模可变计数器vhdl设计

【文件属性】：
文件名称：模可变计数器vhdl设计
文件大小：1KB
文件格式：TXT
更新时间：2011-12-28 02:58:12
vhdl设计 library ieee; use ieee.std_logic_1164.all; use ieee.std_logic_unsigned.all; entity mod2 is port(clk,rst,m,en:in std_logic; cq1:out std_logic_vector(3 downto 0); cq2:out std_logic_vector(3 downto 0)); end mod2; architecture behav of mod2 is signal cql:std_logic_vector(3 downto 0); signal cqh:std_logic_vector(3 downto 0); begin cq2<=cqh; cq1<=cql; process(rst,clk,m) begin if rst='1' then cql<="0000";cqh<="0000"; elsif clk'event and clk='1' then if en='1' then case m is when '0' =>if cql=9 then cql<="0000";cqh<=cqh+1; else cql<=cql+1; end if; if cqh=2 and cql=2 then cqh<="0000";cql<="0000"; end if; if cqh>1 and cql>2 then cqh<="0000";cql<="0000"; end if; when '1' =>if cql=9 then cql<="0000";cqh<=cqh+1; else cql<=cql+1; end if; if cqh=6 and cql=6 then cqh<="0000";cql<="0000"; end if; end case; end if; end if; end process; end behav;