// see https://www.copyandpastesymbols.net/ for keytop characters

#include <Keypad.h>

const byte ROWS = 4;
const byte COLS = 12;

char keys[ROWS][COLS] = {
  {'1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '-', '='},
  {'Q', 'W', 'E', 'R', 'T', 'Y', 'U', 'I', 'O', 'P', '[', ']'},
  {'A', 'S', 'D', 'F', 'G', 'H', 'J', 'K', 'L', ';', '\'', 10 },   // 10 is a newline ASCII character
  {'Z', 'X', 'C', 'V', 'B', 'N', 'M', ' ', ' ', ',', '.' , '/' }
};


byte rowPins[ROWS] = {23, 25, 27, 29};
byte colPins[COLS] = {31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53};

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


void setup() {
  Serial.begin(9600);
}

void loop() {
  char key = keypad.getKey();
  
  if (key != NO_KEY) {
    Serial.print(key);
  }
  
}