![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/03\/ESP32-BME280-Temperature-Humidity-Pressure-Sensor-MQTT-Publish-Arduino-IDE-Node-RED.jpg?resize=1200%2C675&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nRecommended reading:<\/strong> What is MQTT and How It Works<\/a><\/p>\n\n\n\n The following diagram shows a high-level overview of the project we’ll build.<\/p>\n\n\n Before proceeding with this tutorial, make sure you check the following prerequisites.<\/p>\n\n\n\n We’ll program the ESP32 using Arduino IDE, so make sure you have the ESP32 add-on installed.<\/p>\n\n\n\n To use MQTT, you need a broker. We\u2019ll be using Mosquitto broker<\/a> installed on a Raspberry Pi. Read How to Install Mosquitto Broker on Raspberry Pi<\/a>.<\/p>\n\n\n\n You can use any other MQTT broker, including a cloud MQTT broker. We’ll show you how to do that in the code later on.<\/p>\n\n\n\n If you\u2019re not familiar with MQTT make sure you read our introductory tutorial: What is MQTT and How It Works<\/a>.<\/p>\n\n\n\n To use MQTT with the ESP32 we’ll use the Async MQTT Client Library<\/a>.<\/p>\n\n\n\n Installing the Async MQTT Client Library<\/strong><\/p>\n\n\n\n Alternatively, you can go to Sketch <\/strong>> Include Library<\/strong> > Add . ZIP<\/strong> library and select the library you’ve just downloaded.<\/p>\n\n\n\n Installing the Async TCP Library<\/strong><\/p>\n\n\n\n To use MQTT with the ESP, you also need the Async TCP library<\/a>.<\/p>\n\n\n\n Alternatively, you can go to Sketch <\/strong>> Include Library<\/strong> > Add . ZIP<\/strong> library and select the library you’ve just downloaded. <\/p>\n\n\n\n To get readings from the BME280 sensor module, we’ll use the Adafruit_BME280 library<\/a>. You also need to install the Adafruit_Sensor library<\/a>. Follow the next steps to install the libraries in your Arduino IDE:<\/p>\n\n\n\n 1. Open your Arduino IDE and go to Sketch <\/strong>> Include Library<\/strong> > Manage Libraries<\/strong>. The Library Manager should open.<\/p>\n\n\n\n 2. Search for \u201cadafruit bme280<\/strong> \u201d on the Search box and install the library.<\/p>\n\n\n To use the BME280 library, you also need to install the Adafruit Unified Sensor<\/a>. Follow the next steps to install the library in your Arduino IDE:<\/p>\n\n\n\n 3. Search for “Adafruit Unified Sensor<\/strong>“in the search box. Scroll all the way down to find the library and install it.<\/p>\n\n\n After installing the libraries, restart your Arduino IDE.<\/p>\n\n\n\n To learn more about the BME280 sensor, read our guide: ESP32 with BME280 Sensor using Arduino IDE (Pressure, Temperature, Humidity)<\/a>.<\/p>\n\n\n\n For this tutorial you need the following parts:<\/p>\n\n\n\n You can use the preceding links or go directly to MakerAdvisor.com\/tools<\/a> to find all the parts for your projects at the best price!<\/p> Wire the BME280 to the ESP32 as shown in the following schematic diagram with the SDA pin connected to GPIO 21<\/span> and the SCL pin connected to GPIO 22<\/span>.<\/p>\n\n\n Copy the following code to your Arduino IDE. To make it work for you, you need to insert your network credentials as well as the MQTT broker details.<\/p>\n\n\n View raw code<\/a><\/p>\n\n\n\n The following section imports all the required libraries.<\/p>\n\n\n\n Include your network credentials on the following lines.<\/p>\n\n\n\n Insert the Raspberry Pi IP address, so that the ESP32 connects to your broker.<\/p>\n\n\n\n If you’re using a cloud MQTT broker, insert the broker domain name, for example:<\/p>\n\n\n\n Define the MQTT port.<\/p>\n\n\n\n The temperature, humidity and pressure will be published on the following topics:<\/p>\n\n\n\n Initialize a Adafruit_BME280<\/span> object called bme<\/span>.<\/p>\n\n\n\n The temp<\/span>, hum<\/span> and pres<\/span> variables will hold the temperature, humidity and pressure values from the BME280 sensor.<\/p>\n\n\n\n Create an AsyncMqttClient<\/span> object called mqttClient<\/span> to handle the MQTT client and timers to reconnect to your MQTT broker and router when it disconnects.<\/p>\n\n\n\n Then, create some auxiliary timer variables to publish the readings every 10 seconds. You can change the delay time on the interval<\/span> variable.<\/p>\n\n\n\n We haven\u2019t added any comments to the functions defined in the next code section. Those functions come with the Async Mqtt Client library. The function\u2019s names are pretty self-explanatory.<\/p>\n\n\n\n For example, the connectToWifi()<\/span> connects your ESP32 to your router:<\/p>\n\n\n\n The connectToMqtt()<\/span> connects your ESP32 to your MQTT broker:<\/p>\n\n\n\n The WiFiEvent()<\/span> function is responsible for handling the Wi-Fi events. For example, after a successful connection with the router and MQTT broker, it prints the ESP32 IP address. On the other hand, if the connection is lost, it starts a timer and tries to reconnect.<\/p>\n\n\n\n The onMqttConnect()<\/span> function runs after starting a session with the broker.<\/p>\n\n\n\n If the ESP32 loses connection with the MQTT broker, it calls the onMqttDisconnect<\/span> function that prints that message in the serial monitor.<\/p>\n\n\n\n When you publish a message to an MQTT topic, the onMqttPublish()<\/span> function is called. It prints the packet id in the Serial Monitor.<\/p>\n\n\n\n Basically, all these functions that we\u2019ve just mentioned are callback functions. So, they are executed asynchronously.<\/p>\n\n\n\n Now, let\u2019s proceed to the setup()<\/span>. Initialize the BME280 sensor.<\/p>\n\n\n\n The next two lines create timers that will allow both the MQTT broker and Wi-Fi connection to reconnect, in case the connection is lost.<\/p>\n\n\n\n The following line assigns a callback function, so when the ESP32 connects to your Wi-Fi, it will execute the WiFiEvent()<\/span> function to print the details described earlier.<\/p>\n\n\n\n Finally, assign all the callbacks functions. This means that these functions will be executed automatically when needed. For example, when the ESP32 connects to the broker, it automatically calls the onMqttConnect()<\/span> function, and so on.<\/p>\n\n\n\n If your broker requires authentication, uncomment the following line and insert your credentials (username and password).<\/p>\n\n\n\n Finally, connect to Wi-Fi.<\/p>\n\n\n\n In the loop()<\/span>, you create a timer that will allow you to get new readings from the BME280 sensor and publishing them on the corresponding topic every 10 seconds.<\/p>\n\n\n\n Learn more about getting readings from the BME280 sensor: ESP32 with BME280 Temperature, Humidity and Pressure Sensor Guide<\/a>.<\/p>\n\n\n\n To publish the readings on the corresponding MQTT topics, use the next lines:<\/p>\n\n\n\n Basically, use the publish()<\/span> method on the mqttClient<\/span> object to publish data on a topic. The publish()<\/span> method accepts the following arguments, in order:<\/p>\n\n\n\n The QoS (quality of service) is a way to guarantee that the message is delivered. It can be one of the following levels:<\/p>\n\n\n\n With your Raspberry Pi powered on and running the Mosquitto MQTT broker, upload the code to your ESP32.<\/p>\n\n\n\n Open the Serial Monitor at a baud rate of 115200 and you’ll see that the ESP32 starts publishing messages on the topics we’ve defined previously.<\/p>\n\n\n The ESP32 is publishing temperature readings every 10 seconds on the esp32\/bme280\/temperature<\/strong>, esp32\/bme280\/humidity<\/strong>, and esp32\/bme280\/pressure<\/strong> topics. Now, you can use any dashboard that supports MQTT or any other device that supports MQTT to subscribe to those topics and receive the readings.<\/p>\n\n\n\n As an example, we’ll create a simple flow using Node-RED to subscribe to those topics and display the readings on gauges.<\/p>\n\n\n\n If you don’t have Node-RED installed, follow the next tutorials:<\/p>\n\n\n\n Having Node-RED running on your Raspberry Pi, go to your Raspberry Pi IP address followed by :1880.<\/p>\n\n\n\n The Node-RED interface should open. Drag three MQTT in nodes, and three gauge nodes to the flow.<\/p>\n\n\n Click the MQTT node and edit its properties.<\/p>\n\n\n The Server field refers to the MQTT broker. In our case, the MQTT broker is the Raspberry Pi, so it is set to localhost:1883. If you’re using a Cloud MQTT broker, you should change that field. <\/p>\n\n\n\n Insert the topic you want to be subscribed to and the QoS. This previous MQTT node is subscribed to the esp32\/bme280\/temperature<\/strong> topic. <\/p>\n\n\n\n Click on the other MQTT in nodes and edit its properties with the same server, but for the other topics: esp32\/bme280\/humidity<\/strong> and esp32\/bme280\/pressure<\/strong>. <\/p>\n\n\n\n Click on the gauge nodes and edit its properties for each reading. The following node is set for the temperature readings. Edit the other chart nodes for the other readings.<\/p>\n\n\n Wire your nodes as shown below:<\/p>\n\n\n Finally, deploy your flow (press the button on the upper right corner).<\/p>\n\n\n Alternatively, you can go to Menu <\/strong>> Import <\/strong>and copy the following to your Clipboard<\/strong> to create your Node-RED flow.<\/p>\n\n\n View raw code<\/a><\/p>\n\n\n\n Go to your Raspberry Pi IP address followed by :1880\/ui<\/em>.<\/p>\n\n\n\n You should get access to the current BME280 sensor readings on the Dashboard. You can use other dashboard-type nodes to display the readings on different ways.<\/p>\n\n\n That’s it! You have your ESP32 board publishing BME280 temperature, humidity and pressure readings to Node-RED via MQTT.<\/p>\n\n\n\n MQTT is a great communication protocol to exchange small amounts of data between devices. In this tutorial you’ve learned how to publish temperature, humidity and pressure readings from a BME280 sensor with the ESP32 to different MQTT topics. Then, you can use any device or home automation platform to subscribe to those topics and receive the readings. <\/p>\n\n\n\n Instead of a BME280 sensor<\/a>, you can use any other sensor like a DS18B20 <\/a>temperature sensor (ESP32 MQTT \u2013 Publish DS18B20 Temperature Readings<\/a>). <\/p>\n\n\n\n We hope you’ve found this tutorial useful. If you want to learn more about the ESP32, take a look at our resources:<\/p>\n\n\n\nProject Overview<\/h2>\n\n\n\n
![\"BME280](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/03\/BME280-publish-readings-node-red-mqtt.png?resize=885%2C679&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n
Prerequisites<\/h2>\n\n\n\n
Arduino IDE<\/h3>\n\n\n\n
\n
MQTT Broker<\/h3>\n\n\n
![\"Installing](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2017\/01\/mosquitto-broker.png?resize=200%2C197&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nMQTT Libraries<\/h3>\n\n\n\n
\n
async-mqtt-client-master<\/strong><\/del>\u00a0to\u00a0async_mqtt_client<\/strong><\/li>\n\n\n\n\n
AsyncTCP-master<\/strong><\/del>\u00a0to\u00a0AsyncTCP<\/strong><\/li>\n\n\n\nBME280 Sensor Libraries<\/h3>\n\n\n\n
![\"Installing](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2018\/08\/install-bme280.png?resize=786%2C443&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"Installing](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2019\/04\/adafruit_unified_sensor_library.png?resize=750%2C422&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nParts Required<\/h3>\n\n\n\n
\n
![](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2017\/10\/header-200.png?w=1200&quality=100&strip=all&ssl=1\")
<\/a><\/p>\n\n\n\nSchematic Diagram<\/h2>\n\n\n\n
![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2019\/06\/ESP32-bme280_schematic.jpg?resize=768%2C669&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nCode<\/h2>\n\n\n\n
\/*\n Rui Santos & Sara Santos - Random Nerd Tutorials\n Complete project details at https:\/\/RandomNerdTutorials.com\/esp32-mqtt-publish-bme280-arduino\/\n Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files.\n The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.\n*\/\n#include <Wire.h>\n#include <Adafruit_Sensor.h>\n#include <Adafruit_BME280.h>\n#include <WiFi.h>\nextern "C" {\n #include "freertos\/FreeRTOS.h"\n #include "freertos\/timers.h"\n}\n#include <AsyncMqttClient.h>\n\n#define WIFI_SSID "REPLACE_WITH_YOUR_SSID"\n#define WIFI_PASSWORD "REPLACE_WITH_YOUR_PASSWORD"\n\n\/\/ Raspberry Pi Mosquitto MQTT Broker\n#define MQTT_HOST IPAddress(192, 168, 1, XXX)\n\/\/ For a cloud MQTT broker, type the domain name\n\/\/#define MQTT_HOST "example.com"\n#define MQTT_PORT 1883\n\n\/\/ Temperature MQTT Topics\n#define MQTT_PUB_TEMP "esp32\/bme280\/temperature"\n#define MQTT_PUB_HUM "esp32\/bme280\/humidity"\n#define MQTT_PUB_PRES "esp32\/bme280\/pressure"\n\n\/\/ BME280 I2C\nAdafruit_BME280 bme;\n\/\/ Variables to hold sensor readings\nfloat temp;\nfloat hum;\nfloat pres;\n\nAsyncMqttClient mqttClient;\nTimerHandle_t mqttReconnectTimer;\nTimerHandle_t wifiReconnectTimer;\n\nunsigned long previousMillis = 0; \/\/ Stores last time temperature was published\nconst long interval = 10000; \/\/ Interval at which to publish sensor readings\n\nvoid connectToWifi() {\n Serial.println("Connecting to Wi-Fi...");\n WiFi.begin(WIFI_SSID, WIFI_PASSWORD);\n}\n\nvoid connectToMqtt() {\n Serial.println("Connecting to MQTT...");\n mqttClient.connect();\n}\n\nvoid WiFiEvent(WiFiEvent_t event) {\n Serial.printf("[WiFi-event] event: %d\\n", event);\n switch(event) {\n case ARDUINO_EVENT_WIFI_STA_GOT_IP:\n Serial.println("WiFi connected");\n Serial.println("IP address: ");\n Serial.println(WiFi.localIP());\n connectToMqtt();\n break;\n case ARDUINO_EVENT_WIFI_STA_DISCONNECTED:\n Serial.println("WiFi lost connection");\n xTimerStop(mqttReconnectTimer, 0); \/\/ ensure we don't reconnect to MQTT while reconnecting to Wi-Fi\n xTimerStart(wifiReconnectTimer, 0);\n break;\n }\n}\n\nvoid onMqttConnect(bool sessionPresent) {\n Serial.println("Connected to MQTT.");\n Serial.print("Session present: ");\n Serial.println(sessionPresent);\n}\n\nvoid onMqttDisconnect(AsyncMqttClientDisconnectReason reason) {\n Serial.println("Disconnected from MQTT.");\n if (WiFi.isConnected()) {\n xTimerStart(mqttReconnectTimer, 0);\n }\n}\n\n\/*void onMqttSubscribe(uint16_t packetId, uint8_t qos) {\n Serial.println("Subscribe acknowledged.");\n Serial.print(" packetId: ");\n Serial.println(packetId);\n Serial.print(" qos: ");\n Serial.println(qos);\n}\nvoid onMqttUnsubscribe(uint16_t packetId) {\n Serial.println("Unsubscribe acknowledged.");\n Serial.print(" packetId: ");\n Serial.println(packetId);\n}*\/\n\nvoid onMqttPublish(uint16_t packetId) {\n Serial.print("Publish acknowledged.");\n Serial.print(" packetId: ");\n Serial.println(packetId);\n}\n\nvoid setup() {\n Serial.begin(115200);\n Serial.println();\n \n \/\/ Initialize BME280 sensor \n if (!bme.begin(0x76)) {\n Serial.println("Could not find a valid BME280 sensor, check wiring!");\n while (1);\n }\n \n mqttReconnectTimer = xTimerCreate("mqttTimer", pdMS_TO_TICKS(2000), pdFALSE, (void*)0, reinterpret_cast<TimerCallbackFunction_t>(connectToMqtt));\n wifiReconnectTimer = xTimerCreate("wifiTimer", pdMS_TO_TICKS(2000), pdFALSE, (void*)0, reinterpret_cast<TimerCallbackFunction_t>(connectToWifi));\n\n WiFi.onEvent(WiFiEvent);\n\n mqttClient.onConnect(onMqttConnect);\n mqttClient.onDisconnect(onMqttDisconnect);\n \/\/mqttClient.onSubscribe(onMqttSubscribe);\n \/\/mqttClient.onUnsubscribe(onMqttUnsubscribe);\n mqttClient.onPublish(onMqttPublish);\n mqttClient.setServer(MQTT_HOST, MQTT_PORT);\n \/\/ If your broker requires authentication (username and password), set them below\n \/\/mqttClient.setCredentials("REPlACE_WITH_YOUR_USER", "REPLACE_WITH_YOUR_PASSWORD");\n connectToWifi();\n}\n\nvoid loop() {\n unsigned long currentMillis = millis();\n \/\/ Every X number of seconds (interval = 10 seconds) \n \/\/ it publishes a new MQTT message\n if (currentMillis - previousMillis >= interval) {\n \/\/ Save the last time a new reading was published\n previousMillis = currentMillis;\n \/\/ New BME280 sensor readings\n temp = bme.readTemperature();\n \/\/temp = 1.8*bme.readTemperature() + 32;\n hum = bme.readHumidity();\n pres = bme.readPressure()\/100.0F;\n \n \/\/ Publish an MQTT message on topic esp32\/BME2800\/temperature\n uint16_t packetIdPub1 = mqttClient.publish(MQTT_PUB_TEMP, 1, true, String(temp).c_str()); \n Serial.printf("Publishing on topic %s at QoS 1, packetId: %i", MQTT_PUB_TEMP, packetIdPub1);\n Serial.printf("Message: %.2f \\n", temp);\n\n \/\/ Publish an MQTT message on topic esp32\/BME2800\/humidity\n uint16_t packetIdPub2 = mqttClient.publish(MQTT_PUB_HUM, 1, true, String(hum).c_str()); \n Serial.printf("Publishing on topic %s at QoS 1, packetId %i: ", MQTT_PUB_HUM, packetIdPub2);\n Serial.printf("Message: %.2f \\n", hum);\n\n \/\/ Publish an MQTT message on topic esp32\/BME2800\/pressure\n uint16_t packetIdPub3 = mqttClient.publish(MQTT_PUB_PRES, 1, true, String(pres).c_str()); \n Serial.printf("Publishing on topic %s at QoS 1, packetId: %i", MQTT_PUB_PRES, packetIdPub3);\n Serial.printf("Message: %.3f \\n", pres);\n }\n}\n<\/code><\/pre>\n\tHow the Code Works<\/h3>\n\n\n\n
#include <Wire.h>\n#include <Adafruit_Sensor.h>\n#include <Adafruit_BME280.h>\n#include <WiFi.h>\nextern \"C\" {\n #include \"freertos\/FreeRTOS.h\"\n #include \"freertos\/timers.h\"\n}\n#include <AsyncMqttClient.h><\/code><\/pre>\n\n\n\n#define WIFI_SSID \"REPLACE_WITH_YOUR_SSID\"\n#define WIFI_PASSWORD \"REPLACE_WITH_YOUR_PASSWORD\"<\/code><\/pre>\n\n\n\n#define MQTT_HOST IPAddress(192, 168, 1, 106)<\/code><\/pre>\n\n\n\n#define MQTT_HOST \"example.com\"<\/code><\/pre>\n\n\n\n#define MQTT_PORT 1883<\/code><\/pre>\n\n\n\n#define MQTT_PUB_TEMP \"esp32\/bme280\/temperature\"\n#define MQTT_PUB_HUM \"esp32\/bme280\/humidity\"\n#define MQTT_PUB_PRES \"esp32\/bme280\/pressure\"<\/code><\/pre>\n\n\n\nAdafruit_BME280 bme;<\/code><\/pre>\n\n\n\nfloat temp;\nfloat hum;\nfloat pres;<\/code><\/pre>\n\n\n\nAsyncMqttClient mqttClient;\nTimerHandle_t mqttReconnectTimer;\nTimerHandle_t wifiReconnectTimer;<\/code><\/pre>\n\n\n\nunsigned long previousMillis = 0; \/\/ Stores last time temperature was published\nconst long interval = 10000; \/\/ Interval at which to publish sensor readings<\/code><\/pre>\n\n\n\nMQTT functions: connect to Wi-Fi, connect to MQTT, and Wi-Fi events<\/h3>\n\n\n\n
void connectToWifi() {\n Serial.println(\"Connecting to Wi-Fi...\");\n WiFi.begin(WIFI_SSID, WIFI_PASSWORD);\n}<\/code><\/pre>\n\n\n\nvoid connectToMqtt() {\n Serial.println(\"Connecting to MQTT\u2026\");\n mqttClient.connect();\n }<\/code><\/pre>\n\n\n\nvoid WiFiEvent(WiFiEvent_t event) {\n Serial.printf(\"[WiFi-event] event: %d\\n\", event);\n switch(event) {\n case ARDUINO_EVENT_WIFI_STA_GOT_IP:\n Serial.println(\"WiFi connected\");\n Serial.println(\"IP address: \");\n Serial.println(WiFi.localIP());\n connectToMqtt();\n break;\n case ARDUINO_EVENT_WIFI_STA_DISCONNECTED:\n Serial.println(\"WiFi lost connection\");\n xTimerStop(mqttReconnectTimer, 0);\n xTimerStart(wifiReconnectTimer, 0);\n break;\n }\n}<\/code><\/pre>\n\n\n\nvoid onMqttConnect(bool sessionPresent) {\n Serial.println(\"Connected to MQTT.\");\n Serial.print(\"Session present: \");\n Serial.println(sessionPresent);\n}<\/code><\/pre>\n\n\n\nMQTT functions: disconnect and publish<\/h3>\n\n\n\n
void onMqttDisconnect(AsyncMqttClientDisconnectReason reason) {\n Serial.println(\"Disconnected from MQTT.\");\n if (WiFi.isConnected()) { \n xTimerStart(mqttReconnectTimer, 0);\n }\n}<\/code><\/pre>\n\n\n\nvoid onMqttPublish(uint16_t packetId) {\n Serial.println(\"Publish acknowledged.\");\n Serial.print(\" packetId: \");\n Serial.println(packetId);\n}<\/code><\/pre>\n\n\n\nsetup()<\/h3>\n\n\n\n
if (!bme.begin(0x76)) {\n Serial.println(\"Could not find a valid BME280 sensor, check wiring!\");\n while (1);\n}<\/code><\/pre>\n\n\n\nmqttReconnectTimer = xTimerCreate(\"mqttTimer\", pdMS_TO_TICKS(2000), pdFALSE, (void*)0, reinterpret_cast<TimerCallbackFunction_t>(connectToMqtt));\nwifiReconnectTimer = xTimerCreate(\"wifiTimer\", pdMS_TO_TICKS(2000), pdFALSE, (void*)0, reinterpret_cast<TimerCallbackFunction_t>(connectToWifi));<\/code><\/pre>\n\n\n\nWiFi.onEvent(WiFiEvent);<\/code><\/pre>\n\n\n\nmqttClient.onConnect(onMqttConnect);\nmqttClient.onDisconnect(onMqttDisconnect);\n\/\/mqttClient.onSubscribe(onMqttSubscribe);\n\/\/mqttClient.onUnsubscribe(onMqttUnsubscribe);\nmqttClient.onPublish(onMqttPublish);\nmqttClient.setServer(MQTT_HOST, MQTT_PORT);<\/code><\/pre>\n\n\n\nBroker Authentication<\/h4>\n\n\n\n
mqttClient.setCredentials(\"REPlACE_WITH_YOUR_USER\", \"REPLACE_WITH_YOUR_PASSWORD\");<\/code><\/pre>\n\n\n\nconnectToWifi();<\/code><\/pre>\n\n\n\nloop()<\/h2>\n\n\n\n
unsigned long currentMillis = millis();\n\/\/ Every X number of seconds (interval = 10 seconds) \n\/\/ it publishes a new MQTT message\nif (currentMillis - previousMillis >= interval) {\n \/\/ Save the last time a new reading was published\n previousMillis = currentMillis;\n \/\/ New BME280 sensor readings\n temp = bme.readTemperature();\n \/\/temp = 1.8*bme.readTemperature() + 32;\n hum = bme.readHumidity();\n pres = bme.readPressure()\/100.0F;<\/code><\/pre>\n\n\n\nPublishing to topics<\/h3>\n\n\n\n
uint16_t packetIdPub1 = mqttClient.publish(MQTT_PUB_TEMP, 1, true, String(temp).c_str());\nuint16_t packetIdPub2 = mqttClient.publish(MQTT_PUB_HUM, 1, true, String(hum).c_str());\nuint16_t packetIdPub3 = mqttClient.publish(MQTT_PUB_PRES, 1, true, String(pres).c_str());<\/code><\/pre>\n\n\n\n\n
\n
Uploading the code<\/h2>\n\n\n\n
![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/03\/ESP32-Publish-BME280-Readings-MQTT-Serial-Monitor-Arduino-IDE.png?resize=839%2C522&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nPreparing Node-RED Dashboard<\/h2>\n\n\n\n
\n
http://raspberry-pi-ip-address:1880<\/code><\/pre>\n\n\n\n![\"Node-RED](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/03\/0-Node-RED-Drag-6-Nodes-MQTT-In-Chart-Gauge.png?resize=288%2C169&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"MQTT](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/03\/2-MQTT-In-Node-ESP32-Publish-Temperature-Node-RED-Flow.png?resize=499%2C371&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/03\/1-ESP32-Gauge-Temperature-Node-RED-Flow.png?resize=498%2C600&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/03\/3-ESP32-MQTT-Publish-Temperature-Humidity-Pressure-Node-RED-Flow.png?resize=474%2C219&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"Deploy](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2017\/06\/11_deploy_button.png?resize=138%2C40&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n[{"id":"5a45b8da.52b0d8","type":"mqtt in","z":"b01416d3.f69f38","name":"","topic":"esp32\/bme280\/temperature","qos":"1","datatype":"auto","broker":"8db3fac0.99dd48","x":340,"y":120,"wires":[["3042e15e.80a4ee"]]},{"id":"3042e15e.80a4ee","type":"ui_gauge","z":"b01416d3.f69f38","name":"","group":"37de8fe8.46846","order":2,"width":0,"height":0,"gtype":"gage","title":"Temperature","label":"\u00baC","format":"{{value}}","min":0,"max":"40","colors":["#00b500","#f7df09","#ca3838"],"seg1":"","seg2":"","x":610,"y":120,"wires":[]},{"id":"8ff168f0.0c74a8","type":"mqtt in","z":"b01416d3.f69f38","name":"","topic":"esp32\/bme280\/humidity","qos":"1","datatype":"auto","broker":"8db3fac0.99dd48","x":320,"y":200,"wires":[["29251f29.6687c"]]},{"id":"29251f29.6687c","type":"ui_gauge","z":"b01416d3.f69f38","name":"","group":"37de8fe8.46846","order":2,"width":0,"height":0,"gtype":"gage","title":"Humidity","label":"%","format":"{{value}}","min":"30","max":"100","colors":["#53a4e6","#1d78a9","#4e38c9"],"seg1":"","seg2":"","x":600,"y":200,"wires":[]},{"id":"681a1588.8506fc","type":"mqtt in","z":"b01416d3.f69f38","name":"","topic":"esp32\/bme280\/pressure","qos":"1","datatype":"auto","broker":"8db3fac0.99dd48","x":330,"y":280,"wires":[["41164c6.e7b3cb4"]]},{"id":"41164c6.e7b3cb4","type":"ui_gauge","z":"b01416d3.f69f38","name":"","group":"37de8fe8.46846","order":2,"width":0,"height":0,"gtype":"gage","title":"Pressure","label":"hPa","format":"{{value}}","min":"900","max":"1100","colors":["#a346ff","#bd45cb","#7d007d"],"seg1":"","seg2":"","x":600,"y":280,"wires":[]},{"id":"8db3fac0.99dd48","type":"mqtt-broker","z":"","name":"","broker":"localhost","port":"1883","clientid":"","usetls":false,"compatmode":false,"keepalive":"60","cleansession":true,"birthTopic":"","birthQos":"0","birthPayload":"","closeTopic":"","closeQos":"0","closePayload":"","willTopic":"","willQos":"0","willPayload":""},{"id":"37de8fe8.46846","type":"ui_group","z":"","name":"BME280","tab":"53b8c8f9.cfbe48","order":1,"disp":true,"width":"6","collapse":false},{"id":"53b8c8f9.cfbe48","type":"ui_tab","z":"","name":"Home","icon":"dashboard","order":2,"disabled":false,"hidden":false}]\n<\/code><\/pre>\n\tDemonstration<\/h2>\n\n\n\n
http://raspberry-pi-ip-address:1880\/ui<\/code><\/pre>\n\n\n\n![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/03\/5-ESP32-MQTT-Publish-Temperature-Humidity-Pressure-Node-RED-Dashboard.png?resize=822%2C842&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nWrapping Up<\/h2>\n\n\n\n
\n