用2位数码管显示计时时间，最小计时单位为“百毫秒”，计时范围0.1-9.9s。

当第1次按下并松开计时功能键时，秒表开始计时并显示时间；第2次按下并松

开计时功能键时，停止计时，计算两次按下计时功能键的时间，并把时间值送

入数码管显示；第3次按下计时功能键，秒表清零，等待下一次按下计时功能

键。如果计时到9.9s时，将停止计时，按下计时功能键，秒表清零，再按下重

新开始计时。（哈工大单片机大作业内附proteus原理图）-Two digital tube display time of time, the minimum time unit of hundred milliseconds, the time range of 0.1-9.9s. 1st press and release timing function key, the stopwatch starts timing and display time　2nd press and release timing function keys, stop the clock, calculating the time of the timing function key is pressed twice, and The time value into the digital display　3rd timing function key is pressed, the stopwatch is cleared the timing function key is pressed, waiting for the next. Stop the clock if timed to 9.9s, the timing function key is pressed, the stopwatch is cleared, and then press the re-start timing. (HIT SCM operations included proteus diagram)