aqi

The fork of the sensor project from the official joy-it documentation.

The original sensor project was created to:

Measure AQI based on PM2.5 or PM10 with a Raspberry Pi and a SDS011 particle sensor

This fork is created to enable running the sensor Python code on my laptop with Ubuntu 20.04.1 and Python3.

Some changes were applied to the aqi.py file to enable usage of the Python3. Most of changes were connected to strings and bytes handling differences from the Python2.

Additional changes and updates were made to simplify running the lighttpd server on the local laptop.

how to install python3 libraries

Required python3 libraries can be install using the following command: sudo apt install python3-serial

how to enable starting aqi as a non-root user

By default, /dev/ttyUSB0 can't be read by the non-root user. To enable reading it as my laptop user I had to add this user to the dialout group: usermod -a -G dialout $USER

After that you should loggout and login to apply changes but as a work-around you can run the following code:

original_group="$(id -gn)"
newgrp dialout
newgrp $original_group

how to install lighttpd

Run the: sudo apt install lighttpd

how to run sensor

From the cloned aqi repo from the root directory run: python3 python/aqi.py

Program will output something like:

Y: 0, M: 177, D: 0, ID: 0xbc7f, CRC=OK
PM2.5:  3.0 , PM10:  18.2
PM2.5:  3.0 , PM10:  18.7
PM2.5:  3.1 , PM10:  19.6
PM2.5:  3.1 , PM10:  19.8
PM2.5:  3.1 , PM10:  19.2
PM2.5:  2.9 , PM10:  19.2
PM2.5:  2.8 , PM10:  19.8
PM2.5:  2.8 , PM10:  19.4
PM2.5:  2.8 , PM10:  19.2
PM2.5:  2.8 , PM10:  19.1
PM2.5:  2.8 , PM10:  18.7
PM2.5:  2.7 , PM10:  18.6
PM2.5:  2.7 , PM10:  18.9
PM2.5:  2.7 , PM10:  19.1
PM2.5:  2.7 , PM10:  18.0
Going to sleep for 1 min...
PM2.5:  2.9 , PM10:  18.4
PM2.5:  2.9 , PM10:  18.6
...

The file html/aqi.json will contain JSON with the sensor information for the last measurement in each set of measurments (approx. each 1.5 min):

[
  {
    "pm25": 2.2,
    "pm10": 9.8,
    "time": "22.01.2021 17:13:00"
  },
  {
    "pm25": 3,
    "pm10": 22,
    "time": "22.01.2021 17:14:30"
  },
  ...
]

how to run lighttpd server

• copy the template file lighttpd.config.template to the configuration lighttpd.config file
• edit the first line with proper absolute path to the html directory of this project
• run: lighttpd -D -f lighttpd.config

Web page with the current sensor results is available at:

• http://localhost:3000/