Sketch para mapear teclado numerico a letras

LCD_Keypad.ino

#include <Keypad.h>
#include <LiquidCrystal.h>

const int ROWS = 4;
const int COLS = 3;

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

byte colPins[COLS] = {32, 31, 30};
byte rowPins[ROWS] = {33, 34, 35, 36};

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);


const int rs = 8, en = 9, d4 = 4, d5 = 5, d6 = 6, d7 = 7;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);


void setup() {  
  Serial.begin(9600);
  lcd.begin(16, 2);
}
   
void loop() {  
  char key = keypad.getKey();
   
  lcd_print_if(key, '1', "Uno");
  lcd_print_if(key, '2', "Dos");
  lcd_print_if(key, '3', "Tres");
  lcd_print_if(key, '4', "Cuatro");
  lcd_print_if(key, '5', "Cinco");
  lcd_print_if(key, '6', "Seis");
  lcd_print_if(key, '7', "Siete");
  lcd_print_if(key, '8', "Ocho");
  lcd_print_if(key, '9', "Nueve");
  lcd_print_if(key, '0', "Cero");
  lcd_print_if(key, '*', "Asterisco");
  lcd_print_if(key, '#', "Numeral");

  lcd.setCursor(0, 1);
  lcd.print(millis() / 1000);
}

void lcd_print_if(char key, char expected, char* message) {
  if (key == expected) {
    lcd.clear();
    lcd.setCursor(0,0);
    lcd.print(message);
  }  
}