CNT2_18T

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;
ENTITY CNT2_18T IS
 PORT(CO2:IN STD_LOGIC;
      Q:OUT STD_LOGIC);
END CNT2_18T;
ARCHITECTURE bhv OF CNT2_18T IS 
 SIGNAL Q1:STD_LOGIC_VECTOR(0 TO 17);
 BEGIN 
 PROCESS(CO2)  BEGIN
   IF CO2'EVENT AND CO2='1' THEN
     IF Q1<249999 THEN Q1<=Q1+1; Q<='0';
      ELSif Q1=249999 then Q1<=(others=>'0'); Q<='1';
     END IF;  
   END IF;
  END PROCESS;
END bhv;