DHT22 is a great little sensor. It will run at 3.3V, so you can avoid the level-shifting if you run it at 5V. My only concern is the 20-30m of Cat5 cable used to connect the sensor. The DHT22 uses 1-wire to communicate and that generally means using as short a connecting wire as possible.
It may work fine, but I've not tried anything more than a 4" jumper. Also, the sensor communicates when pulled low, so don't forget to use a 10K-100K Ohm pull-up on the data pin. Also add a 1 uF decoupling capacitor across the power and ground right at the DHT22 to mitigate against any voltage drop (which will be a concern with 20-30 meters of cable). Maybe use a 10 uF cap as well as the 1 uF cap for decoupling.
I second using a picoW in the cellar (or use a Pi Zero 2 W). That way all the sensor handling is done in the cellar and you can simply access the current temp/humidity over WiFi from inside the house.If your 20-30 meter cable won't work, those are two options.
If you are not familiar with bare-metal programming for the Pico, you may want to go the Pi Zero 2 W route. While a great deal of fun, the bare metal programming of the Pico has a fairly steep learning curve. This is lessened somewhat by the excellent Pico SDK - but the WiFi access to the PicoW has been a bit of a moving target over the past couple of years.
Good luck with your project.
It may work fine, but I've not tried anything more than a 4" jumper. Also, the sensor communicates when pulled low, so don't forget to use a 10K-100K Ohm pull-up on the data pin. Also add a 1 uF decoupling capacitor across the power and ground right at the DHT22 to mitigate against any voltage drop (which will be a concern with 20-30 meters of cable). Maybe use a 10 uF cap as well as the 1 uF cap for decoupling.
I second using a picoW in the cellar (or use a Pi Zero 2 W). That way all the sensor handling is done in the cellar and you can simply access the current temp/humidity over WiFi from inside the house.If your 20-30 meter cable won't work, those are two options.
If you are not familiar with bare-metal programming for the Pico, you may want to go the Pi Zero 2 W route. While a great deal of fun, the bare metal programming of the Pico has a fairly steep learning curve. This is lessened somewhat by the excellent Pico SDK - but the WiFi access to the PicoW has been a bit of a moving target over the past couple of years.
Good luck with your project.
Statistics: Posted by drankinatty — Sat May 25, 2024 10:28 pm