Home Hardware Wiznet 5100 module and the Arduino

Wiznet 5100 module and the Arduino

by shedboy71

This shows how to add ethernet support to an Arduino using a Wiznet 5100 module, this is similar to the Ethernet shield that is commonly used but this module is a little bit more compact which may be an advantage in some projects. In this example I actually used an Arduino Nano

W5100 is a set of TCP / IP protocol, MAC and PHY in one network chip, with support for direct bus interface, SPI bus.


  • Supports 10/100 Base TX
  • Supports half/full duplex operation
  • Supports auto-negotiation and auto cross-over detection
  • IEEE 802.3/802.3u Compliance
  • Operates 3.3V with 5V I/O signal tolerance
  • Supports network status indicator LEDs
  • Includes Hardware Internet protocols: TCP, IP Ver.4, UDP, ICMP, ARP, PPPoE, IGMP
  • Includes Hardware Ethernet protocols: DLC, MAC
  • Supports 4 independent connections simultaneously
  • Supports MCU bus Interface and SPI Interface
  • Supports Direct/Indirect mode bus access
  • Supports Socket API for easy application programming

Here is the module, a lot of websites offer these

wiznet arduino


The module has some status LEDs, these are as follows

  • PWR: indicates that the module is powered
  • LINK: indicates the presence of a network link and flashes when data is transmitted or received
  • FDX: indicates that the network connection is full duplex
  • SPD: indicates the presence of a 100 Mb/s network connection (as opposed to 10 Mb/s)
  • RX: flashes when data is received
  • TX: flashes when data is sent
  • COL: flashes when network collisions are detected

When I wired my module up and connected my network cable the first 4 LEDs were lit, the RX/TX will flash when the code example is uploaded to your board

So, the connections required are:

PIN Function Arduino PIN
2 Vin 5V +5V
4 SS (Slave Select) 10
5 SCK (SPI Interface) 13
6 MOSI (SPI Interface) 11
7 MISO (SPI Interface) 12
8,9,10 No Connection N/C



This uses an example from the Ethernet library -> WebServer. You can just run that – here it is for reference.

[codesyntax lang=”cpp”]

  Web Server

 A simple web server that shows the value of the analog input pins.
 using an Arduino Wiznet Ethernet shield.

 * Ethernet shield attached to pins 10, 11, 12, 13
 * Analog inputs attached to pins A0 through A5 (optional)

 created 18 Dec 2009
 by David A. Mellis
 modified 9 Apr 2012
 by Tom Igoe


#include <SPI.h>
#include <Ethernet.h>

// Enter a MAC address and IP address for your controller below.
// The IP address will be dependent on your local network:
byte mac[] = {
  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
IPAddress ip(192, 168, 0, 177);

// Initialize the Ethernet server library
// with the IP address and port you want to use
// (port 80 is default for HTTP):
EthernetServer server(80);

void setup() {
  // Open serial communications and wait for port to open:
  while (!Serial) {
    ; // wait for serial port to connect. Needed for Leonardo only

  // start the Ethernet connection and the server:
  Ethernet.begin(mac, ip);
  Serial.print("server is at ");

void loop() {
  // listen for incoming clients
  EthernetClient client = server.available();
  if (client) {
    Serial.println("new client");
    // an http request ends with a blank line
    boolean currentLineIsBlank = true;
    while (client.connected()) {
      if (client.available()) {
        char c = client.read();
        // if you've gotten to the end of the line (received a newline
        // character) and the line is blank, the http request has ended,
        // so you can send a reply
        if (c == '\n' && currentLineIsBlank) {
          // send a standard http response header
          client.println("HTTP/1.1 200 OK");
          client.println("Content-Type: text/html");
          client.println("Connection: close");  // the connection will be closed after completion of the response
          client.println("Refresh: 5");  // refresh the page automatically every 5 sec
          client.println("<!DOCTYPE HTML>");
          // output the value of each analog input pin
          for (int analogChannel = 0; analogChannel < 6; analogChannel++) {
            int sensorReading = analogRead(analogChannel);
            client.print("analog input ");
            client.print(" is ");
            client.println("<br />");
        if (c == '\n') {
          // you're starting a new line
          currentLineIsBlank = true;
        else if (c != '\r') {
          // you've gotten a character on the current line
          currentLineIsBlank = false;
    // give the web browser time to receive the data
    // close the connection:
    Serial.println("client disconnected");



Using your favourite web browser navigate to the address you setup in the code, in this case

I saw the following on the webpage

analog input 0 is 307
analog input 1 is 287
analog input 2 is 340
analog input 3 is 301
analog input 4 is 280
analog input 5 is 279




You may also like