51单片机数码管编程，使用一个双字数码管和三个按键，三个按键分别表示开始，暂停和停止功能：按下开始按键后，数码管开始计时；按下暂停按键后，数码管暂停计时，如果再次按下开始按键，数码管继续计时；按下停止按键，计时停止，数码管上的数字清零。-51 single-chip digital control, using a double word digital tube and three buttons, three buttons that start, pause and stop function: press the start button, the digital tube starts timing　press the pause button, the digital tube pause time , If you press the start button again, the digital tube continues to count　press the stop button, stop the clock, digital control on the number cleared.