#include <Keypad.h>
const uint8_t ROWS = 4;
const uint8_t COLS = 4;
char keys[ROWS][COLS] = {
{'1','2','3','A'},
{'4','5','6','B'},
{'7','8','9','C'},
{'*','0','#','D'}
};
uint8_t colPins[COLS] = { 16, 4, 2, 15 };
uint8_t rowPins[ROWS] = { 19, 18, 5, 17 };
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins,ROWS,COLS);
void setup(){
Serial.begin(9600);
}
void loop(){
char key = keypad.getKey();
if (key){
Serial.print(key);
}
}