Stop receiving information from the broker

HiveMQ Community Edition
1

Hello
I am trying to send a sensor reading in packets of 100 data in Json format. Everything works very well but only for a certain time, suddenly I stopped receiving data from the broker. I am using an Arduino Nano 33 Iot card, for the Mqtt connection I tried the PubSubClient and ArduinoMqttClient libraries and with both I had the same problem.

This is the code how I collect and send the data:

   JsonArray ArSensor1 = doc.createNestedArray("Sensor_1");

    for (int i = 0; i < 99; i++) {
      int var = analogRead(A0);
      for (int x = 0; x <= 1; x++) {
        ArSensor1.add(var);
      }
    }
    WriteBufferingStream bufferedWifiClient(wifiSSLClient, 64);
    serializeJson(doc, Serial);
    client.beginPublish(topic, measureJson(doc), 1);
    serializeJson(doc, bufferedWifiClient);
    bufferedWifiClient.flush();
    client.endPublish();
    doc.clear();

    Serial.println();
    delay(10);
    client.loop();```
2

Hello @AlejandroCA

Welcome to HiveMQ Community. Unfortunately I don’t have Arduino Nano 33 IoT card to troubleshoot the issue from my side but if you can share the full sketch code I can take a quick look and see if I can suggest something. Are you using HiveMQ Cloud? Please share more information on which HiveMQ edition you are using.

Best regards,
Diego from HiveMQ Team

3

hello, here is the complete code, thanks for the help.

#include <ArduinoMqttClient.h>
#include <ArduinoJson.h>
#include <ArduinoJson.hpp>
#include <SPI.h>
#include <WiFiNINA.h>
#include <WiFiSSLClient.h>
#include "avdweb_AnalogReadFast.h"
#ifdef ARDUINO_ARCH_SAMD
#define ser SerialUSB  
#else
#define ser Serial  
#endif


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

WiFiSSLClient wifiSSLClient;
MqttClient mqttClient(wifiSSLClient);

const char broker[] = "#######.s2.eu.hivemq.cloud";
int port = 8883;
const char topic[] = "myTopic";
String Cov = "";

const long interval = 25;
unsigned long previousMillis = 0;

DynamicJsonDocument doc(16384);  

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(F("Attempting to connect to WPA SSID: "));
  Serial.println(F(ssid));
  while (WiFi.begin(ssid, pass) != WL_CONNECTED) {
    // failed, retry
    Serial.print(".");
    delay(3000);
  }

  Serial.println(F("You're connected to the network"));
  Serial.println();
  // You can provide a username and password for authentication
  mqttClient.setUsernamePassword("USER1", "####");

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

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

    while (1)
      ;
  }

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


void loop() {
   unsigned long currentMillis = millis();
  doc.clear();
  if (currentMillis - previousMillis >= interval) {
    // save the last time a message was sent
    previousMillis = currentMillis;


    mqttClient.poll();
    //************ send message, the PLecSens_1rint interface can be used to set the message contents
    mqttClient.beginMessage(topic);

    JsonArray ArSensor1 = doc.createNestedArray("Sensor_1");

    for (int i = 0; i < 399; i++) {
      // int var = analogRead(A0);
      volatile uint16_t result;
      result = analogReadFast(A0);
      
      for (int x = 0; x <= 1; x++) {
        ArSensor1.add(result);
      }
    }

    serializeJson(doc, Serial);
    serializeJson(doc, mqttClient);

    mqttClient.endMessage();
    doc.clear();

    Serial.println();
    Serial.println(mqttClient.connected());
    delay(10);
  }
}
4

Hello @AlejandroCA

Arduino Nano 33 IoT has limited memory and I don’t know which type of analog sensor is connected to A0 pin and the JSON payload being generated but here are some suggestions.

  • The 16384 buffer size that you have set may be too large. You can experiment with smaller buffer sizes if you only need to send a small JSON message.

  • You can remove the serializeJson(doc, Serial); line if you only need to send the message via MQTT, it may consume less memory.

  • In the line 101 you are calling delay(10); after publishing a message to the MQTT broker. This will pause the execution of your program for 10 milliseconds before the next iteration of the loop begins, I think delay(5000); should be more appropriate in this case.

Best regards,
Diego from HiveMQ Team