#include "pico/stdlib.h"
#include <stdio.h>

#define ROWS 4
#define COLS 4

const uint8_t row_pins[ROWS]={8,7,6,5};
const uint8_t col_pins[COLS]={4,3,2,9};

const char key_map[ROWS][COLS] = {
    {'1','2','3','A'},
    {'4','5','6','B'},
    {'7','8','9','C'},
    {'*','0','#','D'}
};

void keypad_init();
char read_keypad();

int main(){
    stdio_init_all();
    keypad_init();

    while(true){
        char key = read_keypad();
        if (key != '\0'){
            printf("Tecla pressionada: %c\n", key);
            sleep_ms(200);
        }
        else{
            sleep_ms(200);
        }
    }
    return 0;
}

void keypad_init(){
    for (int i = 0; i<ROWS; i++){
        gpio_init(row_pins[i]);
        gpio_set_dir(row_pins[i], GPIO_OUT);
        gpio_put(row_pins[i],0);
    }
    for (int i = 0; i<COLS; i++){
        gpio_init(col_pins[i]);
        gpio_set_dir(col_pins[i], GPIO_IN);
        gpio_pull_down(col_pins[i]);
    }
}

char read_keypad(){
    for (int row = 0; row < ROWS; row++){
        gpio_put(row_pins[row], 1);
        for (int col = 0; col < COLS; col++){
            if (gpio_get(col_pins[col])){
                gpio_put(row_pins[row],0);
                return key_map[row][col];
            }
        }
        gpio_put(row_pins[row],0);
    }
    return '\0';
}