定时、计数、显示

设计一系统，系统要求：

1、有一发光二极管闪烁，闪烁周期为2S，有一按键S1对其进行控制（按一次开，再按一次停）

2、对一脉冲源进行计数，所记录的脉冲个数以十进制形式在数码管显示（最大225），有一按键S2对其进行控制（按一次开，再按一次停）。

S1不开是，发光二极管灭；S2不开时数码管显示自己的学号。

-Timing, counting, display

System design, system requirements:

1, a light-emitting diode flashing, blinking cycle 2S, there is a button S1 to control it (click once to open, and then the first stop)

2, a pulsed source counts, the number of pulses recorded in decimal form in the digital tube display (maximum 225), a key S2 to control it (click once to open, and then a pause).

S1 does not open, light-emitting diodes off　S2 not open digital display their student ID number.