Hello all. I've been coding a Johnson Counter like the following:
entity johnson is
generic (n : natural := 4);
port (clk, enable : in std_logic;
count : out std_logic_vector (n-1 downto 0));
architecture behavioural of johnson is
signal reg_john, nxt_john : std_logic_vector (n-1 downto 0);
if (clk'event and clk='1') then
if (enable='1') then
nxt_john<=reg_john (n-2 downto 0) & not reg_john (n-1);
The synthetization was OK. The thing is when I tried to simulate the
code, all the outputs from the count were having the letter 'U'.
Please, take a look at the attached screenshot.
Note that "habilitacion" = "enable" and "cuenta" = "count".
What are those 'U's? How can I fix the simulation in order to work?
Thanks a lot.