College Bell Using RTC DS3231 and UNO

Hai My dear friends…

I need your help as fast as possible. I am a Beginner and trying to make one college alarm as our project. I made one code for that but that is not working properly

I cut short my code due to overflow.

please give me an idea, how to make bell on different times

#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;
int buzzer=13;
int exam;
int exampm;
byte year, month, date, DoW, hour, minute, second;

void setup() {
	// Start the I2C interface
	Wire.begin();
        /*Clock.setSecond(50);//Set the second 
        Clock.setMinute(50);//Set the minute 
        Clock.setHour(20);  //Set the hour 
        Clock.setDoW(2);    //Set the day of the week
        Clock.setDate(27);  //Set the date of the month
        Clock.setMonth(2);  //Set the month of the year
        Clock.setYear(17);  //Set the year (Last two digits of the year)*/

        int buzzer =13;
        pinMode(buzzer,OUTPUT);
	// Start the serial interface
	Serial.begin(115200);
}
void ReadDS3231()
{
  int second,minute,hour,date,month,year,temperature,dow; 
  second=Clock.getSecond();
  minute=Clock.getMinute();
  hour=Clock.getHour(h12, PM);
  date=Clock.getDate();
  month=Clock.getMonth(Century);
  year=Clock.getYear();
  dow=Clock.getDoW();
  temperature=Clock.getTemperature();
  
  Serial.println("20");
  Serial.print(year,DEC);
  Serial.print('-');
  Serial.print(month,DEC);
  Serial.print('-');
  Serial.print(date,DEC);
  Serial.println();
  Serial.print(hour,DEC);
  Serial.print(':');
  Serial.print(minute,DEC);
  Serial.print(':');
  Serial.print(second,DEC);
  Serial.print('\n');
  Serial.print("Temperature=");
  Serial.print(temperature); 
  Serial.print('\n');
  Serial.print(dow); 
  Serial.print('\n');
}
// ######################################################
void normalbell (){
   digitalWrite(buzzer,HIGH);
      delay(5000);
      digitalWrite(buzzer,LOW);
}
void exambell (){
   digitalWrite(buzzer,HIGH);
      delay(7000);
      digitalWrite(buzzer,LOW);
}
void normal_week(){

  int x=Clock.getHour(h12, PM);
  int y=Clock.getMinute();
  int z=Clock.getSecond();
  
     
  //  ---start--------------------- 
     if(x==8 && y==20 && z==5) {
      normalbell();
     }
  Serial.println("FIRST BELL");
  //--------------------------------     
     if(x==8 && y==30 && z==5) {
     normalbell();
     }
  Serial.println("FIRST PERIOD");
      //----------------------------
      
 //### EXAM $$$$$$$$$$$$$$$$

if (exam=1){
  if(x==9 && y==20 && z==5) {
      exambell();
     }
  Serial.println("EXAM BELL");
  delay(15000);
   Serial.println("FIRST PERIOD");
}

//$$$$$$$$ Exam $$$$$$$$$
if (exampm=1){
  if(x==13 && y==20 && z==3) {
      exambell();
     }
  Serial.println("EXAM BELL");
  delay(15000);
   Serial.println("LUNCH TIME");
}
//$$$$$$$$$$$$$$$$$$$

if(x==13 && y==30 && z==5) {
      exambell();
     }
  Serial.println("FIFTH HOUR");
  //---------------------------

}
// FRIDAY TIMETABLE ######################################



void friday_week(){

  int x=Clock.getHour(h12, PM);
  int y=Clock.getMinute();
  int z=Clock.getSecond();
  
     
  //  ---start--------------------- 
     if(x==8 && y==20 && z==5) {
      normalbell();
     }
  Serial.println("FIRST BELL");
  //--------------------------------     
     if(x==8 && y==30 && z==5) {
      normalbell();
     }
  Serial.println("FIRST PERIOD");
      //----------------------------

 //$$$$$$$$ Exam $$$$$$$$$
if (exam=1){
  if(x==9 && y==20 && z==3) {
      exambell();
     }
  Serial.println("EXAM BELL");
  delay(15000);
   Serial.println("FIRST PERIOD");
}
//$$$$$$$$$$$$$$$$$$$
 if(x==9 && y==30 && z==5) {
      exambell();
     }
  Serial.println("SECOND PERIOD");
      //----------------------------

  //$$$$$$$$ Exam $$$$$$$$$
if (exam=1){
  if(x==10 && y==0 && z==3) {
      exambell();
     }
  Serial.println("EXAM BELL");
  delay(15000);
   Serial.println("SECOND PERIOD");
}
//$$$$$$$$$$$$$$$$$$$
      if(x==12 && y==30 && z==5) {
      exambell();
     }
  Serial.println("LUNCH TIME");
  //----------------------------
 //$$$$$$$$ Exam $$$$$$$$$
if (exampm=1){
  if(x==13 && y==50 && z==3) {
      exambell();
     }
  Serial.println("EXAM BELL");
  delay(15000);
   Serial.println("EXAM BELL");
}

 //$$$$$$$$ Exam $$$$$$$$$
if (exampm=1){
  if(x==16 && y==0 && z==3) {
      exambell();
     }
  Serial.println("EXAM BELL");
  delay(15000);
   Serial.println("SEVENTH PERIOD");
}
//$$$$$$$$$$$$$$$$$$$  
  if (x==16 && y==30 && z==5) {
      normalbell();
     }
  Serial.println("LAST BELL");

  //---------------------------;
  //$$$$$$$$ Exam $$$$$$$$$;
 if (exampm=1){
  if(x==16 && y==45 && z==3) {
      exambell();
     }
  Serial.println("EXAM BELL");
  
}
//$$$$$$$$$$$$$$$$$$$;
 //$$$$$$$$ Exam $$$$$$$$$;
if(exampm=1){
  if(x==17 && y==0 && z==3) {
      exambell();
     }
  Serial.println("EXAM BELL");
  delay(15000);
   Serial.println("GOOD BYE");
}
}
//$$$$$$$$$$$$$$$$$$$
//##################################################

I hope you can help me… my friends pls

Try the TimeAlarms library.

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