In reply to dave_59:
task reciever :: recv();
if (on) $display ("%t ,%s,%m",$realtime,name);
begin
this.sda<=intf_rec.sda_pin;
$display("from reciever recv task");
this.reg_clk_out<=intf_rec.cb.reg_clk_out;
$display ("sda=%d,reg_clk_out=%d",this.sda,this.reg_clk_out);
#5000;
end
endtask