#include <Keypad.h>
const int rowno = 4;
const int colno = 4;
char keys[rowno][colno] = 
{{'1','2','3','A'},{'4','5','6','B'},{'7','8','9','C'}, {'*','0','#','D'}};
byte rowPin[rowno] = {9,8,7,6};
byte colPin[colon] = {5,4,3,2};
Keypad keypad = Keypad(makeKeymap(keys), rowPin, colPin, rowno, colno ); 
//实例化Keypad 对象
void setup(){
  Serial.begin(9600);
}



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


  }

}