cnt10.txt

vhdl 十进制加法计数器设计 已经调试成功

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity cnt10 is
 port(clk,rst,en:in std_logic;
       cq:out std_logic_vector(3 downto 0);
       cout:out std_logic);
end entity cnt10;
architecture behav of cnt10 is
begin
 process(clk,rst,en)
 variable cqi: std_logic_vector(3 downto 0); 
begin
if rst='1' then  cqi:= (others=>'0');
elsif clk'event and clk='1' then
if en='1' then
if cqi<9 then cqi:=cqi+1; cout<='0';
else cqi:=(others=>'0');  cout<='1';
end if;
end if;
end if;
cq<=cqi;
end process;
end architecture behav;