#include <avr/io.h>
#include <avr/pgmspace.h>
#define F_CPU 1000000UL
#include <util/delay.h>

#define LCD_RS 0	//MCU pin connected to LCD RS
#define LCD_RW 1	//MCU pin connected to LCD R/W
#define LCD_E 2		//MCU pin connected to LCD E
#define LCD_D4 4	//MCU pin connected to LCD D3
#define LCD_D5 5	//MCU pin connected to LCD D4
#define LCD_D6 6	//MCU pin connected to LCD D5
#define LCD_D7 7	//MCU pin connected to LCD D6
#define LDP PORTD	//MCU port connected to LCD data pins
#define LCP PORTD	//MCU port connected to LCD control pins
#define LDDR DDRD	//MCU direction register for port connected to LCD data pins
#define LCDR DDRD	//MCU direction register for port connected to LCD control pins
#define LCD_CLR 0	//DB0: clear display
#define LCD_HOME 1	//DB1: return to home position


char text[] PROGMEM = "Ahoj C\n"; //text, který bude udržován jen v pamiti FLASH


void LCD_send_char(unsigned char ch)
{
	//Sends Char to LCD
	LDP = (ch&0xf0);
	LCP |= 1<<LCD_RS;	//data
	LCP |= 1<<LCD_E;	//e1
	_delay_ms(1);
	LCP &= ~(1<<LCD_E);	//e0
	_delay_ms(1);
	LDP = ((ch&0x0f)<<4);
	LCP |= 1<<LCD_RS;
	LCP |= 1<<LCD_E;
	_delay_ms(1);
	LCP &= ~(1<<LCD_E);
	_delay_ms(1);
}

void LCD_send_command(unsigned char cmd)
{
	//Sends Command to LCD
	LDP = (cmd&0xf0);
	LCP &= ~(1<<LCD_RS);
	LCP |= 1<<LCD_E;    //e0
	_delay_ms(1);
	LCP &= ~(1<<LCD_E);    //e1
	_delay_ms(1);
	LDP = ((cmd&0x0f)<<4);
	LCP &= ~(1<<LCD_RS);
	LCP |= 1<<LCD_E;
	_delay_ms(1);
	LCP &= ~(1<<LCD_E);
	_delay_ms(1);
}

void LCD_init(void)
{
	//Inisilaisasi LCD
	_delay_ms(15);
	LDP = 0x00;
	LCP = 0x00;
	LDDR |= 1<<LCD_D7 | 1<<LCD_D6 | 1<<LCD_D5 | 1<<LCD_D4;
	LCDR |= 1<<LCD_E | 1<<LCD_RW | 1<<LCD_RS;
	LCD_send_command(0x28); //4-bit 2-line 4×8
	LCD_send_command(0x0c); //disply on, cursor off, bling off
	LCD_send_command(0x06); //shift inc, unsivible
}

void LCD_string(char* str)
{
	unsigned char x = 0;
	while(str[x] != 0)
	{
		_delay_ms(1);
		LCD_send_char(str[x++]);
	}
}

void LCD_flash_string(char str[])
{
	unsigned char x = 0;
	char znak = pgm_read_byte(&(str[x++]));
	while(znak != '\0')
	{
		_delay_ms(1);
		LCD_send_char(znak);
		znak = pgm_read_byte(&(str[x++]));
	}
}

void main (void)
{
	// ledka s odporem bude mezi PB1 a Vcc
	DDRB |= 1<<PB1;   // PB1 = vystup, na portu je po resetu "0", ledka tedy teď svítí 
	_delay_ms(1000);
	LCD_init();
	LCD_send_command(LCD_CLR);
	LCD_send_command(LCD_HOME);
	LCD_send_command(0x80+0);

	LCD_flash_string(text);

	for(;;);
}