用分频器计数器实现7段数码管功能 --27MHZ分频成1hz:LIBRARYIEEE;USEIEEE.STD_LOGIC_1164.ALL;USEIEEE.STD_LOGIC_UNSIGNED.ALL;ENTITYFENPINISPORT(CLK_IN:INSTD_LOGIC;CLK_OUT:OUTSTD_LOGIC);ENDENT