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Altera_Forum's avatar
Altera_Forum
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16 years ago

Verilog module Instantiation

Don't really know whether i should post this Q here or not.

I'm a student using modelsimSE 6.1f.

actually this Q is more to verilog...not on fpga hardware issue

i was wondering,how can i control the input to an instantiated module?

e.g:

module bin2bcdAdder(input1,input2,bcd);

/*

.

.

.

*/

full_adder fa1(input1,input2,SUM,carryOut);

endmodule

the testbench generates 0000 to 1111 into the module bin2bcdAdder

how can i control the input only from 0000 to 1001 can be passed to the instantiated module full_adder?

and i'm trully sorry if i post this Q in the wrong section, or altera forum is only allowing altera's hardware related Q

6 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    You basicaly need to add soething like this somewhere in your code

    if (input == 1001) begin

    input <= 4'b0;

    end

    But I guess you have no clue where to add it right ?

    Well, I can not help you there, not without the code.
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    module bin2bcdAdder(input1,input2,bcd);
input  input1,input2;
output  bcd;
wire  S;
wire  input1,input2; /*without this line, i can't assign the input values to A1,B1 and compile the code*/
reg  A1,B1;
addminus4bit am4b(A1,B1,0,S,V,C);
always @ (A,B)
begin 
if(A>1001|B>1001)
begin
A1=4'b0;
B1=4'b0;
end
else
begin 
A1=input1;
B1=input2;
end
/*some codes here*/
end
endmodule
    well,i tried using the always block...

    or is it useless to use the > comparison?

    do i need to do case for each bit from 0000 to 1001?
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    module bin2bcdAdder(input1,input2,bcd);
   input  input1,input2;
   output  bcd;
  wire  S;
  wire  input1,input2; /*without this line, i can't assign the input values to A1,B1 and compile the code*/
   reg  A1,B1;
addminus4bit am4b(A1,B1,0,S,V,C);
always @ (A,B) // without a clock input this will NEVER work
begin 
if((A>4'b1001)|(B>4'b1001))
begin
   A1<=4'b0;  // proper assigments
   B1<=4'b0;  //proper assigments 
end
else
begin 
   A1<=input1;  // proper assigments
   B1<=input2;  // proper assigments
end
/*some codes here*/
end
endmodule

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    --- Quote Start --- 

    module bin2bcdAdder(input1,input2,bcd);
   input  input1,input2;
   output  bcd;
  wire  S;
  wire  input1,input2; /*without this line, i can't assign the input values to A1,B1 and compile the code*/
   reg  A1,B1;
addminus4bit am4b(A1,B1,0,S,V,C);
always @ (A,B) // without a clock input this will NEVER work
begin 
if((A>4'b1001)|(B>4'b1001))
begin
   A1<=4'b0;  // proper assigments
   B1<=4'b0;  //proper assigments 
end
else
begin 
   A1<=input1;  // proper assigments
   B1<=input2;  // proper assigments
end
/*some codes here*/
end
endmodule

    --- Quote End ---

    not all always block needs a clock rite?may i know why do i need a clock pulse for this one?
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    btw,it's all working now...tq^^

    added A1 and B1 to the output port to simulate it and it runs well

    without the clock generation
  • Altera_Forum's avatar
    Altera_Forum
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    13 years ago

    I am getting error while instantiating modules on condition with the default module. it is giving error if i instantiate default mode.

    the code is much similar to this:

    module top(//parameters);

    addition u0(//parameters passing); line 2

    'ifdef(flag)

    sum u1(//passing the parameters);

    'else

    subtract u2(//passing the parameters);

    'endif

    endmodule

    if the module addition-u0 is removed, then only code is working properly. but i need to operate before conditional execution.

    plz help me.:cry: