说明：   用定时器实现月、日、时、分和秒计时并通过按键控制在LED上分别显示。同时在超级终端上显示。可以通过小键盘设置时间，在数码管上显示。在计算机超级终端中可以对开发板上定时器的时钟进行设置。
(Using Timer month, day, hour, minutes and seconds time control by button LED display, respectively. At the same time show at the Super Terminal. Can set the time through the small keyboard, digital tube display. HyperTerminal on the computer on the development board can set the clock timer.)