Problem running the web server on Arduino Uno R3 and Ethernet shield
Question
I'm trying to run the WebServer example below from the Arduino IDE using an Ethernet shield (Wiznet W5100) that is stacked on top of an Arduino Uno R3. The Ethernet shield is connected using an RJ45 cable to an Internet router. After uploading the code to the board, I see that the requested IP address (192.168.1.177) is printed to the console. The strange behavior that I'm facing here is that when I ping the IP address, I get a response indicating that the IP is reachable from my laptop. Also, I see the Tx, Rx LED lights blinking thereby indicating that the board is receiving the ping msgs and replying to them. This means that the board successfully received an IP address and is now connected to the LAN. However, when I try to access the same IP from the browser to receive the HTML page, no response is returned and the browser takes around 30 seconds displaying loading before returning site not reachable message. I tried different browsers from both the laptop and an iPhone connected to the same LAN with no luck in receiving the web page. Any hint as to what the problem could be is highly appreciated.
See below the code and a picture for the Ethernet shield during the experiment.
/*
Web Server
A simple web server that shows the value of the analog input pins.
using an Arduino Wiznet Ethernet shield.
Circuit:
* 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
modified 02 Sept 2015
by Arturo Guadalupi
*/
#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, 1, 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:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for native USB port only
}
// start the Ethernet connection and the server:
Ethernet.begin(mac, ip);
server.begin();
Serial.print("server is at ");
Serial.println(Ethernet.localIP());
}
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();
Serial.write(c);
// 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();
client.println("<!DOCTYPE HTML>");
client.println("<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(analogChannel);
client.print(" is ");
client.print(sensorReading);
client.println("<br />");
}
client.println("</html>");
break;
}
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
delay(1);
// close the connection:
client.stop();
Serial.println("client disconnected");
}
}
1 answers
solution1
0 2020-06-28 07:42:31
To those who come later here for the same problem, it appeared that there was an issue with the DHCP of the Internet router. It seems like my router's DHCP was not stable when providing IP addresses for devices connected through the Ethernet ports. I replaced the router and the problem went away.
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