4x4 Matrix无法与Arduino一起使用

Question

我买了一个新的4x4键盘矩阵，它无法使用。我像我应该连接它并使用示例代码，但它无法正常工作。我可以用万用表测量液滴但是Arduino Serial没有显示任何东西。

#include <Keypad.h>

const byte numRows= 4; //number of rows on the keypad
const byte numCols= 4; //number of columns on the keypad

//keymap defines the key pressed according to the row and columns just as
//appears on the keypad
char keymap[numRows][numCols]=
{
{'1', '2', '3', 'A'},
{'4', '5', '6', 'B'},
{'7', '8', '9', 'C'},
{'*', '0', '#', 'D'}
};

//Code that shows the the keypad connections to the arduino terminals
byte rowPins[numRows] = {5,4,3,2}; //Rows 0 to 3
byte colPins[numCols]= {6,7,8,9}; //Columns 0 to 3

//initializes an instance of the Keypad class
Keypad myKeypad= Keypad(makeKeymap(keymap), rowPins, colPins, numRows,
numCols);

void setup()
{
Serial.begin(9600);
Serial.print("Started at 9600");
}

//If key is pressed, this key is stored in 'keypressed' variable
//If key is not equal to 'NO_KEY', then this key is printed out
//if count=17, then count is reset back to 0 (this means no key is
  pressed during the whole keypad scan process
void loop()
{
char keypressed = myKeypad.getKey();
if (keypressed != NO_KEY)
{
Serial.print(keypressed);
}
}