DHT Raspberry MQTT Client/Daemon

Linux service to collect and transfer DHT22/DHT11 sensor data via MQTT to Home Assistant A simple Linux python script to query DHT22/DHT11 sensor on Raspberry Pi and send the data to an MQTT broker, e.g., the famous Eclipse Mosquitto. After data made the hop to the MQTT broker it can be used by home automation software, like Home Assistant.

The program can be executed in daemon mode to run continuously in the background, e.g., as a systemd service.

Features

• Tested with DHT22 sensors
• Build on top of Adafruit Python DHT Sensor Library
• Highly configurable
• Data publication via MQTT
• Configurable topic and payload:
  • using the HomeAssistant MQTT discovery format
• Announcement messages to support auto-discovery services
• MQTT authentication support
• No special/root privileges needed
• Daemon mode (default)
• Systemd service, sd_notify messages generated
• Tested on Raspberry Pi 3

Readings

The DHT sensor offers the following readings:

Name	Description
temperature	Air temperature, in [°C] (0.1°C resolution)
humidity	humidity level, in [%] (0.1% resolution)

Prerequisites

An MQTT broker is needed as the counterpart for this daemon. Even though an MQTT-less mode is provided, it is not recommended for normal smart home automation integration. MQTT is huge help in connecting different parts of your smart home and setting up of a broker is quick and easy.

Installation

On a modern Linux system just a few steps are needed to get the daemon working. The following example shows the installation under Debian/Raspbian below the /opt directory:

sudo apt install git python3 python3-pip

git clone https://github.com/R4scal/dht-mqtt-daemon.git /opt/dht-mqtt-daemon

cd /opt/dht-mqtt-daemon
sudo pip3 install -r requirements.txt

Configuration

To match personal needs, all operation details can be configured using the file config.ini. The file needs to be created first:

cp /opt/dht-mqtt-daemon/config.{ini.dist,ini}
vim /opt/dht-mqtt-daemon/config.ini

Execution

A first test run is as easy as:

python3 /opt/dht-mqtt-daemon/dht-mqtt-daemon.py

Using the command line argument --config, a directory where to read the config.ini file from can be specified, e.g.

python3 /opt/dht-mqtt-daemon/dht-mqtt-daemon.py --config /opt/dht-config

The extensive output can be reduced to error messages:

python3 /opt/dht-mqtt-daemon/dht-mqtt-daemon.py > /dev/null