Questions tagged [mqtt]

MQTT (Message Queuing Telemetry Transport) is a machine-to-machine (M2M)/"Internet of Things" connectivity protocol. The MQTT protocol enables a publish/subscribe messaging model in an extremely lightweight way. It is useful for connections with remote locations where a small code footprint is required and/or network bandwidth is at a premium.

Filter by
Sorted by
Tagged with
0 votes
0 answers
26 views

How to thread I/O in wESP32 MQTT loop

I have a simple Arduino program for a wESP32 Silicognition. I just want the program to publish an MQTT message when a button is pressed. My problem is that I have to keep the MQTT client loop running ...
1 vote
0 answers
40 views

ESP32- Sporadic slow receive of MQTT messages

Problem description: Every ~20+ published messages (using terminal), MCU receives that message in a very noticeable delay (mostly ~10 sec, few time it got up to 1 min). Upon receive (printed in Serial ...
  • 870
0 votes
1 answer
29 views

Arduino + ESP8266 to send MQTT messages

I'm wondering if an Arduino Uno (or any other 328 family) that connects via Serial to an ESP8266 can send MQTT messages, rather than AT commands.
  • 870
0 votes
0 answers
29 views

Arduino MQTT Library sending disconnect packets even though it is not called

I am trying to connect to AWS IoT through the Arduino Portenta H7 and I am following this blog (https://create.arduino.cc/projecthub/Arduino_Genuino/securely-connecting-an-arduino-mkr-wifi-1010-to-aws-...
0 votes
1 answer
49 views

PubSub'a - KeepAlive function not as expected

I'm using PubSubClient to pub/sub MQTT messages using ESP8266. As far as I know "Keep-alive" detects when a client went off-line after a period of time. I'm using library's example ...
  • 870
0 votes
0 answers
55 views

subscribing to thingspeak field using MQTT on dragino lg-01

I'm trying to subscribe to a channel field on thingspeak to get the value of it onto my dragino lg-01 before sending it over to my Arduino Uno for action. currently my gateway uses LoRa to receive ...
  • 11
1 vote
0 answers
513 views

ESP32 CAM : How to send good quality images via MQTT

Has anyone here ever used a ESP32 CAM to send an image via MQTT? I'd like to know what are the parameters to initialize the camera with (resolution, jpeg quality, etc.), because once I receive the ...
1 vote
0 answers
156 views

ESP8266 How to run MQTT Client and Http Client in one loop

Scenario: Existing project: read soft serial then do http post New project: MQTT player from other (MrDIY / MrDIY Audio Notifier · GitLab) Objective: Combine together (Result: successful ) Issue: When ...
  • 11
1 vote
0 answers
124 views

How to correctly use SSL certs with the Adafruit SIM800H

I am trying to use a Adafruit Sim800H to connect to Azure using MQTT with an SSL certificate. My first step is trying to put a new SSL certificate onto the board. To do this I am using this example ...
  • 111
2 votes
1 answer
103 views

ArduinoJson library parsing error

I am trying to retrieve JSON mqtt message I received in ESP32. void mqttMsgCallback(char* topic, byte* payload, unsigned int length) { payload[length] = '\0'; String _message = String((char*)...
2 votes
1 answer
1k views

OTA over MQTT for ESP32

Before starting working, I am just researching around how can I achieve OTA over MQTT in ESP32 in using Arduino IDE. The process I understand the esp listen to MQTT messages and then received that ...
1 vote
0 answers
103 views

How to get the value of a measurement transmitted by a BLE device?

I would like to use a BLE temperature sensor (such as the Inkbird IBS-TH1 Mini BLE Sensor), however, I want to be able to display the temperature measurements in my own website. To do this I am ...
  • 177
1 vote
0 answers
120 views

Is it possible to upload a private root certificate to an Arduino Nano33?

I'm trying to connect an Arduino Nano 33 to an mqtt broker with TLS authenticaton on the broker side. To do that I need my Arduino board to have access to the the root certificate. My understanding is ...
1 vote
0 answers
336 views

Multiple MQTT topics

I have 3 nodemcu's(ESP32) each connected with a sensor, from which I get data and send it to aws IoT-core. How can I send all 3 sensor's data by a single MQTT subscription? The below code is for a ...
3 votes
1 answer
725 views

Connect ESP32 via MQTT

For a project I am working on, I need to connect my ESP32 board to another server via MQTT protocol. I am using the Mosquitto MQTT Broker and it is presently on my laptop. Following is the test code I ...
  • 57
1 vote
1 answer
332 views

Message parsing from MQTT server

I'm making a NodeMCU based home automation. I adapted code I found on internet for controlling a device (say LED) via MQTT broker hosted on a Raspberry Pi. It works fine. But when I try to scale it up ...
1 vote
0 answers
863 views

How to avoid MQTT reconnect Loop

I have the following code designed to allow me to control my device from my website using mqtt broker while internet is available. I also built in a local webserver to control the device in case of ...
  • 45
0 votes
1 answer
351 views

I Can't Connect to my MQTT server via arduino

I have mosquitto MQTT installed on my VPS server which I can subscribe and publish to it using paho client thorugh websockets. However when I tried to connect to it through Arduino, I get the ...
0 votes
1 answer
1k views

PubSubClient: Subscription working, but callback never called

I am using an ESP32 (https://heltec.org/project/wifi-kit-32/) with a AM2302 DHT22 and an LDR, talking to mosquitto on a Linux box. Publishing data is working fine, other than the "exceeded ...
0 votes
2 answers
2k views

couldn't connect to MQTT broker via esp8266/32 and pub/sub client

I want to use hiveMQ public broker in my project that's the same broker as what available in PubSubClient esp8266 examples but when I change WiFi SSID and password in example and upload it I got this ...
1 vote
0 answers
28 views

4004 (NOT_FOUND) ON MQTT

I tried to send random data to MQTT but it's not working and I get: { "m2m:rsp" : { "rsc" : 4004, "rqi" : "123456", "pc" : "Resource not found", "to" : "5a185cedc6ad749b:...
2 votes
1 answer
113 views

MQTT connection not being recognised in void loop()

I am trying to publish MPU 9250 readings in the Adafruit IO sending the data from ESP32. The WiFi connection is being established, but the code is not going inside the if(mqtt.connected()) inside the ...
-1 votes
1 answer
161 views

Modbus TCP together with MQTT over same ethernet

I'm currently in a planning phase for a project. I want to read some sensor data over Modbus TCP, do some simple calculations on the Arduino and publish the results over MQTT. Which means I have 2 RJ-...
  • 99
1 vote
0 answers
348 views

Arduino Uno + NodeMCU serial to MQTT

I made a pool monitor with ORP + pH + temp sensor. I had everything working (apart from ORP sensor causing interference with pH sensor, but that is a different topic...) for the past couple days in a ...
  • 11
1 vote
1 answer
1k views

PubSubClient - MQTT_MAX_PACKET_SIZE How is it calculated

I'm using an ESP32, and I want to rule out a probable MQTT error. In PubSubClient , MQTT_MAX_PACKET_SIZE is set to 256. Is 256 the size for message only ? if not, what is left for message only ?
  • 870
1 vote
0 answers
43 views

how to serially off leds in an esp running mqtt

hi im using at tiny 85 to monitor dc switches and to serial print with this code below to esp8266 with local broker to turn leds on and off but its only working through mqtt but not with physical ...
0 votes
1 answer
169 views

ESP32 using PubSub, creating an error when implemted inside a library

I wish to combine into a single library Wifi + MQTT, for a multi devices project. right after boot, getting Wifi - I get an error the moment MQTT server is trying to connect: mqttClient.connect(...
  • 870
0 votes
2 answers
177 views

writing mqtt payload to spiffs file

I'm trying to write the payload of a MQTT message into a file in the SPIFFS file system of my esp32 board. I've tried this: if(file.print((long)payload)) { Serial.println("File was written"); }...
  • 1
1 vote
0 answers
394 views

node mcu disconnect from mqtt server

/* Basic ESP8266 MQTT example This sketch demonstrates the capabilities of the pubsub library in combination with the ESP8266 board/library. It connects to an MQTT server then: - ...
  • 63
1 vote
1 answer
2k views

Convert JSON into string for MQTT

I am trying to publish json object into string with following snippet JSONVar data; data["chipid"] = chipId; data["co2_equivalent"] = co2_equivalent.c_str(); data["tvoc"] = tvoc.c_str(); data["...
  • 115
4 votes
2 answers
8k views

How to connect to MQTT broker with TLS?

I have ESP8266 which is connecting to MQTT broker and it is working ok using user+pass with following code: #include <ESP8266WiFi.h> #include <PubSubClient.h> const char* ssid = "...
  • 143
1 vote
0 answers
154 views

How to edit code from Node-Red to Cayenne

I am working on a project to run some (relays or LED's) on an inputs (Pins) Arduino by esp8266-01s . now while searching on internet I found a video divided it two step that talks about the issue ...
1 vote
2 answers
7k views

esp32-cam publish image to mqtt

I want to publish image capture through ESP32-CAM to MQTT. Have following code : #include "WiFi.h" #include "esp_camera.h" #include "esp_timer.h" #include "img_converters.h" #include "Arduino.h" #...
  • 115
1 vote
0 answers
130 views

How to set ALPN ProtocolName when negotiating SSL using ArduinoBearSSL

I am trying to set up an Arduino MKR Wifi 1010 to push MQTT messages to AWS IOT. I am following this tutorial https://create.arduino.cc/projecthub/Arduino_Genuino/securely-connecting-an-arduino-mkr-...
  • 111
0 votes
1 answer
243 views

How to transmit data from Arduino to Raspberry Pi?

I am planning to build a network with five Arduino Mega devices, each of which will collect data using multiple sensors. Each Arduino will periodically transmit the sensor data to a gateway Raspberry ...
  • 119
1 vote
0 answers
2k views

esp32 arduino wifi disconnect

I have this code running on ESP32 connected to SVM30-J #include <WiFi.h> #include <PubSubClient.h> #include <Arduino_JSON.h> #include <svm30.h> // Replace the next variables ...
  • 115
1 vote
0 answers
400 views

ESP8266 mqtt publish + subscribe + serial read

seems I have some issues in my code as I subscribe for specific mqtt topic and also read same value via serial and publish it to mqtt. It takes time for device connected to serial to change setting ...
0 votes
1 answer
3k views

cast from 'char*' to 'char' loses precision

Bit of a noob here. Im trying to use the sensor number (float) in my mqtt topic, but cant seem to get this right. Any help would be appreciated. Keep getting this error (cast from 'char*' to 'char' ...
0 votes
1 answer
42 views

How to execute commands over desired amount of time

I have a program that receives 4 commands on 4 channels to change the color of an LED using mqtt communication. Lets just focus on two of the channels, the time and the red. I am sending a length of ...
0 votes
1 answer
866 views

MQTT on nano with Ethernet shield not working

I'm using an arduino nano with an ethernet shield (ENC28J60), and ethernet eem to be working (I can create a webserver with Ethercard library).However, i'm stuck when i try to connect to a MQTT ...
  • 143
1 vote
0 answers
836 views

How to parse data most efficiently coming through mqtt with ESP8266

I am writing a program that is currently set up like so: Python script running on my computer. Raspberry pi is the broker for the mqtt data transmission An ESP8266 is programmed to listen to/...
1 vote
1 answer
61 views

How do I change the scope of an object?

I am using the File/Examples/Adafruit MQTT Library/mqtt_ESP8266 example as a model for my code. In the example, the mqtt object is created as a global variable, and everything works fine. However, I ...
  • 11
1 vote
1 answer
3k views

publish json data to mqtt

I am trying to publish JSON data to mqtt with following code snippet #include <Arduino_JSON.h> JSONVar data; data["temperature"] = temperature; data["humidity"] = humidity; data["pressure"] = ...
  • 115
2 votes
1 answer
407 views

Publish chipid to mqtt using ESP32-CAM

I have been trying to push the data of temp, humidity, and pressure from a sensor to MQTT using ESP 32Cam, and was able to do using the following code: pressure = bme.readPressure(); //Convert the ...
1 vote
1 answer
400 views

ESP8266 Arduino MQTT callback with dynamic topics

I have a program that depending on user input, it creates one or several objects that will publish data to a MQTT broker, each one with a different topic. This is already done. The ESP8266 also has ...
0 votes
1 answer
455 views

Obtain retained MQTT message

I’m using ESP8266 with Arduino code. Each device posts a ‘state’ and an ‘avail’ messages for a specific topic. I wish to be able to read those retained messages and not only right after connecting ...
  • 870
1 vote
1 answer
1k views

Impossible to connect ESP32 with Mosquitto on Raspberry using certificates

I installed Mosquitto broker in Raspberry in my local network. I generated certificates in Raspberry as follows: sudo openssl genrsa -out ca.key 2048 sudo openssl req -new -x509 -days 3600 -key ca....
  • 29
0 votes
1 answer
560 views

Waking an ESP8266 from Light-Sleep using a signal from MQTT?

I was wondering if it would be possible to wake an ESP8266 from a request over MQTT while it is in Light-Sleep mode? I am planning to implement a smart switch that would receive messages from a ...
  • 3
0 votes
1 answer
787 views

MQTT PubSubClient connection problem with ESP32

I am experiencing some problems with string in Arduino application with ESP32. I don't understand why this code works: mqtt.setServer ("m20.cloudmqtt.com", port); //is OK and this does not work ...
  • 29
2 votes
2 answers
451 views

Connecting to MQTT causes DHT11 Sensor to stop working?

I have a project I am working on, based on an ESP32 from NodeMCU. I have a bunch of sensors connected to said ESP32 - they all work and the code itself "works" with a minor quirk. The issue in ...