在端口PD输出PWM脉冲,可用示波器测量,或者外加一LED灯，可以看到LED脉宽的变化-PD PWM pulse output port can be used oscilloscope or plus an LED light, you can see the LED pulse width changes

用单片机实现PWM,可以调级占空比,电压变化-MCU PWM can be adjusted to level duty cycle, the voltage change