通过矩阵按键实现1,2,3,4,5,6,7,当有按键按下时,led会亮起,说明按键有效,同时发出声音(The 1,2,3,4,5,6,7 is implemented by a matrix button, and when the button is pressed, the LED will light up, indicating that the key is valid and the sound is made.)