#include <LiquidCrystal.h>

// Pin definitions
#define ROW_PORT PORTF
#define COL_PIN PINK
#define ROW_DDR DDRF
#define COL_DDR DDRK

LiquidCrystal lcd(8, 9, 10, 11, 12, 13);  // Adjust LCD pins if needed

void init_program() {
    ROW_DDR = 0x0F;  // Rows as outputs (lower 4 bits)
    COL_DDR = 0x00;  // Columns as inputs (lower 4 bits)
    ROW_PORT = 0x0F; // Drive rows HIGH
}

void switch_in(uint8_t rowMask) {
    ROW_PORT = rowMask; // Activate only the specified row
    delay(5);           // Allow signals to stabilize
}

uint8_t switch_out() {
    return COL_PIN & 0x0F; // Read only the lower 4 bits (columns)
}

char get_key(uint8_t row, uint8_t col) {
    const char keys[4][4] = {
        {'1', '2', '3', 'A'},
        {'4', '5', '6', 'B'},
        {'7', '8', '9', 'C'},
        {'*', '0', '#', 'D'}
    };
    return keys[row][col];
}

void setup() {
    init_program();
    lcd.begin(16, 2);
    lcd.print("Press a key");
    Serial.begin(9600);
}

void loop() {
    for (int row = 0; row < 4; row++) {
        switch_in(1 << row);  // Activate one row at a time
        uint8_t colValue = switch_out();  // Read column values
        
        for (int col = 0; col < 4; col++) {
            if (colValue & (1 << col)) { // Check if column is active
                char key = get_key(row, col);
                lcd.clear();
                lcd.print("Key: ");
                lcd.print(key);
                Serial.println(key);
                delay(500); // Debounce delay
            }
        }
    }
}