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

#define LCD_RS (1 << PD0) 
#define LCD_EN (1 << PD1) 
#define LCD_D4 (1 << PD4) 
#define LCD_D5 (1 << PD5) 
#define LCD_D6 (1 << PD6) 
#define LCD_D7 (1 << PD7) 

#define VREF 5.0  

void LCD_command(unsigned char cmd) {
    PORTD = (PORTD & 0x0F) | (cmd & 0xF0); 
    PORTD &= ~LCD_RS;                      
    PORTD |= LCD_EN;                      
    _delay_us(1);                          
    PORTD &= ~LCD_EN;                     

    PORTD = (PORTD & 0x0F) | ((cmd << 4) & 0xF0); 
    PORTD |= LCD_EN;                               
    _delay_us(1);                                  
    PORTD &= ~LCD_EN;                             

    _delay_ms(2); 
}

void LCD_data(unsigned char data) {
    PORTD = (PORTD & 0x0F) | (data & 0xF0); 
    PORTD |= LCD_RS;                       
    PORTD |= LCD_EN;                       
    _delay_us(1);                          
    PORTD &= ~LCD_EN;                      

    PORTD = (PORTD & 0x0F) | ((data << 4) & 0xF0); 
    PORTD |= LCD_EN;                              
    _delay_us(1);                                  
    PORTD &= ~LCD_EN;                            

    _delay_ms(1); 
}

void LCD_init() {
   
    DDRD |= (LCD_RS | LCD_EN | LCD_D4 | LCD_D5 | LCD_D6 | LCD_D7);

   
    _delay_ms(15);
    LCD_command(0x02); 
    _delay_ms(1);
    LCD_command(0x28); 
    _delay_ms(1);
    LCD_command(0x0C); 
    _delay_ms(1);
    LCD_command(0x06); 
    _delay_ms(1);
    LCD_command(0x01); 
    _delay_ms(2);
}

void LCD_clear() {
    LCD_command(0x01); 
    _delay_ms(2);
}

void LCD_home() {
    LCD_command(0x02); 
    _delay_ms(2);
}

void LCD_gotoxy(unsigned char x, unsigned char y) {
    unsigned char row_offsets[] = {0x00, 0x40, 0x14, 0x54};
    LCD_command(0x80 | (x + row_offsets[y])); 
    _delay_ms(1);
}

void ADC_init() {
    
    ADMUX = (1 << REFS0);

   
    ADCSRA = (1 << ADEN) | (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0);
}

uint16_t ADC_read(uint8_t channel) {
   
    ADMUX = (ADMUX & 0xF8) | (channel & 0x07);

    
    ADCSRA |= (1 << ADSC);

    
    while (ADCSRA & (1 << ADSC));

   
    return ADC;
}

void LCD_display_voltaj(float voltaj) {
    LCD_clear();
    LCD_home();
    LCD_data('V');
    LCD_data('o');
    LCD_data('l');
    LCD_data('t');
    LCD_data('a');
    LCD_data('j');
    LCD_data(':');
    LCD_gotoxy(0, 1);
    int int_part = (int)voltaj;
    int decimal_part = (int)((voltaj - int_part) * 1000);
    LCD_data(int_part + '0');
    LCD_data('.');
    LCD_data((decimal_part / 100) + '0');
    LCD_data(((decimal_part / 10) % 10) + '0');
    LCD_data('V');
}

int main() {
  
    LCD_init();
    ADC_init();

    
    uint16_t adc_value;
    float voltaj;

    while (1) {
       
        adc_value = ADC_read(0);

      
        voltaj = (float)adc_value * VREF / 1023.0;

        
        LCD_display_voltaj(voltaj);

       
        _delay_ms(500);
    }

    return 0;
}