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verilogsystem-verilogtest-bench

Verilog Testbench Errors for Comparator


I'm new to Verilog and I need to make an 8-bit comparator for when a is equal, less than, and greater than b. Here's what I have for the code (which gives me no errors):

module MagnitudeComparator8bit (input signed [7:0]a,
                                input signed [7:0]b,
                                output eq,
                                output lt,
                                output gt);
    assign eq = a == b;
    assign lt = a < b;
    assign gt = a > b;
endmodule

And here's what I have for the testbench, but when I run the simulation, I run into multiple errors, but I'm not sure where I went wrong. Any help?

module MagnitudeComparatorTestbench;
    reg [7:0] a, b;
    wire eq, lt, gt;

    MagnitudeComparator8bit uut(
       .a(a),
       .b(b),
       .eq(eq),
       .lt(lt),
       .gt(gt)
    );

    initial begin
          $monitor (“%d %b %b %d %d %d”, $time, a, b, eq, lt, gt);
          a=8’b11110000;
          b=8’b11110000;
      #10 a=8’b1001001;
          b=8’b10101010;
      #10 a=8’b11001100;
          b=8’b10101000;
      #10 $finish
   end  
endmodule

Errors:

testbench.sv:14: error: unmatched character (hex ?)
testbench.sv:e: error: unmatched character (hex ?)
testbench.sv:e: error: unmatched character (hex ?)
testbench.sv:e: syntax error
testbench.sv:e: error: unmatched character (hex ?)
testbench.sv:e: error: unmatched character (hex ?)
testbench.sv:e: error: unmatched character (hex ?)
testbench.sv:e: error: malformed statement
testbench.sv:f: error: unmatched character (hex ?)
testbench.sv:f: error: unmatched character (hex ?)
testbench.sv:f: error: unmatched character (hex ?)
testbench.sv:f: syntax error
testbench.sv:f: error: malformed statement
testbench.sv:10: error: unmatched character (hex ?)
testbench.sv:10: error: unmatched character (hex ?)
testbench.sv:10: error: unmatched character (hex ?)
testbench.sv:10: syntax error
testbench.sv:10: error: malformed statement
testbench.sv:11: error: unmatched character (hex ?)
testbench.sv:11: error: unmatched character (hex ?)
testbench.sv:11: error: unmatched character (hex ?)
testbench.sv:11: syntax error
testbench.sv:11: error: malformed statement
testbench.sv:12: error: unmatched character (hex ?)
testbench.sv:12: error: unmatched character (hex ?)
testbench.sv:12: error: unmatched character (hex ?)
testbench.sv:12: syntax error
testbench.sv:12: error: malformed statement
testbench.sv:13: error: unmatched character (hex ?)
testbench.sv:13: error: unmatched character (hex ?)
testbench.sv:13: error: unmatched character (hex ?)
testbench.sv:13: syntax error
testbench.sv:13: error: malformed statement
testbench.sv:14: error: unmatched character (hex ?)
testbench.sv:14: error: unmatched character (hex ?)
testbench.sv:14: error: unmatched character (hex ?)
testbench.sv:14: syntax error
testbench.sv:14: error: malformed statement
testbench.sv:16: syntax error
Exit code expected: 0, received: 40

Solution

  • You have strange quote characters in your post. Those gave me errors after I copy-and-pasted your code. I fixed the quotes. Copy this code :

    module MagnitudeComparatorTestbench;
        reg [7:0] a, b;
        wire eq, lt, gt;
    
        MagnitudeComparator8bit uut(
           .a(a),
           .b(b),
           .eq(eq),
           .lt(lt),
           .gt(gt)
        );
    
        initial begin
              $monitor ("%d %b %b %d %d %d", $time, a, b, eq, lt, gt);
              a=8'b11110000;
              b=8'b11110000;
          #10 a=8'b1001001;
              b=8'b10101010;
          #10 a=8'b11001100;
              b=8'b10101000;
          #10 $finish;
       end  
    endmodule
    

    I also added a semi after $finish.