采用12MHZ时钟频率的单片机，通过一个开关输入，触发定时计数。 按下开关10次，计算按键的平均时间，并通过数码管显示出来。 -12MHZ clock frequency of microcontroller used by a switch input, Trigger Timing counts. Press the switch 10 times, calculate the average time keys, and through digital tube display.