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

// Define pin connections
#define RS 1   // PC1
#define E  0   // PC0
#define D4 3   // PC3
#define D5 2   // PC2
#define D6 5   // PC5
#define D7 4   // PC4

// Function Prototypes
void LCD_Init(void);
void LCD_Command(unsigned char cmd);
void LCD_Data(unsigned char data);
void LCD_SetContrast(uint8_t contrast);
void LCD_EnablePulse(void);
void SendNibble(unsigned char nibble);

int main(void) {
	// Set RS, E, D4-D7 as outputs
	PORTC.DIR |= (1 << RS) | (1 << E) | (1 << D4) | (1 << D5) | (1 << D6) | (1 << D7);

	// Initialize the LCD
	LCD_Init();

	// Set contrast to a middle value (e.g., 32 out of 63)
	LCD_SetContrast(32);

	// Display a test message
	LCD_Command(0x80);       // Set cursor to the first position
	LCD_Data('H');
	LCD_Data('E');
	LCD_Data('L');
	LCD_Data('L');
	LCD_Data('O');

	while (1) {
		// Infinite loop (do nothing)
	}
}

void LCD_Init(void) {
	_delay_ms(20);  // Wait for LCD to power up

	// DOGM162 initialization sequence
	LCD_Command(0x39);  // Function Set: 8-bit, 2-line, instruction set 01
	LCD_Command(0x1C);  // Bias 1/4, 2-line display
	LCD_Command(0x52);  // Booster off, contrast C5 & C4
	LCD_Command(0x69);  // Follower Control
	LCD_Command(0x70);  // Contrast C3, C2, C1, & C0
	LCD_Command(0x0C);  // Display ON, Cursor OFF
	LCD_Command(0x38);  // Function Set: 8-bit, 2-line, instruction set 00
	LCD_Command(0x01);  // Clear Display
	_delay_ms(2);       // Clear display requires longer delay
	LCD_Command(0x06);  // Cursor AutoIncrement
	_delay_ms(2);
}

void LCD_SetContrast(uint8_t contrast) {
	uint8_t HC, LC;

	// Extract high and low contrast bits
	HC = (contrast & 0x30) >> 4;  // Contrast C5 & C4
	LC = (contrast & 0x0F);       // Contrast C3, C2, C1 & C0

	// Send commands to adjust contrast
	LCD_Command(0x39);          // Function Set: 8-bit, 2-line, instruction set 01
	LCD_Command(0x70 | LC);     // Set lower contrast bits (C3-C0)
	LCD_Command(0x50 | HC);     // Set higher contrast bits (C5-C4)
	LCD_Command(0x38);          // Function Set: 8-bit, 2-line, instruction set 00
}

void LCD_Command(unsigned char cmd) {
	PORTC.OUT &= ~(1 << RS);  // RS = 0 for command

	// Send upper nibble
	SendNibble(cmd >> 4);
	LCD_EnablePulse();

	// Send lower nibble
	SendNibble(cmd & 0x0F);
	LCD_EnablePulse();

	_delay_us(50);  // Short delay for command processing
}

void LCD_Data(unsigned char data) {
	PORTC.OUT |= (1 << RS);  // RS = 1 for data

	// Send upper nibble
	SendNibble(data >> 4);
	LCD_EnablePulse();

	// Send lower nibble
	SendNibble(data & 0x0F);
	LCD_EnablePulse();

	_delay_us(50);  // Short delay for data processing
}

void SendNibble(unsigned char nibble) {
	PORTC.OUT &= ~((1 << D4) | (1 << D5) | (1 << D6) | (1 << D7));  // Clear data pins
	if (nibble & 0x01) PORTC.OUT |= (1 << D4);  // Set D4
	if (nibble & 0x02) PORTC.OUT |= (1 << D5);  // Set D5
	if (nibble & 0x04) PORTC.OUT |= (1 << D6);  // Set D6
	if (nibble & 0x08) PORTC.OUT |= (1 << D7);  // Set D7
}

void LCD_EnablePulse(void) {
	PORTC.OUT |= (1 << E);    // Set E HIGH
	_delay_us(1);             // Pulse width
	PORTC.OUT &= ~(1 << E);   // Set E LOW
	_delay_us(100);           // Command processing delay
}