以51系列单片机(AT89C51)为核心，配以相应硬件电路，实现时间的设置、存贮、识别和显示，完成定时器的功能。单片机接收键入的代码，并与在LED数码管上显示出来。当单片机上电时，LED显示0，此时是功能选择部分，选择1代表正定时，2代表倒定时，操作员可按键K8进行选择。选择完后按下K7键确定，接下来输入所要设定的时间，输入完毕再按下K7确认键，系统就开始进行定时了。-51 Series single-chip microcomputer (AT89C51) as the core, with the appropriate hardware circuits to achieve the set time, storage, identification, and show that the completion of the timer function. Single-chip type to receive the code, and on the LED digital tube display. When the single-chip microcomputer at power, LED display 0, at this time is a function of choice of the representatives are from time to time select 1, 2 on behalf of down time, the operator can choose K8 button. K7 options after pressing the button OK, the next to enter the set time, the importation of finished and then press the confirm key K7, the system on a regular basis to begin.