51单片机的入门程序，通过中断口读取按键状态实现按一次按键灯亮，再按一次灯灭的功能，看似简单，其实想做好也不容易。-51 Introduction to SCM process, I read through the interruption of the status of the achievement of key lights by a button, and then eliminate the function of a lamp, which seems to be simple, in fact, would like to do a good job is not easy.