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BH1750 MQTT client for raspberry pi

Purpose of this project

BH1750 is a Light Sensor. The light sensor can be connected to a raspberry pi using the i2c interface. This MQTT client is publishing the LUX value of the BH1750. The project is an addon to the FullPageOS mqttBH1750Client but works also totally independent.

The configuration is done over an ini file.

Implementation notes

The project in implemented and tested with Python 3.11 and runs as systemd service for standard user pi for example in FullPageOS.

The implementaion is using the folling python libraries, which need to be installed:

All this libraries are installed with the setup.sh shell script, which is part of this project. See next section Installation

All the other used python libraries are standard in latest Raspbery PI OS and should be available without installation.

Installation

Precondition: Linux (like FullPageOS) is installed on your Raspberry PI and up and running.

Step 1:

Login with ssh to your kioskdisplay with user pi

Step 2:

Clone this project with:

git clone https://github.com/olialb/mqttBH1750Client

and go inside the project directory:

cd mqttBH1750Client

Step 3:

Call setup:

bash setup.sh

This installs the required python packages and configures a systemd service which is atomatically running the mqtt client after startup. The systemd service is started with the current user rights.

Step 4:

Configure the ini file for your personal needs:

nano mqttBH1750Client.ini

Details of the configuration you can find in next section: Configuration

In case of problems:

If you have issues with your configuration and the service is not running as expected you can stop the service with:

sudo systemctl stop mqttBH1750Client

Adapt the ini file in section [logging] and enable DEBUG logging level. Than activate the virtual python environment and start the service by hand:

source venv/bin/activate
python mqttBH1750Client.py

Check the logging output. After everything is fixed, set the logging level back to ERROR, deactivate the virtual environment and start the systemd service again with:

deactivate
sudo systemctl start mqttBH1750Client

Configuration

In the project directory you find the configuration mqtt-display-client.ini. Adapt this file with an editor like nano:

nano mqttBH1750Client.ini

The file has different sections. Most of the configuration you can keep untouched. The only thing which you need to adapt to your specific environment are:

  • Address of your mqtt broker in section [global]
  • Username and password of your mqtt broker, if needed. In section [global]
  • ID of your display in section [global]

This configuration you find in the first section of the ini file: [global].

Section [global]

This is the main configuration section. This is the only section where you need to adapt somthing to your environment.

  • broker= Set here your mqtt broker address. Apapt the ip address or use url like myLocalMQTTBroker.local
  • port= You can keep the standard port 1883 if you do not have a special setup
  • username= Set here your user name for the broker. Keep it empty if no username is configured
  • password= Password of your mqtt broker
  • topicRoot= configuration of the root path of the published topics
  • deviceName= Unique name of this device
  • reconnectDelay= Retry delay in seconds if connection is lost to broker
  • publishDelay= Publish cycle in seconds for topics
  • fullPublishCycle= Publish cycle even if topic content is not changed. Cycle is fullPublishCycle multiplied with publishCycle in seconds

Section [logging]

Configuration of the python logger which is used to log events

  • level= configuration of the logging level (DEBUG, INFO, WARNING, ERROR, CRITICAL)

Exposed MQTT topics and usage

The MQTT client is exposing the following topics:

lux (numeric)

The current brightness of the display is exposed with the topic brightness kiosk/01/DEVICE_NETWORK_NAME/lux.