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functional coverage for AXI4 WREADY signal

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For AXI write transaction axi wready signal determines whether the slave can accept the data.
For write burst performance i need to capture the latency between "WREADY" and "next WREADY" signal.
For example this ready signal is getting low at clockno 8 and it should remain low for clockno 9 and 10 and the clockno 11 the signal will be high as per the slave configuration. when the multiple burst transacion occurs with (write length > 2) the ready signal behavior will be like above. I want to write a functional coverage like "wready" and next "wready" signal latency is 2 which means when the ready signal is low it will low for 2 clk cycles and then ready will high(if there are multiple write burst transaction).

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You can write assertion property that generates events when it detect how long WREADY is asserted and the specific conditions under which it occurs. By means of a simple function call you can then notify the monitor of the data (# cycles) and capture the information to be passed on to a coverage collector. Doulos demonstrate something very like this (measuring Reset pulse widths) in their UVM training.

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  • 3 months later...



I am trying to code a covergroup which looks at bins having a range between base addr and final addr.

I have a function which calculates the range of address which i want to use in my covergroup.

Basically i want to do this

memory_range : coverpoint range {bins addr[] = {[base_addr, final_addr]};}

which will be dependant on the size of the memory for which i have defined a function. The size and base_addr are read from registers inside the function.

function void calc();

bit [3:0] size;

register read to get size;
register read to get base_addr;
4’b0000: begin
Max_addr = ‘h10000;
Final_addr= base_addr+max_addr;

4’b0001: …….


Presently when i execute this, i see only one bin getting created. The range is not taking effect.

Can anyone please suggest on how I can access the base addr and final addr from the function in my covergroup?

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An example from LRM may help you out (just a suggestion):

Generic coverage groups can be written by passing their traits as arguments to the constructor. For example:
covergroup cg (ref int ra, input int low, int high ) @(posedge clk);
coverpoint ra // sample variable passed by reference
     bins good = { [low : high] };
     bins bad[] = default;
int va, vb;
cg c1 = new( va, 0, 50 ); // cover variable va in the range 0 to 50
cg c2 = new( vb, 120, 600 ); // cover variable vb in the range 120 to 600
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