Problem with Behav Sim vs Post Place & Route Sim

I have a real simple piece of code where I am setting a signal in the
test bench and generating an ack signal in the main code. I have coded
it using state machines since I plan to add to it once I figure out why
it won't work in Post Place & route. The code is shown below.

Thanks in advance for any help..

Joel

-- MAIN CODE
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

---- Uncomment the following library declaration if instantiating
---- any Xilinx primitives in this code.
--library UNISIM;
--use UNISIM.VComponents.all;

entity CDEout is
Port (
FPGA_CLK : in std_logic;
LRESET_n : in std_logic;
LHOLD : in std_logic;
LHOLDA : out std_logic
);
end CDEout;

architecture RTL of CDEout is

type State_Type is (S0,S1,S2);

signal Current_State : State_Type;
signal Next_State : State_Type;

signal CLK : std_logic;
signal RESET : std_logic;

signal set_holda : boolean;
signal rst_holda : boolean;


begin

CLK <= FPGA_CLK;
RESET <= not LRESET_n;

Sync: PROCESS( CLK, RESET)
begin

if (RESET = '1') then
current_state <= S0;
elsif (rising_edge(CLK)) then
current_state <= next_state;
end if;

end process;


PROCESS( CLK, RESET )
begin
if (RESET = '1') then
LHOLDA <= '0';
elsif (rising_edge(CLK)) then
if (set_holda) then
LHOLDA <= '1';
elsif (rst_holda) then
LHOLDA <= '0';
end if;
end if;
end process;


Comb: PROCESS(Current_State, LHOLD)
begin

set_holda <= FALSE;
rst_holda <= FALSE;

case Current_State is

when S0 =>
if (LHOLD = '1') then
set_holda <= TRUE;
next_state <= S1;
else
set_holda <= FALSE;
next_state <= S0;
end if;


when S1 =>

next_state <= S2;

when S2 =>

next_state <= S1;

end case;
end process;

end RTL;


-- TEST BENCH

LIBRARY ieee;
USE ieee.std_logic_1164.ALL;
USE ieee.std_logic_unsigned.all;
USE ieee.numeric_std.ALL;

ENTITY CDEout_tb_vhd IS
END CDEout_tb_vhd;

ARCHITECTURE behavior OF CDEout_tb_vhd IS

-- Component Declaration for the Unit Under Test (UUT)
COMPONENT cdeout
PORT(
FPGA_CLK : IN std_logic;
LRESET_n : IN std_logic;
LHOLD : IN std_logic;
LHOLDA : OUT std_logic
);
END COMPONENT;

--Inputs
SIGNAL FPGA_CLK : std_logic := '0';
SIGNAL LRESET_n : std_logic := '0';
SIGNAL LHOLD : std_logic := '0';

--Outputs
SIGNAL LHOLDA : std_logic;

signal RESET : std_logic := '1';

type State_Type is (S0,S1,S2,S3,S4);
signal Current_State, Next_State : State_Type;



BEGIN

-- Instantiate the Unit Under Test (UUT)
uut: cdeout PORT MAP(
FPGA_CLK => FPGA_CLK,
LRESET_n => LRESET_n,
LHOLD => LHOLD,
LHOLDA => LHOLDA
);

FPGA_CLK <= not FPGA_CLK after 30.303 ns;
RESET <= '0' after 303.03 ns;

-- process
-- begin
--
-- wait for 211 ns;
-- LHOLD <= '1';
--
-- wait;
--
-- end process;
--
Sync: PROCESS( FPGA_CLK, RESET)
begin

if (RESET = '1') then
current_state <= S0;
elsif (rising_edge(FPGA_CLK)) then
current_state <= next_state;
end if;

end process;

Comb: PROCESS(Current_State)
begin

case Current_State is

when S0 =>
LRESET_n <= '0';
next_state <= S1;

when S1 =>
LRESET_n <= '1';
next_state <= S2;

when S2 =>

LHOLD <= '1';
next_state <= S3;

when S3 =>
next_state <= S4;


when S4 =>

next_state <= S3;

end case;

end process;

END;

 

Some additional information:

LHOLDA should go active on the next rising clock edge after LHOLD is
set. This works fine in the Behav sim. In the Post P&R sim, LHOLDA
stays low all the time.

Joel

 

[Mike Treseler]

joel.weddick@lmco.com wrote:

LHOLDA should go active on the next rising clock edge after LHOLD is
set. This works fine in the Behav sim. In the Post P&R sim, LHOLDA
stays low all the time.

I think the problem is in your Post P&R testbench.
But a post route sim is unnecessary.

Your RTL code is inexplicable but I see no errors.
See a single process version of the same description below:

-- Mike Treseler

_____________________________

library IEEE;
use IEEE.STD_LOGIC_1164.all;
use ieee.numeric_std.all;

entity CDEout is
port (
CLK : in std_logic;
LRESET_n : in std_logic;
LHOLD : in std_logic;
LHOLDA : out std_logic -- alt des. int
);
end CDEout;

architecture RTL of CDEout is
begin
one : process(CLK, LRESET_n) is
subtype phase_t is natural range 0 to 3; -- two bits
variable phase_v : phase_t;
constant active_phase_c : phase_t := 1;
constant roll_phase_c : phase_t := 2;
variable lholda_v : std_logic;
begin
template : if (LRESET_n = '0') then
phase_v := 0;
lholda_v := '0';
elsif (rising_edge(CLK)) then
if phase_v = active_phase_c then
if lhold = '0' then
lholda_v := '0';
phase_v := 0;
else
lholda_v := '1';
end if;
end if;
if phase_v < roll_phase_c then
phase_v := phase_v + 1;
else
phase_v := 1; -- 0,1,2,1,2,...
end if;
end if template;
lholda <= lholda_v;
end process one;
end architecture RTL;


-- vsim cdeout_tb_vhd -do "add wave -r *; add wave
/cdeout_tb_vhd/uut/one/*;run 900;"