Post-Place & Route Simulation with ISE

[arkaitz]

Hi all,

I am trying to make a post-place & route simulation of a very simple
design.

In the "top.vhd "file there is declared an entity that contains some
generics and the architecture.

entity top is
generic(
gen1 : real := 3.0;
gen2 : std_logic;
gen3 : std_logic
);
port(
clk : in std_logic;
rst : in std_logic;
input : in std_logic;
output : out std_logic
);
end top;

When I ask ISE to simulate a PPR simulation with modelsim it generates
a file called "top_timesim.vhd". Then generates a "tb_top.tdo" where
there are some modelsim commands that compile the "top.vhd" and
"tb_top.vhd" files.

Modelsim generates a "not default binding for component top" error. I
have seen the top_timesim.vhd file and the generics of my top are
deleted!

Why can be this? Is there any way to avoid this?

Thanks in advance,

Arkaitz.

Note: I have rewriten the generics in "top_timesim.vhd" file and now
it works well.

 

[Brian Philofsky]

arkaitz wrote:

Hi all,

I am trying to make a post-place & route simulation of a very simple
design.

In the "top.vhd "file there is declared an entity that contains some
generics and the architecture.

entity top is
generic(
gen1 : real := 3.0;
gen2 : std_logic;
gen3 : std_logic
);
port(
clk : in std_logic;
rst : in std_logic;
input : in std_logic;
output : out std_logic
);
end top;

When I ask ISE to simulate a PPR simulation with modelsim it generates
a file called "top_timesim.vhd". Then generates a "tb_top.tdo" where
there are some modelsim commands that compile the "top.vhd" and
"tb_top.vhd" files.

Modelsim generates a "not default binding for component top" error. I
have seen the top_timesim.vhd file and the generics of my top are
deleted!

Why can be this? Is there any way to avoid this?

Unfortunately, there is no way for the software to retain the original
generics you defined in the code (at least not yet) and thus when netgen
(the Xilinx ISE netlister) creates the entity for your top module, it
can not recreate those generics in the declaration. Fortunately though,
there is an easy way around this without having to edit the file or the
test bench. If you run netgen with the -a switch (In the ISE GUI it is
the advanced simulation model property, Generate Architecture Only) the
netlist produced will not contain an entity declaration and only contain
the architecture. What this allows you to do is retain the original
entity declaration with the defined generics from your RTL code and bind
the structural timing architecture to that. If you have already run a
functional simulation using that RTL code for that project, then all you
would need to do is flip this switch and that should fix the problem for
you. As long as all of your ports are defined as
std_logic/std_logic_vector, you should not have any problems with this.
This is also an easy way to get around any top-level ports declared as
a buffer rather than an out although I still highly suggest not to
declare any port as a buffer in VHDL.

Good luck,

-- Brian

Thanks in advance,

Arkaitz.

Note: I have rewriten the generics in "top_timesim.vhd" file and now
it works well.

 

[paris]

"arkaitz" <arkagaz@yahoo.com> escribió en el mensaje
news:c1408b8c.0404290218.5106d484@posting.google.com...

Hi all,

I am trying to make a post-place & route simulation of a very simple
design.

In the "top.vhd "file there is declared an entity that contains some
generics and the architecture.

entity top is
generic(
gen1 : real := 3.0;
gen2 : std_logic;
gen3 : std_logic
);
port(
clk : in std_logic;
rst : in std_logic;
input : in std_logic;
output : out std_logic
);
end top;

When I ask ISE to simulate a PPR simulation with modelsim it generates
a file called "top_timesim.vhd". Then generates a "tb_top.tdo" where
there are some modelsim commands that compile the "top.vhd" and
"tb_top.vhd" files.

Modelsim generates a "not default binding for component top" error. I
have seen the top_timesim.vhd file and the generics of my top are
deleted!

Why can be this? Is there any way to avoid this?

Thanks in advance,

Arkaitz.

Note: I have rewriten the generics in "top_timesim.vhd" file and now
it works well.

i dont think you should use "generics" in a "top" entity that you want to
synthesize (correct me if im wrong). I've heard that some tools accept them
and use the default value if specified.
what i do is to "wrap" the generic component, and instantiate it into a
"wrapper" that doesnt contain any generics and where all generics have been
fixed to constants defined in some package. It also eases simulation before
and after synthesis, as you only have to switch wrappers (or architectures)
in the testbench.

 

[arkaitz]

Hi,

Thanks both for the reply.

That's good to receive other people experiences.

I'll try with both tricks.

Regards,

Arkaitz.