PubSubClient: Arduino sketch to create webserver & publish topic payload as soon as link is clicked

[K Smith]

Hi,

I am struggling with this.

I have an Arduino mega with ethernet shield.

I need an Arduino sketch that will create a webserver with a few links on it and publish a specific MQTT topic and payload as soon as a link is clicked.

Each link will have a different topic and payload.

There will be about 10 links on the page.

I have done extensive googling and yesterday spent the day trying to adjust existing code; I would post it up but it is just a mess now.

I thought I'd ask to see of this could be done before posting code.

Thanks

[K Smith]

The muddle comes when trying to use the Arduino as a server for the web page and as a client for the MQTT publishing. 

Within void loop() I call "EthernetClient client" but I then can't call client.publish() as this is not known to the Ethernet library.

So I call the reconnect() function, as listed in the PubSubClient libraries and put the client.publish() commands in there, but the reconnect loop takes 30 seconds or so to update the MQTT topic with the contents of the payload on the server.

I'm sure my mix of server (web) and client (MQTT) architecture is rubbish anyway; I am not a c programmer. Well I'm not a programmer at all actually.

Anyone who knows  PubSubClient & using ardunio as a web server will understand what I'm talking about. Well they might ! What do you think?

[Paul Fremantle]

I think you might be getting a number of things confused.

1)  EthernetClient client should be in the setup() not the loop()

2) PubSubClient is a separate client that uses the EthernetClient in its startup. You can't call publish on EthernetClient, only on PubSubClient.

3) I would suggest getting a standalone PubSubClient example working before integrating into the Web Server. That would help simplify and solve one problem at a time.

4) we can't help decide if its a good idea to put the web server and MQTT client together without a better idea of what you want to achieve.

Paul

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Paul Fremantle

Doctoral Researcher, University of Portsmouth, School of Computing

Visiting Scientist, Institute of the Architecture of Application Systems, Stuttgart

Visiting Lecturer, Software Engineering Programme, Oxford University

Co-Founder, WSO2
Apache Member and Committer

email: paul.fr...@port.ac.uk, pa...@fremantle.org

twitter: pzfreo / skype: paulfremantle / blog: http://pzf.fremantle.org

[Kes Smith]

HI Paul,

Thanks for the ideas. I have been through the PubSubClient Library examples and couldn't figure out how to add a web server to any of those, which is the problem. I just do not know how to do it.

The effect I need is really simple; click on any of the 4 links in the code and immediately publish the topic and topic payload as shown, while the webserver continues to run. 

This is the code I have. I am now going in going in circles.

#include <SPI.h>

#include <Ethernet.h>

#include <EthernetClient.h>

#include <PubSubClient.h>

byte gateway[]         = { 192, 168, 1, 1   };                     // internet access via router

byte subnet[]          = { 255, 255, 255, 0 };                     // subnet mask

byte mac[]             = { 0xAE, 0xAE, 0xBE, 0xAE, 0xFE, 0xAE };   // physical mac address

byte ip_webserver[]    = { 192, 168, 1, 51  };                     // ip of webserver

byte ip_mqtt_server[]  = { 192, 168, 1, 120  };                    // MQTT webserver 

EthernetServer server(80);

void callback(char* topic, byte* payload, unsigned int length) { 

  // handle message arrived

}

IPAddress server2(ip_mqtt_server);

EthernetClient ethClient;

PubSubClient client(server2, 1883, callback, ethClient);

String readString;

void setup() { 

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

                server.begin();

                                

                client.setServer(server2, 1883);               // MQTT

                client.setCallback(callback);                  // MQTT

  

               

              }

void reconnect() {

   

  while (!client.connected())    {

                                       if (client.connect("arduinoClient")) 

                                       

                                           {  

                                               if (readString.indexOf("?lrm-main-on")  >0)  { client.publish("groungfloor/livingroom/mainlight_on_off", "on ");  }

                                               if (readString.indexOf("?lrm-main-off") >0)  { client.publish("groungfloor/livingroom/mainlight_on_off", "off");  }

                                               if (readString.indexOf("?lrm-side-on")  >0)  { client.publish("groungfloor/livingroom/sidelights_on_off","on" );  }

                                               if (readString.indexOf("?lrm-side-off") >0)  { client.publish("groungfloor/livingroom/sidelights_on_off","off");  }

                                                     

                                               //client.subscribe("headlands/groundfloor/bedroom4/temperature_DS18B20");

                                                                                            

                                           } 

                                           

                                           else 

                                           

                                           {

       

                                              Serial.print("failed, rc=");        

                                              Serial.println(" try again in 1 seconds");

                                              // Wait 1 seconds before retrying

                                              delay(1000);                              

         

                                           }

  

                                 }

              }

void loop() 

 //1st open bracket

 { 

  EthernetClient client = server.available();

  // 2nd open bracket

  if (client) {

       // 3rd open bracket    

       while (client.connected()) {   

                //4th open bracket         

                if (client.available()) {

     

                         char c = client.read();

                         //read char by char HTTP request

     

                                     // open bracket with closed bracket

                                     if (readString.length() < 100)    {

                                         //store characters to string

                                         readString += c;

                                          Serial.print(c);             }

                       //5th open bracket

                       if (c == '\n') {       //if HTTP request has ended

          

           ////////////////////////////////////

           //        HTML STARTED            // 

           ////////////////////////////////////

           //////////////////  HTML header statements /////////////////////////          

      

           client.println("<!DOCTYPE HTML PUBLIC '-//W3C//DTD HTML 4.01 Transitional//EN' 'http://www.w3.org/TR/html4/loose.dtd'>");

           client.println("<html xmlns='http://www.w3.org/1999/xhtml'>");

           client.println("<html><head><meta name='viewport' content='width=device-width'><title></title><style>a{color:blue}.content1{width: 20px; float:right;}.content2{width: 20px; float:left;}</style></head><body><center><br/>");

           //////////////////////////////////////////////////////

           //   LINKS to : Computer & Mobile,  LAN  &  WAN     // 

           //////////////////////////////////////////////////////

           

           client.println("<b><font size=+2 color='#CC33FF'>House</font></b><br/><br/>");

                      

           //////// Room Door Switches ////////////////////////////////////

           

           client.println("<b><font size=+1 color='#CC33FF'>Room Door Switches</font></b><br/>");

           client.println("<a href='/?lrm-main-on' target='x2'>LRm, Main Light On</a>&nbsp;&nbsp;&nbsp;<a href='/?lrm-main-off' target='x2'>LRm, Main Light Off</a><br/>");

           client.println("<a href='/?lrm-side-on' target='x2'>LRm, Side Light On</a>&nbsp;&nbsp;&nbsp;<a href='/?lrm-side-off' target='x2'>LRm, Side Light Off</a><br/>");

          

           

           ///////////////////////////////////////////////////////////////////////////////////

           //   CRITICAL ..  below iframe code stops page refresh on the button click       // 

           ///////////////////////////////////////////////////////////////////////////////////

           client.println("<iframe name=x2 style='display:none'></iframe>");

      

           ////////////////////////////////////

           

           client.println("<p></p></center></body></html>");

           ////////////////////////////////////

           //        HTML FINISHED           // 

           ////////////////////////////////////

 

  

           

           /////////////////////////////////////////////

           //        SWITCHING LOGIC BEGINS           // 

           /////////////////////////////////////////////

       

           // LRm Main Door Switch //

           

           // main on 

           if (readString.indexOf("?lrm-main-on")   >0){reconnect(); }

           

           // main off 

           if (readString.indexOf("?lrm-main-off") >0){reconnect(); }

                                                    

  

           // LRm Side Door Switch //

           // on button90, off button91

                      

           // side on 

           if (readString.indexOf("?lrm-side-on")   >0){reconnect();}

           // side off 

           if (readString.indexOf("?lrm-side-off") >0){reconnect();}

                                                    

           

           //clearing string for next read

           readString="";  

           

           delay(1);

           //stopping client

           client.stop();

                

            //5th bracket closed             

            }

         //4th bracket closed

         }

       

      //3rd bracket closed

      }

   //2nd bracket closed

   }

//1st bracket closed

}

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[Paul Fremantle]

Kes

I can't exactly figure out what you are up to here, but one thing is clear - you have mixed up the logic for publishing with the reconnect logic. You are also using the variable client for multiple different clients. I also can't spot a mqtt client loop.

Paul

[Kes Smith]

That's because I don't know anything about C. 

If you know of a simple example anywhere that runs a webster and can client.publish () the moment a Web link on the server is clicked.

I'm not too bothered about how it is achieved.

Thanks

[Paul Fremantle]

Kes

I don't have any examples like that.

Sorry

Paul

[Kes Smith]

Thanks for ideas Paul. 

When I get something going, I will fork it and anyone can then copy or improve it.