所谓 Johnson 计数器， 其实说白了无非就是复杂一点的流水灯实验。 流水灯加上了按键控制，流水灯的开启关闭和变化方向在按键的控制下进行。本实例是带停止控制的双向4bit Johnson 计数器，可以通过 LED 灯直观的在学习板上进行演示。-The so-called Johnson counters, in fact, plainly nothing more than a little water lamp complex experiments. Water lights add a