In reply to Abhisek Sarkar:
Hi Abhisek,
You should try something like as follows:
interface my_interface;
bit clk;
bit start_clk;
always@(start_clk)
begin
while(start_clk)
begin
if(!start_clk)
break;
#5 clk =~clk;
end
end
endinterface
It will work!