CODEWITHSUNDEEP
if-statementverilog
JXXX101
JXXX101

Reputation: 23

Unable To Bind Parameter?

I am trying to create multiple adders via Verilog to compare the speed of each adder.

I am getting the following error Unable to bind parameter WIDTH in arith_unit

This is my code so far:

module arith_unit 
#(
parameter ADDER_TYPE = 0,
parameter WIDTH = 8)
(input [WIDTH-1:0] a,
input [WIDTH-1:0] b,    
output [WIDTH-1:0] sum,
);

////////////////////////////////////////////////////////////////
if (ADDER_TYPE == 0) 
begin
    ripple_carry rc1 (a, b, cin, sum, cout);
end

////////////////////////////////////////////////////////////////
else if (ADDER_TYPE == 1) 
begin
   carry_bypass cb1 (a, b, cin, sum, cout);
end

//// more else statment for ADDER_TYPE...

endmodule  

//////////////////////////////////////////////////////////////////
module ripple_carry_4_bit(a, b, cin, sum, cout);

input [3:0] a,b;
input cin;
wire c1,c2,c3;
output [3:0] sum;
output cout;

full_adder fa0(.a(a[0]), .b(b[0]),.cin(cin), .sum(sum[0]),.cout(c1));
full_adder fa1(.a(a[1]), .b(b[1]), .cin(c1), .sum(sum[1]),.cout(c2));
full_adder fa2(.a(a[2]), .b(b[2]), .cin(c2), .sum(sum[2]),.cout(c3));
full_adder fa3(.a(a[3]), .b(b[3]), .cin(c3), .sum(sum[3]),.cout(cout));

endmodule

////////////////////////////////////////////////////////////////
module ripple_carry (a, b, cin, sum, cout);

input [WIDTH-1:0] a,b;
input cin;
wire c1,c2,c3, c4, c5, c6, c7;
output [WIDTH-1:0] sum;
output cout;

if (WIDTH == 8) begin  //<-------- compiler is pointing here as the problem
    ripple_carry_4_bit rca1 (.a(a[3:0]),.b(b[3:0]),.cin(cin), .sum(sum[3:0]),.cout(c1));
    ripple_carry_4_bit rca2 (.a(a[7:4]),.b(b[7:4]),.cin(c1), .sum(sum[7:4]),.cout(cout));
end

else if (WIDTH == 16) begin
    ripple_carry_4_bit rca1 (.a(a[3:0]),.b(b[3:0]),.cin(cin), .sum(sum[3:0]),.cout(c1));
    ripple_carry_4_bit rca2 (.a(a[7:4]),.b(b[7:4]),.cin(c1), .sum(sum[7:4]),.cout(c2));
    ripple_carry_4_bit rca3 (.a(a[11:8]),.b(b[11:8]),.cin(c2), .sum(sum[11:8]),.cout(c3));
    ripple_carry_4_bit rca4 (.a(a[15:12]),.b(b[15:12]),.cin(c3), .sum(sum[15:12]),.cout(cout));
end

//// more else statment for 32 & 64 bits...

endmodule

I looked online and it seems that my if and else statements are correct. So I am assuming that my WIDTH is declared wrong? I tried passing in WIDTH via module ripple_carry (a, b, cin, sum, cout, WIDTH); kind of how you would do it with C++, but I still get the same error.

I've tested the ripple_carry on its own (no if statements, no parameter) with 8 bits, 16 bits, etc. and it works fine. So I know that my logic for the ripple_carry is fine.

Please help me, thank you.

Upvotes: 0

Views: 1366

Answers (1)

dave_59
dave_59

Reputation: 42698

It would have helped to show the exact error message with the line number, but you are missing a WIDTH parameter declaration in the module ripple_carry.

module ripple_carry #(parameter WIDTH=8)(...

And add it when instantiating it inside the generate block. 

   ripple_carry #(WIDTH) (a, b, cin, sum, cout);

Upvotes: 2

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