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:


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 (, 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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