How i can hold pwrite signal as 1 for for first 16 randomize values?

UVM
,
1

Hi Sir/Mam,
How i can hold my pwrite signal as 1 for first 16 randomization’s?? after 16 randomizes it should be held 0… below is my piece of code… please let me know what changes i have to make in my transaction class such that it should hold my values as said above ?

////////////////////////////////////////////////////////////////////
class apb_seq_item extends uvm_sequence_item;  
  
  rand bit [7:0]paddr;
  rand bit [31:0]pwdata;
  rand bit pwrite;
  bit [31:0] prdata;
 // bit [7:0]cnt;

  constraint paddr_c {paddr[7:0] >= 8'd0; paddr[7:0] < 8'd6;}
  constraint pwdata_c {pwdata[31:0] >= 32'd0; pwdata[31:0] < 32'd6;}
 
  `uvm_object_utils_begin(apb_seq_item)
  `uvm_field_int(paddr,UVM_DEFAULT)
  `uvm_field_int(pwdata,UVM_DEFAULT)
  `uvm_field_int(pwrite,UVM_DEFAULT)
  `uvm_field_int(prdata,UVM_DEFAULT)
  `uvm_object_utils_end
  
  function new(string name= "apb_seq_item");
    super.new(name);
  endfunction
  
 virtual function string convert2str();
    return $sformatf("paddr:%d,pwdata:%d,pwrite:%b,prdata:%d",paddr,pwdata,pwrite,prdata);
  endfunction
  
endclass

/////////////////////sequence///////////////////////////////

class apb_sequence extends uvm_sequence#(apb_seq_item);
  
  `uvm_object_utils(apb_sequence)
  
  function new(string name= "apb_sequence");
    super.new(name);
  endfunction
  
  virtual task body();
    apb_seq_item trans;
    for(int i=0; i<31; i++) begin
      trans=apb_seq_item::type_id::create("trans");
   //   start_item(trans);
      `uvm_info("[Sequence]","Starting sequence",UVM_MEDIUM)
      assert(trans.randomize());
      `uvm_info("[Sequence]",$sformatf("Generated New Items are %s",trans.convert2str()),UVM_MEDIUM)
   //   finish_item(trans);
    end
  endtask
  
endclass


//////////////////////////sequencer//////////////////////////////////

class apb_sequencer extends uvm_sequencer#(apb_seq_item);
 
  `uvm_component_utils(apb_sequencer)
 
  //constructor
  function new(string name, uvm_component parent);
    super.new(name,parent);
  endfunction
   
endclass

////////////////////////////env/////////////////////////////////////

class apb_env extends uvm_env;
 
  `uvm_component_utils(apb_env)
  
  function new(string name = "apb_env", uvm_component parent=null);
    super.new(name, parent);
  endfunction
  
  apb_sequencer s0;
  
  virtual function void build_phase(uvm_phase phase);
    super.build_phase(phase);
    s0 = apb_sequencer::type_id::create("s0", this);
  endfunction

endclass

//////////////////////////test///////////////////////////////////////

  class test extends uvm_test;

   `uvm_component_utils(test)
  
  function new(string name = "test", uvm_component parent=null);
    super.new(name, parent);
  endfunction

  apb_env env;

  virtual function void build_phase(uvm_phase phase);
    super.build_phase(phase);
    env = apb_env::type_id::create("env", this);
  endfunction

  virtual task run_phase(uvm_phase phase);
    apb_sequence seq = apb_sequence::type_id::create("seq");
    phase.raise_objection(this);
    `uvm_info("[Test]","Test started",UVM_MEDIUM)
    seq.start(env.s0);
  //  #50;
    phase.drop_objection(this);
  endtask
    
endclass

///////////////////////top/////////////////////////////////
module top;
  initial begin
    run_test("test");
  end
endmodule
2

In reply to subbarao:

You can reach this by running a loop with 16 iterations and using an inline constraint in your randomize function, forcing pwrite to 1,

for (int i = 0; i < 16; i++) begin
  assert (trans.randomize with {pwrite == 1'b1;};
3

In reply to chr_sue:

actually in my sequence task body i want to randomize my transactions for 32 times… but i have a condition like in 32 times of randomization, i want 16 times pwrite should be 1 and rest 16 pwrite 0…

4

In reply to subbarao:

You can do it like this:

  task body();
    apb_seq_item trans;
    for(int i=0; i<16; i++) begin
      trans=apb_seq_item::type_id::create("trans");
      start_item(trans);
      `uvm_info("[Sequence]","Starting sequence",UVM_MEDIUM)
       assert (trans.randomize with {pwrite == 1'b1;};
      `uvm_info("[Sequence]",$sformatf("Generated New Items are %s",trans.convert2str()),UVM_MEDIUM)
      finish_item(trans);
    end
    for(int i=0; i<16; i++) begin
      trans=apb_seq_item::type_id::create("trans");
      start_item(trans);
      `uvm_info("[Sequence]","Starting sequence",UVM_MEDIUM)
       assert (trans.randomize with {pwrite == 1'b0;};
      `uvm_info("[Sequence]",$sformatf("Generated New Items are %s",trans.convert2str()),UVM_MEDIUM)
      finish_item(trans);
    end

  endtask
5

In reply to chr_sue:

thank you sir, its working…