Transaction Object

A UVM transaction class typically defines all the input and output control signals that can be randomized and driven to the DUT.

Steps to create a UVM transaction object

1. Create custom class inherited from uvm_sequence_item, register with factory and call new

  
  
// my_object is user-given name for this class that has been derived from "uvm_sequence_item"
class my_object extends uvm_sequence_item;
	
	// This is standard code for all components
	function new (string name = "my_object", uvm_component parent = null);
		super.new (name, parent);
	endfunction
	
	// Code for rest of the steps come here
endclass

  

2. Declare variables related to this transaction class

  
  
	// Declare variables and make the ones that has to be randomized as "rand"
	rand bit [15:0] addr;
	rand bit [31:0] data;
	rand bit [2:0]  burst;

  

3. Register the class with factory and apply UVM field macros if required

  
  
	`uvm_object_utils_begin (my_object)
		// Apply the given object macros to the corresponding variables
		`uvm_field_int (addr,  UVM_ALL_ON | UVM_NO_COMPARE)
		`uvm_field_int (data,  UVM_ALL_ON)
		`uvm_field_int (burst, UVM_ALL_ON)
	`uvm_object_utils_end

  

4. Add constraints as required

  
  
	constraint c_addr { addr <= 16'hBFFF; }
	constraint c_burst { burst inside {[0:4]}; }

  

Define convert2string function

  
  
	function string convert2string();
		return $sformatf("addr=0x%0h data=0x%0h burst=0x%0h", addr, data, burst);
	endfunction