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Topic: Connecting Arduino Mega directly to Ubuntu pc - Arduino Web Server not found (Read 938 times) previous topic - next topic


Hi everyone,
This is my first post. I'd like to ask help on how to set up properly the Ethernet Shield W5100 R3 for use with the Arduino Mega 2560 and how to access the Arduino WebServer (displaying analog values) from my web browser (Mozilla Firefox).
I have an Arduino Mega 2560 with a Wiznet W5100-based R3 Ethernet Shield, I've bent the pins 11, 12 and 13 of the Ethernet Shield and put jumper wires to connect them to pins 50,51 and 52 of the MEGA. My OS is Ubuntu MATE 16.04 64-bit. I've set manually an IP address (to connect with eth0), a netmask, and a gateway address for my Arduino from the network settings, and for that purpose, I created a new Ethernet connection.

This is my sketch, a modified WebServer example in which I set the pins 4,10,50,51 and 52 as HIGH

Code: [Select]
  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>

int ethershield0 = 10;
int ethershield1 = 50;
int ethershield2 = 51;
int ethershield3 = 52;
int ethershield4 = 4;
// 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(192,168,7,177);
IPAddress gateway(192,168,7 ,1);
IPAddress subnet(255, 255, 255, 0);

// Initialize the Ethernet server library
// with the IP address and port you want to use
// (port 80 is default for HTTP):
EthernetServer server(8080);

void setup() {
pinMode(ethershield0, OUTPUT);
pinMode(ethershield1, OUTPUT);
pinMode(ethershield2, OUTPUT);
pinMode(ethershield3, OUTPUT);
pinMode(ethershield4, OUTPUT);
 // 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, gateway, subnet);
  Serial.print("server is at ");

void loop() {
  digitalWrite(ethershield0, HIGH);
  digitalWrite(ethershield1, HIGH);
  digitalWrite(ethershield2, HIGH);
  digitalWrite(ethershield3, HIGH);
  digitalWrite(ethershield4, HIGH);
  // 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 disonnected");

The result is that whatever IP and port I set, It displays the IP address in the serial monitor, but when I open it with my web browser, I always end up in the Apache2 server default page (which is not what I want). If I disconnect the RJ45 cable, the web page displays "Connection Failed", if I reconnect, I end up into the Apache2 server default page again. I even switched between straight and crossover RJ45 cables, but it's always the same. Besides, Is a router necessary? But if possible, I want to connect directly my Arduino via Ethernet to my PC.

Any help appreciated, thanks


On your laptop, disable DHCP, enter:

On the Arduino, use:

Then open in your browser.

If that doesn't work, leave the default GW on your laptop blank, and try adding a static route manually:
ip route add via dev eth0



the Ethernet shield doesn't connect on pins 11, 12, 13. it uses the ICSP header for SPI connection. only pin 10 is connected for CS and pin 4 if you insert a SD card


To expand on what Juraj said: As long as the shield is designed in this way, you can just plug it right into your Mega and the correct connections will be made. There is no need for the jumper wires. The only exception would be very old or poorly designed shields which are not mega-compatible.


Hi guys,
Thank you very much for your reply and for your advice, you saved me. I first followed what PieterP wrote:

On your laptop, disable DHCP, enter:

On the Arduino, use:

Then open in your browser."
and additionally, i set 8080 as my port, so i opened in my web browser.
The good news is, it works: it displays the analog values. But the bad news is: my laptop could no longer connect to the Internet after the setup, whether via Ethernet or via WIFI. So i would like to know why it's happening and how to fix it.

Best regards.



You have to reset the network settings on your laptop to DHCP.
If that doesn't work, please post a screenshot of your exact settings.


choose a different  network number for the cable to Arduino then on your main network.
if you use 192.168.1.x for network to Arduino, the main network addresses can't be 192.168.1.x


Hi again, guys
For my own case, I didn't have to enable DHCP again, I just removed the IPv4 route (as PieterP wrote)

ip route add via dev eth0
The server and the Internet are now both working
Thanks a lot from the help.

Best regards


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