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The BME280 sensor is used to measure readings regarding ambient temperature, barometric pressure, and relative humidity. These two components measure humidity and temperature. They are internally composed of a humidity sensing sensor and a thermistor. We can directly connect them with ESP32 to obtain sensor output reading. It provides a calibrated digital output with a 1-wire protocol. Our ESP32 MQTT Publisher is connected with a DHT22 sensor, a BME280 sensor, and a DS18B20 sensor.ĭHT22 is a sensor which measures relative humidity and temperature. This protocol runs on top of TCP / IP in order to provide reliable data delivery.įor a detailed tutorial regarding MQTT, its main components, MQTT broker and working follow the link:ĮSP32 Publish Sensor Readings on MQTT Topics.MQTT uses simple publish/subscribe communication based on a topic.Unlike, most messaging system, we don’t have to assign addresses to MQTT clients.It is a lightweight messaging protocol and helps resource constrained network clients with a simple communication mechanism.MQTT is known as Message Queuing Telemetry Transport protocol.

Node-Red receives the sensor data and displays them in an interactive manner in its dashboard. We have Node-Red as a subscriber to these seven topics.Similarly, this board publishes the DS18B20 temperature readings in Celsius on the MQTT topic: esp32/ds18b20/temperatureC and publishes the DS18B20 temperature readings in Fahrenheit on the MQTT topic: esp32/ds18b20/temperatureF.Likewise, it publishes the BME280 pressure readings on the topic: esp32/bme280/pressure. It publishes the BME280 humidity readings on the topic: esp32/bme280/humidity. It also publishes the BME280 temperature readings on the topic: esp32/bme280/temperature.