How to define transaction class when I used parameterized interface?

UVM
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1

Hi,
I’m writting a VIP used parameterized interface. The address width of interface is configurable.
I learned the chapter ParameterizedTests in UVM Cookbook and implemented the parameterized interface by using config_db API.
But the question is how to define transaction class ? Because the address width is configurable. It seems the driver couldn’t be reused.
like:
module top;
…
a_bus#(.addr_width(4)) bus0;
a_bus#(.addr_width(8)) bus1;// or 16,32,64 width
…
endmodule

class bus_driver extends uvm_driver#(bus_transaction);
virtual a_bus v_a_bus;
…
function void run_phase(phase);
bus_transaction bus_tr;
…
v_a_bus <= bus_tr.addr;
…
endfunction
endclass

class bus_transaction extend uvm_sequence_item;
…
logic[3:0] addr;//if I define like this,this VIP can’t reused by other address width
// or define like logic[7:0] addr;
// but it’s not flexible
…
endclass

So how to define the transaction class can be flexible ?

2

In reply to aluowell:

I would not make the transaction parameterized as this will add significant complexity to using the transactions. Instead, make the address the maximum width needed. Only the required number of bits will be driven on the interface.

3

In reply to aluowell:

Hi,
I’m writting a VIP used parameterized interface. The address width of interface is configurable.
I learned the chapter ParameterizedTests in UVM Cookbook and implemented the parameterized interface by using config_db API.
But the question is how to define transaction class ? Because the address width is configurable. It seems the driver couldn’t be reused.
like:
module top;
…
a_bus#(.addr_width(4)) bus0;
a_bus#(.addr_width(8)) bus1;// or 16,32,64 width
…
endmodule
class bus_driver extends uvm_driver#(bus_transaction);
virtual a_bus v_a_bus;
…
function void run_phase(phase);
bus_transaction bus_tr;
…
v_a_bus <= bus_tr.addr;
…
endfunction
endclass
class bus_transaction extend uvm_sequence_item;
…
logic[3:0] addr;//if I define like this,this VIP can’t reused by other address width
// or define like logic[7:0] addr;
// but it’s not flexible
…
endclass
So how to define the transaction class can be flexible ?

I would not define the interface and the transaction parameterized. Put your parameters in a package, like DATA_WIDTH0 = 8, DARA_WIDTH1=16, etc. In each place you need these parameters import the corresponding package. Than all things are fine.

4

In reply to cgales:

Yes , I think your method is feasible, but it still add complexity about scoreboard. How about parameterized class ? I would like to use this VIP for 2 or more places in my environment in which there are different address width.

5

In reply to chr_sue:

Yes, I try this way before. But I would like to use this VIP for 2 or more places in my environment in which there are different address width. How to resolve this problem if I use your method ?

6

In reply to aluowell:

As I said, the address width should be the biggest width that is supported by the interface. For example, if you can support 8, 16, or 32 bit addresses, use 32 bits in the transaction. In the driver, only the required bits will be driven on the interface.

7

In reply to aluowell:

In reply to chr_sue:
Yes, I try this way before. But I would like to use this VIP for 2 or more places in my environment in which there are different address width. How to resolve this problem if I use your method ?

Because your parameters should be in package which is not local to your agent, but local to your project, you can put in there any parameter.

8

In reply to chr_sue:

I’m still confused that how to reuse the VIP.In fact, my parameters package is local to my project. But my agent how to use different parameters ? Can you write an example ?
For example:


 package params_pkg;
    DATA_WIDTH0 = 8;
    DATA_WIDTH1 = 16;
 endpackage

  import params_pkg::*;
  module top;
   my_bus#(DATA_WIDTH0) bus0;
   my_bus#(DATA_WIDTH1) bus1;
   ...
  endmodule

 class my_driver extend uvm_driver#(my_transaction);
     logic[DATA_WIDTH0 -1 : 0] DATA;
     ...
 endclass

If I define like this, I can use parameterized interface. But how can I used different parameters in my driver ?

9

In reply to cgales:

Ok,thank you very much.

10

In reply to aluowell:

In your example you really need parameterized interface. In the Class-based environment you have to make sure you are using exactly the sam specification for the Virtual interface as you are using in the toplevel module. There is no typedef vor a SV interface possible. Looks like a weakness in SV.

11

In reply to chr_sue:

Ok, thank you very much.