Example of a VHDL Design File with LPM Function Instantiation
For any parameterized function, you must declare all parameters used in the function, their types, and their values. The following example shows a VHDL design file that instantiates the lpm_ram_dq function. Attribute Declarations are used to declare the syn_black_box attribute and the name and type of each parameter. The syn_black_box attribute has the boolean type; refer to Quartus II Help for information on whether a parameter is of integer or string type. Attribute Specifications are then used assign values to each parameter.
The following example shows a direct instantiation of an library of parameterized modules (LPM) function. To use the MegaWizard Plug-In Manager to create the function, and then instantiate it in a design, refer to the Creating a Design for Use with the Synplify Software topic.
entity myram is port (clock, we: in bit; data : in bit_vector (3 downto 0);
address: in bit_vector (1 downto 0);
q: out bit_vector (3 downto 0));
end myram;
architecture arch1 of myram is
-- Declare the component myram_4x4 port (data: in bit_vector (3 downto 0);
address: in bit_vector (1 downto 0);
inclock, outclock, we: in bit;
q: out bit_vector (3 downto 0) );
end component;
-- Declare the syn_black_box and parameters and their types attribute syn_black_box: boolean;
attribute LPM_WIDTH: integer;
attribute LPM_WIDTHAD: integer;
attribute LPM_TYPE: string;
-- Assign values to each attribute attribute syn_black_box of myram_4x4: component is true;
attribute LPM_WIDTH of myram_4x4: component is 4;
attribute LPM_WIDTHAD of myram_4x4: component is 2;
-- Specify the name of the LPM function as the value of the -- LPM_TYPE attribute LPM_TYPE of myram_4x4: component is "LPM_RAM_DQ";
begin
-- Instantiate the LPM component u1: myram_4x4 port map(data, address, clock, clock, we, q);
end arch1;
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