Follow the link below:

sudo apt install python3-matplotlib

sudo pip3 install matplotlib
creat a test file name it testplot.py

import matplotlib.pyplot as plt #import the Python Matplotlib sub-module for graph plotting pyplot.
x = [1,2,3,4] # x axis
y = [1,2,3,4] # y axis
plt.plot(x,y)# plotting the graph
#plt.show() #Displaying the figures
plt.savefig('Matplotlib_save_plot.png')

sudo reboot from the xterm

run with “python3 testplot.py”

This will create a png file. Duble click on it from the remoter ssh file manger and you see the following graph.

• Set up the run environment
  • On the PC download the zip file.
    • in your browser type larry4u.com/data
    • click on data_co2SCD30.7z this will download all files need to run the programs.
    • unzip the file copy the files to the Pi using Bitvise, as follows:
      • to the pi home directory (/home/pi) using your mouse move these files:
        • clean_data_folder.py
        • display_co2.py
        • example.py
        • get_co2.py
        • readCSV.py
        • scd30.py
        • testplot.py
        • VCR_OSD_MONO_1.001.ttf
      • Move these files to /var/www/html and delete the index.html
        • index.php
        • download.php
        • selectFile.php
      • Need one more file by doing a symbolical link to the data_folder in the pi home directory
        • copy and paste the following in the xterm:
          • cd /var/www/html
          • ln -s /home/pi/data_folder data_folder
          • ls -ltra  (this will show all the files plus the linked data_folder
• Load the software for controlling the display module
  • Follow the following link: Using an I2C OLED Display Module with the Raspberry Pi – Raspberry Pi Spy (raspberrypi-spy.co.uk)

• Connecting the SCD30 Hardware

  • Break off 4 of the male-to-male pins
  • Put on the first four pinholes of the SCD30 and solder.
  • 

  SCD30 connection

  • VDD 3v3 Power pin 1
  • GND Ground pin 6
  • TX/SCL I2CL SDA pin 5
  • RX/SDA I2C SDA pin 3
  • PINs as per the chart

   

   

  Steps to read data from SCD30

•  

  • fallow instructions from GitHub – paulvha/scd30_on_raspberry: Program to set and read SCD30 on a raspberry Pi
  • To test if the pi sees the sensor works, run the example.py file you copy to /home/pi directory.
  • In your SSH terminal at the pi home directory, type:
  • python3 -m pip install scd30_i2c
  • Python3 example.py
  • If you see this, the wiring is right.

  Write data to the monitor.

  • Create a folder “data_folder” with the following command:
  • • • In the SSH terminal, type at the pi home directory:
        • mkdir data_folder
  • Run the script scd30.py that you put in the pi directory.
    • from SSH type “python3 scd30.py”
  •  
  • This script reads the SCD30 data and updates the current.txt file that the Website sees and also writes the data to a daily file in the data_folder.
  •  
  • This will run the scd30.py every minute and update the “current.txt” file, which uploaded to the web page.

• Create a crontab job

  • A cron job is an automated program developed for Unix and Linux systems. It allows the user to execute several commands at a specific time on a precise date.
  • We need to run the python script scd30.py every minute. To do that, we use the command crontab.
  • “crontab –l” (that is, lowercase L” lists what is in the file, and crontab –e lets us edit or add new jobs.
  • Type  crontab –e
  • It now asks what editor to use.
  • /bin/nano works much like note pad.
  • vim is used mostly by gurus.
  • ed is an ancient editor.
  • If new to Unix, use nano.
  • Add this line to the bottom of the file:
    • * * * * * python3 /home/pi/scd30.py
    • * * * * * python3 /home/pi/readCSV.py > /home/pi/CSV.log
    • * * * * * python /home/pi/get_co2.py > /home/pi/get_co2.log
    • 5 0 * * * python /home/pi/clean_data_folder.py  >  /home/pi/clean.log
  • This will run these programs at a scheduletime.
  • see Crontab.guru – The cron schedule expression editor for corn details.

  Notes

  • The “current.txt” file is just an HTML file the is updated by the program scd30.py
  • The data files in the directory “data_folder” and are created at the first run after midnight. The files names contain the date it was created. They are CSV files that can be open in excel.
  • i2cdetect -y 1  use this command to test that the monitor and the sense are working. This is what you should see. 3c is the monitor and 61 is the scd30 sensro.