EeliH / koodi101-iot

Koodi101 Internet of Things (IoT)

Raspberry pi – first time setup

1. Login with pi:raspberry (or use ssh pi@<ip>)
2. Type sudo raspi-config
3. Change the password for pi user to something else
4. Under network options, configure the wifi (if needed)
5. Under localization options, configure keyboard layout
6. Under interfacing options, enable SPI and I2C
7. Exit the raspi-config

RPI should now connect to wifi. You can check the ip address by typing ip addr

It should produce output like

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether b8:27:eb:f9:6a:c2 brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.101/24 brd 192.168.1.255 scope global wlan0
       valid_lft forever preferred_lft forever
    inet6 fe80::799c:261a:a62:b56a/64 scope link 
       valid_lft forever preferred_lft forever

In this example, the ip address would be 192.168.1.101

If you want to use ssh to connect to your RPI, you can do it by writing

sudo systemctl enable ssh
sudo systemctl start ssh

Now you can connect from your own machine with ssh pi@<ip> if you are in the same network.

Run the project

Let's update our system and install some needed libraries.

sudo apt-get update
sudo apt-get upgrade
sudo apt-get install python3-pip git
sudo pip3 install requests Adafruit_DHT

First clone your forked version of this repository to the Rasperry pi and go to the iot folder

git clone <url>

You can now try our app by starting it with

ENDPOINT=http://you-server/api/temperature python3 rpi.py

Starting the app automatically

One way to keep raspberry sending information without manual work, is to use cron to run our script every minute.

That can be achieved by opening crontab editor by typing crontab -e

Window will open and you can append the following line at end of the file, of course replacing the endpoint with a correct one.

* * * * * ENDPOINT=http://you-server/api/temperature python3 /home/pi/koodi101-iot/iot/rpi.py >> /home/pi/rpi.log 2>&1

So what does this mean?

• * * * * * ENDPOINT=http://you-server/api/temperature python3 /home/pi/koodi101-template/iot/rpi.py >> /home/pi/rpi.log 2>&1
  • When to run the script, see below
• * * * * * ENDPOINT=http://you-server/api/temperature python3 /home/pi/koodi101-template/iot/rpi.py >> /home/pi/rpi.log 2>&1
  • Pass environmental variable for script to be executed
• * * * * * ENDPOINT=http://you-server/api/temperature python3 /home/pi/koodi101-template/iot/rpi.py >> /home/pi/rpi.log 2>&1
  • Normal command to run a script with python
• * * * * * ENDPOINT=http://you-server/api/temperature python3 /home/pi/koodi101-template/iot/rpi.py >> /home/pi/rpi.log 2>&1
  • Append output to a file
• * * * * * ENDPOINT=http://you-server/api/temperature python3 /home/pi/koodi101-template/iot/rpi.py >> /home/pi/rpi.log 2>&1
  • By default, error messages wouldn't be logged into the file. With this definition, we redirect the to standard output and therefore into the same file.

Cron works by comparing current time to parameters at the beginning of every line. If it matches, it will run the script.

Our example is run every minute, although it should match at anytime, why is it so? Well, cron runs only every minute, so that is why this will work and that is why we can't schedule it to run more often.

There exist cool tool to "translate" cron time entries into human readable form: https://crontab.guru