Ethernet issue...

Hey guys, I’ve got a weird issue happening with my Arduino Duemilanove (ATMEGA168) running with a ladyada ethernet shield (WIZnet W5100). I have some code developed and working, however when I plug in the Arduino with a DC power adapter (instead of being powered through USB) the WIZnet doesn’t seem to respond (to pings or server) until I press the reset button. If I plug it in to USB, the ethernet shield responds as it should right away. Here’s the code I’m using to initialize the ethernet adapter:

#include <Ethernet.h>

// define ethernet properties
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
byte ip[] = { 192, 168, 15, 7 };
byte gateway[] = { 192, 168, 15, 1};
byte subnet[] = { 255, 255, 255, 0};
Server server = Server(23);


void setup()
  Ethernet.begin(mac, ip, gateway, subnet);

void loop(){
  Client client = server.available();
  if (client){ some stuff...


I’ve tried using Arduino 0015-0017 to no avail. I’ve read some stuff about patches to the ethernet libraries, but I’m not certain if those changes are required with the newest versions of the Arduino IDE. Any ideas?


I have the same problem. I think, I will connect an optocoupler to an gpio pin to reset the board from the code.

If someone have a better idea...

Well, I have the same problem - but with the official shield...

Check out that issue - perhaps it is the same? Also - some were talking about being able to reset the daughterboard instead of the whole board with the shield you are using... Sadly, I can't do it with mine.

Looks like the resolution to that problem was to use the LadyADA shield with Wiznet module (which I have) and hard reset it by connecting the reset pin to an IO pin. I will try that out tonight and let you know. However, if you're using the official Arduino Ethernet shield, it doesn't look like you have any other option (besides the 50nF cap fix)?

Thanks for pointing me in the direction of that thread!