说明：  51单片机LED流星雨灯，原理： 利用PWM来模似流星雨：将亮度等级分为8个 ，通过改变每一组LED的亮度来达到流星雨效果。因为流星雨是前面亮后面越来越暗，就像一条龙一样，拖着尾巴过来。
(51 single LED meteor light, principle: the use PWM to die like a meteor shower: The brightness level is divided into eight, each group by changing the brightness of the LED to achieve the effect of the meteor shower. Because meteor shower is getting back in front of bright dark, like one-stop, like dragging tail over.)