Basic mqtt publisher exmaple using YunClient

Official Hardware Classic Yún
1

Hi,

I have spent a few days trying to get my YUN to communicate with a MQTT Broker - I am a total Newbie. I thought I would create this brief thread to assist others.

I first installed a MQTT Broker - Mosquitto. Install using the packages created for your distro (Download | Eclipse Mosquitto)

Open two SSH sessions to the server hosting the broker:
In the one session start the broker:

mosquitto -v

In the second session start a subscriber to the broker:

mosquitto_sub -h localhost -t \# -v

For the subscriber you can subscribe to a specify topic:

mosquitto_sub -h localhost -t outTopic -v

You need to install the PubSubClient library, this can be downloaded from:

The sketch for the Yun is as follows:

#include <YunClient.h>
#include <PubSubClient.h>

#define MQTT_SERVER "x.x.x.x"

#define MQTT_CLIENTID "YUN-Sensor"

void callback(char* topic, byte* payload, unsigned int length) {
  // handle message arrived
}

YunClient yun;
PubSubClient mqtt(MQTT_SERVER, 1883, callback, yun);

void setup()
{
  Serial.begin(9600);
  Bridge.begin();
  if (mqtt.connect(MQTT_CLIENTID)) {
    mqtt.publish("outTopic","hello world");
    mqtt.subscribe("inTopic");
  }
}

void loop()
{
  mqtt.loop();
}

NB: If you subscribed to a specific topic using the mosquitto subcriber, make sure the topic in the YUN Sketch matches.

References:

That's about it
Regards

2

Gregg:
Hi,

I have spent a few days trying to get my YUN to communicate with a MQTT Broker - I am a total Newbie. I thought I would create this brief thread to assist others.

I first installed a MQTT Broker - Mosquitto. Install using the packages created for your distro (Download | Eclipse Mosquitto)

Open two SSH sessions to the server hosting the broker:
In the one session start the broker:

mosquitto -v

In the second session start a subscriber to the broker:

mosquitto_sub -h localhost -t \# -v

For the subscriber you can subscribe to a specify topic:

mosquitto_sub -h localhost -t outTopic -v

You need to install the PubSubClient library, this can be downloaded from:
GitHub - knolleary/pubsubclient: A client library for the Arduino Ethernet Shield that provides support for MQTT.

The sketch for the Yun is as follows:

#include <YunClient.h>

#include <PubSubClient.h>

#define MQTT_SERVER "x.x.x.x"

#define MQTT_CLIENTID "YUN-Sensor"

void callback(char* topic, byte* payload, unsigned int length) {
  // handle message arrived
}

YunClient yun;
PubSubClient mqtt(MQTT_SERVER, 1883, callback, yun);

void setup()
{
  Serial.begin(9600);
  Bridge.begin();
  if (mqtt.connect(MQTT_CLIENTID)) {
    mqtt.publish("outTopic","hello world");
    mqtt.subscribe("inTopic");
  }
}

void loop()
{
  mqtt.loop();
}




NB: If you subscribed to a specific topic using the mosquitto subcriber, make sure the topic in the YUN Sketch matches.

References:
http://knolleary.net/arduino-client-for-mqtt/
http://jpmens.net/2013/10/15/mqtt-on-the-arduino-yun/

That's about it
Regards

Hi friend,
I am working on "Arduino Nano + Ethernet shield"

  • Firmware upload to Arduino is done (example code given in Arduino)
  • Could you please help me in what things (at PC side) to be done to subscribe/ publish the messages.

Thanks in advance

3

sreenivas:
...
I am working on "Arduino Nano + Ethernet shield"

  • Firmware upload to Arduino is done (example code given in Arduino)
  • Could you please help me in what things (at PC side) to be done to subscribe/ publish the messages.
    ...

You might have better luck repost this at:

Interfacing w/ Software on the Computer

http://forum.arduino.cc/index.php?board=12.0

4

I'm interested too in MQTT with arduino Yun.

I have read (here I think: http://blog.mongohq.com/building-mongodb-into-your-internet-of-things-a-tutorial/ ) that the matt library for arduino is not complete and this let me thought: ohu but I have an arduino yun that is much more!

Why do not implement the mqtt publisher inside the linux part? like with mosca ( GitHub - moscajs/mosca: MQTT broker as a module ) for node.js or mosquitto (http://mosquitto.org/documentation/python/ ) with python..
it should be easier (at list I think) also include some security layer (that as far as I got matt per-se does not provide)..

so.. why mqtt in the arduino side? to develop some kind of code usable also for an arduino uno plus ethernet shield?

5

If you type

opkg update
opkg list | grep -i mosquitto

You'll find that mosquitto is available for the yun as an additional package. I think there are topics on the forum where someone described her implementation of yun and mosquitto. Or maybe it's some blog I've read (can't remember really)