count_10.vhd

多功能秒表的设计

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;
ENTITY count_10 IS
  PORT(clk,clr: IN STD_LOGIC;
       co:OUT STD_LOGIC;
       qout: OUT STD_LOGIC_VECTOR(3 DOWNTO 0));
END count_10;

ARCHITECTURE behave OF count_10 IS
    SIGNAL coun_10:STD_LOGIC_VECTOR(3 DOWNTO 0);
BEGIN
 PROCESS(clk,clr)
   BEGIN
     IF(clr='1') THEN 
            coun_10<=(OTHERS=>'0');
     ELSIF(clk'EVENT AND clk='1')THEN 
        co<='0';
        IF (coun_10=9) THEN 
              coun_10<="0000";
			  co<='1';
        ELSIF(coun_10<9) THEN
			coun_10<=coun_10+1;
		END IF;
     END IF;
  END PROCESS;
 qout<=coun_10;
END behave;