#define F_CPU 8000000		// CPU frequency = 8MHz
#include <avr/io.h>
#include <util/delay.h>

#define RS 2				// RS = PD2
#define E  3				// E  = PD3

static void lcd_write(int data) {
	PORTD &= 0x0F;			// clear old data
	PORTD |= (data & 0xF0);	// set new data
	_delay_us(100);
	PORTD |= (1 << E);		// E = 1
	_delay_us(1700);
	PORTD &= ~(1 << E);		// E = 0
}

void lcd_command(unsigned char comm) {
	PORTD &= ~(1 << RS);	// RS = 0
	lcd_write(comm);
	lcd_write(comm << 4);
}

void lcd_putc(unsigned char data) {
	PORTD |= (1 << RS);		// RS = 1
	lcd_write(data);
	lcd_write(data << 4);
}

void lcd_init(void) {
	PORTD &= 0x03;
	DDRD |= 0xfc;
	_delay_ms(100);

	// This places the LCD in 4-bit mode.
	lcd_write(0x30); _delay_ms(5);
	lcd_write(0x30); _delay_ms(1);
	lcd_write(0x30); _delay_us(100);
	lcd_write(0x20); _delay_us(100);

	// Now the LCD is in 4-bit mode.
	lcd_command(0x2C); // N & F
	lcd_command(0x08); // display off
	lcd_command(0x01); // display clear
	lcd_command(0x06); // inc mode, no shift
	lcd_command(0x0C); // display on
	lcd_command(0x02); // home
}

void lcd_puts(const char *str) {
	while (*str)
		lcd_putc(*str++);
}

void lcd_goto(unsigned char pos) {
	lcd_command(pos | 0x80);
}

int main(void) {
	lcd_init();

	lcd_puts("TOHA POBEGAILO");
	lcd_goto(0x40);
	lcd_puts("ZACHET");

	return 0;
}