Send data from DHT22 to ThingSpeak using Python on a Raspberry Pi via crontab.
Based on https://www.hackster.io/adamgarbo/raspberry-pi-2-iot-thingspeak-dht22-sensor-b208f4
This is assuming your Pi is up and running with Raspbian, and that your DHT22 sensor is connected.
First of all, run
sudo apt-get update
You should also run sudo apt-get upgrade, but it might take quite a while. Skip if in a hurry and run it later.
Then run
sudo apt-get install python-dev python-dev git
to install needed libraries.
Then install the Adafruit Python DHT library:
git clone https://github.com/adafruit/Adafruit_Python_DHT.git
cd Adafruit_Python_DHT
sudo python setup.py install
You'll need a ThingSpeak channel, so go create one. Name your channel whatever you like. Field 1 is for temperature, so name apropriately. Field 2 is for humidity, so name apropriately. Field 3 is for temperature of the Pi itself, so name apropriately. Remember that there's no need for a timestamp channel, as it is recorded on each submission.
Then there's time to install this simple snippet of code.
git clone https://github.com/fmandal/dht22.git
Update with your API key and pin number for the DHT22:
cd dht22
nano dht22.py
Change the config variables to reflect your values:
myAPI = "<API FROM THINGSPEAK>"
pin = 4
If you'd like it to run every 5 minutes do so via crontab:
crontab -e
*/5 * * * * python /home/pi/dht22/dht22.py > /dev/null