process(clk,en)begin
if rising_edge(clk) then
if en = '1' then
count <= "0000000";
elsif count < "1111111" then
count <= count + '1';
else
count <= count;
end if;
end if;end process;当按下按键时,产生EN脉冲,计数器清0,EN无效时,计计数xf数器计数,从0--127共计128个数,当计到127时,保持计数值不变,直到使用按...