CM3267 Lab Instruction for Weather Station

Welcome to this module! To get things started, setup your Raspberry Pi (RPi) with the correct Raspbian version. You can use RPi Imager Software to flash the recommended 32-bit Raspbian OS onto your 16/32 GB micro-SD (uSD) card.

Once you pluck the uSD card into the RPi board, boot it and continue setting up the desired language, US keyboard type and location. MAKE SURE NOT to update the OS when the update request prompts out.

NOTE:

• To check if you have the right OS version on the RPi, open a terminal and type uname -r.
• 5.10.17-v7+ should be the output. Otherwise, install the OS manually (on PC) through the image provided here and flash it once more with RPi Imager software.

Download the repo and necessary packages

Open up a terminal and follow the commands below:

cd ~
git clone https://github.com/Nntsyeo/weather_station.git

You should now have a folder named weather_station in your home directory. Feel free to use Thonny ('RPi start button' -> 'Programming' -> 'Thonny Python IDE') to read up the python scripts. Note that you shouldn't run the python scripts through Thonny due to the varying python versions used by the IDE.

Next, you will need to install the python packages through the terminal.

sudo apt-get update
sudo pip3 install Adafruit_DHT matplotlib datetime
sudo pip install pyserial Adafruit_DHT schedule datetime
sudo apt-get install -y python-matplotlib

Now, you should be able to execute the python scripts accordingly:

sudo python V2_weather.py
sudo python3 DHT22_cal.py
sudo python3 weatherplot.py

NOTE:

• V2_weather.py uses the particle sensor on port /dev/ttyUSB0. Thus, to make sure the particle sensor is active on RPi, simply type ls \dev\tty* on the terminal and check if /dev/ttyUSB0 is present (usually at the end of the list).

@1 ----- If /dev/ttyUSB0 is not present, try using the particle sensor on another USB port.
@2 ----- If a different portname is present (for e.g., /dev/ttyUSB2), simply V2_weather.py at line 46 to ser.port = "/dev/ttyUSB<port_number>".

Potential error during the python execution

1. For V2_weatherplot.py:

• Error output: "RuntimeError: module compiled against API version 0xe but this version of numpy is 0xd"

Try doing this:

sudo apt-get install -y libatlas-base-dev
sudo pip3 install numpy --upgrade
cd ~/weather_station
sudo python3 V2_weatherplot.py

Execute V2_weather.py on boot

If you wish to execute the V2_weather.py script on boot, instructions below allow adding of the python execution into the booting sequence.

1. Create a shell script named launcher.sh in /home/pi/Desktop/ directory.

On terminal:

cd ~/Desktop
nano launcher.sh 

Copy the following script into launcher.sh file:

#!/bin/sh
cd /home/pi/weather_station
sudo python V2_weather.py

2. Use crontab method to execute launcher.sh on startup.

Create a log folder for crontab logging via terminal:

cd ~
mkdir logs

And then with the same terminal, use sudo crontab -e (with /bin/nano as the editor if prompted). Add the following line at the end of the crontab script:

@reboot sh /home/pi/Desktop/launcher.sh >/home/pi/logs/cronlog 2>&1 (NOTE) Exit with pressing 'Ctrl-X', 'y' and then 'enter'.

Enter the following to restart your RPi and the python script will run in the background afterwards. sudo reboot

NOTE:

• Your RPi will reboot, and you can still use the RPi as per usual as the python script is actually running at the background.
• To check if there's any error occurred, simply output log file by cat ~/logs/cronlog on terminal. Otherwise, you will have Finaltest.csv (data collection file) created in your /home/pi/weather_station directory.
• (HINT) Adjust the schedule function calls to acquire hourly readings, as by default, the script acquire data in every five (5) seconds.