#define F_CPU 16000000UL
#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>

#define WADDR 0xA2
#define RADDR 0xA3

void init_display();
void init_timer0();
//void init_timer1();
void init_I2C();

void I2Cstart() {TWCR = (1<<TWINT)|(1<<TWSTA)|(1<<TWEN); while (!(TWCR & (1<<TWINT)));}
void I2Csend(uint8_t c) {TWDR = c; TWCR = (1<<TWINT)|(1<<TWEN); while (!(TWCR & (1<<TWINT)));}
void I2Cstop() {TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWSTO);}
uint8_t I2CreadACK()  {TWCR = (1<<TWINT)|(1<<TWEA)|(1<<TWEN); while (!(TWCR & (1<<TWINT))); return TWDR;}
uint8_t I2CreadNACK() {TWCR = (1<<TWINT)|(0<<TWEA)|(1<<TWEN); while (!(TWCR & (1<<TWINT))); return TWDR;}

volatile uint8_t onesec=0;

volatile uint8_t lcdx=0, lcdy=0; 
const char lcdcmd[2] = {0xC0, 0x80};
unsigned char LCDline[2][16]={{"Time    00:00:00"},
                              {"Alarm   00:00:00"}};
                              

int main(void)
{   
    uint8_t hour, min, sec;
    
    DDRB |= 0x80;
    
    init_display();
    init_timer0();  // initialize timer0
    //init_timer1();
    init_I2C();

	//MCUCR &= 0xEF;

	DDRE = 0x00;
	PORTE = 0xC0; // PU enable

    //EICRB |= (1<<ISC71)|(1<<ISC70); // INT7 on rising edge
	EICRB |= (1<<ISC71);
    EICRB |= (1<<ISC71);
    EIMSK |= (1<<INT7);             // enable INT7 - PORTE<7>
					
	
	
	I2Cstart();
	I2Csend(WADDR);
	I2Csend(0x0D);  // OSCOUT register
	I2Csend(0x83); 	// 1 Hz
	I2Cstop();
	
	I2Cstart();
	I2Csend(WADDR);
	I2Csend(0x02);  // seconds register
	I2Cstart();     // restart
	I2Csend(RADDR);
	sec = I2CreadACK();
	min = I2CreadACK();
	hour = I2CreadNACK();
	I2Cstop();

	LCDline[0][8]  = (hour>>4)+'0';
	LCDline[0][9]  = (hour&0x0F)+'0';   
	LCDline[0][11] = (min>>4)+'0';
	LCDline[0][12] = (min&0x0F)+'0';
	LCDline[0][14] = (sec>>4)+'0';
	LCDline[0][15] = (sec&0x0F)+'0';
	
	sei();  // enable global interrupts
	
    // loop forever
    while(1)
    {
		
		PORTB = PINE;
		//PORTB ^= 0x80;
		//_delay_ms(500);
		if(onesec==1)
		{
			onesec = 0;
			
			PORTB ^= 0x80;
		}	
		/*	I2Cstart();
			I2Csend(WADDR);
			I2Csend(0x02);  // seconds register
			I2Cstart();     // restart
			I2Csend(RADDR);
			sec = I2CreadACK();
			min = I2CreadACK();
			hour = I2CreadNACK();
			I2Cstop();

			LCDline[0][8]  = (hour>>4)+'0';
			LCDline[0][9]  = (hour&0x0F)+'0';   
			LCDline[0][11] = (min>>4)+'0';
			LCDline[0][12] = (min&0x0F)+'0';
			LCDline[0][14] = (sec>>4)+'0';
			LCDline[0][15] = (sec&0x0F)+'0';
		} */
    } // while(1)
}

void init_display()
{
    DDRA = 0xFF;
    
    PORTC &= 0xAF;
    DDRC  |= 0x50;
    
    PORTC &= 0xBF;

    PORTA = 0x38;
    PORTC |= 0x10;
    PORTC &= 0xEF;
    PORTA = 0x0C;
    PORTC |= 0x10;
    PORTC &= 0xEF;
    PORTA = 0x01;
    PORTC |= 0x10;;
    PORTC &= 0xEF;  
    _delay_ms(2);
}

void init_timer0()
{
    TCCR0B |= (1<<CS02)|(1<<CS00);	// prescaler 1024
    TCNT0 = 0;			            // initialize counter
    TIMSK0 |= (1 << TOIE0);	        // enable overflow interrupt 
}

//void init_timer1()
//{
//    TCCR1B |= (1<<CS12)|(1<<CS10);	// prescaler 1024
//    //TCNT1 = 1;			        // initialize counter
//    //TIMSK1 |= (1 << TOIE1);	    // enable overflow interrupt 
//}

void init_I2C()
{
    TWSR |= (1<<TWPS0);  // prescaler set to 4
    TWBR = 198;          // 16e6 / (16+2*198*4) = 10 kBit/s
    TWCR |= (1<<TWEN);   // enable I2C
}

ISR(TIMER0_OVF_vect)
{
    if(lcdx==16) {
        PORTC &= 0xBF;
        PORTA = lcdcmd[lcdy];
		PORTC |= 0x10;
        lcdx = 0;
        lcdy = 0x01 & (lcdy+1);
    }
    else {
        PORTC |= 0x40;
        PORTA = LCDline[lcdy][lcdx];
		PORTC |= 0x10;
        lcdx++;
    }
    PORTC &= 0xEF;
}

ISR(INT7_vect)
{
	onesec = 1;
}

//ISR(TIMER1_OVF_vect)
//{
//	PORTE &= 0xFD;
//    TIMSK1 &= ~(1 << TOIE1);
//}