file_Name);
  }
 }
2

Try clearing the alarm’s flag once you wake up.