Question

Design running LEDs with two selects - left-to-right or right-to-left. ( BASYS 3)

Specification

A switch selects the running direction

entity knight_rider is port (ck, sel: in std_logic;

z: out std_logic_vector(15 downto 0));

end knight_rider;

Answer 1

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;

entity knight_rider is
port (
   clk : in std_logic;
   sel : in std_logic;
   z : out std_logic_vector(15 downto 0)
);
end knight_rider;


architecture behave of knight_rider is
signal temp : std_logic_vector(15 downto 0);
begin

  process(clk)
  begin
   if (clk'event and clk = '1') then
   if (sel = '1') then
   temp <= temp(14 downto 0) & temp(15); -- right to left
   else
   temp <= temp(0) & temp(15 downto 1); -- left to right
   end if;
   end if;
  end process;

  z <= temp;

end behave;