采用vhdl硬件描述语言实现的秒表计时器程序源码及顶层电路设计图，实现了计时器，数码管显示，按键控制及蜂鸣器等功能-Using VHDL hardware descr iption language to realize the stopwatch timer program source code and top-level circuit design, the timer, digital tube display, control buttons and a buzzer functio