流水灯循环点亮功能，基于xlinx公式的basys2实验班-water led

51开发板中第3个程序循环流水灯，运行程序后会自动点亮所有小灯并闪烁(The 3rd program in the development board is circulating the running water lamp, which will automatically light all the small lights and blink when the program is running)