Question

Need help with VDHL code. THis is a random number generator. Want to be able so that a number is generated when a button is pushed, not when the clock is high.

library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

-- Uncomment the following library declaration if using

-- arithmetic functions with Signed or Unsigned values

--use IEEE.NUMERIC_STD.ALL;

-- Uncomment the following library declaration if instantiating

-- any Xilinx leaf cells in this code.

--library UNISIM;

--use UNISIM.VComponents.all;

library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

entity RanNum is

port (

clk : in std_logic;

random_num : out std_logic_vector (7 downto 0) --output vector   

);

end RanNum;

architecture Behavioral of RanNum is

begin

process(clk)

variable rand_temp : std_logic_vector(7 downto 0):=(7 => '1',others => '0');

variable temp : std_logic := '0';

begin

if(rising_edge(clk)) then

temp := rand_temp(7) xor rand_temp(6);

rand_temp(7 downto 1) := rand_temp(6 downto 0);

rand_temp(0) := temp;

end if;

random_num <= rand_temp;

end process;

end Behavioral;

Answer 1

use a variable button instead of CLK and when it is 1 generate a number

library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

-- Uncomment the following library declaration if using

-- arithmetic functions with Signed or Unsigned values

--use IEEE.NUMERIC_STD.ALL;

-- Uncomment the following library declaration if instantiating

-- any Xilinx leaf cells in this code.

--library UNISIM;

--use UNISIM.VComponents.all;

library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

entity RanNum is

port (

button : in std_logic;

random_num : out std_logic_vector (7 downto 0) --output vector   

);

end RanNum;

architecture Behavioral of RanNum is

begin

process(button)

variable rand_temp : std_logic_vector(7 downto 0):=(7 => '1',others => '0');

variable temp : std_logic := '0';

begin

if(button = '1') then

temp := rand_temp(7) xor rand_temp(6);

rand_temp(7 downto 1) := rand_temp(6 downto 0);

rand_temp(0) := temp;

end if;

random_num <= rand_temp;

end process;

end Behavioral;