![\"\"](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2018\/05\/featured-image-esp32-mqtt-publish-subscribe.jpg?resize=1200%2C675&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\nProject Overview<\/h2>\n\n\n\n
In this example, there’s a Node-RED application that controls ESP32 outputs and receives sensor readings from the ESP32 using MQTT communication protocol. The Node-RED application is running on a Raspberry Pi.<\/p>\n\n\n\n
We’ll use the Mosquitto broker installed<\/a> on the same Raspberry Pi. The broker is responsible for receiving all messages, filtering the messages, decide who is interested in them and publishing the messages to all subscribed clients.<\/p>\n\n\n\n The following figure shows an overview of what we\u2019re going to do in this tutorial.<\/p>\n\n\n\n Note:<\/strong> there’s also a similar tutorial on how to use the ESP8266 and Node-RED with MQTT<\/a>.<\/p>\n\n\n\n If you like home automation and you want to learn more about Node-RED, Raspberry Pi, ESP8266 and Arduino, we recommend trying our course: Build a Home Automation System with Node-RED, ESP8266 and Arduino<\/a>. We also have a course dedicated to the ESP32: Enroll in Learn ESP32 with Arduino IDE<\/a> course.<\/p>\n\n\n\n These are the parts required to build the circuit (click the links below to find the best price at Maker Advisor<\/a>):<\/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> The BME280 sensor module<\/a> reads temperature, humidity, and pressure. Because pressure changes with altitude, you can also estimate altitude. However, in this tutorial we’ll just read temperature and humidity. There are several versions of this sensor module, but we\u2019re using the one shown in the figure below.<\/p>\n\n\n\n The sensor can communicate using either SPI or I2C communication protocols (there are modules of this sensor that just communicate with I2C, these just come with four pins).<\/p>\n\n\n\n To use SPI communication protocol, use the following pins:<\/p>\n\n\n\n To use I2C communication protocol, the sensor uses the following pins:<\/p>\n\n\n\n We\u2019re going to use I2C communication with the BME280 sensor module. For that, wire the sensor to the ESP32 SDA and SCL pins, as shown in the following schematic diagram.<\/p>\n\n\n\n We’ll also control an ESP32 output, an LED connected to GPIO 4.<\/p>\n\n\n\n Here’s how your circuit should look:<\/p>\n\n\n\n There\u2019s an add-on for the Arduino IDE that allows you to program the ESP32 using the Arduino IDE and its programming language. Follow one of the next tutorials to prepare your Arduino IDE to work with the ESP32, if you haven\u2019t already.<\/p>\n\n\n\n After making sure you have the ESP32 add-on installed, you can continue with this tutorial.<\/p>\n\n\n\n The PubSubClient<\/a> library provides a client for doing simple publish\/subscribe messaging with a server that supports MQTT (basically allows your ESP32 to talk with Node-RED).<\/p>\n\n\n\n The library comes with a number of example sketches. See File<\/strong> >Examples<\/strong> > PubSubClient<\/strong> within the Arduino IDE software.<\/p>\n\n\n\n Important: <\/strong>PubSubClient is not fully compatible with the ESP32, but the example provided in this tutorial is working very reliably during our tests.<\/p>\n\n\n\n To take readings from the BME280 sensor module we’ll use the Adafruit_BME280 library<\/a>. Follow the next steps to install the library in your Arduino IDE:<\/p>\n\n\n\n Alternatively, you can go to Sketch<\/strong> > Include Library<\/strong> > Manage Libraries<\/strong> and type “adafruit bme280<\/strong>” to search for the library. Then, click install.<\/p>\n\n\n\n To use the BME280 library, you also need to install the Adafruit_Sensor library<\/a>. Follow the next steps to install the library:<\/p>\n\n\n\n![\"\"](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2018\/05\/ESP32-MQTT-bme280.png?resize=800%2C425&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\nPrerequisites<\/h2>\n\n\n\n
Parts Required<\/h2>\n\n\n\n
![\"\"](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2018\/05\/parts-required-esp32-bme280-pressure-humidity-temperature.jpg?resize=750%2C339&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\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\nIntroducing the BME280 Sensor Module<\/h2>\n\n\n\n
![\"\"](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2018\/05\/bme280-temperature-humidity-pressure-esp32.jpg?resize=750%2C474&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\nSchematic<\/h2>\n\n\n\n
![\"\"](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2018\/05\/ESP32-bme280-led_bb-1.png?resize=750%2C460&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n![\"\"](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2018\/05\/circuit-breadboard.jpg?resize=600%2C448&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\nPreparing the Arduino IDE<\/h2>\n\n\n\n
Installing the PubSubClient Library<\/h4>\n\n\n\n
pubsubclient-master<\/del> to pubsubclient<\/strong><\/li>Installing the BME280 library<\/h4>\n\n\n\n
Adafruit-BME280-Library-master<\/del> to Adafruit_BME280_Library<\/strong><\/li>Installing the Adafruit_Sensor library<\/h4>\n\n\n\n
![\"\"](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2018\/05\/import-node-red-mqtt-esp32.png?resize=987%2C94&quality=100&strip=all&ssl=1\")
<\/a><\/figure><\/div>\n\n\n\n![\"\"](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2017\/11\/import-nodes.png?resize=523%2C291&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n![\"\"](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2018\/01\/node-red-import-flow.png?resize=503%2C337&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n![\"\"](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2018\/05\/node-red-flow-mqtt-esp32-publish-subscribe.png?resize=506%2C388&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n![\"\"](\"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\n![\"\"](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2018\/05\/node-red-ui-output-temperature-humidity.png?resize=517%2C699&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n\n