编写程序实现：开启内部看门狗，单片机的D口控制发光二极管循环右移位，实现流水功能，并及时喂狗。当按键SW2按下时，程序进入死循环，等待看门狗自复位。-Write a program to achieve: open internal watchdog, SCM D port control cyclic right shift of the light-emitting diode, pipelining feature, and feed the dog in a timely manner. When the button SW2 is pressed, the program enters an infinite loop, waiting for the watchdog since reset.