It's summer time - build your own smart thermometer

Friday, July 5, 2019 at 4:23 PM UTC

During the past days I played around with another Raspberry Pi project. I love this little computer which is so versatile!

I built a thermometer / hygrometer with a Pi 2 for testing and today with a Pi Zero W using the sensor DHT22. I bought a pre-built sensor that includes the 4.7kOhm resistor already on a stable PCB and also comes with a pre-configured 3-wire cable to connect it to the GPIO of the Pi. For the Pi Zero W I had to solder the connector bar to the PCB before I could use the sensor.

The goal is to use it as a device in Apple Homekit. With this combination you can with about spending 35 EUR excl. the SD card.

Regarding the software there are tons of tutorials available but I created my own just to have the luxury of just copy/paste all the commands one after another. You can find it here: https://gitlab.com/obusse/raspi-dth

Automation

Homekit is very poor when it comes to automation with sensors involved. In my case I like to switch on some fans when the temperature raises above a certain level. You cannot do that with the Home app. I recommend to install and use the Eve Home app (https://apps.apple.com/de/app/elgato-eve/id917695792, open this link on your mobile device to install it).

The app also records the values from the sensors which is great!

 






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