I recently purchased a W5100 based ethernet shield for my arduino Uno, and looks like this. I had been following the guide here, and connected the pins accordingly - 5V to 5V, GND to GND, MOSI to 11, MOSO to 12, SCK to 13, and SS to ten.

I booted up a default sketch (webServer, under Ethernet), and plugged in and ethernet cable. - PWR, LINK, SPD,and FDX all lit up, with Rx blinking for first 10 or so seconds. I then go to the IP specified on the arduino sketch, and nada. Also, my router doesn't show the shield under the attached devices.

Therefore, I figure it's a problem with my connections. Can anyone help me? Googling has only brought my lots of info about shields, and little info on these modules.

  • 3
    Just to sanity check - can you post the IP address of your router (or your PC) and the IP address you used in the sketch? Jan 27 '15 at 13:26
  • Router's address is 192.1681.1.1 - a default. The IP used in the sketch, for the Ethernet's
    – Ethan
    Jan 28 '15 at 0:57

First, if you cannot connect to arduino by ethernet, use Serial Monitor and add some Serial.println to your code to log what is going - what part of program Arduino is executing.

W5100 module has no automatic reset module as opposed to Ethernet shield. So try to connect W5100 RST pin to for example D8 and reset module in setup.

Here you are example from my (working) project:

const int W5100_RESET_PIN = 8;

void setup() {
  Serial.println(F("node starting..."));
  pinMode(W5100_RESET_PIN, OUTPUT);
  digitalWrite(W5100_RESET_PIN, LOW);
  digitalWrite(W5100_RESET_PIN, HIGH);
  // give the Ethernet shield a second to initialize:
#ifdef USE_DHCP
  while (Ethernet.begin(mac) == 0) {
    Serial.println(F("DHCP failed."));
  Serial.print(F("static IP..."));
  Ethernet.begin(mac, IPAddress(MY_IP));
  Serial.print(F("local IP:"));
  Serial.println(F("node started."));

Also after setup if your arduino lost ethernet connection and cannot get it again, you can try to reset w5100 and initialize Ethernet again.

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