先产生一个周期和PWM波相同的周期信号，然后给定一个值，如果这个周期信号大于给定值则输出低电平，否则输出高电平所以，通过控制给定值的大小就可以控制Pwm的占空比了-First generating a cycle and the same cycle of the PWM wave signal, and then given a value, the output is low if this periodic signal is greater than a given value, otherwise it outputs a high level so can be controlled by the size of the control setpoint Pwm duty cycle