原创 十进制计数器

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_ARITH.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;
--*************************
ENTITY counter10 is
           PORT(
                  CP:IN Std_Logic;
                  Qout: OUT STD_LOGIC_VECTOR( 3 DOWNTO 0)
               );
END counter10;
--***************************
ARCHITECTURE demux4_behave OF counter10 IS
SIGNAL RST:STD_LOGIC;
SIGNAL QN:STD_LOGIC_VECTOR(3 DOWNTO 0);
BEGIN
     proceSS(CP,RST)
     BEGIN
             IF RST='1'THEN
                  QN<="0000";
             ELSIF CP'EVENT AND CP='1'THEN
                  QN<=QN+1;
             END IF;
    END PROCESS;
    RST<='1'WHEN QN="10" ELSE
         '0';
    Qout<=QN;
END  demux4_behave;