#define F_CPU 16000000UL // Define the CPU frequency as 16 MHz
#include <avr/io.h>
#include <util/delay.h>

// Define LCD pins
#define LCD_E      PIN0_bm // Enable (PC0)
#define LCD_RS     PIN1_bm // Register Select (PC1)
#define LCD_D4     PIN3_bm // Data Bit 4 (PC3)
#define LCD_D5     PIN2_bm // Data Bit 5 (PC2)
#define LCD_D6     PIN5_bm // Data Bit 6 (PC5)
#define LCD_D7     PIN4_bm // Data Bit 7 (PC4)

// Helper macros
#define LCD_E_HIGH() (PORTC.OUTSET = LCD_E)
#define LCD_E_LOW()  (PORTC.OUTCLR = LCD_E)
#define LCD_RS_HIGH() (PORTC.OUTSET = LCD_RS)
#define LCD_RS_LOW()  (PORTC.OUTCLR = LCD_RS)

// Function Prototypes
void lcd_send_nibble(uint8_t nibble);
void lcd_send_byte(uint8_t data, uint8_t is_command);
void lcd_init();
void lcd_print(const char *str);

// Send a nibble (4 bits) to the LCD
void lcd_send_nibble(uint8_t nibble) {
	PORTC.OUTCLR = LCD_D4 | LCD_D5 | LCD_D6 | LCD_D7; // Clear D4-D7
	if (nibble & 0x01) PORTC.OUTSET = LCD_D4;
	if (nibble & 0x02) PORTC.OUTSET = LCD_D5;
	if (nibble & 0x04) PORTC.OUTSET = LCD_D6;
	if (nibble & 0x08) PORTC.OUTSET = LCD_D7;
	
	LCD_E_HIGH();
	_delay_us(1); // Pulse duration
	LCD_E_LOW();
	_delay_us(100); // Command latch time
}

// Send a byte (8 bits) to the LCD
void lcd_send_byte(uint8_t data, uint8_t is_command) {
	if (is_command) {
		LCD_RS_LOW(); // Command mode
		} else {
		LCD_RS_HIGH(); // Data mode
	}
	lcd_send_nibble(data >> 4); // Send high nibble
	lcd_send_nibble(data & 0x0F); // Send low nibble
	_delay_us(50); // Command execution time
}

// Initialize the LCD
void lcd_init() {
	// Set LCD pins as outputs
	PORTC.DIRSET = LCD_E | LCD_RS | LCD_D4 | LCD_D5 | LCD_D6 | LCD_D7;
	_delay_ms(40); // Wait for power-up
	
	// Force 4-bit mode initialization
	lcd_send_nibble(0x03);
	_delay_ms(5);
	lcd_send_nibble(0x03);
	_delay_us(200);
	lcd_send_nibble(0x03);
	_delay_us(200);
	lcd_send_nibble(0x02); // Set to 4-bit mode
	
	// Initialization sequence as per datasheet
	lcd_send_byte(0x39, 1); // Function Set: 4-bit, 2-line, instruction table 1
	lcd_send_byte(0x14, 1); // Bias Set: 1/5
	lcd_send_byte(0x55, 1); // Power Control: booster on, contrast C5, C4
	lcd_send_byte(0x6D, 1); // Follower Control: voltage follower and gain
	lcd_send_byte(0x74, 1); // Contrast Set: C3, C2, C1
	lcd_send_byte(0x38, 1); // Function Set: switch back to normal mode
	lcd_send_byte(0x0C, 1); // Display ON: Display ON, cursor OFF, blink OFF
	lcd_send_byte(0x01, 1); // Clear Display
	_delay_ms(2);           // Allow clear display to complete
	lcd_send_byte(0x06, 1); // Entry Mode Set: Increment cursor, no display shift
}

// Print a string to the LCD
void lcd_print(const char *str) {
	while (*str) {
		lcd_send_byte(*str++, 0); // Send characters in data mode
	}
}

int main() {
	lcd_init(); // Initialize the LCD
	
	while (1) {
		lcd_send_byte(0x01, 1); // Clear Display
		_delay_ms(2);
		lcd_print("EA DOGM162W-A"); // Display text
		_delay_ms(2000);
		
		lcd_send_byte(0x01, 1); // Clear Display
		_delay_ms(2);
		lcd_print("Hello, World!"); // Display text
		_delay_ms(2000);
	}
}