利用定时器，在P2_5上输出PWM波。为了演示，使占空比从1％~99％再从99％~1％连续变化。频 率约为200Hz。可以用于用于直流电机的驱动等方面-Use of timers in the PWM wave output P2_5. For demonstration, so that the duty cycle from 1 ~ 99 ~ 99 from 1 for the changes. Frequency of about 200Hz. Can be used for DC m