#include<avr/io.h>
#include<stdint.h>
#include<stdio.h>
#include<util/delay.h>
#include<avr/interrupt.h>
#include "ks0108.h"
#include "allfonts.h"
#include "twi.h"
#include "ds3231.h"

//TWI frequency is 347khz.DS3231 supports a highest of 400khz

volatile unsigned char Sync;

void print_bcd(uint8_t data)
{
ks0108_putchar('0'+(data>>4));
ks0108_putchar('0'+(data & 0x0F));
}

void print_dec(uint8_t data1)
{
ks0108_putchar('0'+(data1/10));
ks0108_putchar('0'+(data1%10));
}

uint8_t BCDtoDEC(uint8_t bcd_val)
{
return (((bcd_val >> 4) * 10) + (bcd_val & 0x0F));
}


void INT1_enable(void)
{
MCUCR |=(1<<ISC11); //Interrupt on falling edge to detect DS3231 sync pulse
GICR |=(1<<INT1);//INT1 enable
sei();//Global interrupt enable
}

void INT1_disable(void)
{
MCUCR &=~(1<<ISC11); //Interrupt on falling edge to disable
GICR &=~(1<<INT1);//INT1 disable
cli();//Global interrupt disble
}


ISR (INT1_vect)
{
Sync=1;
}

int main(void)
{

uint8_t i,hr,min,sec,yer,mnt,dat,dy;
uint8_t hr_dec,min_dec,sec_dec,Display,Read_rtc;

DDRD=0x00;//Input port
PORTD=0xFF;//Pullup enable

DDRC |=(1<<4); //Make PC4 as output

ks0108_init(0);
_delay_ms(100);
ds3231_init();
_delay_ms(100);



//ds3231_set(0x03,0x45,0x00,0x01,0x16,0x07,0x05,0x03);




Read_rtc=1;//Make it 1 to fetch the data from the RTC

//Now print the constant messages on the display.

//First print the : signs in necessary locations for Time

ks0108_select_font(fixednums15x31,ks0108_read_font_data,BLACK);
ks0108_cursorto(2,0); 
ks0108_putchar(':');
ks0108_cursorto(5,0); 
ks0108_putchar(':');

//Now print the / signs for date

ks0108_select_font(fixednums8x16,ks0108_read_font_data,BLACK);
ks0108_cursorto(2,2); 
ks0108_putchar('/');
ks0108_cursorto(5,2); 
ks0108_putchar('/');

//Lastly print some message
/*
ks0108_select_font(System5x7,ks0108_read_font_data,BLACK);
ks0108_cursorto(0,7);
ks0108_puts("Designed by Sharanya");
*/
_delay_ms(500);//deay some time befre entering main loop


while(1)
{

if(Read_rtc)//A flag was raised to read the values from the RTC
{

ds3231_get(&hr,&min,&sec,&yer,&mnt,&dat,&dy);

//fetch am/pm data into variable i

i=hr;
i&=0b00100000;
i=(i>>5);
hr&=0b00011111; 

//Convert BCD to Decimal

hr_dec=BCDtoDEC (hr);
min_dec=BCDtoDEC (min);
sec_dec=BCDtoDEC (sec);

//Print AM/PM

ks0108_select_font(System5x7,ks0108_read_font_data,BLACK);
ks0108_cursorto(19,4);
if(i==0)
{
ks0108_puts("AM");
}
else if(i==1)
{
ks0108_puts("PM");
}


//Print date,month,year

ks0108_select_font(fixednums8x16,ks0108_read_font_data,BLACK);
ks0108_cursorto(0,2);
print_bcd(dat);
ks0108_cursorto(3,2); 
print_bcd(mnt);
ks0108_cursorto(6,2); 
print_bcd(yer);

//Print Day

ks0108_select_font(System5x7,ks0108_read_font_data,BLACK);
ks0108_cursorto(14,4);
switch(dy)
{
case 1:
ks0108_puts("Sun");
break;

case 2:
ks0108_puts("Mon");
break;

case 3:
ks0108_puts("Tue");
break;

case 4:
ks0108_puts("Wed");
break;

case 5:
ks0108_puts("Thu");
break;

case 6:
ks0108_puts("Fri");
break;

case 7:
ks0108_puts("Sat");
break;
}

Read_rtc=0;
Sync=0;//Now current data already fetched,No need to wait for another second pulse.Just Print it
Display=1;//Enable the display flag in order to print the current data
INT1_enable();//enable the Interrupt to detect seconds further

}


//*******************************************************The per-second sync loop starts here ******************************************************




if(Sync) //If a per-second sync detected
{

PORTC ^=(1<<4);//Toggle the state of LED
Display=1;//Enable the display update
Sync=0;//Sync=0,wait for resync with per-second pulse

//Now update whats necessary

if(sec_dec==59)//if it was 60th sec(counting from 0)
{
sec_dec=0x00;//now reset it to 0
if(min_dec==59)//now if it was 60th min(counting from 0)
{
min_dec=0x00;//reset it to 00
if(hr_dec==12)//if it was 12th hour
{
//it is either a new day or am-pm conversion,read the RTC.
Read_rtc=1;
Display=0;//Disable the display to flag to quit printing
INT1_disable();//Disable the per-second sync pulse detection,Now we will read the RTC
}

else
{
hr_dec++;
}
}

else
{
min_dec++;
}
}

else
{
sec_dec++;
}
}//end of per-second sync loop


//***************************Display every second loop***************************


if(Display==1)//Display only if the flag is Set
{
ks0108_select_font(fixednums15x31,ks0108_read_font_data,BLACK);
ks0108_cursorto(0,0); 
print_dec(hr_dec);
ks0108_cursorto(3,0); 
print_dec(min_dec);
ks0108_cursorto(6,0); 
print_dec(sec_dec);
Display=0;
}



}
}