Old code stopped working

MPC · May 27, 2021, 11:31pm

Hi guys.

I'm basically a noob in programming and I made this program like 4-5 years ago and it worked flawlessly and thus I never updated the code until when I tried to update the IP for it today due to moving flats, but now my code suddenly stopped wont work/compile without errors and I do not know what to do to fix it, and wondering if anyone is able to help. Maybe the library it is based on is outdated?

Premise:

It's a simple Webserver arduino with a ethernet shield. It hosts a basic HTTP website with 3 clickable buttons, each clickable buttons are linked to a radio transmitter, so when they are clicked a radio transmitter linked up to the arduino gets broadcasted and controls some wireless plugs around the house.

Code:

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


const unsigned long TRANSMITTER_ADDRESS = 27612394; //My personal transmitter address
const int PIN_TRANSMITTER = 8;

// Create a transmitter on address TRANSMITTER_ADDRESS, using digital pin PIN_TRANSMITTER to transmit, 
// with a period duration of 260ms (default), repeating the transmitted
// code 2^3=8 times.
NewRemoteTransmitter transmitter(TRANSMITTER_ADDRESS, PIN_TRANSMITTER, 260, 3);

// Ethernet configuration
uint8_t mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED }; // MAC Address
uint8_t ip[] = { 192,168,1,230 };                        // IP Address
EthernetServer server(80);                           // Server Port 80

// RemoteTransmitter configuration
// Connect Transmitter to Pin 11 and receiver to pin 2 (all digital)
// FAN 1 ON/OFF:
// Addr 27612394 unit 0 on, period: 267us.
// Addr 27612394 unit 0 off, period: 267us.
// FAN 2 ON/OFF:
// Addr 27612394 unit 1 on, period: 266us.
// Addr 27612394 unit 2 off, period: 267us.
// FAN 3 ON/OFF:
// Addr 27612394 unit 2 on, period: 267us.
// Addr 27612394 unit 1 off, period: 266us.
// ALL POWER OFF:
// Addr 27612394 group off, period: 267us.


void setup() {
  Ethernet.begin(mac, ip);
  server.begin();
  pinMode(PIN_TRANSMITTER, OUTPUT);
  Serial.begin(9600);
  }

  
void loop() {
  char* command = httpServer();
}


void processCommand(char* command) {
  if        (strcmp(command, "1-on") == 0) {
    transmitter.sendGroup(true); //All fans on
  } else if (strcmp(command, "1-off") == 0) {
    transmitter.sendGroup(false); //All fans off
  } else if (strcmp(command, "2-on") == 0) {
    transmitter.sendUnit(0, true);
  } else if (strcmp(command, "2-off") == 0) {
    transmitter.sendUnit(0, false);
  } else if (strcmp(command, "3-on") == 0) {
    transmitter.sendUnit(1, true);
  } else if (strcmp(command, "3-off") == 0) {
    transmitter.sendUnit(1, false);
  } else if (strcmp(command, "4-on") == 0) {
    transmitter.sendUnit(2, true);
  } else if (strcmp(command, "4-off") == 0) {
    transmitter.sendUnit(2, false);
  }
}

/**
 * HTTP Response with homepage
 */
void httpResponseHome(EthernetClient c) {
  c.println("HTTP/1.1 200 OK");
  c.println("Content-Type: text/html");
  c.println();
  c.println("<html>");
  c.println("<head>");
  c.println(    "<title>MPC NEXA Webserver</title>");
  c.println(    "<style>");
  c.println(        "body { font-family: Arial, sans-serif; font-size:12px; }");
  c.println(    "</style>");
  c.println("</head>");
  c.println("<body>");
  c.println(    "<h1>MPC NEXA Webserver</h1>");
  c.println(    "<ul>");
  c.println(        "<li><a href=\"./?1-on\">Turn on power</a></li>");
  c.println(        "<li><a href=\"./?1-off\">Turn off power</a></li>");
  c.println(    "</ul>");
  c.println(    "<ul>");
  c.println(        "<li><a href=\"./?2-on\">Turn on power 1</a></li>");
  c.println(        "<li><a href=\"./?2-off\">turn off power 1</a></li>");
  c.println(    "</ul>");
  c.println(    "<ul>");
  c.println(        "<li><a href=\"./?3-on\">Turn on power 2</a></li>");
  c.println(        "<li><a href=\"./?3-off\">turn off power 2</a></li>");
  c.println(    "</ul>");
  c.println(    "<ul>");
  c.println(        "<li><a href=\"./?4-on\">Turn on power 3</a></li>");
  c.println(        "<li><a href=\"./?4-off\">turn off power 3</a></li>");
  c.println(    "</ul>");
  c.println(    "<hr>");
  c.println("</body>");
  c.println("</html>");
}

/**
 * HTTP Redirect to homepage
 */
void httpResponseRedirect(EthernetClient c) {
  c.println("HTTP/1.1 301 Found");
  c.println("Location: /");
  c.println();
}

/**
 * HTTP Response 414 error
 * Command must not be longer than 30 characters
 **/
void httpResponse414(EthernetClient c) {
  c.println("HTTP/1.1 414 Request URI too long");
  c.println("Content-Type: text/plain");
  c.println();
  c.println("414 Request URI too long");
}

/**
 * Process HTTP requests, parse first request header line and 
 * call processCommand with GET query string (everything after
 * the ? question mark in the URL).
 */
char*  httpServer() {
  EthernetClient client = server.available();
  if (client) {
    char sReturnCommand[32];
    int nCommandPos=-1;
    sReturnCommand[0] = '\0';
    while (client.connected()) {
      if (client.available()) {
        char c = client.read();
        if ((c == '\n') || (c == ' ' && nCommandPos>-1)) {
          sReturnCommand[nCommandPos] = '\0';
          if (strcmp(sReturnCommand, "\0") == 0) {
            httpResponseHome(client);
          } else {
            processCommand(sReturnCommand);
            httpResponseRedirect(client);
          }
          break;
        }
        if (nCommandPos>-1) {
          sReturnCommand[nCommandPos++] = c;
        }
        if (c == '?' && nCommandPos == -1) {
          nCommandPos = 0;
        }
      }
      if (nCommandPos > 30) {
        httpResponse414(client);
        sReturnCommand[0] = '\0';
        break;
      }
    }
    if (nCommandPos!=-1) {
      sReturnCommand[nCommandPos] = '\0';
    }
    // give the web browser time to receive the data
    delay(1);
    client.stop();
    Serial.print("Restarting Web Server");
    
    return sReturnCommand;
  }
  return '\0';
}

Errors I get while compiling:

G:\Dropbox\Dropbox\Arduino\RemoteControllFans\RemoteControllFans.ino: In function 'char* httpServer()':
G:\Dropbox\Dropbox\Arduino\RemoteControllFans\RemoteControllFans.ino:132:10: warning: address of local variable 'sReturnCommand' returned [-Wreturn-local-addr]
     char sReturnCommand[32];
          ^~~~~~~~~~~~~~
G:\Dropbox\Dropbox\Arduino\RemoteControllFans\RemoteControllFans.ino:171:10: warning: invalid conversion from 'char' to 'char*' [-fpermissive]
   return '\0';
          ^~~~
In file included from C:\Program Files (x86)\Arduino\libraries\Ethernet\src\Dns.cpp:8:0:
C:\Program Files (x86)\Arduino\libraries\Ethernet\src\Dns.cpp: In member function 'uint16_t DNSClient::BuildRequest(const char*)':
C:\Program Files (x86)\Arduino\libraries\Ethernet\src\utility/w5100.h:457:25: warning: result of '(256 << 8)' requires 18 bits to represent, but 'int' only has 16 bits [-Wshift-overflow=]
 #define htons(x) ( (((x)<<8)&0xFF00) | (((x)>>8)&0xFF) )
                      ~~~^~~
C:\Program Files (x86)\Arduino\libraries\Ethernet\src\Dns.cpp:164:18: note: in expansion of macro 'htons'
  twoByteBuffer = htons(QUERY_FLAG | OPCODE_STANDARD_QUERY | RECURSION_DESIRED_FLAG);
                  ^~~~~
Sketch uses 14004 bytes (43%) of program storage space. Maximum is 32256 bytes.
Global variables use 1211 bytes (59%) of dynamic memory, leaving 837 bytes for local variables. Maximum is 2048 bytes.

jremington · May 28, 2021, 12:45am

Those are repairable problems, and should be fixed. The compiler error messages make it very clear what each problem is.

Attempting to return a pointer to a locally declared array is a very serious error, although it is possible that it may have worked.

   return sReturnCommand;

Do your research and if you get stuck, post a specific question.

johnwasser · May 28, 2021, 4:41pm

The value returned by 'httpServer()' is never used so it might as well not return a value:

/*
   Process HTTP requests, parse first request header line and
   call processCommand with GET query string (everything after
   the ? question mark in the URL).
*/
void httpServer()
{
  EthernetClient client = server.available();
  if (client)
  {
    char sReturnCommand[32];
    int nCommandPos = -1;
    sReturnCommand[0] = '\0';
    while (client.connected())
    {
      if (client.available())
      {
        char c = client.read();
        if ((c == '\n') || (c == ' ' && nCommandPos > -1))
        {
          sReturnCommand[nCommandPos] = '\0';
          if (strcmp(sReturnCommand, "\0") == 0)
          {
            httpResponseHome(client);
          }
          else
          {
            processCommand(sReturnCommand);
            httpResponseRedirect(client);
          }
          break;
        }
        if (nCommandPos > -1)
        {
          sReturnCommand[nCommandPos++] = c;
        }
        if (c == '?' && nCommandPos == -1)
        {
          nCommandPos = 0;
        }
      }
      if (nCommandPos > 30)
      {
        httpResponse414(client);
        sReturnCommand[0] = '\0';
        break;
      }
    }
    
    if (nCommandPos != -1)
    {
      sReturnCommand[nCommandPos] = '\0';
    }
    // give the web browser time to receive the data
    delay(1);
    client.stop();
    Serial.print("Restarting Web Server");
  }

  return;
}

SteveMann · May 29, 2021, 1:29am

Those are warnings so your sketch should still work. I've never seen a "Note:" before.

johnwasser · May 30, 2021, 2:30pm

I think you mean "your sketch should still compile."

The compiler warnings point out code that is syntactically legal but semantically dubious. Many times they are warning you of a problem that will cause your sketch to not work correctly. Ignore compiler warnings at your peril!

SteveMann · May 30, 2021, 2:40pm

You are correct. My error.
I have recently gotten into the habit of fixing all warnings even if the code works. I think it makes me a better programmer. Frustratingly, a lot of the warnings come from installed libraries.

MPC · June 1, 2021, 8:32am

Hi guys.

You were all correct... I just did a stupid mistake. The program still compiled properly and worked. The reason why I thought it stopped working was because I got no internet access to the arduino, but it was because the switch I connected it to died.... but anyway due to the errors that I have in my code, it still has problems, like it freezes often (so I need to reset it once or twice a week) so instead of trying to correct the code I made a new program since that was easier for me...

system · September 29, 2021, 8:32am

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