So my workflow is as follows:

  • Create IP in NI LabVIEW FPGA
  • Export via FPGA IP Export Tool
    • Creates a VHDL wrapper (.vhd)
    • Places IP in Design Checkpoint (.dcp) file
  • Open my Vivado Block Design
  • Use or update the VHDL wrapper that uses the Design Checkpoint
  • Synthesis, Implementation, and Run

The NI LabVIEW FPGA IP Export utility provides you with 2 files, a design checkpoint and a wrapper file to use for instantiating your IP using VHDL.

A wrapper file is a very simple vhdl file, it contains the following interface to your design:

entity NiFpgaIPWrapper_fpga_top is
port (
        reset : in std_logic;
        enable_in : in std_logic;
        enable_out : out std_logic;
        enable_clr : in std_logic;
        ctrlind_00_d : in std_logic_vector(0 downto 0);
        ctrlind_01_d_latched : out std_logic_vector(0 downto 0);
        ctrlind_02_c : in std_logic_vector(0 downto 0);
        ctrlind_03_c_echo : out std_logic_vector(0 downto 0);
        ctrlind_04_b : in std_logic_vector(0 downto 0);
        ctrlind_05_a : in std_logic_vector(0 downto 0);
        ctrlind_06_a_and_b : out std_logic_vector(0 downto 0);
        ctrlind_07_a_or_b : out std_logic_vector(0 downto 0);
        Clk40 : in std_logic
);
end NiFpgaIPWrapper_fpga_top;

However, in some situations using this method results in a problem, specifically Vivado will give a ‘Black Box Undefined error’ during the opt_design step of the Implementation phase.

“ERROR: [DRC INBB-3] ‘Black Box Instances: Cell ‘design_1_i/…’ of type ‘design_1_i/…’ has undefined contents and is considered a black box. The contents of this cell must be defined for opt_design to complete successfully.”

I have created a github.com repository where I have isolated this problem and make it very easy for someone to reproduce this error:

https://github.com/fpganow/black.box

But first, here is a screenshot of the error message: (left-clicking always opens in a new tab)

Log output:

https://github.com/fpganow/black.box/blob/main/pictures/black.box.instance.error.txt

Starting DRC Task
INFO: [DRC 23-27] Running DRC with 2 threads
ERROR: [DRC INBB-3] Black Box Instances: Cell 'design_1_i/my_wrapper_0/U0/ni_wrapper/MyLabVIEWIP' of type 'design_1_my_wrapper_0_0_NiFpgaAG_fpga_top' has undefined contents and is considered a black box. The contents of this cell must be defined for opt_design to complete successfully.
INFO: [Project 1-461] DRC finished with 1 Errors
INFO: [Project 1-462] Please refer to the DRC report (report_drc) for more information.
ERROR: [Vivado_Tcl 4-78] Error(s) found during DRC. Opt_design not run.

Time (s): cpu = 00:00:03 ; elapsed = 00:00:02 . Memory (MB): peak = 1760.746 ; gain = 0.000
INFO: [Common 17-83] Releasing license: Implementation
44 Infos, 8 Warnings, 1 Critical Warnings and 2 Errors encountered.
opt_design failed
ERROR: [Common 17-39] 'opt_design' failed due to earlier errors.

INFO: [Common 17-206] Exiting Vivado at Sun Feb 7 13:17:50 2021...

 

 

 

And then I removed the .dcp file from my vivado project and used the generated .v file.

Also, I chose to use -rename_top just to be sure that the IP I was exporting has the name I am expecting.

By john

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