bench: Test ARP requests in HWITL

cocotb/cocotb_top_hwitl.vhd

@@ -72,6 +72,19 @@ begin
 			tx_n => open
 		);
 
-	button_n <= (others => '1');
+	test_seq : process is
+	begin
+		wait until bench_ready = '1';
+
+		button_n <= (others => '1');
+		wait for 1 us;
+
+		wait until rising_edge(clk);
+		button_n(0) <= '0';
+		wait until rising_edge(clk);
+		button_n(0) <= '1';
+
+		wait;
+	end process test_seq;
 
 end architecture bench;

design/top_hwitl.vhd

@@ -301,4 +301,22 @@ begin
 		end if;
 	end process receiver;
 
+	arp_request_test : process(clk, rst) is
+	begin
+		if rst then
+			arp_in.arp_ip        <= (x"C0", x"A8", x"02", x"01");
+			arp_in.arp_query_stb <= '0';
+
+		elsif rising_edge(clk) then
+			arp_in.arp_query_stb <= not button_n(0);
+
+			if arp_out.arp_ok_stb then
+				report "Found MAC: " & mac_to_string(arp_out.arp_mac);
+			end if;
+			if arp_out.arp_fail_stb then
+				report "ARP failed";
+			end if;
+		end if;
+	end process arp_request_test;
+
 end architecture eth;