ESP8266 NodeMCU MQTT - Post DS18B20 Sensor Readings (Arduino) | Random nerd tutorials (2023)

Learn how to publish DS18B20 temperature readings over MQTT with ESP8266 (NodeMCU) on any platform that supports MQTT or any other MQTT client. As an example, we will send the sensor readings to the Node-RED board and the ESP8266 will be programmed using the Arduino IDE.

Literature recommendations: What is MQTT and how does it work?

project description

The diagram below shows a high-level overview of the project we are going to create.

• The ESP8266 requests temperature readings from the DS18B20 sensor. The readings are published inesp/ds18b20/temperaturais;
• Node-RED is subscribedesp/ds18b20/temperaturaTheme. So it receives temperature readings from the DS18B20 and displays the readings on an indicator/chart;
• You can get the reads on any other MQTT compatible platform and manipulate them however you like.

previous requirements

Before proceeding with this tutorial, be sure to review the following prerequisites.

Arduino-IDE

We will be programming the ESP8266 using the Arduino IDE, so make sure you have the ESP8266 plugin installed.

• Installation des ESP8266 Boards in der Arduino IDE (Windows, Mac OS X, Linux)

MQTT-Corridor

To be able to use MQTT, you need a broker. we will useinsect repellentinstalled on a RaspberryPi. ReadHow to Install Mosquitto Broker on Raspberry Pi.

You can use any other MQTT broker, including a cloud MQTT broker. We'll show you how to do this in code later.

If you are not familiar with MQTT, be sure to read our introductory tutorial:What is MQTT and how does it work?.

MQTT Libraries

To use MQTT with ESP8266 we use theAsynchronous MQTT client library.

Installing the Async MQTT client library

1. Click here to download the Async MQTT client library🇧🇷 You should have a .zip folder in your Downloads folder
2. Extract the .zip folder and you should getasync-mqtt-client-masterPasta
3. Rename your folderasync-mqtt-client-masterProcliente_async_mqtt
4. move thatcliente_async_mqttinto the Arduino IDE libraries installation folder
5. Finally, open your Arduino IDE again

Alternatively you can go toDescribe>include library>add . postal codeLibrary and select the library you just downloaded.

Install the ESPAsync TCP library

In order to be able to use MQTT with ESP, you also need theESPAsync TCP-Bibliothek.

1. Click here to download the ESPAsync TCP Client Library🇧🇷 You should have a .zip folder in your Downloads folder
2. Extract the .zip folder and you should getESPAsyncTCP-MasterPasta
3. Rename your folderESPAsyncTCP-MasterProESPAsyncTCP
4. move thatESPAsyncTCPinto the Arduino IDE libraries installation folder
5. Finally, open your Arduino IDE again

Alternatively you can go toDescribe>include library>add . postal codeLibrary and select the library you just downloaded.

DS18B20 Temperatursensorbibliotheken

To connect to the DS18B20 temperature sensor, you need to install theBiblioteca One Wire de Paul StoffregenIt is inDallas Temperaturbibliothek🇧🇷 Follow the steps below to install these libraries.

1. Open your Arduino IDE and go toDescribe>include library>manage libraries🇧🇷 The library manager should open.

2. Type "a cable” in the search box and install Paul Stoffregen's OneWire library.

3. Then search for "Dallas' and install Miles Burton's DallasTemperature library.

After installing the libraries, restart your Arduino IDE.

To learn more about the DS18B20 temperature sensor, read our guide:ESP8266 DS18B20 Temperature Sensor with Arduino IDE (single, multiple, web server)

required parts

You will need the following parts for this tutorial:

• ESP8266(FileComparison of the best ESP8266 development boards)
• DS18B20 temperature sensor–DS18B20 with ESP8266 guidance
• 4.7K ohms resistance
• Raspberry Pi Board(FileThe best Raspberry Pi starter kits)
• MicroSD Card - Class 10 16GB
• Raspberry Pi power supply (5V 2.5A)
• Jumper fios
• Protoboard

You can use the links above or go directlyMakerAdvisor.com/herramientasto find all the parts for your projects at the best price!

schematic representation

Connect the DS18B20 to the ESP8266 as shown in the schematic diagram below, with the DS18B20's data pin connected to theGPIO4(D2).

Code

Copy the following code into your Arduino IDE. In order for it to work for you, you need to enter your network credentials as well as your MQTT broker details.

/* Rui Santos Full project details at https://RandomNerdTutorials.com/esp8266-nodemcu-mqtt-publish-ds18b20-arduino/ Permission is granted at no charge to anyone who obtains a copy of this software and accompanying documentation. The above copyright notice and this permission notice must be included in all copies or substantial portions of the Software.*/#include <OneWire.h>#include <DallasTemperature.h>#include <ESP8266WiFi.h>#include <Ticker.h >#include <AsyncMqttClient.h>#define WIFI_SSID "REPLACE_WITH_YOUR_SSID"#define WIFI_PASSWORD "REPLACE_WITH_YOUR_PASSWORD" // Raspberri Pi Mosquitto MQTT Broker#define MQTT_HOST IPAddress(192, 168, 1, XXX)// For an MQTT broker in the cloud, enter the domain name //#define MQTT_HOST "example.com"#define MQTT_PORT 1883// Temperature MQTT Topics#define MQTT_PUB_TEMP "esp/ds18b20/temperature"// GPIO where the DS18B20 is connected with const int oneWireBus = 4; // Configure an instance of oneWire to communicate with any OneWireOneWire device oneWire(oneWireBus); // Pass our OneWire reference to the Dallas temperature sensor DallasTemperaturesensors(&oneWire); // Temperature value float temp;AsyncMqttClient mqttClient;Ticker mqttReconnectTimer;WiFiEventHandler wifiConnectHandler ;WiFiEventHandler wifiDisconnectHandler ;Ticker wifiReconnectTimer;unsigned long prevMillis = 0; // Stores the last time the temperature was published const long interval = 10000; //Interval at which sensorvoid readings are published void connectToWifi() { Serial.println("Connecting to Wi-Fi..."); WiFi.begin(WIFI_SSID, WIFI_PASSWORD); } void onWifiConnect(const WiFiEventStationModeGotIP& event) { Serial.println("Connected to Wi-Fi"); connectToMqtt();}void onWifiDisconnect(const WiFiEventStationModeDisconnected& event) {Serial.println("Disconnected from Wi-Fi"); mqttReconnectTime.detach(); // Make sure we don't reconnect to MQTT while reconnecting to Wi-Fi wifiReconnectTimer.once(2, connectToWifi);}void connectToMqtt() { Serial.println("Connecting to MQTT... ") ; mqttClient.connect();}void onMqttConnect(bool sessionPresent) {Serial.println("Connected to MQTT."); Serial.print("Session exists: "); Serial.println(sessionPresent);}void onMqttDisconnect(AsyncMqttClientDisconnectRason Reason) {Serial.println("Disconnected from MQTT."); if (WiFi.isConnected()) {mqttReconnectTimer.once(2, connectToMqtt); }}/*void onMqttSubscribe(uint16_t packageId, uint8_t qos) { Serial.println("Subscription confirmed."); Serial.print("PackageID:"); Serial.println(PackageID); Serial.print(" qos: "); Serial.println(qos); } void onMqttUnsubscribe(uint16_t packageId) { Serial.println("Unsubscribe confirmed"); Serial.print("PackageID:"); Serial.println(packetId);}*/void onMqttPublish(uint16_t packetId) { Serial.print("Publishing confirmed."); Serial.print("PackageID:"); Serial.println(packetId); } void setup() { sensors.begin(); Serial.begin(115200); Serial.println(); wifiConnectHandler = WiFi.onStationModeGotIP(onWifiConnect); wifiDisconnectHandler = WiFi.onStationModeDisconnected(onWifiDisconnect); mqttClient.onConnect(onMqttConnect); mqttClient.onDisconnect(onMqttDisconnect); //mqttClient.onSubscribe(onMqttSubscribe); //mqttClient.onUnsubscribe(onMqttUnsubscribe); mqttClient.onPublish(onMqttPublish); mqttClient.setServer(MQTT_HOST, MQTT_PORT); // If your broker requires authentication (username and password), set it below //mqttClient.setCredentials("REPlACE_WITH_YOUR_USER", "REPLACE_WITH_YOUR_PASSWORD"); connectToWifi();}void loop() { unsigned long currentMillis = millis(); // Every X seconds (interval = 10 seconds) // Publish a new MQTT message if (currentmillis - oldMillis >= interval) { // Store the last time a new metric was published OldMillis = currentMillis; // New readings from temperaturesensors.requestTemperatures(); // Temperature in degrees Celsius temp =sensors.getTempCByIndex(0); // Temperature in Fahrenheit //temp =sensors.getTempFByIndex(0); // Publish an MQTT message on the topic esp/ds18b20/temp uint16_t packageIdPub1 = mqttClient.publish(MQTT_PUB_TEMP, 1, true, String(temp).c_str()); Serial.printf("Publication on topic %s at QoS 1, Package ID: %i ", MQTT_PUB_TEMP, Package IdPub1); Serial.printf("message: %.2f \n", temporary); 🇧🇷

see raw code

How the code works

In the next section, all required libraries are imported.

#include <OneWire.h>#include <DallasTemperature.h>#include <ESP8266WiFi.h>#include <Ticker.h>#include <AsyncMqttClient.h>

Please enter your network credentials in the following lines.

#define WIFI_SSID "REPLACE_WITH_YOUR_SSID" #define WIFI_PASSWORD "REPLACE_WITH_YOUR_PASSWORD"

Enter the Raspberry Pi's IP address for the ESP8266 to connect to your broker.

#define IP address MQTT_HOST(192, 168, 1, 106)

If you are using a cloud MQTT broker, enter the broker's domain name, for example:

#define MQTT_HOST "ejemplo.com"

Configure El Puerto MQTT.

#define MQTT_PORT 1883

We will post at temp noesp/ds18b20/temperaturaTheme. If you want to change the theme, change it on the next line.

#define MQTT_PUB_TEMP "esp/ds18b20/temperatura"

You can create more themes if you want.

Please configure your DS18B20 in the following lines. In our case it is related to thatGPIO4🇧🇷 You can connect it to any other GPIO.

// GPIO where the DS18B20 is connected to const int oneWireBus = 4; // Configure an instance of oneWire to talk to any OneWire device OneWire oneWire(oneWireBus); // Pass our OneWire reference to the Dallas temperature sensorDallasTemperaturesensors(&oneWire);

ÖTemperatureThe variable contains the temperature value of the DS18B20 temperature sensor.

fluctuation temperature;

Create oneAsyncMqttClientnamed objectmqtt-Clientto handle the MQTT client and timers to reconnect to your MQTT broker and router when the connection is lost.

AsyncMqttClient mqttClient;Ticker mqttReconnectTimer;WiFiEventHandler wifiConnectHandler;WiFiEventHandler wifiDisconnectHandler;Ticker wifiReconnectTimer;

Then create some timer helper variables to publish the readings every 10 seconds. You can change the delay time torestVariable.

unsigned previous longMillis = 0; // Stores the last time the temperature was published const long interval = 10000; // Interval at which sensor readings are posted

MQTT functions: connect to WiFi, connect to MQTT and WiFi events

We do not add comments to the functions defined in the following section of code. These functions are included in the Async Mqtt Client library. The function names are self-explanatory.

For example himconnectToWifi()Connect your ESP8266 to your router:

void connectToWifi () {Serial.println ( "Conectando a Wi-Fi ..."); WiFi.begin (WIFI_SSID, WIFI_PASSWORD);}

ÖConnection to Mqtt()Connect your ESP8266 to your MQTT broker:

void connectToMqtt () { Serial.println ( "Conectando ao MQTT ..."); mqttClient.conectar();}

ÖonMqttConnect()The function is executed after starting a session with the broker.

void onMqttConnect(bool sessionPresent) {Serial.println("Connected to MQTT."); Serial.print ("Aktuelle Sitzung: "); Serial.println (Presentsession);}

MQTT functions: detach and publish

When the ESP8266 loses the connection to the MQTT broker, it calls theonMqttDisconnectFunction that prints this message on the serial monitor.

void onMqttDisconnect (AsyncMqttClientDisconnectRason Reason) {Serial.println ("Desconectado do MQTT."); if (WiFi.isConnected()) {mqttReconnectTimer.once(2, connectToMqtt); }}

When you send a message to an MQTT topic, theonMqttPublish()function is called. Prints the package ID in Serial Monitor.

void onMqttPublish(uint16_t packageId) { Serial.print("Publishing confirmed"); Serial.print("PackageID:"); Serial.println(package id);}

Basically, all of the functions we just mentioned are callback functions. Therefore, they are executed asynchronously.

configure()

Now let's get to thoseconfigure()🇧🇷 Initialize the DS18B20 sensor and start serial communication.

sensores.begin();Serial.begin(115200);

The next two lines create handlers that allow the MQTT broker and the Wi-Fi connection to reconnect when the connection is lost.

wifiConnectHandler = WiFi.onStationModeGotIP(onWifiConnect);wifiDisconnectHandler = WiFi.onStationModeDisconnected(onWifiDisconnect);

Finally assign all callback functions. This means that these functions are carried out automatically when required. For example, when the ESP8266 connects to the broker, it automatically calls theonMqttConnect()function and so on.

mqttClient.onConnect(onMqttConnect);mqttClient.onDisconnect(onMqttDisconnect);//mqttClient.onSubscribe(onMqttSubscribe);//mqttClient.onUnsubscribe(onMqttUnsubscribe);mqttClient.onPublish(onMqttPublish);mqttClient.setServer(MQTT_HOST, MQTT_PORT);

Broker Authentication

If your broker requires authentication, uncomment the following line and enter your credentials (username and password).

mqttClient.setCredentials("REPLACE_WITH_YOUR_USERNAME", "REPLACE_WITH_YOUR_PASSWORD");

Finally, connect to Wi-Fi.

connectToWifi();

cycle()

nocycle(), create a timer to post new temperature readings foresp/d18b20/temperaturatopic every 10 seconds.

unsigned long currentMillis = millis(); // every X seconds (interval = 10 seconds) // post a new MQTTif(currentMillis - previousMillis >= interval) { // store the last time a new reading was posted previousMillis = current Millis; // New readings from temperaturesensors.requestTemperatures(); // Temperature in degrees Celsius temp =sensors.getTempCByIndex(0);

If you prefer the temperature in Fahrenheit, comment out the following line:

//temp = sensores.getTempFByIndex(0);

Learn more about the DS18B20 temperature sensor:ESP8266 DS18B20 Temperature Sensor with Arduino IDE (single, multiple, web server).

Post in topics

To post a message to an MQTT topic, use the following line:

uint16_t paqueteIdPub1 = mqttClient.publish(MQTT_PUB_TEMP, 1, grün, String(temp).c_str());

If you want to post further reading on other topics, you can duplicate this line at the top of thecycle().

Basically use thethe mail()method notmqtt-ClientPurpose of publishing data on a topic. Othe mail()The method accepts the following arguments, in this order:

• Subject MQTT(const char*)
• QoS (uint8_t): Quality of service: can be 0, 1 or 2
• Hold flag (bool): Hold flag
• Payload (const char*)

QoS (Quality of Service) is a way to ensure that the message is delivered. It can be one of the following levels:

• 0: The message is delivered once or not at all. The message is not recognized. There is no possibility of duplicate messages;
• 1: The message is delivered at least once, but can be delivered more than once;
• 2: the message is always delivered exactly once;
• Learn more about MQTT QoS.

Laden of Codes

With the Raspberry Pi powered on and the Mosquitto MQTT runner running, upload the code to your ESP8266.

Open Serial Monitor with a baud rate of 115200 and you will see the ESP8266 start sending messages.

Prepare the Node-RED board

The ESP8266 publishes temperature readings every 10 secondsesp/ds18b20/temperaturaTheme. Now you can use any MQTT capable board or any other MQTT capable device to subscribe to this topic and get the reads.

As an example, let's create a simple flow using Node-RED to subscribe to this topic and display the metrics in an indicator or chart.

If you don't have Node-RED installed, follow the tutorials below:

• Introducing Node-RED on the Raspberry Pi
• Installation and first steps with the Node-RED panel

With Node-RED running on your Raspberry Pi, go to your Raspberry Pi's IP address followed by: 1880.

http://raspberry-pi-ip-adresse:1880

The Node-RED interface should open. Drag an MQTT node, a Graph node, and a Caliber node into the stream.

Click on the MQTT node and edit its properties as follows:

The Server field refers to the MQTT broker. In our case, the MQTT broker is the Raspberry Pi, so it's set to localhost:1883. If you are using a Cloud MQTT broker, you must change this field. Enter the topic you want to subscribe to and the QoS.

Set the following properties for the indicator node.

Edit the chart node as follows:

Connect your nodes as shown below:

Finally, implement your flow (press the button in the top right corner).

Alternatively you can go toMenu>importand copy the following into yoursclipboardto create your Node-RED stream.

[{"id":"3eb4b485.bb948c","type":"mqtt de","z":"b01416d3.f69f38","name":"","subject":"eng/ds18b20/temperatur", "qos": "1", "Datentyp": "Auto", "Agent": "8db3fac0.99dd48", "x": 930, "y": 120, "Kabel": [["706fecd4.6f91a4 " , "47ed6377.491d6c"]]},{"id":"706fecd4.6f91a4","type":"ui_gauge","z":"b01416d3.f69f38","name":"","group" : " 37de8fe8.46846","order":2,"width":0,"height":0,"gtype":"calibrator","title":"Temperature","label":"ºC","format ":"{{value}}","min":0,"max":"40","colors":["#00b500","#f7df09","#ca3838"],"sec1": " " ,"seg2":"","x":1190,"y":100,"wires":[]},{"id":"47ed6377.491d6c","type":"ui_chart","z " :"b01416d3.f69f38","name":"","group":"2b7ac01b.fc984","order":4,"width":0,"height":0,"label":"Temperatur " , "chartType":"line","legend":"false","xformat":"HH:mm:ss","interpolate":"linear","nodata":"","point":false , "ymin":"","ymax":"","removeOlder":1,"removeOlderPoints":"","removeOlderUnit":"3600","cutout":0,"useOneColor":false,"colors " : ["#1f77b4","#aec7e8","#ff7f0e","#2ca02c","#98 df8a","#d62728","#ff9896","# 9467bd"," #c5b0d5"],"useOldStyle":false,"outputs":1,"x":1190,"y":160,"wires ":[[]]},{"id":"8db3fac0 .99dd48", "type":"mqtt-broker","z":"","name":"","broker":"localhost" ,"port":"1883","clientid":"" ,"usetls":false,"compatmode":false,"keepalive":"60","cleansession":true,"birthTopic":""," geburtQos":"0","birthPayload":"","closeTopic":" ","closeQos":"0","closePayload":"","willTopic":"","willQos":"0" ,"willPayload":""},{"id":" 37de8fe8.46846", "type":"ui_group","z":"","name":"DS18B20","tab":"53b8c8f9. cfbe48","order":1,"disp":true, "width": "6","collapse":false},{"id":"2b7ac01b.fc984","type":"ui_group"," z":"","name":"SENSORS","tab":"99ab8dc5.f435c","disp":true,"width":"6","collapse":false},{"id": "53b8c8f9.cfbe48","type":"ui_tab","z":"","name":"Home","icon":"dashboard","order":2,"disabled":false," hidden":false},{"id":"99ab8dc5.f435c ","type ":"ui_tab","z":"","name":"HTTP","icon":"panel","command ":1,"deaktiviert":false,"hidden":false }]

see raw code

Demonstration

Navigate to your Raspberry Pi's IP address followed by:1880/ui.

http://raspberry-pi-ip-address:1880/ui

You must have access to the current sensor readings on the dashboard (display and graph).

Is this! You have your ESP8266 board to publish sensor readings to Node-RED via MQTT.

Packaging

MQTT is an excellent communication protocol for exchanging small amounts of data between devices. In this tutorial, you learned how to send DS18B20 temperature readings to an MQTT topic using the ESP8266. You can then use any home automation device or platform to subscribe to this topic and get readings.

Instead of a DS18B20 you can use any other sensor:

• ESP8266 MQTT - Post BME280 temperature, humidity and pressure readings
• ESP8266 MQTT - Post DHT11/DHT22 temperature and humidity measurements

We hope you found this tutorial useful. If you're interested in learning more about the ESP8266, take a look at our resources:

• Home automation with ESP8266
• MicroPython programming with ESP32 and ESP8266
• More ESP8266 NodeMCU projects…

Thank you for reading.