Component Instantiation not driving outputs

[nfirtaps]

Hello, I am creating a FIFO IP core in ISE. Everything goes well with
the generation however when I write a small VHDL file that port maps
the outputs and inputs to the FIFO I can see the outputs are not being
driven. In the simulator the outputs are 'U'. Here's a little
background before I paste in my code. The abbreviations ef and ff
stand for empty flag (which should be '1' after the FIFO is reset), and
full flag (which should be '0' after the fifo is reset). Here is some
code does this look right for the port mapping and instantiation?
Also, do I have to make signals for the port mapping, or can I directly
use the signals in the entity description instead of have to make
std_logic and assign them in the behavioral?

Thanks in advance...

entity fpga_fifo_filler is
Port ( clk : in STD_LOGIC; -- clk that will map to the fifo
instance
enable : in STD_LOGIC; --enable on the fifo
reset : in std_LOGIC; -- reset on the fifo
fpga_fifoef : out STD_LOGIC; --the fifo empty flag
fpga_fifoff : out STD_LOGIC); --the fifo full flag
end fpga_fifo_filler;

architecture Behavioral of fpga_fifo_filler is

signal clk_wire : std_logic; --I put these here for the port map,
signal enable_wire : std_logic; --It will also synthesize if I just map
the enable on the entity
signal reset_wire : std_logic; --Is it even necessary to have these
signals?
signal fpga_fifoef_wire : std_logic;
signal fpga_fifoff_wire : std_logic;

component wrapped_async_fifo
port (
din: IN std_logic_VECTOR(15 downto 0);
rd_clk: IN std_logic;
rd_en: IN std_logic;
rst: IN std_logic;
wr_clk: IN std_logic;
wr_en: IN std_logic;
dout: OUT std_logic_VECTOR(15 downto 0);
empty: OUT std_logic;
full: OUT std_logic);
end component;

begin

Inst_wrapped_async_fifo : wrapped_async_fifo
port map(
din => "0000000000000000",
rd_clk => '0',
rd_en => '0',
rst => reset_wire,
wr_clk => clk_wire, --map the clk_wire and feed the clock to the
fifo
wr_en => enable_wire, -- map the enable ...
dout => open,
empty => fpga_fifoef_wire, --these signals are not driven in
simulation why????
full => fpga_fifoff_wire --not driven in simulation why????
);

--Inputs
clk_wire <= clk; -mapping, again do I need these?
reset_wire <= reset;
enable_wire <= enable;

--Outputs
fpga_fifoef <= fpga_fifoef_wire;
fpga_fifoff <= fpga_fifoff_wire;

end Behavioral;

 

[Arnim]

Hi,

On which simulator? Are there warnings during analyze/elaborate about
wrapped_async_fifo not being bound?

however when I write a small VHDL file that port maps the outputs and
inputs to the FIFO I can see the outputs are not being driven. In
the simulator the outputs are 'U'.

Which signals exactly? For instance, fpga_fifo_filler.fpga_fifoef_wire
or fpga_fifo_filler.Inst_wrapped_async_fifo.empty?
Are all inputs to Inst_wrapped_async_fifo at expected values?

Regarding the *_wire signals, you could connect the ports of
Inst_wrapped_async_fifo to the corresponding entity ports of
fpga_fifo_filler. Intermediate signals are only required if you want to
read the outputs of Inst_wrapped_async_fifo somewhere else inside
fpga_fifo_filler.

In fact, assigning clk to an intermediate signal generates a delta cycle
on your clock network which might lead to unintended simulation
behavior. You really want to avoid this unless you know exactly what
you're doing.


Cheers

Arnim

 

[nfirtaps]

Arnim, thanks for your reply.

This is on the Fuse simulator through ISE. There is a warning that
reads:

Warning: No entity is bound for inst

I guess this would be my problem, I have checked the Xilinx website on
this matter
http://www.xilinx.com/xlnx/xil_ans_display.jsp?iLanguageID=1&iCountryID=1&getPagePath=22548

which tells me to make sure that the .xco file has
Synthesis/Imp+Simulation is selected, and it is. Also it tells me to
verify that either the .v or .vhd (depending on the "View Instantiation
Template" language setting for the core) exists in the project
directory. I do not see a wrapped_async_fifo.vhd file anywhere but the
instance is under my vhdl module (fpga_fifo_filler) which is named
Inst_wrapped_async_fifo - wrapped_async_fifo. Thanks for pointing me
to that warning? Which I would think should be an error?

Do you have any ideas of what I do to bound this instantiation?

Thanks,
Lloyd

 

[Arnim]

This is on the Fuse simulator through ISE. There is a warning that
reads:

Warning: No entity is bound for inst

I guess this would be my problem.I do not see a
wrapped_async_fifo.vhd file anywhere but the instance is under my
vhdl module (fpga_fifo_filler) which is named Inst_wrapped_async_fifo
- wrapped_async_fifo. Thanks for pointing me to that warning?
Which I would think should be an error?

Yes, this is a very severe warning as it implies that the instance ports
are not properly connected to the rest of the design.

Do you have any ideas of what I do to bound this instantiation?

It seems to me that the default binding does not work correctly in your
case. That's hard to diagnose without sitting in front of your machine.
Have a look at

http://tams-www.informatik.uni-hamburg.de/vhdl/doc/faq/FAQ1.html#default_binding

Especially the paragraph that explains the "set of default binding
rules". Basically, you could check whether all of the follwing rules are
fulfilled in your design:

1. entity of wrapped_async_fifo is analyzed before architecture
of fpga_fifo_filler is analyzed (log file of the compile?)
2. your component declaration for wrapped_async_fifo is identical
to the corresponding entity (except formatting)
3. *all* the component ports are actually mapped in the port map to
"thingies" of the same type

Issue 3 might be violated in your design, as you have an "open" mapped
to dout and these "00.."/'0' literals mapped to other ports. I'm not
100% sure about this, but you could try to define signals of exactly the
same type as the component ports. Like

signal din_wire : std_logic_VECTOR(15 downto 0);
[...]
din_wire <= (others => '0');
[...]
din => din_wire

and so on. Also have a signal dout_wire mapped to dout.


Or try to instantiate the entity as described in the following text of
the document.


Hope this helps

Arnim

 

[jtw]

Are you including the Xilinx Coregen and/or Unisim libraries in your file
that instantiates the FIFO?

JTW

This is on the Fuse simulator through ISE. There is a warning that
reads:

Warning: No entity is bound for inst

I guess this would be my problem.I do not see a
wrapped_async_fifo.vhd file anywhere but the instance is under my
vhdl module (fpga_fifo_filler) which is named Inst_wrapped_async_fifo
- wrapped_async_fifo. Thanks for pointing me to that warning?
Which I would think should be an error?

Yes, this is a very severe warning as it implies that the instance ports
are not properly connected to the rest of the design.

Do you have any ideas of what I do to bound this instantiation?

It seems to me that the default binding does not work correctly in your
case. That's hard to diagnose without sitting in front of your machine.
Have a look at

http://tams-www.informatik.uni-hamburg.de/vhdl/doc/faq/FAQ1.html#default_binding

Especially the paragraph that explains the "set of default binding
rules". Basically, you could check whether all of the follwing rules are
fulfilled in your design:

1. entity of wrapped_async_fifo is analyzed before architecture
of fpga_fifo_filler is analyzed (log file of the compile?)
2. your component declaration for wrapped_async_fifo is identical
to the corresponding entity (except formatting)
3. *all* the component ports are actually mapped in the port map to
"thingies" of the same type

Issue 3 might be violated in your design, as you have an "open" mapped
to dout and these "00.."/'0' literals mapped to other ports. I'm not
100% sure about this, but you could try to define signals of exactly the
same type as the component ports. Like

signal din_wire : std_logic_VECTOR(15 downto 0);
[...]
din_wire <= (others => '0');
[...]
din => din_wire

and so on. Also have a signal dout_wire mapped to dout.


Or try to instantiate the entity as described in the following text of
the document.


Hope this helps

Arnim

 

[nfirtaps]

JTW,
I have the following lines in my code

library unisim;
library unisim.vcomponents.all;

library xilinxcorelib;

I have the ISE Simulator Lite, I _think_ this could be because I have
the lite version.

Let me briefly recap the following "warnings" I get which prevent me
from simulating my FIFO Xilinx core.

warning while synthesizing : Instatiating black box (warning at line
where I instantiate the core)
warning while simulating : No entity is bound for inst

Are you including the Xilinx Coregen and/or Unisim libraries in your file
that instantiates the FIFO?

JTW

This is on the Fuse simulator through ISE. There is a warning that
reads:

Warning: No entity is bound for inst

I guess this would be my problem.I do not see a
wrapped_async_fifo.vhd file anywhere but the instance is under my
vhdl module (fpga_fifo_filler) which is named Inst_wrapped_async_fifo
- wrapped_async_fifo. Thanks for pointing me to that warning?
Which I would think should be an error?

Yes, this is a very severe warning as it implies that the instance ports
are not properly connected to the rest of the design.

Do you have any ideas of what I do to bound this instantiation?

It seems to me that the default binding does not work correctly in your
case. That's hard to diagnose without sitting in front of your machine.
Have a look at

http://tams-www.informatik.uni-hamburg.de/vhdl/doc/faq/FAQ1.html#default_binding

Especially the paragraph that explains the "set of default binding
rules". Basically, you could check whether all of the follwing rules are
fulfilled in your design:

1. entity of wrapped_async_fifo is analyzed before architecture
of fpga_fifo_filler is analyzed (log file of the compile?)
2. your component declaration for wrapped_async_fifo is identical
to the corresponding entity (except formatting)
3. *all* the component ports are actually mapped in the port map to
"thingies" of the same type

Issue 3 might be violated in your design, as you have an "open" mapped
to dout and these "00.."/'0' literals mapped to other ports. I'm not
100% sure about this, but you could try to define signals of exactly the
same type as the component ports. Like

signal din_wire : std_logic_VECTOR(15 downto 0);
[...]
din_wire <= (others => '0');
[...]
din => din_wire

and so on. Also have a signal dout_wire mapped to dout.


Or try to instantiate the entity as described in the following text of
the document.


Hope this helps

Arnim

 

[Duth]

Hi,

It is ideal to open a case with Xilinx Tech Support with this question.
Here are some things thhat you can look into. Confirm that the output
netlist created out of coregen in Proj Nav is set to VHDL and not
verilog. Since ISE Simulator is a mixed language simulator you will not
get an error about the language. What you can do to confirm this is to
right click on "view generated HDL file" for the xco file and ensure it
is VHDL. It defaults to verilog if both synthesis and simulator tools
are mixed language, i.e XST and ISE Simulator

Also you do not need to have xilinxcorelib, as long as the wrapper file
is in the project directory. I suspect the main reason you have unbound
issue is because of the fact that it is not able to see the VHDL model.

Also ensure you are using the latest version of ISE as well. With 8.1i
there were some issues with the coregen flow that have been fully
addressed in 8.2i.

Thanks
Duth
PS: The lite version does not limit you from simulating any Xilinx
provided product. The only limtiation is deration when you reach 10,000
lines of code

JTW,
I have the following lines in my code

library unisim;
library unisim.vcomponents.all;

library xilinxcorelib;

I have the ISE Simulator Lite, I _think_ this could be because I have
the lite version.

Let me briefly recap the following "warnings" I get which prevent me
from simulating my FIFO Xilinx core.

warning while synthesizing : Instatiating black box (warning at line
where I instantiate the core)
warning while simulating : No entity is bound for inst

Are you including the Xilinx Coregen and/or Unisim libraries in your file
that instantiates the FIFO?

JTW

This is on the Fuse simulator through ISE. There is a warning that
reads:

Warning: No entity is bound for inst

I guess this would be my problem.I do not see a
wrapped_async_fifo.vhd file anywhere but the instance is under my
vhdl module (fpga_fifo_filler) which is named Inst_wrapped_async_fifo
- wrapped_async_fifo. Thanks for pointing me to that warning?
Which I would think should be an error?

Yes, this is a very severe warning as it implies that the instance ports
are not properly connected to the rest of the design.

Do you have any ideas of what I do to bound this instantiation?

It seems to me that the default binding does not work correctly in your
case. That's hard to diagnose without sitting in front of your machine.
Have a look at

http://tams-www.informatik.uni-hamburg.de/vhdl/doc/faq/FAQ1.html#default_binding

Especially the paragraph that explains the "set of default binding
rules". Basically, you could check whether all of the follwing rules are
fulfilled in your design:

1. entity of wrapped_async_fifo is analyzed before architecture
of fpga_fifo_filler is analyzed (log file of the compile?)
2. your component declaration for wrapped_async_fifo is identical
to the corresponding entity (except formatting)
3. *all* the component ports are actually mapped in the port map to
"thingies" of the same type

Issue 3 might be violated in your design, as you have an "open" mapped
to dout and these "00.."/'0' literals mapped to other ports. I'm not
100% sure about this, but you could try to define signals of exactly the
same type as the component ports. Like

signal din_wire : std_logic_VECTOR(15 downto 0);
[...]
din_wire <= (others => '0');
[...]
din => din_wire

and so on. Also have a signal dout_wire mapped to dout.


Or try to instantiate the entity as described in the following text of
the document.


Hope this helps

Arnim

 

[luke9876]

For anybody who googles this..
I had the same problem with "unbounded blackbox" when I tried to simulate a fifo made in core-gen (I named it myfifo) . I am using Xilinx ISE10.1, and got around the problem by removing my myfifo.xco file and adding the simulation file generated along with the core.
In Project Navigator-> Sources for: Behavioral Simulation I deleted my fifo.xco and added myfifo.vhd. Core-gen produces the myfifo.ngc (what synthesis uses) and myfifo.vhd (what the simulator will use). Synthesis still gives a warning about 'black box', but it finds the myfifo.ngc component to synthesize with and it simulates now.
Hope this helps...