4位二进制记数器cnt4e.vhd源程序:
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY cnt4e IS
PORT(clk,ena:IN STD_LOGIC;
cout:OUT STD_LOGIC;
q:BUFFER INTEGER RANGE 0 TO 15);
END cnt4e;
ARCHITECTURE one OF cnt4e IS
BEGIN
PROCESS(clk,ena)
BEGIN
IF clk 'EVENT AND clk='1' THEN
IF ena='1' THEN
IF q=15 THEN q<=0;
cout<='0';
ELSIF q=14 THEN q<=q+1;
cout<='1';
ELSE q<=q+1;
END IF;
END IF;
END IF;
END PROCESS;
END one;
七段显示译码器Dec7s.vhd源程序:
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY Dec7s IS
PORT(a:IN BIT_VECTOR(3 DOWNTO 0);
led7s:OUT BIT_VECTOR(7 DOWNTO 0));
END;
ARCHITECTURE one OF Dec7s IS
BEGIN
PROCESS(A)
BEGIN
CASE A(3 DOWNTO 0)IS
WHEN"0000"=>LED7S<="00111111";
WHEN"0001"=>LED7S<="00000110";
WHEN"0010"=>LED7S<="01011011";
WHEN"0011"=>LED7S<="01001111";
WHEN"0100"=>LED7S<="01100110";
WHEN"0101"=>LED7S<="01101101";
WHEN"0110"=>LED7S<="01111101";
WHEN"0111"=>LED7S<="00000111";
WHEN"1000"=>LED7S<="01111111";
WHEN"1001"=>LED7S<="01101111";
WHEN"1010"=>LED7S<="01110111";
WHEN"1011"=>LED7S<="01111100";
WHEN"1100"=>LED7S<="00111001";
WHEN"1101"=>LED7S<="01011110";
WHEN"1110"=>LED7S<="01111001";
WHEN"1111"=>LED7S<="01110001";
WHEN OTHERS=>NULL;
END CASE;
END PROCESS;
END one;
原理图:
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