#include <Keypad.h>
#include <FastLED.h>

const byte ROWS = 4;
const byte COLS = 10;

char hexaKeys[ROWS][COLS] = {
  {'K','L','M','N','O','P','R','S','T','U'},
  {'A','B','C','D','E','F','G','H','I','J'},
  {'k','l','m','n','o','p','r','s','t','u'},
  {'a','b','c','d','e','f','g','h','i','j'}
};
byte rowPins[ROWS] = {A0, A1, A2, A3};
byte colPins[COLS] = {2, 3, 4, 5, 6, 7, 8, 9, 10, 11};

Keypad klawiatura = Keypad(makeKeymap(hexaKeys), rowPins, colPins, ROWS, COLS);

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

void loop(){
  char klawisz = klawiatura.getKey();
  
  if (klawisz){
    Serial.println(klawisz);
  }
}