PWM

代码说明：

说明：  通过一个计数器来实现输出信号的占空比要求，可以将duty_cycle分配到拨码开关上,LED分配到发光二极管上,然后调节拨码开关,即可看到LED的亮度发生变化.(The duty cycle of the output signal can be assigned to the dial switch by a counter, and the LED can be assigned to the light emitting diode. Then the brightness of the LED can be seen by adjusting the dial switch.)