Ethernet Shield with index.htm SDcard.

Projects Discussion and Showcase Home Automation
17

You don't have to answer. If you manage to get by the hardware problem, then I would suspect this comparison:

        if(readString.trim() == ("GET /?C=1678 HTTP/1.1")){
          //client.println("<h1>Clave Ok</h1>");
          Portada();
       }else{
          //client.println("<h1>Clave Erronea</h1>");
       }

Just talking out loud here. I would try this instead. But that is just me.

        if(strcmp(readString.trim(), "GET /?C=1678 HTTP/1.1") == 0) {
          //client.println("<h1>Clave Ok</h1>");
          Portada();
       }else{
          //client.println("<h1>Clave Erronea</h1>");
       }