0

I'm having trouble programming an Arduino Uno with this sketch, the sketch compiles and I get full serial output and an IP address, but no web browser can connect to it.

I've tried this Arduino example (https://www.arduino.cc/en/Tutorial/WebServer) and it works right out of the box, I don't understand why my code therefore doesn't work.

My code is below:

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

// Bootup millisecond counter
const unsigned long started     = millis();

// Serial settings
const int SERIAL_BAUDRATE       = 9600;

// Non-DHCP ethernet settings:
// Device MAC address: DE:AD:BE:EF:FE:ED
const byte mac[] = {
  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
};
IPAddress ip(
  192, 168, 1, 177
);

// Pins
const int P_RELAY               = 7;
const int P_ON_LED              = 8;
const int P_OFF_LED             = 9;
const int P_SW_MAN              = 10;

// Relay power states
const char B_RELAY_ON           = HIGH;
const char B_RELAY_OFF          = LOW;

// Relay switching state
boolean RELAY_STATE             = false;

// Network/web data
EthernetServer server(80);
String readString;
String localIp;

// Testing switches
const boolean connectToEthernet = true;
const boolean hostWebServer     = true;
const boolean useDHCP           = false;
const boolean testRelay         = false;

// Testing settings
const int testRelayDelay        = 500;

// Formats an IPAddress nicely as a string for printing
String displayAddress(IPAddress address) {
  return String(address[0]) + "." +
         String(address[1]) + "." +
         String(address[2]) + "." +
         String(address[3]);
}

void setup() {
  const unsigned long started = millis();
  delay(50); // allow some time (50 ms) after powerup and sketch start, for the Wiznet W5100 Reset IC to release and come out of reset.
  Serial.begin(SERIAL_BAUDRATE);
  Serial.println("HTTP Web Remote Power-Point Controller.");
  Serial.println();
  if (connectToEthernet) {
    Serial.println("Connecting to Ethernet...");
    if (useDHCP) {
      Ethernet.begin(mac);
      Serial.println("Obtaining IP address...");
      localIp = displayAddress(Ethernet.localIP());
    } else {
      Ethernet.begin(mac, ip);
      localIp = displayAddress(ip);
    }
    if (localIp != "0.0.0.0") {
      Serial.println("Connected. IP: " + localIp);
      if (hostWebServer) {
        Serial.println("Starting Ethernet server...");
        server.begin();
        Serial.println("Started.");
      }
    } else {
      Serial.println("Error: No address provided via DHCP.");
      Serial.println("Please check your network connection and settings, and try again.");
      while (1);
    }
  }
  Serial.println("Configuring pins...");
  pinMode(P_RELAY, OUTPUT);
  pinMode(P_ON_LED, OUTPUT);
  pinMode(P_OFF_LED, OUTPUT);
  pinMode(P_SW_MAN, INPUT_PULLUP);
  Serial.println("Pins configured.");
  Serial.println("Pin Information: \n            Relay: " + String(P_RELAY) + 
                                  "\n           On LED: " + String(P_ON_LED) + 
                                  "\n          Off LED: " + String(P_OFF_LED) + 
                                  "\n    Manual Switch: " + String(P_SW_MAN));
  if (hostWebServer && connectToEthernet) {
    Serial.println("Remote controller interface is running at http://" + localIp + "/");
  }
  if (testRelay) {
    Serial.println("Testing relay mode enabled.");
    Serial.println("Toggling relay every " + String(testRelayDelay) + " milliseconds...");
  }
  const unsigned long starttime = (millis() - started);
  Serial.println("Startup took " + String(starttime) + " milliseconds.");
}

void loop() {
  if (testRelay) {
    delay(testRelayDelay);
    if (RELAY_STATE) {
      toggleRelay(false);
    } else {
      toggleRelay(true);
    }
  }
  if (useDHCP) {
    byte dhcpRenew = Ethernet.maintain();
    if (dhcpRenew == 1) {
      Serial.println("Dynamic DHCP lease renewal failed.");
    } else if (dhcpRenew == 2) {
      Serial.println("Dynamic DHCP lease was renewed.");
    } else if (dhcpRenew == 3) {
      Serial.println("Dynamic DHCP lease rebind failed.");
    } else if (dhcpRenew == 4) {
      Serial.println("Dynamic DHCP lease was rebound.");
    }
  }
  EthernetClient client = server.available();
  if (client) {
    Serial.println("Client connected to web server.");
    while (client.connected()) {
      if (client.available()) {
        char c = client.read();
        if (readString.length() < 100) {
          readString += c;
        }

        if (String(c) == "\n") {
          Serial.println("Data received from HTTP client: " + String(readString));

          // HTTP header
          client.println("HTTP/1.1 200 OK");
          client.println("Content-Type: text/html");
          client.println("Connection: close");
          client.println();

          // HTTP body
          if (readString.indexOf("?state") > 0) {
            if (RELAY_STATE) {
              client.print("1");
            } else {
              client.print("0");
            }
          } else {
            client.println("<!DOCTYPE HTML>");
            client.println("<html lang=\"en\">");
            client.println("<head>");
            client.println("<title>Power-Point Controller</title>");
            client.println("</head>");
            client.println("<body>");
            client.println("<h1>hello world</h1>");
            client.println("</body>");
            client.println("</html>");
          }

          delay(10);

          client.stop();
          Serial.println("Client disconnected from web server.");

          if (readString.indexOf("?relay=1") > 0) {
            toggleRelay(true);
          } else if (readString.indexOf("?relay=0") > 0) {
            toggleRelay(false);
          }

          readString = "";
        }
      }
    }
  }
}

void toggleRelay(bool state) {
  if (state == true) {
    digitalWrite(P_OFF_LED, LOW);
    digitalWrite(P_RELAY, B_RELAY_ON);
    digitalWrite(P_ON_LED, HIGH);
    RELAY_STATE = true;
    Serial.println("Relay State: ON");
  } else if (state == false) {
    digitalWrite(P_ON_LED, LOW);
    digitalWrite(P_RELAY, B_RELAY_OFF);
    digitalWrite(P_OFF_LED, HIGH);
    RELAY_STATE = false;
    Serial.println("Relay State: OFF");
  }
}
  • 3
  • 3
    When you say "my code therefore doesn't work", what serial output messages did you get ? Did the server IP address answers to a ping from client side ? (useDHCP and testRelay are false, so test your source without that superfluous code). – J. Piquard Dec 22 '16 at 7:41
  • Everything looked like it worked as expected, except it didn't. Read my comment on the accepted answer as to the reason :) – Thomas Jones Dec 23 '16 at 6:24
2

I don't understand why my code therefore doesn't work.

Without any in-depth analysis of your code I would suspect that you have simply run out of memory. It is easy to forget that the Arduino Uno is a very small machine with limited resources.

Here are some steps forward:

  1. Check memory status (compile and run-time).
  2. Use the F() macro to force string literals to be stored in program memory.
  3. Reduce String class operators especially on print statements. Simply replace with multiple print statements.

Cheers!

  • This was part of the answer, the other part which I discovered just now was me using pin 10 for something without realising Ethernet wanted it. Thanks a lot! – Thomas Jones Dec 23 '16 at 6:23

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.