Build and simulate 4×1 mux, 8×1 mux, 1×4 demux and 1×8 demux in VHDL

4×1 8×1 multiplexer 1×4 demux and 1×8 demux

4×1 Multiplexer

Code:

library ieee;
use ieee.std_logic_1164.all;

entity mux41 is
port ( d : in std_logic_vector (0 to 3);
	   s : in std_logic_vector (0 to 1);
       o : out std_logic);
end mux41;

architecture vdc of mux41 is
begin
process (d,s)
begin
	case s is
		when “00” => o<= d(0);
		when “01” => o<= d(1);
		when “10” => o<= d(2);
		when “11” => o<= d(3);
	end case;
end process;
end vdc;

Simulation Waveform:

8×1 Multiplexer

Code:

library ieee;
use ieee.std_logic_1164.all;

entity mux81 is
port ( d : in std_logic_vector (0 to 7);
	   s : in std_logic_vector (0 to 2);
       o : out std_logic);
end mux81;

architecture mux_archi of mux81 is
begin
process (d,s)
begin
	case s is
		when “000” => o<= d(0);
		when “001” => o<= d(1);
		when “010” => o<= d(2);
		when “011” => o<= d(3);
        when “100” => o<= d(4);
		when “101” => o<= d(5);
		when “110” => o<= d(6);
		when “111” => o<= d(7);
        when others => o<= ‘0’;
	end case;
end process;
end mux_archi;

Simulation Waveform:

1×4 Demultiplexer

Code:

library ieee;
use ieee.std_logic_1164.all;

entity demux14 is
port ( i : in std_logic;
	   s : in std_logic_vector (0 to 1);
       o : out std_logic_vector (0 to 3));
end demux14;

architecture demux_archi of demux14 is
begin
process (i,s)
begin
	case s is
		when "00" => o(0)<= i;
		when "01" => o(1)<= i;
		when "10" => o(2)<= i;
		when "11" => o(3)<= i;
        when others => o<= "0000";
	end case;
end process;
end demux_archi;

Simulation Waveform:

1×8 Demultiplexer

Code:

library ieee;
use ieee.std_logic_1164.all;

entity demux18 is
port ( i : in std_logic;
	   s : in std_logic_vector (0 to 2);
       o : out std_logic_vector (0 to 7));
end demux18;

architecture demux_archi of demux18 is
begin
  process (i,s)
begin
     o <= "00000000";
	case s is
		when "000" => o(0)<= i;
		when "001" => o(1)<= i;
		when "010" => o(2)<= i;
		when "011" => o(3)<= i;
when "100" => o(4)<= i;
		when "101" => o(5)<= i;
		when "110" => o(6)<= i;
		when "111" => o(7)<= i;
        when others => o<= "00000000";
	end case;
end process;
end demux_archi;

Simulation Waveform:

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