Officine Innesto
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Interfacing Arduino MKR or ESP via MQTT - Node-RED 101

A very basic tutorial on how to interface a microcontroller to an MQTT broker and interact with data on Node-RED.

BeginnerWork in progress1 hour15,941
Interfacing Arduino MKR or ESP via MQTT - Node-RED 101

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Code

MQTTexample.ino

Arduino
MQTT example code
/* This example shows how to use MQTT on the main dev boards on the market
 * HOW TO USE:
 * under connect method, add your subscribe channels.
 * under messageReceived (callback method) add actions to be done when a msg is received.
 * to publish, call client.publish(topic,msg)
 * in loop take care of using non-blocking method or it will corrupt.
 * 
 * Alberto Perro - Officine Innesto 2019
 */
 
#define BROKER_IP    "192.168.1.1"
#define DEV_NAME     "mqttdevice"
#define MQTT_USER    "mqtt_user"
#define MQTT_PW      "mqtt_password"

const char ssid[] = "wifi_ssid";
const char pass[] = "wifi_password";

#include <MQTT.h>

#ifdef ARDUINO_SAMD_MKRWIFI1010
#include <WiFiNINA.h>
#elif ARDUINO_SAMD_MKR1000
#include <WiFi101.h>
#elif ESP8266
#include <ESP8266WiFi.h>
#else
#error unknown board
#endif

WiFiClient net;
MQTTClient client;
unsigned long lastMillis = 0;

void connect() {
  Serial.print("checking wifi...");
  while (WiFi.status() != WL_CONNECTED) {
    Serial.print(".");
    delay(1000);
  }

  Serial.print("\nconnecting...");
  while (!client.connect(DEV_NAME, MQTT_USER, MQTT_PW)) {
    Serial.print(".");
    delay(1000);
  }
  Serial.println("\nconnected!");
  client.subscribe("/hello"); //SUBSCRIBE TO TOPIC /hello
}

void messageReceived(String &topic, String &payload) {
  Serial.println("incoming: " + topic + " - " + payload);
}

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, pass);

  // Note: Local domain names (e.g. "Computer.local" on OSX) are not supported by Arduino.
  // You need to set the IP address directly.
  //
  // MQTT brokers usually use port 8883 for secure connections.
  client.begin(BROKER_IP, 1883, net);
  client.onMessage(messageReceived);
  connect();
}

void loop() {
  client.loop();
  if (!client.connected()) {
    connect();
  }
  // publish a message roughly every second.
  if (millis() - lastMillis > 1000) {
    lastMillis = millis();
    client.publish("/hello", "world"); //PUBLISH TO TOPIC /hello MSG world
  }  
}

Credits

Officine Innesto

Officine Innesto

10 projects • 77 followers
Innovative company that deals with design & technology, connecting the physical with the digital world. Education - R&D - prototyping & more
Thanks to Joël Gähwiler.

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