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dallasMQTT

dallasMQTT is a service that will periodically poll an arbitray number of dallas 1 wire sensors and publish the data to an MQTT broker.

Installation

dallasMQTT is availably via pypi, so all you need to do is run:

pip install -U dallasMQTT

assuming you have pip installed. (which is the recommended way to install. If you need to use a development version of dallasMQTT you can clone the repo and install it locally with:

git clone https://github.com/mtreinish/dallasMQTT.git

and then install it with:

pip install -e dallasMQTT

which will install dallasMQTT in your python environment in editable mode for local development.

If you don't have pip installed you can manually install dallasMQTT by cloning the repo and installing it from the repo base dir with:

python setup.py install

but, note installing via pip is the recommended and supported method of installing dallasMQTT. (even from a local git clone)

Configuration

To configure dallasMQTT you need to create configuration yaml file that will tell dallasMQTT how to access sensors, how to use MQTT, etc. The basic format of the file with the 3 sections is:

mqtt:
    hostname: foo

sensors:
    - id: id number
      name: 'My Sensor'

default:
    poll_rate: 60
    base_topic: a_topic

MQTT Section Configuration

This section is used to configure how dallasMQTT will connect to an MQTT broker. To configure the mqtt section there are 3 options it currently takes:

  • hostname
  • username
  • password

of these only hostname is required. The other 2 options are optional you can use username and password if client auth is desired (or required by your mqtt broker).

Sensor Section Configuration

The sensor section of the yaml config file is used to specify which sensors are to be polled and how to label them in the mqtt topics. It takes in a list of sensors of arbitrary size that takes in a combination of sensor ids and names for example if there were 3 sensors it would look something like:

sensors:
    - id: 28-000001
      name: Sensor1
    - id: 28-000002
      name: Sensor2
    - id: 28-000003
      name: Sensor3

This pattern is just repeated for how ever many sensors you want dallasMQTT to poll. The name field is fairly self explanatory, and it is just the name of the sensor that will be used as the second half of the topic on mqtt, like:

$base_topic/$name

The id field is used to specify the sensor id to poll. dallasMQTT will poll the sensor file at:

/sys/bus/w1/devices/``$id``/w1_slave

So ensuring you put the proper id here is important otherwise dallasMQTT will not be able to read the sensor data.

This section was written to be sufficiently broad so that in the future additional sensor types could be added to dallasMQTT. This would be a very simple addition and would just require adding an optional driver field to each list element which would tell dallasMQTT which class to use for polling sensors. (these additional sensor wouldn't necessarily have to be dallas 1 wire either) But, as of right now there is only 1 class, DallasTemp, for 1 wire temperature sensors, so this field doesn't exist. However, if/when dallasMQTT is updated to include other sensor types the documentation will be updated. (and backwards compatibility will be adhered to so as to not break anyone)

Default Section configuration

The default section is where you configure settings that contol the basic operation of dallasMQTT. There are 3 options in this section right now:

  • base_topic
  • poll_rate
  • max_threads

All 3 options are optional.

base_topic is used to set the basic topic used on MQTT for sending sensor data. The messages will be sent on mqtt like:

$base_topic/$sensor_name

by default this is set to dallasMQTT.

poll_rate is used to specify a time in seconds to wait between polling the sensors on a worker thread. Note this is not time between individual sensors but between polling all the sensors being handled by a single thread. Each sensor in that group will be polled serially without any wait time between them.

max_threads is used to specify the maximum number of threads that dallasMQTT will launch to poll sensors with. If there are less sensors in the configuration file a single worker thread will be launched for each sensor. If there are more sensors than threads the sensors will be equally distributed to the number of workers specified. Each worker will handle polling the list of sensors it received.

Usage

To run dallasMQTT is fairly straightforward. After dallasMQTT is installed you just run:

dallasMQTT config.yaml

where config.yaml is the path to your yaml config file.