用vhdl语言描述时钟的功能，并通过七段译码显示输出。-VHDL language used to describe the function of the clock and through the Seven-Segment display decoder output.

七段LED数码显示器是数字系统中常用的数码显示元件，二进制数不能直接在LED数码管上显示，需要用一个BCD七段译码器进行译码。下图给出了一个七段显示译码器的框图及相应的七段LED数码管的示意图。-Seven-segment LED digital display is commonly used in digital systems digital display devices, a binary number can not be directly displayed on the LED