// Real time clock and calendar with set buttons using DS3231 and Arduino
                    
#include <Wire.h>         // include Wire library code (needed for I2C protocol devices) 

#include <LiquidCrystal_I2C.h>
// include Wire library code (needed for I2C protocol devices)
LiquidCrystal_I2C lcd(0x27,16,2);

void setup() 
{
Serial.begin(9600);
Wire.begin();             // Join i2c bus
lcd.init();
lcd.backlight();
pinMode(8, INPUT);
pinMode(9,OUTPUT);
}
char Time[] = "Time:         ";
char ti[] ="Time: HH:MM:SS";
char Calendar[]="Date:         ";
char ca[]="Date: DD/MM/YY";
byte i,pre, second, minute, hour,day, date, month, year;
char bs = "";
//String d,h;
int x=0,y=0,k=0,l=0,al=0; 
byte h[2], m[2], d[2];

void DS3231_display()
{
  
// Convert BCD to decimal
second = (second >> 4) * 10 + (second & 0x0F);
minute = (minute >> 4) * 10 + (minute & 0x0F);
hour = (hour >> 4) * 10 + (hour & 0x0F);
date = (date >> 4) * 10 + (date & 0x0F);
month = (month >> 4) * 10 + (month & 0x0F);
year = (year >> 4) * 10 + (year & 0x0F);
// End conversion

Time[12+i] = second % 10 + 48; //Converting to ASCII
Time[11+i] = second / 10 + 48;
Time[10+i] = ':';
Time[9+i] = minute % 10 + 48;
Time[8+i] = minute / 10 + 48;
Time[7+i] = ':';
Time[6+i] = hour % 10 + 48;
Time[5+i] = hour / 10 + 48;
Calendar[12+i] = year % 10 + 48;
Calendar[11+i] = year / 10 + 48;
Calendar[10+i] = '/';
Calendar[9+i] = month % 10 + 48;
Calendar[8+i] = month / 10 + 48;
Calendar[7+i] = '/';
Calendar[6+i] = date % 10 + 48;
Calendar[5+i] = date / 10 + 48;


lcd.setCursor(0,0);
lcd.print(Time);
lcd.setCursor(0,1);
lcd.print(Calendar);
}

int editbutton()
{
int alarm,hp,mp,dp,tp,yp;
alarm = 0;
hp = hour;
mp = minute;
dp = date;
tp = month;
yp = year;
int j,k=1;
    
char ins1[] = "Leave button";
char ins2[] = "Press button";     


for(j=0;j<k;j++)
{
lcd.clear();

if(digitalRead(8)==0)
{
hour = 0;  
while(true)
{  
hour = hour + 1;
if(digitalRead(8)==1)
break;
if(hour > 23)
{
hour = 0;
lcd.clear();
}
lcd.setCursor(0,0);
lcd.print(ins1);
lcd.setCursor(0,1);
lcd.print("hour ");
lcd.print(hour);
delay(500);  

}
}

lcd.clear();
if(digitalRead(8)==1)
{
minute = 0;  
while(true)
{
minute = minute + 1;  
if(digitalRead(8)==0)
break;
if(minute > 59)
{
minute = 0;
lcd.clear();
}
lcd.setCursor(0,0);
lcd.print(ins2);
lcd.setCursor(0,1);
lcd.print("minute ");
lcd.print(minute);  
delay(500);
}
}

lcd.clear();
if(digitalRead(8)==0)
{
date = 0;  
while(true)
{
date = date + 1;
if(digitalRead(8)==1)
break;
if(date > 30)
{
date = 0;
lcd.clear();
}
lcd.setCursor(0,0);
lcd.print(ins1);
lcd.setCursor(0,1);
lcd.print("date ");
lcd.print(date);  
delay(500);
}
}

lcd.clear();
if(digitalRead(8)==1)
{
month = 0;  
while(true)
{
month = month + 1;
if(digitalRead(8)==0)
break;
if(month > 12)
{
month = 0;
lcd.clear();
}
lcd.setCursor(0,0);
lcd.print(ins2);
lcd.setCursor(0,1);
lcd.print("month ");
lcd.print(month);  

delay(500);
}
}

lcd.clear();
if(digitalRead(8)==0)
{
year = 0;  
while(true)
{
year = year + 1;
if(digitalRead(8)==1)
break;
if(year > 50)
{
year = 0;
lcd.clear();
}

lcd.setCursor(0,0);
lcd.print(ins1);
lcd.setCursor(0,1);
lcd.print("year ");
lcd.print(year);  
delay(500);
}
}

lcd.clear();

for (int tc=0; tc<5 ; tc++)
{
  
if(alarm == 0)
{
lcd.setCursor(0,0);
lcd.print("To Set Alarm 1"); 
lcd.setCursor(0,1);
lcd.print("Press Button ");
lcd.print(tc);
delay(2000);
}
if ((digitalRead(8) == 0 && alarm < 2) || k == 2)  
{
lcd.clear();    
h[alarm] = hour - 1;
m[alarm] = minute - 1;
d[alarm] = date - 1;
alarm = alarm + 1;
tc = 0;
lcd.setCursor(0,0);

lcd.print("Alarm ");
lcd.print(alarm);
lcd.print(" Set");
delay(5000);
}

lcd.clear();
if(alarm == 1)
{
lcd.setCursor(0,0);
lcd.print("To Set Alarm 2");
lcd.setCursor(0,1);
lcd.print("Hold Button Now");
delay(2000);
lcd.clear();
}

if(digitalRead(8) == 0 && k<=1)
{
lcd.setCursor(0,0);  
lcd.print("Hold Button");
lcd.setCursor(0,1);
lcd.print("Set Alarm Time");  
delay(1000);  
k=k+1;
}

if(k==2)
{
break;  
}

delay(2000);
//lcd.clear();
}
}


if(alarm != 0)
{
hour = hp;
minute = mp;
date = dp;
month = tp;
year = yp;
}

return alarm;
}

void loop() 
{
while(digitalRead(8)==0)
{
al = editbutton();
Serial.println(al);

if(al==0)
{
hour = hour - 1;
minute = minute - 1;
date = date - 1;
month = month - 1;
year = year - 1;
}

// Convert decimal to BCD
minute = ((minute / 10) << 4) + (minute % 10);
hour = ((hour / 10) << 4) + (hour % 10);
date = ((date / 10) << 4) + (date % 10);
month = ((month / 10) << 4) + (month % 10);
year = ((year / 10) << 4) + (year % 10);
// End conversion
// Write data to DS3231 RTC
Wire.beginTransmission(0x68); // Start I2C protocol with DS3231 address
Wire.write(0); // Send register address
Wire.write(0); // Reset sesonds and start oscillator
Wire.write(minute); // Write minute
Wire.write(hour); // Write hour
Wire.write(day); // NOT USED
Wire.write(date); // Write date
Wire.write(month); // Write month
Wire.write(year); // Write year
Wire.endTransmission(); // Stop transmission and release the I2C bus
delay(300); // Wait 300ms
}
 
i=1;
y = y + 1;  

if (al > 0) ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
{
for (int x =0;x<al;x++)
{
if(d[x] == date && h[x] == hour && m[x] == minute)
{
lcd.clear();  
lcd.setCursor(0,0);
lcd.print("Alarm SET ON");  
delay(500);  
digitalWrite(9, HIGH);
delay(500);  
digitalWrite(9, LOW);
}
else
{
digitalWrite(9,LOW);  
}  
}
}

if(Serial.available()>0)
{
bs = Serial.read();
if(bs == 'e')
{
Serial.println("Enter Hour");  
while(x==0)
{
x = Serial.parseInt();
}
Serial.println(x);
pre = hour;
hour = x;
x=0;
}
if(hour > 23)
{
Serial.println("Invalid Entry For Hour");
hour = pre;
}
if(bs == 'e')
{
Serial.println("Enter Minute");
while(x==0)
{
x = Serial.parseInt();
}
Serial.println(x);
pre = minute;
minute = x;
x=0;
}
if(minute > 59)
{
Serial.println("Invalid Entry For Minute");
minute = pre;
}
if(bs == 'e')
{
Serial.println("Enter date");  
while(x==0)
{
x = Serial.parseInt();
}
Serial.println(x);
pre = date;
date = x;
x=0;
}
if(date > 31)
{
Serial.println("Invalid Entry For date");
date = pre;
}
if(bs == 'e')
{
Serial.println("Enter Month");  
while(x==0)
{
x = Serial.parseInt();
}
Serial.println(x);
pre = month;
month = x;
x=0;
}
if(month > 12)
{
Serial.println("Invalid Entry For Month");
month= pre;
}
if(bs == 'e')
{
Serial.println("Enter Year");  
while(x==0)
{
x = Serial.parseInt();
}
Serial.println(x);  
pre = year;
year = x;
x=0;
}
if(year > 25)
{
Serial.println("Invalid Entry For Year");
year = pre;
}


// Convert decimal to BCD
minute = ((minute / 10) << 4) + (minute % 10);
hour = ((hour / 10) << 4) + (hour % 10);
date = ((date / 10) << 4) + (date % 10);
month = ((month / 10) << 4) + (month % 10);
year = ((year / 10) << 4) + (year % 10);
// End conversion

if(bs=='v')
{
Serial.println(al);
  
Serial.println(h[0]);
Serial.println(hour);

Serial.println(m[0]);
Serial.println(minute);

Serial.println(d[0]);
Serial.println(date);

}

// Write data to DS3231 RTC
Wire.beginTransmission(0x68); // Start I2C protocol with DS3231 address
Wire.write(0); // Send register address
Wire.write(0); // Reset sesonds and start oscillator
Wire.write(minute); // Write minute
Wire.write(hour); // Write hour
Wire.write(day); // NOT USED
Wire.write(date); // Write date
Wire.write(month); // Write month
Wire.write(year); // Write year
Wire.endTransmission(); // Stop transmission and release the I2C bus
delay(300); // Wait 300ms
}

Wire.beginTransmission(0x68); // Start I2C protocol with DS3231 address
Wire.write(0); // Send register address
Wire.endTransmission(false); // I2C restart
Wire.requestFrom(0x68, 7); // Request 7 bytes from DS3231 and release I2C bus at end of reading
second = Wire.read(); // Read seconds from register 0
minute = Wire.read(); // Read minuts from register 1
hour = Wire.read(); // Read hour from register 2
day = Wire.read(); //NOT USED
date = Wire.read(); // Read date from register 4
month = Wire.read(); // Read month from register 5
year = Wire.read(); // Read year from register 6


DS3231_display(); // Display time & calendar

if(y==5)
{
Serial.println("To edit date and time enter e");
y=0;
}

Serial.println(ti);
Serial.println(Time);
Serial.println(ca);
Serial.println(Calendar);
Serial.println("\n");

delay(1000); // Wait 50ms
}