//DS1307 RTC Interfacing with PIC16F877A

// LCD module connections
sbit LCD_RS at RB2_bit;
sbit LCD_EN at RB3_bit;
sbit LCD_D4 at RB4_bit;
sbit LCD_D5 at RB5_bit;
sbit LCD_D6 at RB6_bit;
sbit LCD_D7 at RB7_bit;
sbit LCD_RS_Direction at TRISB2_bit;
sbit LCD_EN_Direction at TRISB3_bit;
sbit LCD_D4_Direction at TRISB4_bit;
sbit LCD_D5_Direction at TRISB5_bit;
sbit LCD_D6_Direction at TRISB6_bit;
sbit LCD_D7_Direction at TRISB7_bit;
/////////////////////
///// global variables////
unsigned short sec;
unsigned short minute;
unsigned short hour;
unsigned short day;
unsigned short date;
unsigned short month;
unsigned short year;
unsigned short temp;
char time[9];
char ddate[11];
//////functions ////////

//////////
unsigned short read_ds1307(unsigned short address)// address byte
{
I2C1_Start();//Determines if I²C bus is free and issues START signal.
I2C1_Wr(0xd0); //address 0x68 followed by direction bit (0 for write, 1 for read) 0x68 followed by 0 --> 0xD0
I2C1_Wr(address);//address of ds1307 to be read 
I2C1_Repeated_Start();//to change from write condition to read condition
I2C1_Wr(0xd1); //0x68 followed by 1 --> 0xD1
temp=I2C1_Rd(0);//Reads one byte from the slave, and sends not acknowledge signal 
I2C1_Stop();//Issues STOP signal
return(temp);//BCD byte
}
/////////
void write_ds1307(unsigned short address,unsigned short w_data)//address and w_data bytes
{
I2C1_Start(); // issue I2C start signal
//address 0x68 followed by direction bit (0 for write, 1 for read) 0x68 followed by 0 --> 0xD0
I2C1_Wr(0xD0); // send byte via I2C (device address + W)
I2C1_Wr(address); // send byte (address of DS1307 location)
I2C1_Wr(w_data); // send data (data to be written)
I2C1_Stop(); // issue I2C stop signal
}
/////////////////////////
unsigned char BCD2UpperCh(unsigned char bcd)
{
return ((bcd >> 4) + '0');//get ASCII character
}
////////
unsigned char BCD2LowerCh(unsigned char bcd)
{
return ((bcd & 0x0F) + '0');
}
///////
void init(){
I2C1_Init(100000); //DS1307 I2C is running at 100KHz
PORTB = 0;
TRISB = 0; // Configure PORTB as output
TRISC = 0xFF;

Lcd_Init();                // Initialize LCD
Lcd_Cmd(_LCD_CLEAR);       // Clear LCD display
Lcd_Cmd(_LCD_CURSOR_OFF);  // Turn cursor off

Lcd_Out(1, 1, "TIME:");
Lcd_Out(2, 1, "DATE:");

//Set Time
write_ds1307(0,0x80); //address 0 , data 10000000 :Reset second to 0 sec. and stop Oscillator  ,DS1307 TIMEKEEPER REGISTERS Figure 3
write_ds1307(1,0x06); //write min 06
write_ds1307(2,0x12); //write hour 12
write_ds1307(3,0x07); //write day of week 7:satarday
write_ds1307(4,0x16); // write date 16
write_ds1307(5,0x04); // write month 04
write_ds1307(6,0x16); // write year 16 --> 2016
write_ds1307(7,0x10); //SQWE output at 1 Hz , control address 0x07 , enable bit bit4
write_ds1307(0,0x00); //Reset second to 0 sec. and start Oscillator
}
///////main function////////////
void main(){
init();

while(1)
{
sec=read_ds1307(0); // read second
minute=read_ds1307(1); // read minute
hour=read_ds1307(2); // read hour
day=read_ds1307(3); // read day
date=read_ds1307(4); // read date
month=read_ds1307(5); // read month
year=read_ds1307(6); // read year

time[0] = BCD2UpperCh(hour);
time[1] = BCD2LowerCh(hour);
time[2] = ':';
time[3] = BCD2UpperCh(minute);
time[4] = BCD2LowerCh(minute);
time[5] = ':';
time[6] = BCD2UpperCh(sec);
time[7] = BCD2LowerCh(sec);
time[8] = '\0';

ddate[0] = BCD2UpperCh(date);
ddate[1] = BCD2LowerCh(date);
ddate[2] ='/';
ddate[3] = BCD2UpperCh(month);
ddate[4] = BCD2LowerCh(month);
ddate[5] ='/';
ddate[6] = '2';
ddate[7] = '0';
ddate[8] = BCD2UpperCh(year);
ddate[9] = BCD2LowerCh(year);
ddate[10] = '\0';

Lcd_Out(1,6,time);
Lcd_Out(2,6,ddate);
Delay_ms(50);
}
}

unsigned short myBcd2Dec(unsigned short bcd){
return ((bcd >> 4)*10+(bcd & 0x0F));
}
Example: myBcd2Dec(01000101) = 45

unsigned short myDec2Bcd(unsigned short dec){
return (((dec/10)<<4)(dec%10));
}
Example: myDec2Bcd(45) = 01000101

// LCD module connections
sbit LCD_RS at RB2_bit;
sbit LCD_EN at RB3_bit;
sbit LCD_D4 at RB4_bit;
sbit LCD_D5 at RB5_bit;
sbit LCD_D6 at RB6_bit;
sbit LCD_D7 at RB7_bit;

sbit LCD_RS_Direction at TRISB2_bit;
sbit LCD_EN_Direction at TRISB3_bit;
sbit LCD_D4_Direction at TRISB4_bit;
sbit LCD_D5_Direction at TRISB5_bit;
sbit LCD_D6_Direction at TRISB6_bit;
sbit LCD_D7_Direction at TRISB7_bit;
// End LCD module connections
unsigned short read_ds1307(unsigned short address)
{
  unsigned short r_data;
  I2C1_Start();
  I2C1_Wr(0xD0); //address 0x68 followed by direction bit (0 for write, 1 for read) 0x68 followed by 0 --> 0xD0
  I2C1_Wr(address);
  I2C1_Repeated_Start();
  I2C1_Wr(0xD1); //0x68 followed by 1 --> 0xD1
  r_data=I2C1_Rd(0);
  I2C1_Stop();
  return(r_data);
}
//////////////////////////////////////////
void write_ds1307(unsigned short address,unsigned short w_data)
{
  I2C1_Start(); // issue I2C start signal
  //address 0x68 followed by direction bit (0 for write, 1 for read) 0x68 followed by 0 --> 0xD0
  I2C1_Wr(0xD0); // send byte via I2C (device address + W)
  I2C1_Wr(address); // send byte (address of DS1307 location)
  I2C1_Wr(w_data); // send data (data to be written)
  I2C1_Stop(); // issue I2C stop signal
}
/////////////////////////////////////////////////
unsigned char BCD2UpperCh(unsigned char bcd)
{
  return ((bcd >> 4) + '0');
}

unsigned char BCD2LowerCh(unsigned char bcd)
{
  return ((bcd & 0x0F) + '0');
}

//////global variables//////////////////
unsigned short  second;
unsigned short  minute;
unsigned short  hour;
unsigned short  hr;
unsigned short  day;
unsigned short  dday;
unsigned short  month;
unsigned short  year;
unsigned short  ap;

unsigned short set_count = 0;
short set;

char time[] = "00:00:00 PM";
char date[] = "00-00-00";
/////////////////////////
bit oldstate;                                    // Old state flag
////////////////////
void main()
{
   I2C1_Init(100000); //DS1307 I2C is running at 100KHz

   CMCON = 0x07;   // To turn off comparators
   ADCON1 = 0x06;  // To turn off analog to digital converters

   TRISA = 0x07;
   PORTA = 0x00;

   Lcd_Init();                        // Initialize LCD
   Lcd_Cmd(_LCD_CLEAR);               // Clear display
   Lcd_Cmd(_LCD_CURSOR_OFF);          // Cursor off
   Lcd_out(1,1,"Time:");
   Lcd_out(2,1,"Date:");

   while(1)
   {
                set = 0;
         /////////
                if (Button(&PORTA, 0, 10, 0)) {               // Detect logical one
                        oldstate = 1;                              // Update flag
                        }

                if (oldstate && Button(&PORTA, 0, 10, 1)) {   // Detect one-to-zero transition
                        oldstate = 0;                              // Update flag
                        set_count++;
                                if(set_count >= 7)
                                {
                set_count = 0;
                                }

                }

        /////////////////////
     if(set_count)
     {
        //////////////////////////
                if (Button(&PORTA, 1, 10, 0)) {               // Detect logical one
                        oldstate = 1;                              // Update flag
                        }
                        /////
                if (oldstate && Button(&PORTA, 0, 10, 1)) {   // Detect one-to-zero transition
                        oldstate = 0;                              // Update flag
                        set = 1;
                }
          /////////////////////
 
                if (Button(&PORTA, 2, 10, 0)) {               // Detect logical one
                        oldstate = 1;                              // Update flag
                        }
                if (oldstate && Button(&PORTA, 0, 10, 1)) {   // Detect one-to-zero transition
                        oldstate = 0;                              // Update flag
                        set = -1;
                        }
          /////////////////////////
        if(set_count && set)
        {
          switch(set_count)
          {
            case 1:
                    hour=Bcd2Dec(hour);
                                        hour = hour + set;
                    hour=Dec2Bcd(hour);
                                        if((hour & 0x1F) >= 0x13)
                    {
                      hour = hour & 0b11100001;
                      hour = hour ^ 0x20;
                    }
                    else if((hour & 0x1F) <= 0x00)
                    {
                      hour = hour | 0b00010010;
                      hour = hour ^ 0x20;
                    }
                    write_ds1307(2, hour); //write hour
                                                   
                    
                    break;
            case 2:
                     minute = Bcd2Dec(minute);
                                         minute = minute + set;
                     if(minute >= 60)
                        minute = 0;
                     if(minute < 0)
                        minute = 59;
                     minute = Dec2Bcd(minute);
                                         write_ds1307(1, minute); //write min
                     break;
            case 3:
                    if(abs(set))
                      write_ds1307(0,0x00); //Reset second to 0 sec. and start Oscillator
                    break;
            case 4:
                     day = Bcd2Dec(day);
                                         day = day + set;
                     day = Dec2Bcd(day);
                                         if(day >= 0x32)
                        day = 1;
                     if(day <= 0)
                        day = 0x31;
                     write_ds1307(4, day); // write date 17
                     break;
            case 5:
                    month = Bcd2Dec(month);
                                        month = month + set;
                    month = Dec2Bcd(month);
                                        if(month > 0x12)
                      month = 1;
                    if(month <= 0)
                      month = 0x12;
                    write_ds1307(5,month); // write month 6 June
                    break;
            case 6:
                    year = Bcd2Dec(year);
                                        year = year + set;
                    year = Dec2Bcd(year);
                                        if(year <= -1)
                       year = 0x99;
                    if(year >= 0x50)
                       year = 0;
                    write_ds1307(6, year); // write year
                    break;
          }
        }
     }

      second = read_ds1307(0);
      minute = read_ds1307(1);
      hour = read_ds1307(2);
       hr = hour & 0b00011111;
       ap = hour & 0b00100000;
      dday = read_ds1307(3);
      day = read_ds1307(4);
      month = read_ds1307(5);
      year = read_ds1307(6);

//////////////////////////
      time[0] = BCD2UpperCh(hr);
      time[1] = BCD2LowerCh(hr);
      time[3] = BCD2UpperCh(minute);
      time[4] = BCD2LowerCh(minute);
      time[6] = BCD2UpperCh(second);
      time[7] = BCD2LowerCh(second);

      date[0] = BCD2UpperCh(day);
      date[1] = BCD2LowerCh(day);
      date[3] = BCD2UpperCh(month);
      date[4] = BCD2LowerCh(month);
      date[6] = BCD2UpperCh(year);
      date[7] = BCD2LowerCh(year);
      ///////
      if(ap)
      {
         time[9] = 'P';
         time[10] = 'M';
      }
      else
      {
         time[9] = 'A';
         time[10] = 'M';
      }
////////////////////////////

      Lcd_out(1, 6, time);
      Lcd_out(2, 6, date);
      Delay_ms(100);


   }
}