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.

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MQTT over serial

I'm planning to build a 32 relay IOT node next to my Raspberry Pi. The relays will be controlled by an Arduino Mega 2560. The Pi will run Home Assistant and Mosquitto so I would prefer to communicate ...
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1answer
43 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 ...
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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 ...
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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 = "...
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1answer
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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"] = ...
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MQTT bridging with Arduino and ESP8266 - What software should I use?

Sorry for the vagueness in my question, I am just looking for ideas to point me in the correct direction please... I wish to connect many (read: 20+) different sensors to a local wifi network and ...
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ESP8266 MQTT client error

#include <PubSubClient.h> #include <ESP8266WiFi.h> //EDIT THESE LINES TO MATCH YOUR SETUP #define MQTT_SERVER "YOUR.MQTT.SERVER.IP" const char* ssid = "YOUR_SSID"; const char* password = "...
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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" #...
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Convert byte* to int in Arduino

I am trying to convert byte* value to int here is how I have it. void mqttCallback(char* topic, byte* payload, unsigned int length) { String topicStr = topic; int* payload_value; int ...
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811 views

Mosquitto TLS over WifiMulti on ESP8266

With these few lines I am able to attach my certificate, tell it to WifiClientSecure the certificate, start the wifi as well as the mosquito pubsubclient: WiFiClientSecure espClient; WiFi.begin(ssid, ...
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1answer
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ESP8266 fail to connect MQTT broker

I am using NodeMCU dev board with ESP8266 WIFI. Every time I try to connect to my local broker it returns this error: failed, rc=-2 try again in 5 seconds I am using Ubuntu 18.04, my local brokers ...
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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 ...
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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 ...
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1answer
934 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....
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Notoriously unstable ESP8266 MQTT-client

I am doing a project where an ESP8266 receives data from an Arduino Uno and publishes it via MQTT. After a random amount of time, it will stop sending data to my MQTT broker. It might be an hour, it ...
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1answer
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ESP8266 deep sleep and MQTT

I am working on a project were I am putting my board into deep sleep mode, and it wakes up with an interrupt from a sensor. When it wakes from deep sleep I would like to send a message to my MQTT ...
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1answer
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Use MQTT to update internal clock

I write code to upload to ESP8266. I wish to use time stamp in order to log events. I found an NTP sketch, I can work with ( since it has a wifi connection ), but I wish to keep my code as simple as ...
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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 ...
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Mosquitto doesn't work after reboot [closed]

When i restart my raspberry pi 4 and check for mosquitto status it brings to me active: failed it seems to be it works for just the first time when i setup it all i need is to communicate esp32 with ...
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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:...
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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 ...
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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 ...
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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: - ...
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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 ...
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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-...
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361 views

Controled in the led by Arduino UNO to Firebase through ESP8266-01+ MIT App Inventor

exchange community , help me community :( I want to control led by MIT App Inventor with used Arduino UNO to Firebase through ESP8266-01 Notes : 1-The led connected pin 11 on Arduino-Uno 2-The ...
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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 ...
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264 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 ...
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472 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/...
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1answer
235 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 ...
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602 views

MQTT subscribe callback fails to be called in ESP8266 deepsleep mode

Refer to ESP8266 deep sleep and MQTT I executed the code in the given link. However i am not able to receive the subscribe message that are send from MQTT test broker(MQTT Lens) on the serial ...
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2answers
359 views

How to get a list of IPs in a LAN using NodeMcu?

I'm going to create an IoT system. I use a Raspberry Pi as a MQTT broker and as a webserver. Every day, the Pi gets a new IP address, so I need to find its new IP address via ESP8266 to use this ...
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39 views

Arduino clients suddenly not able to connect (or publish) to MQTT

we are struggling with a project that has things (arduinos as clients) communicating to our MQTT broker (mosquitto) running on a DigitalOcean droplet (inside a docker). We have about 200 things at ...
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137 views

I can't send GPS data to server

I am trying to send gps location data every 3 seconds to mqtt server if it's updated but my device shows weird stack errors and resets. What i am missing? I am using tinygps++ and pubsubclient as ...
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274 views

Real-time Pub/Sub thru MQTT between JoyStick and OnBoard Drive units [both ESP8266] - Connection issues

I looked around for solutions to my issue by searching on the forum and elsewhere and haven't seen similar issues - (https://arduino.stackexchange.com/search?page=2&tab=Relevance&q=MQTT%...
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ESP8266 MQTT periodically disconnecting

I use an MQTT to communicate with an ESP8266. I'm using cloudmqtt.com and PubSubClient. Sometimes the ESP disconnects from the MQTT and reconnects. I checked the log from cloud and I got this data ...
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536 views

Soft WDT with HX711 and PubSubClient libraries

I'm using NodeMCU 0.9 My sketch crashes if the following 2 include are present in the sketch: #include <PubSubClient.h> #include <HX711.h> I obtain a Soft WDT reset If I do not use ...
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3answers
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ESP-01 not waking correctly up after deep sleep

I have an ESP-01 that I want to measure pool temperature with. It will send the data over MQTT to the broker. I have connected RST to GPIO16 so I can use the deep sleep functionality. Currently I am ...
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1answer
2k views

MQTT not working on ESP8266 (Nodemcu 0.9)

I'm trying to use NodeMCU on my ESP8266 (NodeMCU 0.9) but the board keep crashing and I don't understand why. I tested the mqtt broker using command line and it works perfectly, so I can suppose that ...
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1answer
228 views

How can I call the constructor of a Class after it called once? [closed]

I have a problem with Classes. I have a bunch of code, that code is uses Adafruit MQTT FONA library. I call the Class for make new Instance and Connect to specified server with this code; ...
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1answer
34 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 ...
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1answer
541 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 ...
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1answer
377 views

Mqtt not subscribe on topic that's converted from String to char array

I am still not sure what should be the exact Title for this question, because I don't know where the problem is. I am using #include <MQTTClient.h> mqtt library to subscribe on a topic. This ...
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2answers
839 views

Using MQTT to send time stamp - to Arduino

In previous question in this forum - I asked about updating clock on an ESP8266, using MQTT broker to send a time stamp on demand, in following manner: 1) ESP8266 sends a publish containing the ...
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1answer
213 views

Arduino Uno - MQTT message using PUBSUB on ESP8266

I'm trying to write code involving MQTT messages to operate an ESP8266 relay ( a Sonoff device ), using PubSub library. For some, unknown for me, reason - messages larger than 99 chars are not sent. ...
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1answer
713 views

String & Char concatenations

A newbie in Arduino- and I'm trying to concatenate string and chars ( well in python it is quite different ). I'm trying to post a MQTT message- constructed following format to the client.publish(...
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1answer
207 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 ?
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92 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"); }...
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1answer
149 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 ...
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1answer
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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' ...