版本1： clock_pro: process(clk) is
begin
if clk='0' then
clk<='1' after 10ns, '0' after 20ns;
end if;
end process clock_pro;
版本2： clock_pro: process is
begin
clk='1' after 10ns, '0' after 20ns;
wait until clk='0';
end process clock_pro;
版本3：clock_pro: process is
begin
clk='1' after 10ns, '0' after 20ns;
wait for clk='0';
end process clock_pro;
发表评论 评论 (0 个评论)