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How to read a text file in a VerilogA code

Alifa

 Hello every body!

I will greatly appreciate your help.

In order to test a serial DAC I need to input the DAC with serial bits ( any pattern like 01110001111), one bit at a clock cycle. So my text file (bit_sequence.txt) looks like this:

 1

0

 1

0

0

1

.

.

.

Basically, I want a VerilogA model that reads "bit_sequence.txt" and output one bit at a clock cycle to my DAC circuit. I tried the following code. It compiles with no error, but I can't see the above pattern in my simulation. Moreover, after running simulation, the bit_sequence.txt gets empty! :)

module fileReader_1output(out1, clk);
input clk;
output out1;
electrical out1, clk;

parameter real vtrans = 1.0;
parameter fileName = "~/bit_sequence.txt";

integer fileHandle;
integer decimal_output;
integer captured_data;

analog begin

    @ (initial_step)
        fileHandle = $fopen(fileName);
    @ (final_step)
        $fclose(fileHandle);
    @ (cross (V(clk) - vtrans,+1)) begin
                 
        decimal_output = $fscanf(fileHandle,"%d", captured_data);
        V(out1)<= decimal_output; //captured_data;    

     end
end

endmodule

Parents
  • Andrew Beckett

    Which simulator are you using and which version? I just took your code and added a little extra to make it complete:

    `include "disciplines.vams"

    module forum35 (a);
    output a;
    electrical a;

    real A,B,C,D;
    integer fid,retval;

    analog initial begin
      fid=$fopen("forumresults.csv","r");
      retval=4;
      while(retval == 4) begin
        retval = $fscanf(fid, "%e,%e,%e,%e", A, B, C, D);
        $display("%e,%e,%e,%e", A, B, C, D);
      end
    end

    endmodule

    It then worked fine (I changed the filename). I see:

    Reading file: /export/home/username/tools/spectre/forumresults.csv
    3.290000e-06,1.280000e+06,4.957780e-01,1.940000e-07
    3.320000e-06,1.290000e+06,4.948000e-01,1.920000e-07
    3.420000e-06,1.330000e+06,4.956510e-01,1.870000e-07
    3.420000e-06,1.330000e+06,4.956510e-01,1.870000e-07

    The last line would be a duplicate because retval would probably have been -1 for end of file (I didn't check).

    This is using Spectre16.1 - but would be a bit surprised if this is particularly fussy about the version...

    Andrew.

Reply
  • Andrew Beckett

    Which simulator are you using and which version? I just took your code and added a little extra to make it complete:

    `include "disciplines.vams"

    module forum35 (a);
    output a;
    electrical a;

    real A,B,C,D;
    integer fid,retval;

    analog initial begin
      fid=$fopen("forumresults.csv","r");
      retval=4;
      while(retval == 4) begin
        retval = $fscanf(fid, "%e,%e,%e,%e", A, B, C, D);
        $display("%e,%e,%e,%e", A, B, C, D);
      end
    end

    endmodule

    It then worked fine (I changed the filename). I see:

    Reading file: /export/home/username/tools/spectre/forumresults.csv
    3.290000e-06,1.280000e+06,4.957780e-01,1.940000e-07
    3.320000e-06,1.290000e+06,4.948000e-01,1.920000e-07
    3.420000e-06,1.330000e+06,4.956510e-01,1.870000e-07
    3.420000e-06,1.330000e+06,4.956510e-01,1.870000e-07

    The last line would be a duplicate because retval would probably have been -1 for end of file (I didn't check).

    This is using Spectre16.1 - but would be a bit surprised if this is particularly fussy about the version...

    Andrew.

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