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Topic: Arduino Uno R3 + Ethernet hangs after a few day's (Read 1 time) previous topic - next topic


Hi everyone,

My first post here hope someone can tell me what i do wrong ...  :)

The project is for a central heating system. The purpose is to operate it over ethernet.

First of all thank you for reading my post  ;).

Arduino uno R3, software v1.0.2 on Mac os x

The problem:
The ethnetnet shield is unreachable after a few day's. I did look for some solutions, i found that my SRAM memory was overflowing so i made a new program. The SRAM usage is printed in web browser and reports over 1300byte of free memory so i guess there is no more problem with the SRAM.
Also when the shield is unreachable the program is still running, so i still have hot water but can not access the web interface anymore.

Comments, suggestions on the code are appreciated  :)

My program:

Code: [Select]

byte mac[] = {
 0xDE, 0xAD, 0xBE, 0x57, 0x49, 0x5A };

IPAddress ip(192,168,2, 38);

static char baseurl[]="";

byte gateway[] = {
 192, 168, 2, 1 };
byte subnet[] = {
 255, 255, 255, 0 };

String readString = "";

EthernetServer server(80);

void setup() {


 sensors.setResolution(outsideThermometer, 10);
 pinMode(4, OUTPUT);                  // SD select pin
 digitalWrite(4, HIGH);               // Explicitly disable SD
 pinMode(10, OUTPUT);                  // Ethernet select pin
 digitalWrite(10, LOW);               // Explicitly enable Network

 Ethernet.begin(mac, ip, gateway, subnet);

 Serial.print("server is at ");



Code: [Select]
void loop() {



 // Every 5 Sec update temperature
 if((long)millis()-eventTimeout>=0) {
   eventTimeout=(long)millis() + 5000;
   Tbuiten = GetTemperature(outsideThermometer);

 // Every 3 Sec update verwarming
 if((long)millis()-eventTimeout2>=0) {
   eventTimeout2=(long)millis() + 3000;

   // boiler temperatuur  23°c = 852 90°C= 676ohm => 67°C/155,79
   Tboiler = (23 + ((GetTemperatureVerwarming(A1, 5)-852)  * 430 / 1000));
   // ketel temperatuur omzetting
   //831 -> 1K4 + 540 (23°C) => 3,3V * 540 /(540+1405) / 1,1V/1023 (10bit) = 831
   Tketel = (23 + ((GetTemperatureVerwarming(A0, 5)-852)  * 475 / 1000));


   if(mode == 2){
     // Verwarming Dag
     if(Tbuiten <= -10){
       Twens = 70;
     else if(Tbuiten > 27){
       Twens = 0;
     else {

       Twens = ( 70 - ((Tbuiten + 10) / k));
   else if(mode == 3){
     // Verwarming Nacht
     if(Tbuiten <= -10){
       Twens = 45;
     else if(Tbuiten > 20){
       Twens = 0;
     else {

       Twens = ( 45 - ((Tbuiten + 10) / (2*k)));
   //Do(byte mode, int Tketel, int Tboiler, int Tout, float Twens)
   Viessmann.Do(mode, Tketel, Tboiler, Tbuiten, Twens);




Code: [Select]

void listenForEthernetClients(float fTbuiten, float fTketel, float fTboiler, float fTwens) {

 boolean SBrander = 1;
 boolean SPverw = 1;
 boolean SPboil = 1;
 boolean data_found=0;

 char Tketel[7] = "100.0";
 char Tboil[7] = "100.0";
 char Tbuiten[7] = "100.0";
 char Tomloop[7] = "0.0";

 byte lengte = 0;

 // Convert float to string

 //clearing string for next read


 // listen for incoming clients
 EthernetClient client = server.available();

 if (client) {

   // an http request ends with a blank line
   boolean currentLineIsBlank = true;

   while (client.connected()) {
     if (client.available()) {
       char c = client.read();

       if( c == '?')
         data_found = true;

       //read first 100 chars
       //read char by char HTTP request
       if ((lengte < 25) && (data_found)) {

         lengte ++;
         //store characters to string
         readString += c;

         if (readString.length() > 30) {
           readString = "";

       else if((lengte >= 25) && (data_found)) {

         if(readString.indexOf("cmd=0") >0)//checks for on
           mode = 0;

         if(readString.indexOf("cmd=1") >0)//checks for on
           mode = 1;

         if(readString.indexOf("cmd=2") >0)//checks for on
           mode = 2;

         if(readString.indexOf("cmd=3") >0)//checks for on
           mode = 3;
         data_found = false;


       // 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(F("HTTP/1.1 200 OK Content-Type: text/html Connnection: close"));
         client.println(F("<!DOCTYPE HTML><html><meta http-equiv=\"refresh\" content=\"5;URL='"));
         // add a meta refresh tag, so the browser pulls again every 5 seconds:


         client.println(F("'\"><center><p><h1>Welcome to Viessmann Atola Ethernet Shield V1.0  </h1></p><hr><br> <h2><font color=\"blue\">-- Status online -- <br> Temperatuur Ketel: "));
         client.println(F(" &degC<br> Temperatuur Boiler: "));
         client.println(F(" &degC<br> Temperatuur Buiten: "));
         client.println(F(" &degC<br> Gewenste omloop temperatuur: "));
         client.println(F(" &degC<br> <br> Status Brander: "));

         if (Viessmann.BranderStatus())

         client.println(F("<br> Status Pomp verwarming: "));

         if (Viessmann.PompVerwarmingStatus())

         client.println(F("<br> Status pomp Boiler: "));

         if (Viessmann.PompBoilerStatus())

         client.println(F("<br></font></h2></center><hr><center><form METHOD=get>"));

         // knoppen

           client.println(F("<button type=submit name=\"cmd\" value=\"0\"><B STYLE=\"color: red;\">Verwarming Uit</B></button>"));
           client.println(F("<button type=submit name=\"cmd\" value=\"0\">Verwarming Uit</button>"));

           client.println(F("<button type=submit name=\"cmd\" value=\"1\"><B STYLE=\"color: red;\">Enkel Warmwater</B></button>"));
           client.println(F("<button type=submit name=\"cmd\" value=\"1\">Enkel Warmwater</button>"));

           client.println(F("<button type=submit name=\"cmd\" value=\"3\"><B STYLE=\"color: red;\">Verwarming Nacht</B></button>"));
           client.println(F("<button type=submit name=\"cmd\" value=\"3\">Verwarming Nacht</button>"));

           client.println(F("<button type=submit name=\"cmd\" value=\"2\"><B STYLE=\"color: red;\">Verwarming Dag</B></button></form></center><hr>"));
           client.println(F("<button type=submit name=\"cmd\" value=\"2\">Verwarming Dag</button></form></center><hr>"));

         client.println(F("FreeMemory: "));
         client.println(F(" KB</html>"));

       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:


   byte g=0;
   while((client.status() != 0) && g < 100) { // ADDED Aug 2 (http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1235991468)


Kind regards,


Code: [Select]

String readString = "";

Stability problems in a sketch that uses the String class immediately raises the possibility that you have hit the known problem with the String class.

I haven't checked what use you're making of String and it may be blameless in this case, but even if it isn't causing the current problem it is a loaded gun pointed at your foot. I suggest you remove all use of the String class from your sketch and see whether that makes any difference.


If the ethernet shield is connected to a router, have you checked it to see if there any clues there. also, have you counted the number of connections to the arduino before the connection is lost?
Google forum search: Use Google Search box in upper right side of this page.
Why I like my 2005 Rio Yellow Honda S2000  https://www.youtube.com/watch?v=pWjMvrkUqX0


Allright! I will remove the strings  i used the string for checking if there was an variable added in the URL :).

Anyway, I think its going out of sockets, I cannot connect but program keeps running.
I red about problems with closing the sockets but they were old, don't know if they are still bugs.
I also tried to disable the SD card but still no success.

Can anyone confirm an error / bug with the sockets in wiznet?


Although this is an old post, there were problems with the ethernet lib before arduino 1.0.5.

I saw a memory leak (using a periodic dump of free mem) with older libs after I realized that my arduino also stopped sending ethernet packets after some days. These probs were gone after using arduino 1.0.5 and the arduino runs since several weeks and months now.

Bad news for using enc28j60 ethernet shields, I am using a pollin netio with arduino compatible boot loader etc called netino. This guy still needs a watchdog to prevent it from hanging around.


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