forcing 1,0 internal signal

[Elinore]

Hi

In Xilinx XST document, I took 4bit counter example and modified it.

I am wondering this will work in read chip, while the simulation after
place and route, seems okay.



--4-bit unsigned up counter
--an asynchronous clear and a clock enable.
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity counter is
port(
C, CLR, CE : in std_logic;
Q : out std_logic_vector(3 downto 0)
);
end counter;

architecture archi of counter is
signal tmp: std_logic_vector(3 downto 0);
signal clear: std_logic; -- modified
signal enable: std_logic; -- modified
begin

clear <= CLR; -- modified
enable <= CE; -- modified

clear <= '0'; -- modified : ground connect?
enable <= '1'; -- modified : VCC connect ?

process (C, CLR)
begin
if (CLR='1') then
tmp <= "0000";
elsif (C'event and C='1') then
if (CE='1') then
tmp <= tmp + 1;
end if;
end if;
end process;
Q <= tmp;
end archi;

 

[Mike Treseler]

I am wondering this will work in read chip, while the simulation after
place and route, seems okay.

If you expect it to no never CLR and always CE
then yes. It might be easier to just edit the
code:

process (C)
begin
if rising_edge(C) then
tmp <= tmp + 1;
end if;
end process;


-- Mike Treseler