#define F_CPU 8000000UL
#define SCL_CLOCK 100000L
#define time 100L

#include <avr/io.h>
#include <compat/twi.h>
#include <util/delay.h>

//Protutypes of TWI functions
void TWI_init ();
bool TWI_start (unsigned char address);
void TWI_start_wait (unsigned char address);
char TWI_rep_start (unsigned char address);
void TWI_stop ();
bool TWI_write (unsigned char data);
char TWI_readACK ();
char TWI_readNAK ();

//Prototupe of LCD functions
void LCD_send_command (uint8_t data);
void LCD_send_data (uint8_t data);
void LCD_init ();

int main(void){
    PORTD = 0xFF;
    DDRD = 0xFF;
    
    TWI_init();
    //Если не сможем подключиться к микросхеме, мигаем.
    if (TWI_start(0x4E)){
  while (true){
   PORTD = 0x00;
   _delay_ms(250);
   PORTD = 0xFF;
   _delay_ms(250);
  }
    }
    
    //Если не может записать байт, мигаем быстро быстро.
    if (TWI_write(0xFF)){
  while (true){
   PORTD = 0x00;
   _delay_ms(10);
   PORTD = 0xFF;
   _delay_ms(10);
  }
    }
    /*
    LCD_init();
    LCD_send_data('H');
    LCD_send_data('e');
    LCD_send_data('l');
    LCD_send_data('l');
    LCD_send_data('o');
    LCD_send_data(' ');
    LCD_send_data('W');
    LCD_send_data('O');
    LCD_send_data('R');
    LCD_send_data('L');
    LCD_send_data('D');
    */
    
    while (true){
  
    }
}

// TWI_atmega8
void TWI_init(){
    TWSR = 0x00;
    TWBR = ((F_CPU / SCL_CLOCK) - 16) / 2;
}

bool TWI_start (unsigned char address){
    uint8_t twst;
    
    TWCR |= (1 << TWINT) | (1 << TWSTA) | (1 << TWEN);
    while (!(TWCR & (1 << TWINT)));
    
    twst = (TW_STATUS & 0xF8);
    if ((twst != TW_START) && (twst != TW_REP_START))
    return 1;

    TWDR = address;
    TWCR |= (1 << TWINT) | (1 << TWEN);
    while (!(TWCR & (1 << TWINT)));
    
    twst = (TW_STATUS & 0xF8);
    if ((twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK)){
  return true;
    } else {
  return false;
    }
}

void TWI_start_wait(unsigned char address){
    uint8_t   twst;
    while (true){
  // send START condition
  TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
  // wait until transmission completed
  while(!(TWCR & (1<<TWINT)));
  // check value of TWI Status Register. Mask prescaler bits.
  twst = TW_STATUS & 0xF8;
  if ( (twst != TW_START) && (twst != TW_REP_START)) continue;
  // send device address
  TWDR = address;
  TWCR = (1<<TWINT) | (1<<TWEN);
  // wail until transmission completed
  while(!(TWCR & (1<<TWINT)));
  // check value of TWI Status Register. Mask prescaler bits.
  twst = TW_STATUS & 0xF8;
  if ((twst == TW_MT_SLA_NACK )||(twst ==TW_MR_DATA_NACK)){
   /* device busy, send stop condition to terminate write operation */
   TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
   // wait until stop condition is executed and bus released
   while(TWCR & (1<<TWSTO));
   continue;
  }
  //if( twst != TW_MT_SLA_ACK) return 1;
  break;
    }
}

char TWI_rep_start(unsigned char address){
    return TWI_start(address);
}

bool TWI_write (unsigned char data){
    uint8_t twst;
    TWDR = data;
    TWCR |= (1 << TWINT) | (1 << TWEN);
    while (!(TWCR & (1 << TWINT)));
    
    twst = TW_STATUS & 0xF8;
    if (twst != TW_MT_DATA_ACK){
  return 1;
    } else {
  return 0;
    }
}

void TWI_stop (){
    TWCR |= (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);
    while (TWCR & (1 << TWSTO));
}