Arduino UNO R4 WiFi sending data to node-red

[lukas12345678]

Hello everybody ,

I want to send data from sensors that are connected to my Arduino UNO R4 WiFi [https://amzn.eu/d/8ZAUdRp](https://Arduino UNO R4 Wifi) to node-red via my Wifi. I have found many sketches, but they all had some kind of flaw so they did not even compile. I have already tested that my Arduino can connect to the internet and I have set up an MQTT broker in my node-red. Now I just need a proper code to get started. Can anybody help me, please?

[lukas12345678]

#include <WiFi.h>
#include <PubSubClient.h>

// WiFi
const char *ssid = "xxxxxxxx"; // Enter your WiFi name
const char *password = "xxxxxxxx";  // Enter WiFi password

// MQTT Broker
const char *mqtt_broker = "broker.emqx.io";
const char *topic = "emqx/esp32";
const char *mqtt_username = "emqx";
const char *mqtt_password = "public";
const int mqtt_port = 1883;

// Set software serial baud to 115200;
Serial.begin(115200);
// Connecting to a Wi-Fi network
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.println("Connecting to WiFi..");
}
client.setServer(mqtt_broker, mqtt_port);
client.setCallback(callback);
while (!client.connected()) {
    String client_id = "esp32-client-";
    client_id += String(WiFi.macAddress());
    Serial.printf("The client %s connects to the public MQTT broker\n", client_id.c_str());
    if (client.connect(client_id.c_str(), mqtt_username, mqtt_password)) {
        Serial.println("Public EMQX MQTT broker connected");
    } else {
        Serial.print("failed with state ");
        Serial.print(client.state());
        delay(2000);
    }
}

For example this code does not compile, because it shows : Compilation error: 'WiFi' does not name a type
I have looked up this problem and many people encountered the same issue, however there does not seem to be a proper solution... I have already downloaded many libaries...

[lukas12345678]

Thank you for your answer!

I have tried the following Example: WiFiSimpleReceive

*
  ArduinoMqttClient - WiFi Simple Receive

  This example connects to a MQTT broker and subscribes to a single topic.
  When a message is received it prints the message to the Serial Monitor.

  The circuit:
  - Arduino MKR 1000, MKR 1010 or Uno WiFi Rev2 board

  This example code is in the public domain.
*/

#include <ArduinoMqttClient.h>
#if defined(ARDUINO_SAMD_MKRWIFI1010) || defined(ARDUINO_SAMD_NANO_33_IOT) || defined(ARDUINO_AVR_UNO_WIFI_REV2)
  #include <WiFiNINA.h>
#elif defined(ARDUINO_SAMD_MKR1000)
  #include <WiFi101.h>
#elif defined(ARDUINO_ARCH_ESP8266)
  #include <ESP8266WiFi.h>
#elif defined(ARDUINO_PORTENTA_H7_M7) || defined(ARDUINO_NICLA_VISION) || defined(ARDUINO_ARCH_ESP32) || defined(ARDUINO_GIGA) || defined(ARDUINO_OPTA)
  #include <WiFi.h>
#elif defined(ARDUINO_PORTENTA_C33)
  #include <WiFiC3.h>
#elif defined(ARDUINO_UNOR4_WIFI)
  #include <WiFiS3.h>
#endif

//#include "arduino_secrets.h"
///////please enter your sensitive data in the Secret tab/arduino_secrets.h
char ssid[] = "xxxxxxxx";    // your network SSID (name)
char pass[] = "xxxxxxxxx";    // your network password (use for WPA, or use as key for WEP)

// To connect with SSL/TLS:
// 1) Change WiFiClient to WiFiSSLClient.
// 2) Change port value from 1883 to 8883.
// 3) Change broker value to a server with a known SSL/TLS root certificate 
//    flashed in the WiFi module.

WiFiClient wifiClient;
MqttClient mqttClient(wifiClient);

const char broker[] = "TestBroker";
int        port     = 1883;
const char topic[]  = "arduino/simple";

void setup() {
  //Initialize serial and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }

  // attempt to connect to WiFi network:
  Serial.print("Attempting to connect to WPA SSID: ");
  Serial.println(ssid);
  while (WiFi.begin(ssid, pass) != WL_CONNECTED) {
    // failed, retry
    Serial.print(".");
    delay(5000);
  }

  Serial.println("You're connected to the network");
  Serial.println();

  // You can provide a unique client ID, if not set the library uses Arduino-millis()
  // Each client must have a unique client ID
  // mqttClient.setId("clientId");

  // You can provide a username and password for authentication
  // mqttClient.setUsernamePassword("username", "password");

  Serial.print("Attempting to connect to the MQTT broker: ");
  Serial.println(broker);

  if (!mqttClient.connect(broker, port)) {
    Serial.print("MQTT connection failed! Error code = ");
    Serial.println(mqttClient.connectError());

    while (1);
  }

  Serial.println("You're connected to the MQTT broker!");
  Serial.println();

  Serial.print("Subscribing to topic: ");
  Serial.println(topic);
  Serial.println();

  // subscribe to a topic
  mqttClient.subscribe(topic);

  // topics can be unsubscribed using:
  // mqttClient.unsubscribe(topic);

  Serial.print("Waiting for messages on topic: ");
  Serial.println(topic);
  Serial.println();
}

void loop() {
  int messageSize = mqttClient.parseMessage();
  if (messageSize) {
    // we received a message, print out the topic and contents
    Serial.print("Received a message with topic '");
    Serial.print(mqttClient.messageTopic());
    Serial.print("', length ");
    Serial.print(messageSize);
    Serial.println(" bytes:");

    // use the Stream interface to print the contents
    while (mqttClient.available()) {
      Serial.print((char)mqttClient.read());
    }
    Serial.println();

    Serial.println();
  }
}

and it compiled and was able to connect to my Wifi, however I still can´t connect to the MQTT broker as I get the following message:

Attempting to connect to WPA SSID: xxxxxxxxxxx

You're connected to the network

Attempting to connect to the MQTT broker: TestBroker

MQTT connection failed! Error code = -2

The port of my MQTT Broker in node-red is:

I guess for const char broker[] = "TestBroker"; I have to write something different than just the name...

[lukas12345678]

The only information I could find is the following table:

However, my error code states "-2" and I only can see 2 Connection Refused: Identifier rejected in the table...

[lukas12345678]

Your help is much appreciated! I am sorry that I came across as impolite...
I am just frustrated that I couldn't make it work as I imagined it being more straight forward😒.
I will try a few things and come back here, when I made progress.

[lukas12345678]

Hello,

with the help of my friend Fabian, I have managed to find a solution:

1. Open the Example: WiFi UDP Send and Receive String for Arduino UNO R4 Wifi.

2. Add your network name and password under "arduino_secrets.h".

3. Copy the number of the local port

unsigned int localPort = 2394;

4. Start Node-Red and connect an inject with Udp out. In Udp out add the number of the local port, the ID from IPAddress remoteIp(XXXXXXXX); and send a test message. You can also choose to attach to local port, which you can see on the serial monitor (IDE) after a message is received.

5. If it works, add a Udp in and connect it to a debug node. In Udp in add the number of the local port (in this case 2394) and that´s it

Please let me know, wether it works for you or not