* Question
What are the ways to integrate a module into a black box in Synplify Pro?
* Answer
In Synplify Pro, a leading synthesis tool used for FPGA and ASIC designs, integrating a module into a black box is a useful technique, especially when you want to preserve the hierarchy of a design or manage proprietary IP cores without exposing their internal details. Here’s how you can integrate a module into a black box in Synplify Pro:
1. Declare the Black Box:
– You need to declare the module you intend to use as a black box in your Verilog or VHDL code. This declaration informs Synplify Pro that it should not attempt to synthesize the module and should instead treat it as an external entity.
– For Verilog, you can declare a black box by creating a module declaration with no internal definitions (i.e., no logic inside the module declaration). Use the `( black_box )` attribute before the module declaration to explicitly specify it as a black box.
“`verilog
( black_box )
module MyBlackBox(input clk, input rst, input [7:0] data_in, output [7:0] data_out);
endmodule
“`
– For VHDL, you declare an entity without an architecture, or you can use the attribute `syn_black_box` in the entity declaration:
“`vhdl
attribute syn_black_box : boolean;
attribute syn_black_box of MyBlackBox : entity is true;
entity MyBlackBox is
port (clk : in std_logic;
rst : in std_logic;
data_in : in std_logic_vector(7 downto 0);
data_out : out std_logic_vector(7 downto 0));
end entity MyBlackBox;
“`
2. Reference the Black Box in Your Design:
– Use the black box in your design as you would use any other module or component. Connect it in your top-level module or wherever it is required. Since the internals are not defined in the synthesis tool, you must ensure that the actual implementation matches the interface declared.
3. Handling Black Box during Synthesis:
– When you run synthesis in Synplify Pro, the tool will recognize the black box attribute and will not try to synthesize it. It will expect that the implementation for this module will be provided later during the design flow, typically during place and route.
– Make sure to provide the correct definitions or netlist for the black box component during the later stages of your FPGA or ASIC design process, such as during simulation or physical implementation.
4. Constraints and Simulation:
– Apply any necessary timing and physical constraints to the black box ports just as you would with any other module. These constraints are crucial for ensuring that the synthesized design meets timing requirements.
– For simulation purposes, you need to have a simulation model of the black box. This model should accurately represent the behavior of the actual hardware module to ensure that the simulation results are valid.
Using black boxes in Synplify Pro helps in managing complex designs by modularizing them and protecting intellectual property while still allowing for full design validation and integration.
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