The MQTT protocol has taken great strength in recent years since it is simple, safe, practical and lightweight perfect for IoT and M2M applications.

Thanks to the contribution of developers and developers of MQTT applications, there are public MQTT Broker for Internet monitoring and control tests, are available to connect from any MQTT client in this case we will use HIVEMQ, which has dashboard to view MQTT connections and Web sockets, since it is public should have some considerations that we will see below.

Oficial Website: HiveMQ

Dashboard MQTT: HiveMQ

Connections Broker MQTT

Broker: broker.hivemq.com
TCP Port: 1883
Websocket Port: 8000

Other publics Broker’s

Test

Then we will do 2 tests:

Connection Broker MQTT HIVEMQ with Node-RED.
Connection Broker MQTT HIVEMQ with ESP8266 & Node-RED.

Connection Broker MQTT HIVEMQ with Node-RED

Node-RED MQTT Parameters

Using Node-RED previously installed on a local server in my network, we will make the MQTT connection with HIVEMQ to validate the connection from any MQTT client.

Connection Broker MQTT HIVEMQ with ESP8266 & Node-RED

In this case the module ESP8266 12E NodeMCU configured as client MQTT read a temperature sensor DS18B20 Protocol (Onewire) sends the temperature via MQTT to the Broker HIVEMQ and Node-RED installed in the local network requests the value of temperature and graph On Node-RED Dashboard.

MQTT Topic

“temperature/PDAControl/sensor”

Message

Temperature value examples “28.9”

Architecture MQTT

Full Video Explained ESP8266 HiveMQ & Node-RED

Similar Tests

Arduino IDE Code

The ESP8266 module is configured as an MQTT client and performs the periodic temperature reading of the DS18B20 sensor, connected to the D4 pin (Gpio 02), supply to 5v, with its respective recommended resistance in the maxim datasheet.

Requires libraries:

PubSubClient.h
OneWire.h
DallasTemperature.h

/* MQTT Client Temperature Onewire
* More information about projects PDAControl 
* PDAControl English http://pdacontrolen.com 
* Mas informacion sobre proyectos PDAControl
* PDAControl Espanol http://pdacontrolen.com 
* Channel Youtube https://www.youtube.com/c/JhonValenciaPDAcontrol/videos 
*/

#include < ESP8266WiFi.h >
#include < PubSubClient.h >
#include < OneWire.h >
#include < DallasTemperature.h >

// Data wire is plugged into port 2 on the Arduino
#define ONE_WIRE_BUS 2 // pin 2

// Setup a oneWire instance to communicate with any OneWire devices (not just Maxim/Dallas temperature ICs)
OneWire oneWire(ONE_WIRE_BUS);

// Pass our oneWire reference to Dallas Temperature. 
DallasTemperature sensors(&oneWire);

// Update these with values suitable for your network.

const char* ssid = "************";
const char* password = "************";
const char* mqtt_server = "broker.hivemq.com"; /// MQTT Broker
int mqtt_port = 1883;

WiFiClient espClient;
PubSubClient client(espClient);
long lastMsg = 0;
char msg[50];
int value = 0;

void setup() { 
 Serial.begin(115200);
 // Start up the library
 sensors.begin();
 
 setup_wifi();
 client.setServer(mqtt_server, mqtt_port);
 client.setCallback(callback);

 Serial.println("Connected ");
 Serial.print("MQTT Server ");
 Serial.print(mqtt_server);
 Serial.print(":");
 Serial.println(String(mqtt_port)); 
 Serial.print("ESP8266 IP ");
 Serial.println(WiFi.localIP()); 
 Serial.println("Modbus RTU Master Online");

 
}

void setup_wifi() {

 delay(10);
 // We start by connecting to a WiFi network
 Serial.println();
 Serial.print("Connecting to ");
 Serial.println(ssid);

 WiFi.begin(ssid, password);

 while (WiFi.status() != WL_CONNECTED) {
 delay(500);
 Serial.print(".");
 }

 Serial.println("");
 Serial.println("WiFi connected");
 Serial.println("IP address: ");
 Serial.println(WiFi.localIP());
}

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

void reconnect() {
 // Loop until we're reconnected
 while (!client.connected()) {
 Serial.print("Attempting MQTT connection...");
 // Attempt to connect
 if (client.connect("ESP8266Client")) {

 Serial.println("connected");
 // client.subscribe("event");
 } else {
 Serial.print("failed, rc=");
 Serial.print(client.state());
 Serial.println(" try again in 5 seconds");
 // Wait 5 seconds before retrying
 delay(5000);
 }
 }
}
void loop() {
 
 sensors.requestTemperatures();
 float celsius = sensors.getTempCByIndex(0);
 Serial.println(sensors.getTempCByIndex(0));
 
 char temperaturenow [15];
 dtostrf(celsius,7, 3, temperaturenow); //// convert float to char 
 client.publish("temperature/PDAControl/sensor", temperaturenow); /// send char 
 
 if (!client.connected()) {
 reconnect();

 }
 client.loop();

 delay(10000);
 
}

Materials and where to buy

Conclusions and recommendations

We consider that although technically the broker is public we do not realize applications that are constantly connected to this broker, and since it is free public HIVE has several legal aspects that must be taken into account.

We only perform fast tests, although it should be noted that they have mounted their IoT applications with this broker without any apparent inconvenience the service is active and public.

With a broker in the cloud (intenet) from anywhere we could connect our devices and applications without limits of IP addresses and other restrictions, currently research plans and services of MQTT servers.

In next tutorials we will try other public MQTT servers and interactions with FRED (Node-RED).

ESP8266 & Public MQTT Broker HiveMQ & Node-RED

Connections Broker MQTT

Other publics Broker’s

Test

Connection Broker MQTT HIVEMQ with Node-RED

Node-RED MQTT Parameters

Connection Broker MQTT HIVEMQ with ESP8266 & Node-RED

Architecture MQTT

Full Video Explained ESP8266 HiveMQ & Node-RED

Similar Tests

Arduino IDE Code

Materials and where to buy

Conclusions and recommendations

Other publics Broker’s

References

Leave a Reply Cancel reply