Use the 'include directive to include all your header files within the module body.
When synthesizing header files in the Quartus® Prime Software, do not add the header file to the list of files in the Quartus® Prime project. Header files should not be analyzed as separate Verilog HDL files. Instead, use the `include directive so that the header file is correctly analyzed when the Quartus® Prime Software analyzes the top-level file.
If you add a header file containing only parameter values to the list of files in the Quartus® Prime project, you may see an error like the following:
Error (10839): Verilog HDL error at <filename>.v(<line number>): declaring global objects is a SystemVerilog feature
The following example instantiates an lpm_dff function with its parameter set in another file (param.v).
. . .
//file : dffveri.v
module dffveri (q, data, clock);
`include "param.v"
//parameter width = 5;
//coming from param.v
input [width-1:0] data;
input clock;
output [width-1:0] q;
lpm_dff dfff (.data(data), .clock(clock), .q(q));
defparam dfff.lpm_width = width;
endmodule
. . .
//file param.v
parameter width = 5;