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Honored Contributor
Honored ContributorSignal not assigned in init state
Hello,
I am working on a simple state machine but for some reason the output value is not assigned correctly. First it is supposed to go into state init and assign default values to my 4x8bit internal signals (key_int), then should go to state assign to assign and combine the internal signals into 1x32bit output signal (key). And that is where it fails. When I run my test bench it always shows that key="00000000000000000000000000000000". Although key_int(0..3) are set to x"61" during the init phase. I already placed a counter in both states so I don't get a timing problem. I also replace the array with 4x std_logic_vector signals and assiged those during init with the same result. Surpringly: when I assign key directly in init it takes it. What am I doing wrong here? Btw I am using Quartus II 15.0.0. if that makes any difference.use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
use ieee.numeric_std.all;
entity buttonToKey is port(
clk_50 : in std_logic;
button : in std_logic_vector(5 downto 1);
key: out std_logic_vector(31 downto 0)
);
end buttonToKey;
architecture behavior of buttonToKey is
type state_type is ( init, evaluate, assign );
signal state : state_type := init;
type my_array_type is array (0 to 3) of std_logic_vector(7 downto 0);
signal key_int : my_array_type;
signal index : integer := 0;
signal count : unsigned( 18 downto 0 ) := ( others => '0' );
begin
process( clk_50 )
begin
if rising_edge( clk_50 ) then
if state = init AND count = 100 then -- init and assign default char
state <= assign;
key_int( 3 ) <= x"61"; -- ASCII 'a'
key_int( 2 ) <= x"61";
key_int( 1 ) <= x"61";
key_int( 0 ) <= x"61";
count <= ( others => '0' );
elsif state = evaluate then -- check which button is pressed
if button = "10000" then -- button 5: increment ASCII character
state <= assign;
count <= ( others => '0' );
if unsigned( key_int( index ) ) = x"7A" then -- run circular between ASCII char 'a' and 'z'
key_int( index ) <= x"61";
else
key_int( index ) <= key_int( index ) + 1;
end if;
elsif button = "00001" then -- button 1: move to next position (start with 1)
state <= evaluate;
if index = 3 then
index <= 0; -- overflow protection
else
index <= index + 1;
end if;
else
state <= evaluate;
end if;
elsif state = assign AND count = 100 then -- assign any changed keys to output
count <= ( others => '0' );
state <= evaluate;
key <= key_int( 3 ) & key_int( 2 ) & key_int( 1 ) & key_int( 0 );
else
count <= count + 1;
end if;
end if;
end process;
end behavior;
BEGIN
-- code that executes only once
button <= "00000";
wait for 80 ns;
button <= "00000";
wait for 80 ns;
button <= "00000";
wait for 80 ns;
button <= "00000";
wait for 80 ns;
WAIT;
END PROCESS init;
always : PROCESS
-- optional sensitivity list
-- ( )
-- variable declarations
BEGIN
-- code executes for every event on sensitivity list
WAIT;
END PROCESS always;
-- clock generation process
process
begin
clk_50 <= '1';
wait for 10 ns;
clk_50 <= '0';
wait for 10 ns;
end process;
END buttonToKey_arch;
