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1. pingback from knolleary » Blog Archive » CurrentCostuino • November 19, 2008

2. pingback from knolleary » Blog Archive » Updated Client for MQTT library • January 29, 2009

3. pingback from Delphi can do MQTT too! • February 23, 2009

4. pingback from Updated Arduino MQTT client « knolleary • July 24, 2009

5. john cohn • January 1, 2010

   Hello and happy new year ! !. I was wondering if you’d have a few minutes to help me think through how to get your MQTT client for the arduino working wiht the Asynclabs WiShield for 802.11 (http://asynclabs.com/wiki/index.php?title=WiShield_1.0) . The WiShield uses the uip TCP/IP stack.. not the one in the standard Ethernet.h used by the Arduino ethernet shields. I’ve been fiddling with your code to see if I can map over to the different IP stack, but I’m afraid it’s a little beyond me. A few minutes of coaching from you might get me there. Please let me know if you’re available to talk. Thanks !
   -jc

6. nick • January 1, 2010

   Hi John – porting this library to other shields has been on my todo list for a while; so I’m happy to help if I can.

   I’ve had a quick look and it should be possible to do. The API provided by Ethernet.h is very simple; connect, read, write, disconnect, not much else. The trick will be figuring out how the equivalent functionality is surfaced by the WiShield library. The sample apps provided with WiShield should help do this.

   I’m back in the office next week; give me a shout on Sametime and we can take a close look.

7. john cohn • January 2, 2010

   Nick,
   Will do .. I just set up a mtg for us on Monday.. let me know if the time’s OK. I look forward to speaking with you about this and some other schemes. Thanks !
   -jc

8. Mark • January 3, 2010

   Hi
   Just wanted to say thanks for creating this client. Using this I have created a small web page that shows the temperature from a network connected Arduino. It is hosted on a tiny home server, so may take a few seconds to open….
   http://metphoto.homeunix.net/met_current/cgi-bin/ardtemp.pl

   I am no programmer, so could I ask for a small example of how to decode a message from a RSMB? I just cant quite get the code right to do this.

   Thanks
   Mark

9. Jerry • January 25, 2010

   Thanks for the MQTT client code Nick – I’ve been experimenting with this off and on for a month or two, using it with an Arduino duemilanove to demo MQTT to colleagues as a better way to read data from sensors than using the web server/Ethernet shield examples that are getting more coverage. BTW Mark’s PDF and project (link above) is a useful worked example, demonstrates the whole thing end to end and fills in some gaps in an unassuming kind of way.

10. Dave Nice • March 3, 2010

    Hi Nick,

    I’ve been using the MQTT library and I’ve got a couple of questions:

    If I lose my MQTT connection (e.g. unplug the network cable and wait for the library to realise it’s been disconnected), to get reconnected I have to call client.disconnect() first. Is this expected behaviour?

    Also, I have a 250ms pause at the end of my loop function. The effect of this is that client.loop() gets called less often. In your API doc it seems to indicate that I only need to call often enough to prevent the connection timing out and maintain my own preferred level of service on time to receive a message, is this correct?

    Thanks,

    Dave

11. nick • March 4, 2010

    Dave,

    #1 I haven’t done much with that scenario, so I couldn’t say for sure. There is no state cleared when you call disconnect, so it shouldn’t be necessary.

    #2 250ms will be fine. For a publishing-only client, you can get away with calling loop() once every keep-alive interval (fixed at 15secs). For a subscribed client, the same is true, but you will only get a message-arrived callback whilst in a call to loop() – it is up to you how timely you want the message delivery to be.

12. pingback from Progress! « Nick Marshall – Final Year Project • March 19, 2010

13. pingback from chemicaloliver » MQTT, Arduino, Old Ammeters and Bandwidth Monitoring • June 13, 2010

14. pingback from chemicaloliver » MQTT, Mosquitto and PHP • July 3, 2010

15. pingback from Updated Arduino MQTT Client « knolleary • July 20, 2010

16. pingback from MQTT, Mosquitto and PHP | chemicaloliver • September 4, 2010

17. pingback from A Smarter Planet needs lightweight messaging | The lost outpost • December 4, 2010

18. pingback from MQ Telemetry Transport » Blog Archive » MQTT ported to the mbed platform • December 20, 2010

19. pingback from Prototyping – Arduino and Ubuntu | The lost outpost • December 21, 2010

20. Andy Piper • December 27, 2010

    I found that this wouldn’t compile with current avr / Arduino 0021 IDE on Ubuntu. It was reporting an error avr/lib/gcc/../../avr/include/math.h:439: error: expected unqualified-id before ‘double’ (and a couple more compile issues related to that). I seem to have resolved it by commenting out #include “WConstants.h” in PubSubClient.cpp … you might also want to revisit the example you’ve posted here since the Ethernet library now requires SPI.h to be included. HTH

21. nick • December 27, 2010

    Thanks Andy. Funnily enough, I discovered the very same thing in the last couple of hours myself. I will be pushing updates soon.

    Update: version 1.5 now available above.

22. pingback from Updated Arduino MQTT Client « knolleary • December 27, 2010

23. pingback from Lightweight Messaging and Linux | The lost outpost • January 28, 2011

24. pingback from Arduino, Wifly and MQTT « Nick Marshall | Final Major Project • May 15, 2011

25. pingback from Nanode – a cheap networked arduino clone | Mosquitto • June 8, 2011

26. pingback from Arduinos, MQTT and Light levels - Matt Daubneys Blog • September 4, 2011

27. pingback from MQTT Caller Display – Hacking the BT Caller Display 50 Serial Port | chemicaloliver • October 2, 2011

28. Lee Wenger • October 14, 2011

    Hi Nick,

    I tried to post a comment here yesterday about some issues running the library (and examples) with the Arduino 1.0 build – did you get it? I assume you probably have to approve comments before they get posted and thats why its not showing up – thats all cool – i’d just appreciate any help you might have to offer.

    I have another question for you – It looks like the library assumes that you’re running communications over ethernet – i’d be interested in your thoughts about running it over zigbee – ideally the communications protocol would be abstracted and any actual comms protocol could be substituted in as needed. In my case, i’d want to bridge from zigbee to ethernet at some bridge point but it would be terribly cool I think if I could publish content from my wireless sensor network that is only connected wirelessly via the xbee v2 modules but directly into mqtt which then get routed around and ultimately bridged into ethernet and out to the internet as necessary. The reverse case would also be helpful. My C skills seriously suck or i’d just attempt it myself – i’m trying to improve but it will be awhile before I can tackle something like this.

29. Lee Wenger • October 14, 2011

    hmm – looks like the issue is that I can’t post the error output – I’ve tried to post it a couple times and seems to fail every time. I’m getting an error when I try and compile and upload to an arduino with the new Arduino 1.0 Beta. As I mentioned I’d give you the actual error output but your form here doesn’t seem to want to take it. All of the errors appear to stem from instantiating a virtual object somewhere within the library – “cannot declare field ‘PubSubClient::_client’ to be of abstract type ‘Client’ and then a number of errors that seem to be similarly related – …the following virtual functions are pure within ‘Client’ and then several. So it looks like the compiler used to allow you instantiate a virtual class and/or a class with virtual functions and now the compiler barfs on this. Just wondering if there are any easy ways to fix this?

    Thanks for the help – and seriously thanks for creating the library!

30. nick • October 14, 2011

    Hi Lee,
    Looks like your original comments with the error output went straight past moderation into the spam heap. Sorry about that.
    You need to grab the very latest code from github to get Arduino 1.0 Beta support – I’ve not done a zipped up release of that code yet.
    I had thought about making the library more agnostic of the transport, but ultimately I decided to keep the size down by dedicating it to one underlying library.
    MQTT itself does assume a TCP-based network layer beneath it, so with something like ZigBee a bit more work is needed to keep the same level of message assurance MQTT provides. This is where the MQTT-S protocol could come in – have a look on the docs page of mqtt.org – which is intended for the type of thing you describe.

    I’m hoping to do some more in this direction at some point.

31. Lee Wenger • October 15, 2011

    Thanks Nick for speedy reply – that did the trick.

    I’ll read up on MQTT-S thanks for the pointer.

    Again -thanks for your effort on this library – definitely a worthy addition to the arduino collective.

    lw

32. naxe • November 26, 2011

    Hi Nick
    Thanks Nick for your library .It works very well.
    I have a question about how to get the subscribe data form server and send out to serial port? The “void subscribe(topic)” do not have return data……

33. nick • November 26, 2011

    Hi Naxe,
    the call to subscribe() just sets up the subscription on the server; it doesn’t return a message. When the server sends your client a message, the callback function you provided in the constructor will get called.
    N

34. naxe • November 28, 2011

    Thank you ,i get it……

35. Dougie • February 22, 2012

    I think your example would be improved by adding a couple of lines in the callback function to do something with the message from MQTT.

    So I added
    Serial.begin(9600);
    in the setup() function

    and
    void callback(char* topic, byte* payload, int length) {
    // handle message arrived
    Serial.println(“Callback”);
    Serial.print(“Topic:”);
    Serial.println(topic);
    Serial.print(“Length:”);
    Serial.println(length);
    Serial.print(“Payload:”);
    Serial.write(payload,length);
    Serial.println();
    }

    I’ve also changed the Ethernet.begin(mac, ip); to Ethernet.begin(mac); so that the Arduino running as a client gets a DHCP address. My MAC address was generated using the technique at [Nick says: URL removed as it linked to a dead domain] as I don’t like using DE:AD:BE:EF:FE:ED since it’s not unique.

36. riddle • April 7, 2012

    Hi Nick,
    I just started playing with Arduino, could you give me some guidance on how can I use your library with Wifly Shield ? I am using Arduino Uno and SparkFun Wifly Shield. What I have done so far is I have successfully requested to a web site and get response using that shield.

37. nick • April 7, 2012

    Hi, I’ve not done it myself, but it should be fairly straightforward.

    You need an updated version of the WiFly shield library, I think this is the one: https://github.com/dpslwk/WiFly

    There is also this fork of my library that may be needed – https://github.com/dpslwk/pubsubclient

    At some point, I’ll merge the changes back into this library.

38. riddle • April 21, 2012

    Hi Nick,
    Thanks for the links. I’ve got it running and now getting more excited.

39. Nick_Liu • May 10, 2012

    Hi Nick:

    It’s now MQTT can on the wifi shield ??

40. pingback from RaspberryPi and MQTT Mosquitto | HumpA Blog • June 8, 2012

41. Doug • June 9, 2012

    I’m getting the following when using arduino IDE 1.0.1 and compiling the basic example

    mqtt_basic.pde:-1: error: invalid conversion from ‘void (*)(char*, byte*, int)’ to ‘void (*)(char*, uint8_t*, unsigned int)’
    mqtt_basic.pde:-1: error: initializing argument 3 of ‘PubSubClient::PubSubClient(uint8_t*, uint16_t, void (*)(char*, uint8_t*, unsigned int))’

42. nick • June 9, 2012

    Hi Doug. Yeah, I forgot to update the example when I made a minor api change in the last release. It’s fixed on github.

43. Eddie • June 16, 2012

    You sure it’s fixed? I’m getting the same prob.. v1.8. Says it was updated 3 months ago.

44. Eddie • June 16, 2012

    Example up the top compiles..

    Anyone tried using this code with cosm.com?

    https://cosm.com/docs/beta/mqtt/

45. nick • June 16, 2012

    Yes, the version on this page is the same as the one on github which is newer than the version in the v1.8 release.

    I’ve used it with Cosm in the past, and as you’ll see from my recent blog post, I’ve been doing other MQTT things with Cosm.

46. Eddie • June 16, 2012

    I’m a bit of a newbie to the scene.. How do I get meaningful values from the char* topic and byte* payload?

    I tried looping through the array but was nothing meaningful..

47. Eddie • June 16, 2012

    Sorry disregard that last message. Worked it out

48. Alessandro • June 21, 2012

    Could anybody post a quick example on using this library with Cosm?

    I’ve been able to test subscriptions from the arduino to a broker in my local network and to test.mosquitto.org, but not with api.cosm.com.

    1) I am using 216.52.233.121 (api.cosm.com)
    2) I call client.connect(“arduinoClient”) not sure if this is a problem
    3) It claims to connect (client.connect returns true), then I subscribe to “api_key/v2/feeds/myfeedid.csv”
    4) Nothing comes back in the callback

    I am certain the topic works since I can use it with mosquitto_sub.

    Any ideas?

    Thanks

    Alessandro

49. ilium007 • June 22, 2012

    Eddie – it would have been nice of you had of posted how you ‘worked it out; for others who are trying to do the same thing !

    Can someone please tell me how to get from the byte array back into a meaningful string ?

50. nick • June 22, 2012

    ilium007 – it depends what you mean by meaningful string.

    For the topic, it is already defined as a char* – a null-terminated string – so can be used as you would expect, such as pass to the Arduino String constructor.

    But the payload is not at all guaranteed to be null-terminated – as that entirely depends on what the publisher sent.

    There are plenty of string functions available for byte-arrays that are not null-terminated, for example strncmp for comparing strings of specified length:

    void callback(char* topic, byte* payload, unsigned int length) {
      if (length == 3 && strncmp(payload,"foo",3) {
         // Foo!
      }
    }
    

    If you want to use Arduino’s String object, then there is a extra step needed – as it doesn’t have a constructor that takes a byte-array and length. The extra step is to convert the byte array into a null-terminated char array.

    The expensive (but safe) way of doing this would be to allocate a new char array of length length+1, copy over the payload bytes and then set the last byte to NULL. You could then pass this array to the String constructor.

    There is an easier way of doing this, as long as length is not too big (for now, lets say under 100 – I won’t get into the whys of this here). In this instance, you can do the following:

    void callback(char* topic, byte* payload, unsigned int length) {
      // As long as length isn't too big, we can add a null to the payload:
      payload[length] = '\0';
      String strPayload = String((char*)payload);
    }
    

    This takes advantage of the fact that the client pre-allocates a large buffer for packets that is bigger than the payload that is returned in the callback. Setting payload[length] is safe to do as it is within the pre-allocated buffer.

    Hope that helps.

51. ilium007 • June 23, 2012

    (Nick says: three quick-fire comments collapsed down into one)

    Cheers !! I have a had a play with all of the above but I am not sure what the line:

    payload[length] = '';

    is saying.

    Also, when I run the first example I get the error:

    “invalid conversion from ‘byte*’ to ‘const char*’

    –

    This is what I have done with my callback function:

    void callback(char* topic, byte* payload, unsigned int length)
    {
      lcd.clear();
      lcd.setCursor(0,0);
      
      if ((payload[0])==80 && (payload[1])==80)
      {
        lcd.print("PUMP:");
        if (payload[2]==48 && payload[3]==49)
        {
          lcd.print("ON");
          //turn on the pump here; set digital pin high to trigger SSR
    
        }
        else if (payload[2]==48 && payload[3]==48)
        {
          lcd.print("OFF");
          //turn off the pump here; set digital pin low to trigger SSR
        }
        else
        {
          lcd.print("NA");
        }
      }
      delay(5000);
      lcd.clear();
    }
    

    I am not sure if this is the best way to handle a very simple MQ type message protocol. ANy suggestions welcome. I am trying to write a simple protocol that I will use to measure water in my various water tanks and then turn on/off pumps and open/close solenoid valves as necessary.

    –

    I should have added. At present to turn on a pump I would send a message:

    PP01

    to turn off:

    PP00

52. nick • June 23, 2012

    ilium007,
    that first example should have been strncmp((char*)payload,"foo",3) – it needs the explicit cast to the right type.

    The payload[length] = ''; line is actually payload[length] = '\0';. This sets the byte immediately after the payload to the null byte – which allows payload to be treated as a null-terminated string.

    I would change your if statements to be something like:

    if (length == 4 && strncmp((char*)payload,"PP01",4)==0) {
      // turn pump on
    } else if (length == 4 && strncmp((char*)payload,"PP00",4)==0) {
      // turn pump off
    }
    // etc
    

    That said, I would suggest changing your topic structure slightly. Rather than have a single topic for all commands you want to send to the arduino, use a different topic for each device connected. For example:

    foo/pump1
    foo/solenoid1
    foo/pump2
    ...
    

    You can then subscribe to foo/#. You would then publish a simple ’0′ or ’1′ to the appropriate topic to signify off or on. You may even publish the messages with the ‘retained’ flag set, so that if the Arduino loses its connection and reconnects, it’ll get back the last known state of all the devices when it resubscribes.

    Following this approach means the callback would be something like:

    //Note the use of strcmp rather than strncmp
    // this is because topic is already a null-terminated
    // string.
    if (strcmp(topic,"foo/pump2")==0) { 
     if (payload[0] == '0') {
      // Turn off
     } else if (payload[0] == '1') {
      // Turn on
     }
    } // etc
    

    (Wrap your code in <pre></pre> tags)

    ((I’m going to collapse your comments down to a single one))

    (((I should probably create a mailing-list of something for this sort of discussion, to save space here)))

53. ilium007 • June 24, 2012

    OK thanks. This has got me tearing my hair out ! I wasn’t brought up on C programming and I am having a hell of a time working out what data type I need to get these values in to publish to the MQTT queue from the Arduino.

    I have a Maxbotix sensor which I am getting a pulse width value (long) and converting into an int value through division to get a distance in cm. I assumed it would be easy to get this data type onto the queue via the publish method. I see it takes a topic as an array of characters but again I am stuck on the payload. It takes a byte array as the payload, as in, a NON null terminated array of bytes. How do I go from the int value to a byte array.

    Thanks

54. ilium007 • June 24, 2012

    My bad – I have just re-read the API reference and I now see that the publish method can take a char* for topic (I’m cool with that) and a char* for payload. I just need to get my int into a char*

    I am sure this is dead simple – I just don’t know how to do it ! I have run out of pins on my EtherTen and I can’t run Ethernet, my maxbotix sensor, LCD shield and serial. Serial has had to lose out to the LCD so now my only method of debugging my code is via LCD and MQTT !

55. nick • June 24, 2012

    ilium007 – check out the itoa C function:

    char payload[10];
    int i=1234; 
    itoa(i, payload, 10);
    

56. ilium007 • June 24, 2012

    Invalid conversion from long int to char*

    I didnt even know there was a data type of ‘long int’

    This is my code:
    for(int i = 0; i < arraySize; i++)
    {
    digitalWrite(swPin, HIGH); //bring high for 21us to start MaxSonar ranging
    delayMicroseconds(39);
    digitalWrite(swPin, LOW);
    pulse = pulseIn(pwPin, HIGH);
    cm = pulse/58; //58uS per cm
    //rangeValue[i] = pulse/58;

    char payload[10];
    itoa(cm, payload, 10);

    mqttClient.publish("tanks/status",cm);

    delay(10);
    }

    I am trying to output the distance measurement in the MQTT message. pulse is initiated as ‘long’, cm is an int

57. nick • June 24, 2012

    There’s lots of information on converting types on google… suggest you have a look there for now. Rather than debug your code here, I’ll mail you tomorrow.

58. ilium007 • June 24, 2012

    Apologies. Thanks for the help so far.

59. infohound • July 13, 2012

    Hi Nick. Thanks for writing and distributing this MQTT library for Arduino. Is there any way that you could post a quick Arduino example of how to print a received message (from a subscribed topic) using the callback function? I’ve reviewed the comments and documentation and am able to connect and publish messages, but just haven’t been able to quite figure this out. Thanks in advance for your time and help.

60. nick • July 13, 2012

    infohound, do you mean print the payload to Serial?

    Here are a couple examples that ought to work:

    // See caveats of this approach in comment #50
    void callback(char* topic, byte* payload, unsigned int length) {
      // As long as length isn't too big, we can add a null to the payload:
      payload[length] = '\0';
      String strPayload = String((char*)payload);
      Serial.println(strPayload);
    }
    

    void callback(char* topic, byte* payload, unsigned int length) {
      for (int i=0; i<length; i++) {
        Serial.print((char)payload[i]);
      }
      Serial.println();
    }
    

61. infohound • July 14, 2012

    Thanks Nick, but unfortunately neither of those worked. I had tried the first suggestion when reading the comments previously and just tried it again (along w/ the other) after your response. Unfortunately, I still can’t get it to work. I can successfully connect, subscribe and publish messages but can’t seem to receive them. I keep getting an “Error: Connection timed out” message from the Mosquitto broker that I’m using to publish. Other clients are able to receive the published messages but I haven’t been able to figure this out. Thanks again for your help and I’ll keep plugging away at it. If you happen to think of something that may help please let me know. Thanks again.

62. infohound • July 14, 2012

    Scratch that! I just got it. Thanks again for your help Nick!

63. Des • August 9, 2012

    Is this likely to work easily with other Wifi shields? e.g.
    http://bit.ly/OUByca

    Thanks!

64. nick • August 12, 2012

    Hi Des – it should work with any WiFi shield whose library extends the Arduino Ethernet client library. Following that link to RobotShop.com, I couldn’t find any details on what libraries their shields use, so I cannot say for certain.

65. Johan • August 14, 2012

    Hi Nick,

    Thanks alot for the effort, do you know whether your library supports the ethernet ENC28J60 chipset?

66. nick • August 14, 2012

    Hi Johan, there is a fork on github that claims support for that chipset (as is found on the Nanode, for example) – but I have to admit I haven’t kept up to date with where it has got to. https://github.com/njh/NanodeMQTT/

67. Johan • August 14, 2012

    @Nick, thanks for the reply, I’ll give it a shot.

68. Johan • August 14, 2012

    Hi Nick, tried, but Nanode with MQTT has severe space implications on my ATMega328. Is there no change that it might word with the EtherCard libaries that support ENC28J60? https://github.com/jcw/ethercard?

69. nick • August 15, 2012

    Hi Johan. The simple difference between the ENC28J60 hardware and the WizNet hardware used in the official shield is that WizNet implements the TCP layer of the networking stack for you, where as with the ENC28J60, you have to implement TCP yourself on the ATMega328.

    EtherCard, and older libraries for the ENC*, were intended for the simple request-response exchanges in HTTP. This meant their TCP implementation did not need to worry about multiple packet exchanges, or connections that lasted more than this simple exchange.

    MQTT requires a sustained TCP session, so requires more of TCP to be implemented.

    I see in the README for EtherCard there is experimental support for streamed data. Depending where that has got to and how reliable that is, then it might be feasible to port my library to use that as the underlying network layer. But that wouldn’t be a simple drop-in replacement and would require quite a lot of work.

    If at some point the EtherCard library was wrapped in a library that was API compatible with the official Ethernet library, then it would be easier to port.

70. Josh Hawley • August 29, 2012

    Hey Nick,
    Whenever I publish from the Arduino I receive the message ~10 times on my client. I am attempting to publish sensor data so it can be viewed by other devices. Any ideas on a good process that I can use to narrow down where the message is getting duplicated?

    Setup:
    Moquitto MQTT Broker 1.0.2 cygwin (http://mosquitto.org)
    MqttDotNet library for .Net (http://sourceforge.net/projects/mqttdotnet/)
    Arduino Uno R3 with and Arduino Ethernet Shield
    This library as of 8/26/2012.

71. nick • August 30, 2012

    Hi Josh. I would start by grabbing something like IA92 (http://mqtt.org/wiki/doku.php/ia92) to subscribe to the topic. Using a second subscriber will confirm if the duplicate messages are coming from the publisher (arduino) or are an issue with the subscriber (.NET client).

    If IA92 also receives the 10 messages, then the issue is on the arduino side. The next thing to check is the logic in your code. Add some tracing (ie Serial.println) to verify how many times your code is really calling publish. If it is genuinely only calling publish once, then it starts to get a bit more involved. At that point, I’d use something like Wireshark to look at the network traffic to see what is happening at the MQTT level.

    Hope that helps – if you want to follow up, drop me an email (nick at this domain).

72. Andrew Toth • October 9, 2012

    Nick,

    Nice work! Have this running on a Nanode connected to an LED message board vis RS232. Mode connectedness to come.

    Enjoying the projects on your site. Thanks for all your efforts.

73. soilboy • October 22, 2012

    Hi

    Has anybody got this library to work with cosm? I have the same issue as Alessandro a few months ago but not sure If he had any comments.

    I can publish fine to a public broker but NOT cosm.

    Cheers

74. nick • October 23, 2012

    Hi Soilboy – I have just successfully connected to cosm and subscribed to a feed – so it is possible. I think the problem Alessandro, and presumably you, are hitting is to do with the maximum packet size the client supports.

    Cosm allows you to specify your api in two different ways; either as the username or prefixed to the topic.

    If you prefix it to the topic, then every publish you receive will include the full api key (as the full topic is included in the packet). The additional 48 characters of API key may be pushing the packet size over the limit.

    I found that by specifying the api key as the username, rather than prefixing it, then the messages arrived as expected. This does mean you cannot use different api keys for each topic you may want access to from the arduino.

    The alternative is to increase the value of MQTT_MAX_PACKET_SIZE in PubSubClient.h.

    Hope that helps.

75. nick • October 27, 2012

    Following up my last comment, although I could connect, it was always a fairly unstable connection. I’ll write a post soon, but if you want to use this library with Cosm, you should grab the latest version from github – not the current ‘released’ version (1.8). The Cosm broker does not like MQTT packets being split over multiple TCP packets – which this library was doing. I have changed the code to not do this and now the connection is solid.

76. pingback from Updated Arduino Client for MQTT « knolleary • November 11, 2012

77. Josh Hawley • November 19, 2012

    What are the defaults for the smaller overloads on publish()? I assume that the length is calculated from the array that is passed in? Is retain set on or off by default? I looked in the API documentation, but it did not specify the default values.

78. nick • November 19, 2012

    Hi Josh – thanks for the question; Retain is false, and the payload is assumed to be a null-terminated string so its length can be determined. I’ve updated the API docs.

79. Franz Garsombke • February 5, 2013

    Thanks for a great and useful framework!

    I was wondering if this framework works with the RedFly-Shield?

    https://github.com/watterott/RedFly-Shield
    http://www.watterott.com/en/Arduino-RedFly-Shield

    Thanks again.

    Franz Garsombke

80. nick • February 5, 2013

    Hi Franz. I’m not aware of anyone using that shield with the library. I’ve had a quick look at its library and it looks like it implements the appropriate Client interface for it to work – but I’d want to try it out to be sure. I’m currently without a development environment thanks to a catastrophic attempt to upgrade Ubuntu on my laptop – once it’s back on its feet, I’ll have a closer look.

81. Franz Garsombke • February 5, 2013

    Thanks for checking into the library Nick. I just received the RedFly (from Germany!) and have somebody soldering it up. I will let you know if it works or not. Your framework works perfectly with the Ethernet Shield.

    I’ve had a few catastrophic upgrades Now I never upgrade Ubuntu, and just start clean

    Take care.

    Franz

82. Franz Garsombke • February 13, 2013

    Finally got the RedFly shield working. For some reason the RedFlyClient class extends Server which doesn’t make much sense to me.

    https://github.com/watterott/RedFly-Shield/blob/master/src/libraries/RedFly/RedFlyClient.h

    The PubSubClient input parameter is ‘Client’ so of course there is no matching function call. Doh!

    So, my guess is that it will not work without modifications to one of the libraries.

83. Nuno • April 13, 2013

    Hi!

    I’m working with an Arduino project and I would like to abstract the communication layer using this MQTT library. I did not see in any place whether the library works or not with a bluetooth shield instead an ethernet. Where I can find more information?

    Thanks!

84. nick • April 13, 2013

    Hi, I don’t know anyone using the library with a bluetooth shield, but the communication layer is already abstracted out so it should be possible. The library uses the Client interface for handling the network connection – by default it uses EthernetClient, but you can pass your own instance in one of the constructors. If you have, or can write, a library that uses that interface, it should work.

85. Nuno • April 30, 2013

    Hi Nick,
    Thank you for your answer. To clarify, I don’t have a bluetooth shield like I said, I’m working with a bluetooth modem like this: https://www.sparkfun.com/products/10393 Basically the pins RX/TX are connected to the Arduino board.
    Right now, I have a mini-library called “SerialClient” that it’s an encapsulation of a SoftwareSerial object with the Client interface. I’m using a SoftwareSerial object to have the hardwareSerial for debugging purposes.
    With this solution I still have a problem because the bluetooth modem is seen as a SerialPort in my computer. I also developed a proxy to forward all bytes from the serial port (bluetooth) to the final MQTT server.

    It works very well, now I can finally talk with my project through a MQTT server Or if you want, it’s easy to switch to the HardwareSerial and this way the Arduino can be connected using the USB cable.

    Later I can publish the mini-library in Github if it’s useful to anyone.

    Thank you!

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