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

//******************************16x02 LCD*********************************
/*
RS  ->  PD2
E   ->  PD3
D4-D7-> PD4-PD7
*/
#define RS 2
//#define RW 1
#define E 3
#define DDR_port DDRD
#define data_pins PORTD
#define control_pins PORTD


void lcd_cmd(unsigned char c);
void lcd_data(unsigned char d);
void lcd_string(unsigned char *s);
void lcd_setcursor(uint8_t row, uint8_t col);
void lcd_init();

void lcd_cmd(unsigned char c){
	data_pins = (c&0xF0);   //upper nibble 
	control_pins &=~(1<<RS); //RS =0
	//control_pins &=~(1<<RW); // RW = 0
	control_pins |=(1<<E);   // E = 1
	_delay_ms(1);
	control_pins &=~(1<<E);  //E = 0
	
	data_pins = ((c<<4)&0xF0);   //lower nibble 
	control_pins &=~(1<<RS); //RS =0
	//control_pins &=~(1<<RW); // RW = 0
	control_pins |=(1<<E);   // E = 1
	_delay_ms(1);
	control_pins &=~(1<<E);  //E = 0
}

void lcd_data(unsigned char d){
	data_pins = (d&0xF0);   //upper nibble 
	control_pins |=(1<<RS); //RS =1
	//control_pins &=~(1<<RW); // RW = 0
	control_pins |=(1<<E);   // E = 1
	_delay_ms(1);
	control_pins &=~(1<<E);  //E = 0
	
	data_pins = ((d<<4)&0xF0);   //lower nibble
	control_pins |=(1<<RS); //RS =1
	//control_pins &=~(1<<RW); // RW = 0
	control_pins |=(1<<E);   // E = 1
	_delay_ms(1);
	control_pins &=~(1<<E);  //E = 0
}

void lcd_string(unsigned char *s){
	while(*s!=0){
		lcd_data(*s);
		s++;
	}
}

void lcd_setcursor(uint8_t row, uint8_t col) {
    if (row == 0) {
        lcd_cmd(0x80 + col);
    } else if (row == 1) {
        lcd_cmd(0xC0 + col);
    }
}

void lcd_init(){
	
	DDR_port = 0xFC; //set Port D as output b1111 1100
	
	lcd_cmd(0x33);
	lcd_cmd(0x32);
	lcd_cmd(0x28);
	lcd_cmd(0x06);
	lcd_cmd(0x0C);
	lcd_cmd(0x01);
}

//******************************Keypad******************************
/*
Rows connected to PC0 to PC3
Columns connected to PB0 to PB3
*/
// Keypad key map
const char keypad_keys[4][4] = {
    {'1', '2', '3', '+'},
    {'4', '5', '6', '-'},
    {'7', '8', '9', '*'},
    {'.', '0', '=', '/'}
};

void keypad_init(void) {
    // Set rows as input (PC0-PC3),
    DDRC &= 0xF0;

    // Set columns as output (PB0-PB3)
    DDRB |= 0x0F;
}

char keypad_scan(void) {
  char key = 0;
  for (uint8_t col = 0; col < 4; col++) {
    //Set each col high
    PORTB = (PORTB & 0xF0)|(1<<col);
    
    for (uint8_t row = 0; row < 4; row++) {
      // Check if the key is pressed (row  is high)
      if (PINC & (1 << row)) {
        // Simple mapping, return character based on position
        //return "123+456-789*.0=/"[row * 4 + col];
        //return keypad_keys[row][col];
        key = keypad_keys[row][col];
        break;
      }
    }
  }
  //return 0; // No key pressed
  return key;
}


//******************************main******************************

int main(void) {
    // Initialize LCD and Keypad
    lcd_init();
    keypad_init();

    char key = 0;

    // Display welcome message
    lcd_string("Welcome!");
    _delay_ms(1000);
    lcd_cmd(0x01);  // Clear display

    while (1) {
      key = keypad_scan(); // Scan for keypress
      lcd_cmd(0x01);  // Clear display

      if (key != 0) {
        lcd_setcursor(0,0);
        lcd_string("Key: ");
        lcd_data(key);  // Display key on LCD
      }
      _delay_ms(100);
      //for (volatile int i = 0; i < 100000; i++);  // Debounce delay
    }

    return 0;
}