I have been playing with DHT11 for some time, only to find out that this sensor is a bad joke. I finally decided to upgrade to the DHT22, which is a magnitude better than the previously mentioned one. I wanted to be able to measure outside temperature and air humidity and use these readings in my heat-pump system. Currently I use “software only” approach, since I had no reliable humidity sensor available, but I’d rather have local readings. I decided to use a step-up version of the Funky sensor, because it provides stable 3.3V that the DHT22 needs. I based my code on Nathan’s DHT22 project, nothing fancy indeed.
The DHT needs pin 3 cut away and the others slightly bent so it can be soldered directly to the Funky. I have a 10K resistor between the data and VCC line, as required:
The whole project fits in a nice small plastic box and is powered by a single AAA battery. Should last for few months.
Here is how the readings appear in emoncms, the box was inside as I powered it up and then I took it outside:
The code is on github.