https://github.com/wesley-dean/dht11_mqtt
Publish temperature and humidity readings to an MQTT broker from a DHT11 sensor on a Raspberry Pi
https://github.com/wesley-dean/dht11_mqtt
Last synced: 28 days ago
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Publish temperature and humidity readings to an MQTT broker from a DHT11 sensor on a Raspberry Pi
- Host: GitHub
- URL: https://github.com/wesley-dean/dht11_mqtt
- Owner: wesley-dean
- Created: 2024-07-05T19:40:25.000Z (10 months ago)
- Default Branch: main
- Last Pushed: 2025-03-31T12:54:37.000Z (about 1 month ago)
- Last Synced: 2025-04-04T23:08:18.895Z (about 1 month ago)
- Language: Python
- Size: 65.4 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# DHT11 to MQTT Publisher
This tool is designed to run from a Raspberry Pi with a DHT11
temperature / humidity sensor attached to pin 4 (top-right pin,
furthest from the Ethernet port) and publish the results to
an MQTT broker as a JSON object.
For a good walkthrough about the wiring of the sensor, how to
interact with the sensor using C, check out
[Scott Campbell](https://www.circuitbasics.com/author/circuitbasicsgmail-com/)
's
[article](https://www.circuitbasics.com/how-to-set-up-the-dht11-humidity-sensor-on-the-raspberry-pi/)
. It looks like the article was written in 2016; however, the
diagrams are still correct. The sample Python code is written
for Python 2 (which has since been deprecated); updating it for Python 3
takes seconds.. like 5 of them.
## Configuration
The tool is configured with a series of environment variables; however, in
the probable event that it's inconvenient to set a bunch of variables every
time the tool is used, a `.env` file is supported and a sample is provided
with the tool's defaults.
* **PIN**: the pin on the GPIO where the signal wire is connected
default: 4
* **MQTT_HOST**: the MQTT broker's hostname or IP address
default: 127.0.0.1 (localhost)
* **MQTT_PORT**: the port on the MQTT broker listening for traffic
default: 1883 (unencrypted)
* **MQTT_TIMEOUT**: MQTT broker connection timeout before pinging the broker
default: 60 (seconds)
* **READ_TIMEOUT**: in the event of a read error, how long to wait efore retry
default: 2 (seconds)
* **DELAY**: how long between successful reads before looping
default: 60 (seconds)
* **TOPIC**: the MQTT topic where data should be published
default: test
* **LOG_LEVEL**: logging verbosity (lower is more verbose)
DEBUG=10, INFO=20, WARNING=30, ERROR=40, CRITICAL=50
default: 20
## Setup
The tool is a simple Python script. Included in this repository
is a `requirements.txt` file that lists the modules that are used
to support the tool. Therefore, before running the tool the
first time, install the requirements with:
```sh
pip3 install -r ./requirements.txt
```
## Updates
It is possible that there are updates to this tool, most likely
as a result of dependency updates. In that case, the tool can
be updated with:
```sh
git pull origin main
pip3 install -r ./requirements.txt
```
## Running the Tool
The tool is a simple Python script, so it can be run with:
```sh
python3 ./temperature.py
```
This will start the tool in the foreground and it'll run
until stopped (control-c or SIGINT).
### Running the Tool at Startup
A hackish, "just make it go" way of having the tool start
at boot at just run in the background is:
```crontab
@reboot while true ; do "${HOME}/dht11_mqtt/temperature.py" ; sleep 5 ; done
```
Add that line to your crontab (`crontab -e`), reboot, and you're
good to go.
## Using Home Assistant
My use-case for this project was feeding temperature data to a
[Home Assistant](https://home-assistant.io/) instance through an
MQTT broker. Earlier iterations of this project exposed a
RESTful API which, when queried, would return a JSON object with
the data. The pulling / polling approach had a number of challenges
and having [Flask](https://flask.palletsprojects.com/en/3.0.x/)
listen for traffic... it was all more work than it was worth,
especially when the Raspberry Pi was offline or the sensor was
being weird or whatever.
So, this project was an MQTT-based refactor that allowed
Home Assistant to subscribe to topics populated with data
published by this tool.
The MQTT broker used when developing this tool was
[Eclipse Mosquitto](https://mosquitto.org/). Home Assistant
provides an
[MQTT Broker add-on](https://github.com/home-assistant/hassio-addons/blob/master/mosquitto/DOCS.md)
that works very well. Moreover, Home Assistant provides
[documentation for integrating with Mosquitto](https://www.home-assistant.io/integrations/mqtt)
.
### Configuring Home Assistant
The Home Assistant
[documentation for MQTT Sensors](https://www.home-assistant.io/integrations/sensor.mqtt/#temperature-and-humidity-sensors)
provides a good treatment of the topic; for your convenience,
here's some sample configuration:
```YAML
mqtt:
sensor:
- name: "Temperature"
state_topic: "office/sensor1"
suggested_display_precision: 1
unit_of_measurement: "°F"
value_template: "{{ value_json.temperature_f }}
unique_id: "office/sensor1/temperature_f"
name: "Office Temperature"
icon: "mdi:thermometer"
- name: "Humidity"
state_topic: "office/sensor1"
unit_of_measurement: "%"
value_template: "{{ value_json.humidity }}"
unique_id: "office/sensor1/humidity"
name: "Office Humidity"
icon: "mdi:water-percent"
```